| SloRice | 09-27-2004 11:24 PM |
Nationally Competative SM Setup for STi
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With proper fundage this winter, I plan on making a Street Mod (SM) monster. But I need some help with the setup part of the car. Yes, I know, it's all about the driver too....and I'm going to take care of that part....Evolution Schools, here I come! But the car needs to be properly setup also. Right now S/C M3's are owning SM nationally and I think a well balanced STi is just what the doctor ordered to challenge them.
So lets go down the list of what needs to be done. If I missed anything, please chime in.
1. Motor
2. Suspension
3. Brakes
4. Weight reduction
5. Wheels/Tires
6. Steering
Motor
current setup
-Turboback
-Blitz SUS Intake
-Blitz SBC-ID boost controller
[email�protected][email�protected] on a Mustang Dyno
-225FT-LBS or more from 3000-6000RPM
needed setup
-UTEC
-Turboback (can I run just DP or does it have to be full exhaust?)
-Intake (maybe)
-Turbo (makes more power but spools at a lower RPM - yes it's an oxy moron, I know The car already has a lot of low end grunt to pull itself out of a turn in 2nd, but it needs a little more or needs to come on boost quicker - if it falls on its face up top, then it falls on its face, i'm not a highway racer)
-TMIC (maybe - something with less pressure drop than stock, if there is such an IC out there)
-Injectors/FP (as needed)
-External or Internal wastegate (I hear that going external gives a lot of extra power)
Suspension
Current Setup
-Tein Flex Coilovers (-3 degrees camber front/-1 rear, a little toe out in the front - can't remember the amount though)
-Perrin RSB and Endlinks
Needed Setup
-Stiffer Coilovers or pieced together spring/strut/camber plate setup
-Big Sway Bars front and rear with endlinks
-Corner Weighted
Brakes
Current Setup
-Stock Brembos with Carbotech Bobcat pads
-ATE Superblue brake fluid
Needed Setup
-I think the stock calipers will work ok
-Slotted Rotors
-More aggressive pads (maybe Panther Plus's)
-SS lines
-ATE fluid
-Anyway to get over the sensitive ABS?
Weight Reduction
Current Setup
-Stock
Needed Setup
-I'd like new front seats as the stocks are really uncomfortable
-Any other info on this topic appreciated
Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers
Needed Setup
-Maybe a wider rim
-I like the V700's, but maybe try the V710's as I have heard mixed opinions on the Hoosier S04's and I've heard good things about the V710's
Steering
Current Setup
-Stock
Needed Setup
-Steering Rack bushings since I heard they help with turn in b/c the STi sucks at it!
-Other than that, I don't know
This is at the brainstorming stage right now b/c I want to do it once and once only. I know I've probably missed a lot of stuff, but that's why I'm asking the board. So any help on other stuff to add or parts to use would be great.
thanks,
Tim
So lets go down the list of what needs to be done. If I missed anything, please chime in.
1. Motor
2. Suspension
3. Brakes
4. Weight reduction
5. Wheels/Tires
6. Steering
Motor
current setup
-Turboback
-Blitz SUS Intake
-Blitz SBC-ID boost controller
[email�protected][email�protected] on a Mustang Dyno
-225FT-LBS or more from 3000-6000RPM
needed setup
-UTEC
-Turboback (can I run just DP or does it have to be full exhaust?)
-Intake (maybe)
-Turbo (makes more power but spools at a lower RPM - yes it's an oxy moron, I know The car already has a lot of low end grunt to pull itself out of a turn in 2nd, but it needs a little more or needs to come on boost quicker - if it falls on its face up top, then it falls on its face, i'm not a highway racer)
-TMIC (maybe - something with less pressure drop than stock, if there is such an IC out there)
-Injectors/FP (as needed)
-External or Internal wastegate (I hear that going external gives a lot of extra power)
Suspension
Current Setup
-Tein Flex Coilovers (-3 degrees camber front/-1 rear, a little toe out in the front - can't remember the amount though)
-Perrin RSB and Endlinks
Needed Setup
-Stiffer Coilovers or pieced together spring/strut/camber plate setup
-Big Sway Bars front and rear with endlinks
-Corner Weighted
Brakes
Current Setup
-Stock Brembos with Carbotech Bobcat pads
-ATE Superblue brake fluid
Needed Setup
-I think the stock calipers will work ok
-Slotted Rotors
-More aggressive pads (maybe Panther Plus's)
-SS lines
-ATE fluid
-Anyway to get over the sensitive ABS?
Weight Reduction
Current Setup
-Stock
Needed Setup
-I'd like new front seats as the stocks are really uncomfortable
-Any other info on this topic appreciated
Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers
Needed Setup
-Maybe a wider rim
-I like the V700's, but maybe try the V710's as I have heard mixed opinions on the Hoosier S04's and I've heard good things about the V710's
Steering
Current Setup
-Stock
Needed Setup
-Steering Rack bushings since I heard they help with turn in b/c the STi sucks at it!
-Other than that, I don't know
This is at the brainstorming stage right now b/c I want to do it once and once only. I know I've probably missed a lot of stuff, but that's why I'm asking the board. So any help on other stuff to add or parts to use would be great.
thanks,
Tim
| trhoppe | 09-27-2004 11:59 PM |
You want to win nationally in SM? :lol:
Motor:
400-450WHP - get there however you need to
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
Brakes:
Stainless lines and PP pads is all you need
Fenders:
They go away
Tires:
315/35/17 V710 would be the #1 tire choice right now on 17x10.5s
-Tom
Motor:
400-450WHP - get there however you need to
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
Brakes:
Stainless lines and PP pads is all you need
Fenders:
They go away
Tires:
315/35/17 V710 would be the #1 tire choice right now on 17x10.5s
-Tom
| Patrick L | 09-28-2004 12:03 AM |
[QUOTE=trhoppe]
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
[/QUOTE]
[url]http://www.zzyzxmotorsports.com/products/performance/[/url]
Double adjustable Koni shocks by Advance Design.
[QUOTE]Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers [/QUOTE]
:lol:
CCW's 17's or 18's at 10-10.5" wide
and for the brakes I would get some good track pads. You be getting them hot.
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
[/QUOTE]
[url]http://www.zzyzxmotorsports.com/products/performance/[/url]
Double adjustable Koni shocks by Advance Design.
[QUOTE]Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers [/QUOTE]
:lol:
CCW's 17's or 18's at 10-10.5" wide
and for the brakes I would get some good track pads. You be getting them hot.
| DrBiggly | 09-28-2004 12:18 AM |
255s aren't going to cut it; not even close. With 285s on ESP STis this year, you can take it to the bank that you're going to have to have bigger and grippier. (Anybody have a picture of Joel's car somewhere?)
Is the car a capable platform? Sure! But you're going to need a lot of development. If I were you, I would start right now, tomorrow, this week with no delays on getting the suspension modeling done that Tom proposed. Excluding the cost of the car, you should have somewhere in the range of $50k for total development this year in order to go for top rankings. (Time, dyno, parts, tires, suspension engineering/modeling, etc.) Steve's X1/9 has $60k of development...on a Fiat (over the course of about 4 years if I remember hearing right.)
Keep that in mind and keep us informed...hope to see you at events. If you can take top honors next year I will be quite impressed. Good luck! :)
Is the car a capable platform? Sure! But you're going to need a lot of development. If I were you, I would start right now, tomorrow, this week with no delays on getting the suspension modeling done that Tom proposed. Excluding the cost of the car, you should have somewhere in the range of $50k for total development this year in order to go for top rankings. (Time, dyno, parts, tires, suspension engineering/modeling, etc.) Steve's X1/9 has $60k of development...on a Fiat (over the course of about 4 years if I remember hearing right.)
Keep that in mind and keep us informed...hope to see you at events. If you can take top honors next year I will be quite impressed. Good luck! :)
| eastcoastbumps | 09-28-2004 12:21 AM |
[QUOTE=SloRice]-Turbo (makes more power but spools at a lower RPM - yes it's an oxy moron, I know The car already has a lot of low end grunt to pull itself out of a turn in 2nd, but it needs a little more or needs to come on boost quicker - if it falls on its face up top, then it falls on its face, i'm not a highway racer) [/quote]
Smaller turbos spool faster. You can't find a turbo that will do both. The only thing that might come close is an 18G. It will spool slower but you'll make more top end and you'll be able to push it a bit farther than the VF39.
You could also run anti-lag in SM. Look into Link, Hydra and AEM standalone units. I don't think all of them support the USDM STi yet, but they all have the capabilites of running anti lag.
[quote]-Injectors/FP (as needed) [/quote]
You will need injectors with any more power.
[quote]-External or Internal wastegate (I hear that going external gives a lot of extra power) [/quote]
An external gate won't give you any extra power. Its just a different way of controling boost. 17psi is 17psi no matter if its controled by an internal or external gate.
[quote]
-Anyway to get over the sensitive ABS? [/quote]
Turn it off.
[quote]
Weight Reduction
Current Setup
-Stock
Needed Setup
-I'd like new front seats as the stocks are really uncomfortable
-Any other info on this topic appreciated [/quote]
Go with Sparco Evos or something similar with 3" 4 or 5pt harnesses. You can remove the rear seat in SM along with your stereo.
[quote]
Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers
Needed Setup
-Maybe a wider rim
-I like the V700's, but maybe try the V710's as I have heard mixed opinions on the Hoosier S04's and I've heard good things about the V710's [/quote]
Look into 17x8 SSR comps, Enkei RPF1's or Kosie's in 35 or 40mm offset if you're running very stiff suspension and big bars. This won't be good for wheel bearings but it will be good for lap times. You're on your own with tire selection. Just make sure you get something wide.
I've been running SM for the past two years. As of now, its my driving that is holding me back. My car is hardly close to the limits of the rules. EJ207 is going in this winter and I'll hopefully have a good set of race rubber and other suspension goodies before the snow melts in the spring.
Pete
Smaller turbos spool faster. You can't find a turbo that will do both. The only thing that might come close is an 18G. It will spool slower but you'll make more top end and you'll be able to push it a bit farther than the VF39.
You could also run anti-lag in SM. Look into Link, Hydra and AEM standalone units. I don't think all of them support the USDM STi yet, but they all have the capabilites of running anti lag.
[quote]-Injectors/FP (as needed) [/quote]
You will need injectors with any more power.
[quote]-External or Internal wastegate (I hear that going external gives a lot of extra power) [/quote]
An external gate won't give you any extra power. Its just a different way of controling boost. 17psi is 17psi no matter if its controled by an internal or external gate.
[quote]
-Anyway to get over the sensitive ABS? [/quote]
Turn it off.
[quote]
Weight Reduction
Current Setup
-Stock
Needed Setup
-I'd like new front seats as the stocks are really uncomfortable
-Any other info on this topic appreciated [/quote]
Go with Sparco Evos or something similar with 3" 4 or 5pt harnesses. You can remove the rear seat in SM along with your stereo.
[quote]
Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers
Needed Setup
-Maybe a wider rim
-I like the V700's, but maybe try the V710's as I have heard mixed opinions on the Hoosier S04's and I've heard good things about the V710's [/quote]
Look into 17x8 SSR comps, Enkei RPF1's or Kosie's in 35 or 40mm offset if you're running very stiff suspension and big bars. This won't be good for wheel bearings but it will be good for lap times. You're on your own with tire selection. Just make sure you get something wide.
I've been running SM for the past two years. As of now, its my driving that is holding me back. My car is hardly close to the limits of the rules. EJ207 is going in this winter and I'll hopefully have a good set of race rubber and other suspension goodies before the snow melts in the spring.
Pete
| SloRice | 09-28-2004 09:15 AM |
Well this really wasn't what I wanted to hear. I guess I figured get a little more power, better suspension and couple other things and I would be fine, but apperently that is not the case. I just compared my times before Nationals to times of people I ran against that went to Topeka and said, wow, I could actually be competative b/c my car is not even nearly setup - see NWOR vs. ASCC vs. FWR - I beat Fessler and almost beat Raglin, both of which looked like they had their ups and downs in Topeka. But it seems like thats going to come at a price that I'm not willing/able to do. I can't see myself destroying a $30K car just to go racing......guess I'll just consider myself a weekend warrior still. :(
Someone had proposed that it would be much cheaper to go the ESP route, but I honestly have no clue about the rules of ESP...hell, I don't even know all the rules of SM.
I guess my bubble just got busted....
Someone had proposed that it would be much cheaper to go the ESP route, but I honestly have no clue about the rules of ESP...hell, I don't even know all the rules of SM.
I guess my bubble just got busted....
| dwx | 09-28-2004 12:32 PM |
Well right now the top 3 M3s are above everyone else, 1 of them is S/C'd the other 2 are NA. One has an E46 engine and the other has an E36 engine. I wouldn't set a goal at catching those guys.
I've seen competitive ESP STIs compare favorably to SM times, so I think you could run SM at a national level in a STI with not a huge investment. Here is my setup currently and I trophied at all the national events I went to this year:
1) EJ257 (which you have)
2) PE1818 turbo. Here I see two options for you. Either send the VF35 to deadbolt and have him swap an 1818 wheel into it or buy a PE1818. I would think an 18G turbo would also be very similar.
3) UTEC/Hydra/reflashed ECU. Get the ECU tuned to make more torque across the whole powerband. With the reflash or Hydra you can change the AVCS parameters as well. I made 340whp/342ft-lbs on a Mustang dyno. Raise the revlimiter to 7500 rpm.
3a) Get it tuned for race gas. You can make a ton more power on 110/116 octane gas than anything else, especially if you are using an 18G or 20G. My car was only tuned for about 98 octane. Buy a spare front O2 sensor, they are cheap in the grand scheme of things. :)
4) GC Advance Design coilovers. I use them and love them. Koni double adjustable struts would be just as good I imagine. Front/rear camber plates. I run 550f/600r springs. Swaybars front/rear, bushings if you really want.
5) Wide tires. I don't think you need 315 tires by any stretch of the imagination. On the STI I'd run 275/40/17 because the gearing is short. Or run 285/30/18 if you like shifting into 3rd a lot. You can run 285s on 18x8.5" wheels if you want. Or 275 on 17x8.5. Having 18x10 wheels is nice and all but it's a huge expense.
6) weight reduction. Race seats are good for reduction and keeping you in the seat. I hate even good stock seats after using race seats and a harness all year.
7) Faster steering rack. Completely changes the way the car drives. I'm not sure it's 100% necessary though.
Honestly with a very good driver having 300whp, 275/285 tires, and a decent suspension will trophy nationally.
50k? That's insane.
I've seen competitive ESP STIs compare favorably to SM times, so I think you could run SM at a national level in a STI with not a huge investment. Here is my setup currently and I trophied at all the national events I went to this year:
1) EJ257 (which you have)
2) PE1818 turbo. Here I see two options for you. Either send the VF35 to deadbolt and have him swap an 1818 wheel into it or buy a PE1818. I would think an 18G turbo would also be very similar.
3) UTEC/Hydra/reflashed ECU. Get the ECU tuned to make more torque across the whole powerband. With the reflash or Hydra you can change the AVCS parameters as well. I made 340whp/342ft-lbs on a Mustang dyno. Raise the revlimiter to 7500 rpm.
3a) Get it tuned for race gas. You can make a ton more power on 110/116 octane gas than anything else, especially if you are using an 18G or 20G. My car was only tuned for about 98 octane. Buy a spare front O2 sensor, they are cheap in the grand scheme of things. :)
4) GC Advance Design coilovers. I use them and love them. Koni double adjustable struts would be just as good I imagine. Front/rear camber plates. I run 550f/600r springs. Swaybars front/rear, bushings if you really want.
5) Wide tires. I don't think you need 315 tires by any stretch of the imagination. On the STI I'd run 275/40/17 because the gearing is short. Or run 285/30/18 if you like shifting into 3rd a lot. You can run 285s on 18x8.5" wheels if you want. Or 275 on 17x8.5. Having 18x10 wheels is nice and all but it's a huge expense.
6) weight reduction. Race seats are good for reduction and keeping you in the seat. I hate even good stock seats after using race seats and a harness all year.
7) Faster steering rack. Completely changes the way the car drives. I'm not sure it's 100% necessary though.
Honestly with a very good driver having 300whp, 275/285 tires, and a decent suspension will trophy nationally.
50k? That's insane.
| trhoppe | 09-28-2004 12:46 PM |
You know, I misread the first post. I thought it said "Win SM nationally" instead of "trophy".
To trophy, you only need the basic STX/STU setup with 275 Hoosiers and a bigger turbo with boost + driving skizzils. If you want to WIN, you will need all those things I listed as those top 3 M3s are just that far ahead.
-Tom
To trophy, you only need the basic STX/STU setup with 275 Hoosiers and a bigger turbo with boost + driving skizzils. If you want to WIN, you will need all those things I listed as those top 3 M3s are just that far ahead.
-Tom
| SloRice | 09-28-2004 01:32 PM |
thats alright Tom, I wouldn't mind taking on the M3's, but if it comes at that much of a price, it's not worth it. But, if I take 4th, GAME ON! :D
Thanks for the input Phil....Jen and Phil Croy said I should talk to you. Couple questions on your info though....
1. no questions
2. Unfortunately, I'm turbo knowledge challenged. I understand how they work, but I've only recently started researching which one to go with, so I really don't know a whole lot of "which is better than which" turbo. Why did u go with a PE1818? From your post, it obviously is related to my current turbo (VF39). What is the difference between an 18G and PE1818?
3. I'm thinking I want to do a UTEC b/c I understand how to tune it versus the Hydra or reflash. But I get the benefit of AVCS with the later two. What is AVCS....I heard it's kind of like VTEC, but could be way off.
3a. Why a spare front O2 sensor? Does race gas burn them out?
4. Where would one get the Advanced Design coilovers? What kind of pricing on them? What makes them so good? I see you run 550f/600r. But it seems like all the other subie setups are stiffer in the front than in the rear. Why the different route?
5. Don't think I want to run a 18 inch rim. So what kind of offset would I need for a 17x8.5 inch rim to fit the 275's? Right now i'm getting rubbing in the rear with the stock BBS's and 255/40/17's. I rub on the trailing arm and the Perrin RSB...but never rubbed on the stock RSB and a little bit on the springs. Also, would I have to roll the fenders or would the tires stick out.
Damn, I feel like Cole Trickle from Days of Thunder. I just drive the car....I don't know anything about a turn here, a wedge there :lol:
Thanks for the input Phil....Jen and Phil Croy said I should talk to you. Couple questions on your info though....
1. no questions
2. Unfortunately, I'm turbo knowledge challenged. I understand how they work, but I've only recently started researching which one to go with, so I really don't know a whole lot of "which is better than which" turbo. Why did u go with a PE1818? From your post, it obviously is related to my current turbo (VF39). What is the difference between an 18G and PE1818?
3. I'm thinking I want to do a UTEC b/c I understand how to tune it versus the Hydra or reflash. But I get the benefit of AVCS with the later two. What is AVCS....I heard it's kind of like VTEC, but could be way off.
3a. Why a spare front O2 sensor? Does race gas burn them out?
4. Where would one get the Advanced Design coilovers? What kind of pricing on them? What makes them so good? I see you run 550f/600r. But it seems like all the other subie setups are stiffer in the front than in the rear. Why the different route?
5. Don't think I want to run a 18 inch rim. So what kind of offset would I need for a 17x8.5 inch rim to fit the 275's? Right now i'm getting rubbing in the rear with the stock BBS's and 255/40/17's. I rub on the trailing arm and the Perrin RSB...but never rubbed on the stock RSB and a little bit on the springs. Also, would I have to roll the fenders or would the tires stick out.
Damn, I feel like Cole Trickle from Days of Thunder. I just drive the car....I don't know anything about a turn here, a wedge there :lol:
| dwx | 09-28-2004 01:44 PM |
Advance Design stuff you can get from Ground Control themselves. The whole setup however is probably going to be close to $3k.
Yes race gas burns out front O2 sensors.
Honestly to run a 275 tire on a 17" rim you would want something around +40 offset. Otherwise you may have to look into wheel spacers. It's hard to say though, all cars seem to be a little different when it comes to that stuff.
I have a WRX and run stiffer rear rates than front to get the back end to come around without running an excessively large swaybar in the rear. It seemed to work for me. STI may be different.
Yes race gas burns out front O2 sensors.
Honestly to run a 275 tire on a 17" rim you would want something around +40 offset. Otherwise you may have to look into wheel spacers. It's hard to say though, all cars seem to be a little different when it comes to that stuff.
I have a WRX and run stiffer rear rates than front to get the back end to come around without running an excessively large swaybar in the rear. It seemed to work for me. STI may be different.
| trhoppe | 09-28-2004 02:12 PM |
[quote]I have a WRX and run stiffer rear rates than front to get the back end to come around without running an excessively large swaybar in the rear. It seemed to work for me. STI may be different.[/quote]
On the STi IMHO that higher rear rate is not needed because of the center diff.
-Tom
On the STi IMHO that higher rear rate is not needed because of the center diff.
-Tom
| SloRice | 09-28-2004 02:57 PM |
With the Tein Coilovers, I didn't notice much of a difference when I put the bigger Perrin RSB on. It helped rotation a little bit, but not as much as I thought it would. Maybe it's not big enough???
But the car does seem to rotate pretty good with 559f/448r that the Tein Flex's have.
But the car does seem to rotate pretty good with 559f/448r that the Tein Flex's have.
| zzyzx | 09-28-2004 03:41 PM |
Isn't anti-lag legal in SM? Talk about powering out of slow corners... It would negate the whole large turbo spool issue and issues related to larger than stock diameter tires.
[QUOTE=trhoppe]
On the STi IMHO that higher rear rate is not needed because of the center diff.
[/QUOTE]
Fehrman was running 550F/1000R at Nats and his car looked pretty stable out on course...
- Steve
[QUOTE=trhoppe]
On the STi IMHO that higher rear rate is not needed because of the center diff.
[/QUOTE]
Fehrman was running 550F/1000R at Nats and his car looked pretty stable out on course...
- Steve
| dwx | 09-28-2004 03:52 PM |
[QUOTE=zzyzx]Isn't anti-lag legal in SM? Talk about powering out of slow corners... It would negate those whole large turbo spool issue and issues related to larger than stock diameter tires.
Fehrman was running 550F/1000R at Nats and his car looked pretty stable out on course...
- Steve[/QUOTE]
:devil:
Fehrman was running 550F/1000R at Nats and his car looked pretty stable out on course...
- Steve[/QUOTE]
:devil:
| jmott | 09-28-2004 04:29 PM |
This years winner only had around 350crank horsepower.
The big advantage the BMWs have over the STI is weight distribution and possibly weight in general. An SM prepped e36 m3 probably weighs around 2700lbs if not under. The other issues are throttle response and area under the power curve and gearing. An SM sti might have to cook up some custom gear ratios, and be sure that they don't sacrifice low RPM power when cooking up extra horsepower.
[QUOTE=trhoppe]You want to win nationally in SM? :lol:
Motor:
400-450WHP - get there however you need to
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
Brakes:
Stainless lines and PP pads is all you need
Fenders:
They go away
Tires:
315/35/17 V710 would be the #1 tire choice right now on 17x10.5s
-Tom[/QUOTE]
The big advantage the BMWs have over the STI is weight distribution and possibly weight in general. An SM prepped e36 m3 probably weighs around 2700lbs if not under. The other issues are throttle response and area under the power curve and gearing. An SM sti might have to cook up some custom gear ratios, and be sure that they don't sacrifice low RPM power when cooking up extra horsepower.
[QUOTE=trhoppe]You want to win nationally in SM? :lol:
Motor:
400-450WHP - get there however you need to
Suspension:
Sorted like hell. Be prepared to model suspension geometry and do lots and lots of testing. A nice GC coilover or a built Koni with 12K/10K would be a good start IMHO
Brakes:
Stainless lines and PP pads is all you need
Fenders:
They go away
Tires:
315/35/17 V710 would be the #1 tire choice right now on 17x10.5s
-Tom[/QUOTE]
| ColinL | 09-28-2004 04:46 PM |
anti-lag is legal, but I've never seen anyone besides Dennis Grant attempt to use it.
notice 'attempt'. :p
it would help autocross a lot for any car making >10 psi. if you were running 25+ psi, which would be easily achieved on a variety of race fuels (some unleaded! same the o2 sensor :lol: ), it would be night and day.
I hate to sound pessimistic but I don't know that the top E36 M3s could be caught.
notice 'attempt'. :p
it would help autocross a lot for any car making >10 psi. if you were running 25+ psi, which would be easily achieved on a variety of race fuels (some unleaded! same the o2 sensor :lol: ), it would be night and day.
I hate to sound pessimistic but I don't know that the top E36 M3s could be caught.
| zzyzx | 09-28-2004 04:52 PM |
[QUOTE=ColinL]anti-lag is legal, but I've never seen anyone besides Dennis Grant attempt to use it.
notice 'attempt'. :p
[/QUOTE]
Odd. I would think doing anti-lag on a 4G63 would be a known quantity. I mean, how many rally cars do this on this motor w/o issues?
[QUOTE=ColinL]
it would help autocross a lot for any car making >10 psi. if you were running 25+ psi, which would be easily achieved on a variety of race fuels (some unleaded! same the o2 sensor :lol: ), it would be night and day.
[/QUOTE]
I think that a good turbo / anti-lag setup would far exceed any NA setup in terms of power delivery in an autox.
110 octane + 25 psi + EJ257 + anti-lag = teh fastAr! ;)
- Steve
notice 'attempt'. :p
[/QUOTE]
Odd. I would think doing anti-lag on a 4G63 would be a known quantity. I mean, how many rally cars do this on this motor w/o issues?
[QUOTE=ColinL]
it would help autocross a lot for any car making >10 psi. if you were running 25+ psi, which would be easily achieved on a variety of race fuels (some unleaded! same the o2 sensor :lol: ), it would be night and day.
[/QUOTE]
I think that a good turbo / anti-lag setup would far exceed any NA setup in terms of power delivery in an autox.
110 octane + 25 psi + EJ257 + anti-lag = teh fastAr! ;)
- Steve
| SloRice | 09-28-2004 04:53 PM |
can someone explain how anti-lag works?
How good is it for the motor?
How good is it for the motor?
| jmott | 09-28-2004 05:02 PM |
[QUOTE=zzyzx]Odd. I would think doing anti-lag on a 4G63 would be a known quantity. I mean, how many rally cars do this on this motor w/o issues?
I think that a good turbo / anti-lag setup would far exceed any NA setup in terms of power delivery in an autox.
110 octane + 25 psi + EJ257 + anti-lag = teh fastAr! ;)
- Steve[/QUOTE]
have you ever driven a car with anti lag? do you have any idea if the power delivery is smooth/reliable?
is it practical to use or will it costs thousands in replacing worn parts?
do you realize that vic sias can throw a supercharger on his car and make 500hp and have no lag at all?
actually if you really wanted to win SM and not just be a turbo sackrider, you would seriously consider taking the turbo off entirely and using a supercharger instead.
I think that a good turbo / anti-lag setup would far exceed any NA setup in terms of power delivery in an autox.
110 octane + 25 psi + EJ257 + anti-lag = teh fastAr! ;)
- Steve[/QUOTE]
have you ever driven a car with anti lag? do you have any idea if the power delivery is smooth/reliable?
is it practical to use or will it costs thousands in replacing worn parts?
do you realize that vic sias can throw a supercharger on his car and make 500hp and have no lag at all?
actually if you really wanted to win SM and not just be a turbo sackrider, you would seriously consider taking the turbo off entirely and using a supercharger instead.
| zzyzx | 09-28-2004 05:07 PM |
:eek:
... and here I was gonna ask some Qs about your S/W. I guess I'd better not. :(
Oh, and regarding Vic's setup, check the FI displacement limites for SM...
- Steve
... and here I was gonna ask some Qs about your S/W. I guess I'd better not. :(
Oh, and regarding Vic's setup, check the FI displacement limites for SM...
- Steve
| jmott | 09-28-2004 05:26 PM |
[QUOTE=zzyzx]:eek:
... and here I was gonna ask some Qs about your S/W. I guess I'd better not. :(
Oh, and regarding Vic's setup, check the FI displacement limites for SM...
- Steve[/QUOTE]
Vic is very capable of destroking it a little to meet those limits.
I'm sorry that because of my experience autocrossing both STIs and E36s that I think a supercharged STI deserves some consideration would cause you not to be interested in my software.
:(
... and here I was gonna ask some Qs about your S/W. I guess I'd better not. :(
Oh, and regarding Vic's setup, check the FI displacement limites for SM...
- Steve[/QUOTE]
Vic is very capable of destroking it a little to meet those limits.
I'm sorry that because of my experience autocrossing both STIs and E36s that I think a supercharged STI deserves some consideration would cause you not to be interested in my software.
:(
| dwx | 09-28-2004 06:30 PM |
I gave some serious thought to using a supercharged 2.5 with a good air/water IC setup. Since I'm rebuilding the engine anyways. I think with a built 9:1 CR motor running 14psi on an efficient SC you might have a better car. I know the turbo setup I have right can be competitive, the lag and on/off throttle response is pretty amazing in the car. It's very comparable to some NA cars I've driven. I'm not unhappy with the power/torque the car makes with the gearing it has, so I don't want to do a 180 and switch to something different. I was using a FMIC last year and next year will go back to a TMIC setup which should be even less lag.
I don't think Sias would destroke the motor just so he could bolt on a S/C. He's been there done that. He's making less HP with the NA motor but the powerband is better. The E46 plots I've seen aren't exactly torquey down low. It would be nice if you could change the diffs on the WRX as easily as you can on a RWD car to change gear ratios.
I don't know that Dennis has ever run anti-lag on his car. He runs launch control at ProSolos. Dennis' car is geared to run to like 72mph in 2nd gear. I think that absolutely kills his car in Solo2, I don't know why he geared it that way.
Anti-lag can be smooth in engagement it depends how its setup. Anti-lag is the process of allowing some air into the engine and severely retarding timing such that unburnt fuel and the little air you are pumping ignite in the exhaust manifold, keeping the turbo spooled when off throttle. The amount it keeps spooled is more of a trial and error process. Honestly if you kept it at 1-2psi that's good enough.
The Link ECU has sort of a ghetto anti-lag mode where you just change the throttle plate so that it's open 20% all the time. The car idles at like 2000 rpm but it means when you are off-throttle the engine is still getting air.
Alternatively you can use some kind of bypass valve connected to the intake manifold. It's something that needs to be actuated when you are off throttle only. The idle valve on the WRX is probably not large enough to get the amount of air you want.
Here are a couple drawbacks to anti-lag:
1) It's hard on the exhaust valves, the turbo, and the exhaust manifold.
2) The car doesn't engine brake anymore
3) The car is never under vacuum, which has interesting effects on the f brakes.
Given the short duration of autocross and how much you are actually off the gas I don't think the issue of reliability of parts is such an issue. If the ALS is setup incorrectly you could see EGTS approaching 2000F which is going to cause all kinds of problems. Like anything else though if you set it up correctly, it'll work well. Guys use turbos/manifolds, etc. for entire seasons in rally and the ALS is in use much much more often than what it would be for autocross. I wouldn't condone using it on a car that you can't be without.
I don't think Sias would destroke the motor just so he could bolt on a S/C. He's been there done that. He's making less HP with the NA motor but the powerband is better. The E46 plots I've seen aren't exactly torquey down low. It would be nice if you could change the diffs on the WRX as easily as you can on a RWD car to change gear ratios.
I don't know that Dennis has ever run anti-lag on his car. He runs launch control at ProSolos. Dennis' car is geared to run to like 72mph in 2nd gear. I think that absolutely kills his car in Solo2, I don't know why he geared it that way.
Anti-lag can be smooth in engagement it depends how its setup. Anti-lag is the process of allowing some air into the engine and severely retarding timing such that unburnt fuel and the little air you are pumping ignite in the exhaust manifold, keeping the turbo spooled when off throttle. The amount it keeps spooled is more of a trial and error process. Honestly if you kept it at 1-2psi that's good enough.
The Link ECU has sort of a ghetto anti-lag mode where you just change the throttle plate so that it's open 20% all the time. The car idles at like 2000 rpm but it means when you are off-throttle the engine is still getting air.
Alternatively you can use some kind of bypass valve connected to the intake manifold. It's something that needs to be actuated when you are off throttle only. The idle valve on the WRX is probably not large enough to get the amount of air you want.
Here are a couple drawbacks to anti-lag:
1) It's hard on the exhaust valves, the turbo, and the exhaust manifold.
2) The car doesn't engine brake anymore
3) The car is never under vacuum, which has interesting effects on the f brakes.
Given the short duration of autocross and how much you are actually off the gas I don't think the issue of reliability of parts is such an issue. If the ALS is setup incorrectly you could see EGTS approaching 2000F which is going to cause all kinds of problems. Like anything else though if you set it up correctly, it'll work well. Guys use turbos/manifolds, etc. for entire seasons in rally and the ALS is in use much much more often than what it would be for autocross. I wouldn't condone using it on a car that you can't be without.
| zzyzx | 09-28-2004 06:37 PM |
[QUOTE=dwx]
3) The car is never under vacuum, which has interesting effects on the f brakes.
[/QUOTE]
Interesting side note.
Well, we are talking SM, so nothing stopping you from throwing in the H6 3.0 w/a supercharger. :)
- Steve
3) The car is never under vacuum, which has interesting effects on the f brakes.
[/QUOTE]
Interesting side note.
Well, we are talking SM, so nothing stopping you from throwing in the H6 3.0 w/a supercharger. :)
- Steve
| dwx | 09-28-2004 06:58 PM |
I think the brake thing is more a byproduct of the setup you have. If the throttle plate is open then air from the turbo is getting into the engine. If you have some kind of bypass setup I think the engine would still be under vacuum all the time. Would need to find some place for the air in the turbo to go though.
| thechickencow | 09-28-2004 07:30 PM |
Phil you may want to look into a vacuum setup for brake assist. I think RRE has done that setup before and I can give you some contacts if that would help.
I hadn't paid much attention yet since I haven't felt a need, so I don't know if it'll work on your application.
I hadn't paid much attention yet since I haven't felt a need, so I don't know if it'll work on your application.
| jbrennen | 09-29-2004 02:34 PM |
Here's a thread I started on building an SM Evo... The thread has been running off and on for about 9 months... You may find some useful information there, but mostly I think it's just brainstorming and bouncing ideas around:
[url]http://forums.evolutionm.net/showthread.php?t=52830[/url]
My Evo is capable of trophying nationally in SM, but to be honest, there are ESP Evos which are also capable of trophying in SM -- they make up for having less power by having better drivers. :)
This year, my Evo was typically less than a second per side behind the SM leaders in ProSolos (but then my Evo never went up against the Sias or Richardson cars). Next year, I will have more weight reduction done, wider tires, more horsepower, and likely a double adjustable suspension. I expect that the car will have what it takes to win ProSolos in 2005 -- and it just might happen if my driving skills continue to improve.
FWIW, my car dynoed at 323 WHP and 301 ft-lbs, compared to same dyno 226 WHP and 240 ft-lbs when stock. Over the offseason, I hope to get that up to about 350 WHP and 350 ft-lbs on the Evo's stock turbo and stock bottom end.
I think that 350 HP / 350 ft-lbs at the wheels would certainly be enough to be competitive for an SM STi (isn't that about what your WRX has, Phil?), but if you can get more power, go for it.
In summary, do all of the weight reduction you can, get somewhere in the neighborhood of 350hp/350tq at the wheels, fit 285 tires, and you should have a strong trophy contender.
[url]http://forums.evolutionm.net/showthread.php?t=52830[/url]
My Evo is capable of trophying nationally in SM, but to be honest, there are ESP Evos which are also capable of trophying in SM -- they make up for having less power by having better drivers. :)
This year, my Evo was typically less than a second per side behind the SM leaders in ProSolos (but then my Evo never went up against the Sias or Richardson cars). Next year, I will have more weight reduction done, wider tires, more horsepower, and likely a double adjustable suspension. I expect that the car will have what it takes to win ProSolos in 2005 -- and it just might happen if my driving skills continue to improve.
FWIW, my car dynoed at 323 WHP and 301 ft-lbs, compared to same dyno 226 WHP and 240 ft-lbs when stock. Over the offseason, I hope to get that up to about 350 WHP and 350 ft-lbs on the Evo's stock turbo and stock bottom end.
I think that 350 HP / 350 ft-lbs at the wheels would certainly be enough to be competitive for an SM STi (isn't that about what your WRX has, Phil?), but if you can get more power, go for it.
In summary, do all of the weight reduction you can, get somewhere in the neighborhood of 350hp/350tq at the wheels, fit 285 tires, and you should have a strong trophy contender.
| Storm | 09-29-2004 09:38 PM |
You know those huge HP numbers aren't gonna mean squat when you can't reach them until you're 'just' about to hit the brakes...... SM (and autocross in general) is more favorable to higher torque at lower RPMs.
Jay Storm
Jay Storm
| jbrennen | 09-29-2004 10:37 PM |
[QUOTE=Storm]You know those huge HP numbers aren't gonna mean squat when you can't reach them until you're 'just' about to hit the brakes...... SM (and autocross in general) is more favorable to higher torque at lower RPMs.[/QUOTE]
I agree about mid-range torque being very important. But that's a given -- this is an STi we're talking about, not a VTEC Honda. You can't get an STi to 350 peak HP without getting a usable 275+ HP over a very wide range. Chasing for the highest peak HP number doesn't mean much by itself, but if you can get 350 WHP with anything approaching a reasonable torque curve for a 2.5L turbo engine, you won't be disappointed.
Just as one data point, my Evo, with a smaller engine and a lower peak HP number, has 275+ HP at the wheels from about 4950 RPM all the way to the 7850 RPM rev limiter. That's from 41 MPH to 65 MPH in 2nd gear. That's very usable power.
I agree about mid-range torque being very important. But that's a given -- this is an STi we're talking about, not a VTEC Honda. You can't get an STi to 350 peak HP without getting a usable 275+ HP over a very wide range. Chasing for the highest peak HP number doesn't mean much by itself, but if you can get 350 WHP with anything approaching a reasonable torque curve for a 2.5L turbo engine, you won't be disappointed.
Just as one data point, my Evo, with a smaller engine and a lower peak HP number, has 275+ HP at the wheels from about 4950 RPM all the way to the 7850 RPM rev limiter. That's from 41 MPH to 65 MPH in 2nd gear. That's very usable power.
| jmott | 09-30-2004 02:18 AM |
have you done any datalogging during runs?
can you stay at 4900rpms throughout a whole autocross typically?
[QUOTE=jbrennen]I agree about mid-range torque being very important. But that's a given -- this is an STi we're talking about, not a VTEC Honda. You can't get an STi to 350 peak HP without getting a usable 275+ HP over a very wide range. Chasing for the highest peak HP number doesn't mean much by itself, but if you can get 350 WHP with anything approaching a reasonable torque curve for a 2.5L turbo engine, you won't be disappointed.
Just as one data point, my Evo, with a smaller engine and a lower peak HP number, has 275+ HP at the wheels from about 4950 RPM all the way to the 7850 RPM rev limiter. That's from 41 MPH to 65 MPH in 2nd gear. That's very usable power.[/QUOTE]
can you stay at 4900rpms throughout a whole autocross typically?
[QUOTE=jbrennen]I agree about mid-range torque being very important. But that's a given -- this is an STi we're talking about, not a VTEC Honda. You can't get an STi to 350 peak HP without getting a usable 275+ HP over a very wide range. Chasing for the highest peak HP number doesn't mean much by itself, but if you can get 350 WHP with anything approaching a reasonable torque curve for a 2.5L turbo engine, you won't be disappointed.
Just as one data point, my Evo, with a smaller engine and a lower peak HP number, has 275+ HP at the wheels from about 4950 RPM all the way to the 7850 RPM rev limiter. That's from 41 MPH to 65 MPH in 2nd gear. That's very usable power.[/QUOTE]
| SloRice | 09-30-2004 10:04 AM |
thanks for the info jbrennen. Definately gonna take a little time to dig through that one.
| ColinL | 09-30-2004 10:06 AM |
[QUOTE=jmott]have you done any datalogging during runs?
can you stay at 4900rpms throughout a whole autocross typically?[/QUOTE]
seems like a rhetorical question... by the information he's provided it seems intuitive that if he goes much below 40 mph at any time he'll need to consider downshifting to 1st.
the stock Evo turbo is awesome though. you could gain midrange by going to a GT2871, but the loss in topend wouldn't be worth it. likewise, I'd never consider a supercharger. there's not enough displacement or valve area to make SM-competitive power-- an EJ257 or 4G63 cannot play by the same rules than an S50 can.
(btw I sold my '95 M3 to buy the Evo.)
can you stay at 4900rpms throughout a whole autocross typically?[/QUOTE]
seems like a rhetorical question... by the information he's provided it seems intuitive that if he goes much below 40 mph at any time he'll need to consider downshifting to 1st.
the stock Evo turbo is awesome though. you could gain midrange by going to a GT2871, but the loss in topend wouldn't be worth it. likewise, I'd never consider a supercharger. there's not enough displacement or valve area to make SM-competitive power-- an EJ257 or 4G63 cannot play by the same rules than an S50 can.
(btw I sold my '95 M3 to buy the Evo.)
| dwx | 09-30-2004 10:52 AM |
There is a local guy here who had the GT2871 on his car until the engine blew. AMS did most of the tuning and buildup on that car, had an AEM standalone, etc. The car was incredibly fast in straights but it just didn't have the oomph coming out of corners that it needed. He didn't drive it especially well either which could be the cause of that. I really think the 2871 would be the turbo to have for my car next year but I just don't want to spend the money on the custom setup when I'm happy with the power the car is making now.
2nd gear with the STI 6MT is really short. My main powerband is from about 3500rpm to 6500rpm. I run a 7500 rpm redline. I spent too much time this year between 5000 and 7500 rpm, that's not where the car is making the most torque. About half the courses I did this year I shifted into 3rd and just left it in 3rd. Some guys said my car sounded like a shifter cart when I'd start off. :) I never had a single instance where I had noticable turbo lag coming out of a corner in 2nd gear, but did have a couple instances in 3rd where the RPMs would drop too low.
Next year I'll probably be using some taller tires, and I think it will help more than hurt. Even though it may hurt acceleration somewhat, I won't be shifting as often and hitting the revlimiter. It's not a huge difference, 2mph at 60mph. I can't think of any courses I did this year, including ProSolos (except Atlanta) where I didn't shift into 3rd or start banging off the revlimiter at some point. Now I know how all those 2.5RS guys feel. :)
2nd gear with the STI 6MT is really short. My main powerband is from about 3500rpm to 6500rpm. I run a 7500 rpm redline. I spent too much time this year between 5000 and 7500 rpm, that's not where the car is making the most torque. About half the courses I did this year I shifted into 3rd and just left it in 3rd. Some guys said my car sounded like a shifter cart when I'd start off. :) I never had a single instance where I had noticable turbo lag coming out of a corner in 2nd gear, but did have a couple instances in 3rd where the RPMs would drop too low.
Next year I'll probably be using some taller tires, and I think it will help more than hurt. Even though it may hurt acceleration somewhat, I won't be shifting as often and hitting the revlimiter. It's not a huge difference, 2mph at 60mph. I can't think of any courses I did this year, including ProSolos (except Atlanta) where I didn't shift into 3rd or start banging off the revlimiter at some point. Now I know how all those 2.5RS guys feel. :)
| MNbiker | 09-30-2004 12:30 PM |
Phil or anyone else,
Have you thought about changing the 6MT gear ratios? Seems like this would be a better solution, versus shifting all the time or trying to change gearing via odd tire sizes. I'm sure custom gears wouldn't be cheap, but what is in SM? ;)
-Steve
Have you thought about changing the 6MT gear ratios? Seems like this would be a better solution, versus shifting all the time or trying to change gearing via odd tire sizes. I'm sure custom gears wouldn't be cheap, but what is in SM? ;)
-Steve
| ColinL | 09-30-2004 12:59 PM |
personally I'd put on shorter tires and try to drive in 3rd all the time instead of 2nd. 2nd would be still used in really slow sections of course.
plus you'd gain the benefit of being able to lower the piss out of the car, which never hurts as long as you have adjustable lateral links.
you can still lower with the tall tires, but then you really do have the fenders 'go away' as someone said earlier. screw that...
plus you'd gain the benefit of being able to lower the piss out of the car, which never hurts as long as you have adjustable lateral links.
you can still lower with the tall tires, but then you really do have the fenders 'go away' as someone said earlier. screw that...
| omahasubaru | 09-30-2004 01:44 PM |
[quote]Wheels/Tires
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers [/quote]
Still need more rubber than that. Try a set of [url=http://www.zzyzxmotorsports.com]zzyzx motorsports[/url] coilovers for more strut clearance and spring rates around 850f/1100r something stiff that will allow the tires to stick out without hitting the fenders and a good 30% difference front to rear for rotation.
Then pick up some 315/35-18 race tires and some custom 18x10" wheels.
Contact patch will be very important as a lot of the SM cars will be running very wide tires and lots of power 500hp+.
Current Setup
-Stock BBS wheels
-255/40/17 V700 Victorracers [/quote]
Still need more rubber than that. Try a set of [url=http://www.zzyzxmotorsports.com]zzyzx motorsports[/url] coilovers for more strut clearance and spring rates around 850f/1100r something stiff that will allow the tires to stick out without hitting the fenders and a good 30% difference front to rear for rotation.
Then pick up some 315/35-18 race tires and some custom 18x10" wheels.
Contact patch will be very important as a lot of the SM cars will be running very wide tires and lots of power 500hp+.
| MNbiker | 09-30-2004 01:51 PM |
[QUOTE=ColinL]personally I'd put on shorter tires and try to drive in 3rd all the time instead of 2nd. 2nd would be still used in really slow sections of course.[/QUOTE]
The problem is, such tires don't exist in the Hoosier or Kumho DOT race tires - at least not in the kind of widths necessary for a "Nationally Competitive" SM Impreza. 245/45-16's are only marginally shorter than stock, and aren't wide enough. The shortest "wide" tires are the 285/30-18's, which are also only marginally shorter than stock. Am I missing something?
-Steve
The problem is, such tires don't exist in the Hoosier or Kumho DOT race tires - at least not in the kind of widths necessary for a "Nationally Competitive" SM Impreza. 245/45-16's are only marginally shorter than stock, and aren't wide enough. The shortest "wide" tires are the 285/30-18's, which are also only marginally shorter than stock. Am I missing something?
-Steve
| dwx | 09-30-2004 03:29 PM |
I ran 245/45/16 all year. Jack ran 245s as well, our cars were pretty competitive at least in ProSolos. I ran one event with 275/45/16 tires which are over an inch taller. Next year I'm going to wear out the 275/45/16s and try the 265/45/16 V710s. I'd really like to think I don't need 315 tires to be competitive in a <2700lb AWD car. I really don't want to buy or run 18" wheels. When you are putting down 300+ whp to the rear wheels like Sias or Richardson's cars, it helps to have 315 tires.
Steve: The only readily available option for the 6MT is to convert it to a 4.44 final drive instead of the 3.9, and then you really would be in 3rd the whole time. You might have to shift into 5th on some courses. :)
There is not a single car nationally running in SM that's 500hp.
Steve: The only readily available option for the 6MT is to convert it to a 4.44 final drive instead of the 3.9, and then you really would be in 3rd the whole time. You might have to shift into 5th on some courses. :)
There is not a single car nationally running in SM that's 500hp.
| Templar | 09-30-2004 05:05 PM |
I am planning on running a 285 30 18 on 10 inch rims next year (provided I can afford the rims by then). The thing to remember is that I am not in an STi, but a WRX with an RA ratio gearset. RA ratios with a 7400 rev limit, I can still hit 65 mph with this tire, but it is low enough to pull me through just about any tight corner you could think of. I really can't imagine putting a 315 on. The 285 is already pushing the borders of offset and torque steer. The 35mm offset that is required to get everything to fit is so far outside the steering access, that without a LSD in the front, the torque steer would be unbelievable.
Also, remember in this discussion that the contact patch would be the same on a 315 and a 285 if on the same rim width, and the same weight car. The main difference would be how the contact patch changes shape under extreme side load conditions. I would bet that the BMWs that are running 315s in the rear are not running them on a 10 or 10.5 inch rim.
Also, remember in this discussion that the contact patch would be the same on a 315 and a 285 if on the same rim width, and the same weight car. The main difference would be how the contact patch changes shape under extreme side load conditions. I would bet that the BMWs that are running 315s in the rear are not running them on a 10 or 10.5 inch rim.
| MNbiker | 09-30-2004 05:20 PM |
[QUOTE=Templar]I am planning on running a 285 30 18 on 10 inch rims next year (provided I can afford the rims by then). The thing to remember is that I am not in an STi, but a WRX with an RA ratio gearset. RA ratios with a 7400 rev limit, I can still hit 65 mph with this tire, but it is low enough to pull me through just about any tight corner you could think of.[/QUOTE]
This sounds like the perfect setup. It's only money, right? ;)
-Steve
This sounds like the perfect setup. It's only money, right? ;)
-Steve
| dwx | 09-30-2004 05:21 PM |
I was contemplating putting an RA gearset or more likely a Kaaz gearset into my old 5MT case. I just didn't think it was worth the trouble though. The RA gearset is a good choice because you don't have the weight of the 6MT (+75-80lbs), but I'm still leery about its ability to handle 350ft-lbs of torque at the wheels in a ProSolo launch. With the 275/45/16 tires I can hit about 63mph with my current rev limiter, that's good enough.
I believe Vic Sias uses 18x12 wheels for the 315 tires. There are _2_ M3s that I know of running that wide of a tire and that's it. It's not like every single one out there has 285 or 315 tires. Bob Tunnell is plenty fast in his 285 tired underpowered M3. He really shouldn't be in the same ballpark as Reitmer and Sias from a car perspective, but that's what great driving will do for you.
I've never really experienced torque steer in the WRX. Running 245 tires at +40 offset or running the 275s at effectively a 35mm offset. I'm using a quicker steering rack though which may be less apt to torque steer. I also have a front LSD. :)
The first thing you should do in a 5MT equipped WRX is buy a quaife LSD for the front.
I've always wondered about the effects of running the track in the WRX larger than the front. In the front you have all kinds of room but in the rear is where you need the spacers. Generally I tried to keep the spacers equal in the front and rear, I was always too lazy at test and tunes to swap spacers in and out.
I believe Vic Sias uses 18x12 wheels for the 315 tires. There are _2_ M3s that I know of running that wide of a tire and that's it. It's not like every single one out there has 285 or 315 tires. Bob Tunnell is plenty fast in his 285 tired underpowered M3. He really shouldn't be in the same ballpark as Reitmer and Sias from a car perspective, but that's what great driving will do for you.
I've never really experienced torque steer in the WRX. Running 245 tires at +40 offset or running the 275s at effectively a 35mm offset. I'm using a quicker steering rack though which may be less apt to torque steer. I also have a front LSD. :)
The first thing you should do in a 5MT equipped WRX is buy a quaife LSD for the front.
I've always wondered about the effects of running the track in the WRX larger than the front. In the front you have all kinds of room but in the rear is where you need the spacers. Generally I tried to keep the spacers equal in the front and rear, I was always too lazy at test and tunes to swap spacers in and out.
| AUTOwrXER | 09-30-2004 05:47 PM |
[QUOTE=Templar]Also, remember in this discussion that the contact patch would be the same on a 315 and a 285 if on the same rim width, and the same weight car. The main difference would be how the contact patch changes shape under extreme side load conditions. I would bet that the BMWs that are running 315s in the rear are not running them on a 10 or 10.5 inch rim.[/QUOTE]
Please explain what you mean by the above statement. Even though the rim width remains the same, you should have more tire in contact with the ground running 315s. My 285s still look a bit "pinched" on the 10.5" wheels. I'm considering 315s next season for more contact patch.
Joel
Please explain what you mean by the above statement. Even though the rim width remains the same, you should have more tire in contact with the ground running 315s. My 285s still look a bit "pinched" on the 10.5" wheels. I'm considering 315s next season for more contact patch.
Joel
| zzyzx | 09-30-2004 06:12 PM |
Ditto on Joel's request.
And you're not going to be competitive in SM w/o a front LSD. Oh, and a rear LSD... one that actually works.
I only wish that Hoosier or Kumho offered a 265/275 on 16s or 17s that was stock diameter or smaller. That simply isn't / hasn't been the case thus far, and there's no indication that will change anytime soon.
Hey Joel - could you tell us how much your 18s weigh?
- Steve
And you're not going to be competitive in SM w/o a front LSD. Oh, and a rear LSD... one that actually works.
I only wish that Hoosier or Kumho offered a 265/275 on 16s or 17s that was stock diameter or smaller. That simply isn't / hasn't been the case thus far, and there's no indication that will change anytime soon.
Hey Joel - could you tell us how much your 18s weigh?
- Steve
| Templar | 09-30-2004 06:51 PM |
[QUOTE=AUTOwrXER]Please explain what you mean by the above statement. Even though the rim width remains the same, you should have more tire in contact with the ground running 315s. My 285s still look a bit "pinched" on the 10.5" wheels. I'm considering 315s next season for more contact patch.
Joel[/QUOTE]
Given that a tire is running an appropriate pressure amount, contact patch size is a function of two factors: vehicle weight and downforce. Of course downforce is only a factor when the car is in motion and aerodynamics are working correctly. I doubt any SM legal cars would be able to provide enough downforce for that to be much of a factor in contact patch size. The shape of the contact patch is another matter. The shape is determined by wheel width. The wider the wheel, the wider the contact patch, but it shortens front to rear, therefore, keeping the overall area the same. A wider, shorter contact patch is better for cornering grip. Now, having said all this, I have argued with people who say it is of no benfit to put wider tires on a WRX because the contact patch won't be bigger. However, the WRX is a heavy car (3000 lbs in stock form) and the STI even heavier. The weight of these cars is plenty to take advantage of a much wider than 225 tire (or the joke of 205s that comes on WRXs stock). Also, when the tire is exposed to extreme cornering loads, the contact patch can move on the tire. What happens to most people is that it rolls off of the usable tread and onto sidewall. Once you start getting into wider tires, the contact patch has a tendency to move and deform less, and when it does move and deform, it generally stays within the confines of the intended tread material.
I hope I explained that partially well. I could really do a better job of it with diagrams and props, but no one could see that. :lol:
Oh, and Steve,
I didn't mean to imply that I recommend trying to race competitively in SM without the addition of a Front LSD, or upgraded rear for that matter, I was just making a statement about what kind of forces the extreme offsets will invoke on the steering system.
Joel[/QUOTE]
Given that a tire is running an appropriate pressure amount, contact patch size is a function of two factors: vehicle weight and downforce. Of course downforce is only a factor when the car is in motion and aerodynamics are working correctly. I doubt any SM legal cars would be able to provide enough downforce for that to be much of a factor in contact patch size. The shape of the contact patch is another matter. The shape is determined by wheel width. The wider the wheel, the wider the contact patch, but it shortens front to rear, therefore, keeping the overall area the same. A wider, shorter contact patch is better for cornering grip. Now, having said all this, I have argued with people who say it is of no benfit to put wider tires on a WRX because the contact patch won't be bigger. However, the WRX is a heavy car (3000 lbs in stock form) and the STI even heavier. The weight of these cars is plenty to take advantage of a much wider than 225 tire (or the joke of 205s that comes on WRXs stock). Also, when the tire is exposed to extreme cornering loads, the contact patch can move on the tire. What happens to most people is that it rolls off of the usable tread and onto sidewall. Once you start getting into wider tires, the contact patch has a tendency to move and deform less, and when it does move and deform, it generally stays within the confines of the intended tread material.
I hope I explained that partially well. I could really do a better job of it with diagrams and props, but no one could see that. :lol:
Oh, and Steve,
I didn't mean to imply that I recommend trying to race competitively in SM without the addition of a Front LSD, or upgraded rear for that matter, I was just making a statement about what kind of forces the extreme offsets will invoke on the steering system.
| AUTOwrXER | 09-30-2004 10:21 PM |
[QUOTE=zzyzx]
Hey Joel - could you tell us how much your 18s weigh?
- Steve[/QUOTE]
They came in at 21.25 pounds. CCW is probably 1-2 lbs heavier than Kodiak, but I wanted the piece of mind of not having to worry about wheel failures. The same size in a BMW fitment is about .75 lbs. lighter. We need more material on the back of the wheel to clear the Brembos.
Hey Joel - could you tell us how much your 18s weigh?
- Steve[/QUOTE]
They came in at 21.25 pounds. CCW is probably 1-2 lbs heavier than Kodiak, but I wanted the piece of mind of not having to worry about wheel failures. The same size in a BMW fitment is about .75 lbs. lighter. We need more material on the back of the wheel to clear the Brembos.
| AUTOwrXER | 09-30-2004 10:27 PM |
Templar,
Agreed regarding contact patch size and shape. The important factor is that the shape of the contact patch is a factor of the wheel AND the tire. My 285s put about .5" more width on the ground than the 275s. A wider and shorter contact patch is capable of generating more cornering force, but less acceleration and braking force. Acceleration and braking is not as much of a factor for me as cornering force. I can outbrake the pony cars and accelerate at least as well in all situations. We got owned in steady-state cornering day one at Nationals.
Joel
Agreed regarding contact patch size and shape. The important factor is that the shape of the contact patch is a factor of the wheel AND the tire. My 285s put about .5" more width on the ground than the 275s. A wider and shorter contact patch is capable of generating more cornering force, but less acceleration and braking force. Acceleration and braking is not as much of a factor for me as cornering force. I can outbrake the pony cars and accelerate at least as well in all situations. We got owned in steady-state cornering day one at Nationals.
Joel
| ColinL | 09-30-2004 11:49 PM |
this whole talk about the physics of the contact patch considers only a tire at rest.
when forces are acting upon it, I guarantee you that a 315's contact patch is larger than a 285. it's the same reason a taller drag slick gets better traction than a short one of the same width...
when forces are acting upon it, I guarantee you that a 315's contact patch is larger than a 285. it's the same reason a taller drag slick gets better traction than a short one of the same width...
| driggity | 10-01-2004 12:29 AM |
[QUOTE=dwx]I've always wondered about the effects of running the track in the WRX larger than the front. In the front you have all kinds of room but in the rear is where you need the spacers. Generally I tried to keep the spacers equal in the front and rear, I was always too lazy at test and tunes to swap spacers in and out.[/QUOTE]
In theory a wider rear track would make the car more reluctant to rotate. There is somebody who had a wider rear track (I think on an old body style RS) and reported that it was harder to rotate after that change.
In theory a wider rear track would make the car more reluctant to rotate. There is somebody who had a wider rear track (I think on an old body style RS) and reported that it was harder to rotate after that change.
| SloRice | 10-04-2004 06:47 PM |
Joel, what kind of rims are you running and what offset are you using to have a 10.5" rim?
tia
tia
| AUTOwrXER | 10-05-2004 04:26 PM |
PM'd ya!
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