| anti.team | 09-30-2004 09:38 PM |
Axleback Removal in DS?
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I've been thinking: I really would like to have a straightpipe from the axleback. It would get rid of that restrictive muffler and sound cool (but not too bad, I know many people that have them) and would even help my turbo spool quicker to boot (a boon at autocross)
Unfortunately I have neither the time nor the money right now to make this happen. So I was wondering, would it be within the DS rules to completely remove the axleback? I know I can modify the exhaust from the cat back, but would it constitute an illegal weight reduction?
Unfortunately I have neither the time nor the money right now to make this happen. So I was wondering, would it be within the DS rules to completely remove the axleback? I know I can modify the exhaust from the cat back, but would it constitute an illegal weight reduction?
| solo-x | 09-30-2004 09:51 PM |
read your rulebook
13.10.E
Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted provided the system meets the requirements of 3.5.
3.5 [b]MUFFLERS[/b]
Adequate mufflers are required for Solo II events. The criterion of "adequacy" is not what the exhaust system consists of, but the sound level. Any car deemed by the Event Chairman or his designated representative to be excessively loud shall not compete without acceptable modifications installed on the car.
The only other comment on exhaust is in section 3.3.3, item 13. "Exhaust must exit behind the driver or to the side of the car."
seems to me like your idea is well and good. go forth and make more noise!
nate - am i a rules geek yet?
13.10.E
Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted provided the system meets the requirements of 3.5.
3.5 [b]MUFFLERS[/b]
Adequate mufflers are required for Solo II events. The criterion of "adequacy" is not what the exhaust system consists of, but the sound level. Any car deemed by the Event Chairman or his designated representative to be excessively loud shall not compete without acceptable modifications installed on the car.
The only other comment on exhaust is in section 3.3.3, item 13. "Exhaust must exit behind the driver or to the side of the car."
seems to me like your idea is well and good. go forth and make more noise!
nate - am i a rules geek yet?
| afpdl | 09-30-2004 10:12 PM |
You can take off the whole cat back and stick a six inch peice of gutter in its place if you want to. You just have to have somthing after the last cat and pass the noise restrictions.
| thechickencow | 09-30-2004 10:21 PM |
Just FYI-
My straightpipe cost me $36. I'm pretty sure if you can afford to autocross you can afford that.
Jay
My straightpipe cost me $36. I'm pretty sure if you can afford to autocross you can afford that.
Jay
| anti.team | 10-01-2004 05:41 AM |
$36? Sure I could afford that! But then I couldn't afford autocross.
So the rule says "Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted". Does a removal count as a substitution? A substiution for nothing?
So the rule says "Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted". Does a removal count as a substitution? A substiution for nothing?
| afpdl | 10-01-2004 05:45 AM |
Ive seen it go unprotested at alot of national tours and never heard of it being protested at nationals so Im going to have to say yes.
| anti.team | 10-01-2004 05:56 AM |
Also, was your straightpipe mandrel bent? Does it use a flange that was hack sawed off of the regular axleback? These are my requirements for a straightpipe: It's got to be mandrel bent; it's got to come out at the same spot as the original axleback; it can't scavenge parts from the existing axleback.
I'm picky and that drives the price up.
I'm picky and that drives the price up.
| Scooby Freak | 10-01-2004 07:46 AM |
[QUOTE=anti.team]Also, was your straightpipe mandrel bent? Does it use a flange that was hack sawed off of the regular axleback? These are my requirements for a straightpipe: It's got to be mandrel bent; it's got to come out at the same spot as the original axleback; it can't scavenge parts from the existing axleback.
I'm picky and that drives the price up.[/QUOTE]
Mine was hack sawed right above the axle, then a relatively straight piece was welded on, the cheaper route.
-jeff
I'm picky and that drives the price up.[/QUOTE]
Mine was hack sawed right above the axle, then a relatively straight piece was welded on, the cheaper route.
-jeff
| neuspeed | 10-01-2004 08:59 AM |
My friend just took the whole axle back right after the rear axle off..
| MNbiker | 10-01-2004 09:03 AM |
[QUOTE=anti.team]These are my requirements for a straightpipe: It's got to be mandrel bent; it's got to come out at the same spot as the original axleback; it can't scavenge parts from the existing axleback.
[/QUOTE]
Mine is all of that, and it cost me $63. And that was for 3" pipe.
-Steve
[/QUOTE]
Mine is all of that, and it cost me $63. And that was for 3" pipe.
-Steve
| anti.team | 10-01-2004 09:09 AM |
Yeah, that's my plan too. I know I can get a straightpipe for around $50, but that's $50 for something virtually non-functional. I could use $50 elswhere.
| solo-x | 10-01-2004 09:57 AM |
[QUOTE=solo-x]read your rulebook
13.10.E
Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted [b]provided the system meets the requirements of 3.5.[/b]
3.5 [b]MUFFLERS[/b]
Adequate mufflers are required for Solo II events. [b]The criterion of "adequacy" is not what the exhaust system consists of, but the sound level.[/b] Any car deemed by the Event Chairman or his designated representative to be excessively loud shall not compete without acceptable modifications installed on the car.
The only other comment on exhaust is in section 3.3.3, item 13. [b]"Exhaust must exit behind the driver or to the side of the car."[/b]
seems to me like your idea is well and good. go forth and make more noise!
nate - am i a rules geek yet?[/QUOTE]
it is really quite straight-forward, i don't see where you are getting confused?
nate
13.10.E
Any part of the exhaust system beyond (downstream from) the header/manifold or catalytic converter, if so equipped, may be substituted [b]provided the system meets the requirements of 3.5.[/b]
3.5 [b]MUFFLERS[/b]
Adequate mufflers are required for Solo II events. [b]The criterion of "adequacy" is not what the exhaust system consists of, but the sound level.[/b] Any car deemed by the Event Chairman or his designated representative to be excessively loud shall not compete without acceptable modifications installed on the car.
The only other comment on exhaust is in section 3.3.3, item 13. [b]"Exhaust must exit behind the driver or to the side of the car."[/b]
seems to me like your idea is well and good. go forth and make more noise!
nate - am i a rules geek yet?[/QUOTE]
it is really quite straight-forward, i don't see where you are getting confused?
nate
| anti.team | 10-01-2004 10:16 AM |
[QUOTE=solo-x]it is really quite straight-forward, i don't see where you are getting confused?
nate[/QUOTE]
I'm not quite sure who you think is confused. I bought up the point that a removal of the axle-back isn't technically a substitution of that part of the exhaust, despite the fact that it would fit within the rest of the criteria. Then the conversation turned towars straightpipe designs and prices. Looking back at the thread I see little to no evidence of any confusion.
nate[/QUOTE]
I'm not quite sure who you think is confused. I bought up the point that a removal of the axle-back isn't technically a substitution of that part of the exhaust, despite the fact that it would fit within the rest of the criteria. Then the conversation turned towars straightpipe designs and prices. Looking back at the thread I see little to no evidence of any confusion.
| DrBiggly | 10-01-2004 10:36 AM |
It seems like a big deal to you, so I wouldn't do it were I in your shoes. :)
| anti.team | 10-01-2004 10:39 AM |
It is a big deal! I want to be positive that I'm working within the rules here. That way when I beat the pants off of everyone they can't say that it was because I had some sort of advantage (besides being fast as hell, that's my personal advantage!)
| leecea | 10-01-2004 12:17 PM |
Is their any evidence that dropping the muffler helps with anything except weight? I've heard it saves 20-25lbs, which is good, but not that it helps spool up or power.
In any event, I doubt it will make a difference unless you are consistently losing by tiny margins.
In any event, I doubt it will make a difference unless you are consistently losing by tiny margins.
| DrBiggly | 10-01-2004 12:33 PM |
I wouldn't say overwhelming evidence that it helps much, but it does feel a bit more free on the top end of the rev range according to two folks I know who have done this mod. Actually, there are 3 folks who have done it. One in an STi.
The pipe wasn't mandrel bent, just barely bent and the end came out at an angle; basically the straightest piece of pipe possible under the car. End was even with the bumper the way it was cut. Looked a touch funky, sounded cool and gained a little power.
The bit about it needing to be 3" and mandrel bent is completely overkill and entirely misguided. The 3" part is going to make it less effective than the 2.5" part and the mandrel bend will yield no actual gains in the real world (paper gains are there for sure though) due to the small amount of power you're pushing through it in D-stock anyway.
Note: Group N rally cars use 2.5" exhaust and it isn't by accident. :)
The pipe wasn't mandrel bent, just barely bent and the end came out at an angle; basically the straightest piece of pipe possible under the car. End was even with the bumper the way it was cut. Looked a touch funky, sounded cool and gained a little power.
The bit about it needing to be 3" and mandrel bent is completely overkill and entirely misguided. The 3" part is going to make it less effective than the 2.5" part and the mandrel bend will yield no actual gains in the real world (paper gains are there for sure though) due to the small amount of power you're pushing through it in D-stock anyway.
Note: Group N rally cars use 2.5" exhaust and it isn't by accident. :)
| anti.team | 10-01-2004 01:17 PM |
Mandrel bends are just sweet though. No kinks! Amazing! And I think a 3" pipe is unneccesary also.
The theory behind the spool up is that it is due to a reduction in backpressure from the elimination of the supposedly restrictive Subaru muffler.
The theory behind the spool up is that it is due to a reduction in backpressure from the elimination of the supposedly restrictive Subaru muffler.
| thechickencow | 10-01-2004 01:18 PM |
Mine is $hitty, 2.5", not mandrel bent, the flange was made by the dude, and the hangers are crap. But it saves me weight from the stock muffler and it flows better.
| DrBiggly | 10-01-2004 01:24 PM |
[QUOTE=anti.team]Mandrel bends are just sweet though. No kinks! Amazing! And I think a 3" pipe is unneccesary also.
The theory behind the spool up is that it is due to a reduction in backpressure from the elimination of the supposedly restrictive Subaru muffler.[/QUOTE]
The "kink" on the piece of pipe if you do it correctly is minimal. I agree that mandrel bends are important, but I would only focus on that if you were doing a turbo back. You might gain 0.002hp from a mandrel bent straight-pipe over a regular version but it certainly would not be worth the extra expense. Real world gains I think are really just non-existent.
The car would definitely spool a little quicker and feel a little better with the pipe, no doubt. I wasn't debating that at all. I'm a big fan of this particular mod on stock cars. :)
The theory behind the spool up is that it is due to a reduction in backpressure from the elimination of the supposedly restrictive Subaru muffler.[/QUOTE]
The "kink" on the piece of pipe if you do it correctly is minimal. I agree that mandrel bends are important, but I would only focus on that if you were doing a turbo back. You might gain 0.002hp from a mandrel bent straight-pipe over a regular version but it certainly would not be worth the extra expense. Real world gains I think are really just non-existent.
The car would definitely spool a little quicker and feel a little better with the pipe, no doubt. I wasn't debating that at all. I'm a big fan of this particular mod on stock cars. :)
| anti.team | 10-01-2004 01:46 PM |
I agree that a mandrel bent pent pipe isn't going to provide any appreciable gains over an otherwise equivalent and correctly kink-bent pipe. At least not any appreciable power or flow gains. Now the coolness gains, on the other hand, are off the charts. Let me break it down like this:
mandrel bends = cool
See? Irrefutable evidence.
mandrel bends = cool
See? Irrefutable evidence.
| fliz | 10-01-2004 01:53 PM |
[QUOTE=thechickencow] and the hangers are crap. [/QUOTE]
Does a bunch of steel wire wound back and forth really count as a hanger?
Does a bunch of steel wire wound back and forth really count as a hanger?
| thechickencow | 10-01-2004 01:55 PM |
[QUOTE=fliz]Does a bunch of steel wire wound back and forth really count as a hanger?[/QUOTE]
Its 'hanging' there isn't it?
I guess i should've said hange[b][I]r[/I] [/b]
Its 'hanging' there isn't it?
I guess i should've said hange[b][I]r[/I] [/b]
| DrBiggly | 10-01-2004 01:56 PM |
[QUOTE=anti.team]I agree that a mandrel bent pent pipe isn't going to provide any appreciable gains over an otherwise equivalent and correctly kink-bent pipe. At least not any appreciable power or flow gains. Now the coolness gains, on the other hand, are off the charts. Let me break it down like this:
mandrel bends = cool
See? Irrefutable evidence.[/QUOTE]
:lol:
Irrefutable.
However, since you said you were on a tight budget that is why I recommended against mandrel bends. :)
mandrel bends = cool
See? Irrefutable evidence.[/QUOTE]
:lol:
Irrefutable.
However, since you said you were on a tight budget that is why I recommended against mandrel bends. :)
| afpdl | 10-01-2004 02:01 PM |
[QUOTE=anti.team]I bought up the point that a removal of the axle-back isn't technically a substitution of that part of the exhaust.[/QUOTE]
It is technically a substitution the rules say you can replace the cat back. By taking the muffler off and leaving the midpipe on there you have effectively replaced your cat back with a short pipe that ends around the rear axel. No where in the rules does it say you must replace ever single portion of the cat back, so as long as there is somthing to the back of the cat your good to go.
Nate doesnt the needs to exit behind the driver rule only apply in street prepared and on? I dont remember reading that anywhere in the stock rules.
It is technically a substitution the rules say you can replace the cat back. By taking the muffler off and leaving the midpipe on there you have effectively replaced your cat back with a short pipe that ends around the rear axel. No where in the rules does it say you must replace ever single portion of the cat back, so as long as there is somthing to the back of the cat your good to go.
Nate doesnt the needs to exit behind the driver rule only apply in street prepared and on? I dont remember reading that anywhere in the stock rules.
| Xio | 10-01-2004 06:28 PM |
Hrm. Could this be protested by some jackhole as a weight reduction? (Remember this is DS rules we're talking about)
| afpdl | 10-01-2004 06:31 PM |
Its been done for years for weight reduction, its not illegal.
| solo-x | 10-01-2004 10:02 PM |
[QUOTE=anti.team]I'm not quite sure who you think is confused. I bought up the point that a removal of the axle-back isn't technically a substitution of that part of the exhaust, despite the fact that it would fit within the rest of the criteria. Then the conversation turned towars straightpipe designs and prices. Looking back at the thread I see little to no evidence of any confusion.[/QUOTE]
i'm not trying to be rude, but i assumed confusion because you asked the same question twice. like afpdl said, the rules don't define exactly what a "substitution" is. therefore if the other restrictions are met by whatever exhaust system you have, you are golden. be it just the b-pipe, a Ti dump in the tunnel, or whatever. protest commitees will read the rule the same way so you need not worry.
[QUOTE=afpdl]Nate doesnt the needs to exit behind the driver rule only apply in street prepared and on? I dont remember reading that anywhere in the stock rules.[/QUOTE]
that clause applies to all vehicles. it's a safety precaution and something that tech is supposed to look at before giving you your sticker. i'm not sure what the protest procedure would be in the case that someone's exhaust did not terminate behind the driver. theoretically, it would never be an issue because tech would have caught it, but...
nate
i'm not trying to be rude, but i assumed confusion because you asked the same question twice. like afpdl said, the rules don't define exactly what a "substitution" is. therefore if the other restrictions are met by whatever exhaust system you have, you are golden. be it just the b-pipe, a Ti dump in the tunnel, or whatever. protest commitees will read the rule the same way so you need not worry.
[QUOTE=afpdl]Nate doesnt the needs to exit behind the driver rule only apply in street prepared and on? I dont remember reading that anywhere in the stock rules.[/QUOTE]
that clause applies to all vehicles. it's a safety precaution and something that tech is supposed to look at before giving you your sticker. i'm not sure what the protest procedure would be in the case that someone's exhaust did not terminate behind the driver. theoretically, it would never be an issue because tech would have caught it, but...
nate
| zoomfactor | 10-01-2004 11:09 PM |
Well do everything...I just finished putting on a 3" high-flow cat in the place of the factory third and I can only say...:) :devil:
Oh crap...can't read -- you said stock, sorry :D
[SIZE=4]edited for personal stupidity and lack of reading comprehension[/SIZE]
Oh crap...can't read -- you said stock, sorry :D
[SIZE=4]edited for personal stupidity and lack of reading comprehension[/SIZE]
| ChrisDP | 10-02-2004 02:16 AM |
[CrocodileDundeevoice]That's not a straightpipe, now THIS is a straightpipe[/CrocodileDundeevoice]
[IMG]http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNTg1NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg[/IMG]
DS straightpipe, actually still using it for STX... 2.5", took the shiny tip off because it adds a pound... much lighter than the stock 22lb muffler :) $9 for pipe, machined a flange from 1/4" steel and welded it up myself.
I think the biggest advantage for a stock car is that it allows you to hear the engine with a helmet on.
[IMG]http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNTg1NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg[/IMG]
DS straightpipe, actually still using it for STX... 2.5", took the shiny tip off because it adds a pound... much lighter than the stock 22lb muffler :) $9 for pipe, machined a flange from 1/4" steel and welded it up myself.
I think the biggest advantage for a stock car is that it allows you to hear the engine with a helmet on.
| 0260B4U | 10-03-2004 01:35 AM |
I ran around for a while with my axleback off, had my TBE in the garage just waiting for gaskets to come. On a stock car it actually sounds good IMO
And if you just running for fun and not reall yon national level, I doubt anyone would protest. And if they did they are a dickhead
And if you just running for fun and not reall yon national level, I doubt anyone would protest. And if they did they are a dickhead
| afpdl | 10-03-2004 02:20 AM |
And they would lose the protest as its LEGAL in all classes
| nate49509 | 10-03-2004 03:31 PM |
[IMG]http://images7.fotki.com/v114/photos/1/173442/761141/PA040044-vi.jpg [/IMG]
Here's mine. Its strait pipe from the cat back. I run STX and this is about the only thing I've done engine wise. Didn't really notice and real gains, but it does seem a little smoother under WOT. I love how is sounds at idle and WOT.
Here's mine. Its strait pipe from the cat back. I run STX and this is about the only thing I've done engine wise. Didn't really notice and real gains, but it does seem a little smoother under WOT. I love how is sounds at idle and WOT.
| anti.team | 10-03-2004 08:24 PM |
I'll have to check yours out next weekend, Nate. Looks good from here though.
| neuspeed | 10-03-2004 09:03 PM |
[QUOTE=ChrisDP][CrocodileDundeevoice]That's not a straightpipe, now THIS is a straightpipe[/CrocodileDundeevoice]
[IMG]http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNTg1NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg[/IMG]
DS straightpipe, actually still using it for STX... 2.5", took the shiny tip off because it adds a pound... much lighter than the stock 22lb muffler :) $9 for pipe, machined a flange from 1/4" steel and welded it up myself.
I think the biggest advantage for a stock car is that it allows you to hear the engine with a helmet on.[/QUOTE]
So you finally ditched the hitch?
[IMG]http://www.we-todd-did-racing.com/wetoddimage.wtdr/wNTg1NjU5NnM0MTNkZmQzMXk1NDE%3D.jpg[/IMG]
DS straightpipe, actually still using it for STX... 2.5", took the shiny tip off because it adds a pound... much lighter than the stock 22lb muffler :) $9 for pipe, machined a flange from 1/4" steel and welded it up myself.
I think the biggest advantage for a stock car is that it allows you to hear the engine with a helmet on.[/QUOTE]
So you finally ditched the hitch?
| DrBiggly | 10-04-2004 09:28 AM |
This mod is more than 100% legal in all classes, and yes that includes stock classes. :)
| anti.team | 10-04-2004 09:43 AM |
More than 100% legal? You gotta admit, that's a lot more legality!
| DrBiggly | 10-04-2004 09:54 AM |
Illegal for no classes at any time means >=100% legality for me. :lol: :)
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