| jkjersey | 09-05-2002 08:01 PM |
aerodynamics of the GC8 RS
the aerodynamics of the RS bumper vs say my 1995 impreza L
I heard stories that above 100 mph the air its like throwing a shoebox in the air vs a football is this true. I love the styling and looks of the bumper but even with my impreza L 100 mph speeds are often seen. I mean I have turbo conversion and such plans in the works so I wanna know is it the hood that throws off the aerodynamics or is it the bumper with that big air dam in the middle.. please let me know. What speeds do you RS owners get to notice the drag factor ... what is the coefficient drag on an impreza RS pre 2002. And also can anyone find out the coefficient drag on my car a 1995 impreza L .
thank you , jayk
I heard stories that above 100 mph the air its like throwing a shoebox in the air vs a football is this true. I love the styling and looks of the bumper but even with my impreza L 100 mph speeds are often seen. I mean I have turbo conversion and such plans in the works so I wanna know is it the hood that throws off the aerodynamics or is it the bumper with that big air dam in the middle.. please let me know. What speeds do you RS owners get to notice the drag factor ... what is the coefficient drag on an impreza RS pre 2002. And also can anyone find out the coefficient drag on my car a 1995 impreza L .
thank you , jayk
| moogooob | 09-05-2002 08:22 PM |
Wouldn't be able to compare the two cars, or tell you about areodynamics, but i can tell you at 100 the RS is rock solid.
[SIZE=1]Disclaimer: I have never ever ever driven over the speed limit, my comment is for eduactional purposes only, [/SIZE]
[SIZE=1]Disclaimer: I have never ever ever driven over the speed limit, my comment is for eduactional purposes only, [/SIZE]
| Joncas | 09-05-2002 09:35 PM |
I notice some serious drag/hp limitation around 105-110. Could be gearing in the auto I don't know. A stock RS will do ~134. I've seen the car do that.
It was tested it in a straight tunnel in PA. Nightime, enclosed, deserted... about as safe as it gets. Not that I recommend it.
It was tested it in a straight tunnel in PA. Nightime, enclosed, deserted... about as safe as it gets. Not that I recommend it.
| Avenger | 09-05-2002 09:37 PM |
There was an artical on SCC about the drag friction of the GC8 and it was like a brick wall compaired to the other vehicles they tested.
| jkjersey | 09-05-2002 10:09 PM |
hmm sum good replies esp the last 2
Well thank you for the replies please more replies would be appreciated I am trying to figure out if the from bumper is what causes the drag or the hood scooped out hood. I have a feeling its the bumper... but I do not know for sure. You see I do allot of highway driving and when I do the turbo conversion I mean I will not be racing mustangs but I don't want a brick car it looks sick asssssss I mean i really love the look of the bumper so I may get it anyway but I do know one thing the hood makes a huge difference on a L owners car see annointed's pic for example I mean his front bumper isn't really that intrusive so I would think that aerodynamics still would be ok> ? check the link
[url]http://www.subarureview.com/bio.php?name=annointed[/url]
ty for all the replies so far, jay K
[url]http://www.subarureview.com/bio.php?name=annointed[/url]
ty for all the replies so far, jay K
| ian22b | 09-05-2002 11:09 PM |
Frontal area has a lot to do with the drag generated by a cars aero package. You may not care much for nascar (I know I don't) but if you look back to the early 70's they demonstrated how variations to frontal aerodynamics could drasically change a car. Dodge had the Charger (same as the road runner), and the Charger Daytona (same as the Superbird) and the Charger Daytona took a stock daytona and added a cone to the front so that the front area was changed to a more bullet like shape. The Charger Dayton was so much faster than the other nascar vehicles it was outlawed (well the cocepts behind it were out lawed so no one could do it).
Ok, the point of that was, it is probably the front end that is causing most of the drag. But I don't think the L is the much more aerodynamic though, and the RS should handle better because it does not let as much air underneath it.
Also the scoop on the hood probably messes up airflow too, but odds are those effects are negligable.
Well I said a lot there, and nothing at the same time, i think that takes talent. lol...
Odd aerodynamic detail, the Porsche 928 is the most Aerodynamic porshce ever made (well when driven backwards, some of the boys at igolstat god bored and put some cars in the wind tunel backwards).
Ok, the point of that was, it is probably the front end that is causing most of the drag. But I don't think the L is the much more aerodynamic though, and the RS should handle better because it does not let as much air underneath it.
Also the scoop on the hood probably messes up airflow too, but odds are those effects are negligable.
Well I said a lot there, and nothing at the same time, i think that takes talent. lol...
Odd aerodynamic detail, the Porsche 928 is the most Aerodynamic porshce ever made (well when driven backwards, some of the boys at igolstat god bored and put some cars in the wind tunel backwards).
| Kostamojen | 09-06-2002 01:33 AM |
The 95's have freakin huge bricks for sideview mirrors... Some more aerodynamic mirrors might help.
There is also a front lip that seems like it might make the L bumper more aerodynamic and get rid of some of the under-car flow, but It has to be imported and costs $$$...
[url]http://www.rs25.com/Forums/showthread.php?s=&threadid=3652[/url]
There is also a front lip that seems like it might make the L bumper more aerodynamic and get rid of some of the under-car flow, but It has to be imported and costs $$$...
[url]http://www.rs25.com/Forums/showthread.php?s=&threadid=3652[/url]
| jkjersey | 09-06-2002 03:30 AM |
RS bumper vs L LIP
Kostamojen well do you think the aerodynamics of the L Lip would be much better than say the RS front bumper or a wings west replica V6 front bumper... I know you are not an engineer but just a younger dude like me (23) but like I just dont want to be in a situation that when I upgrade I will be like dam how come it isnt cutting through the air on the highway when going faster... say 95mph+
Would mirrors really help the smaller tucked in ones... I have seen them around.... should I upgrade the bumper or no is the question should I go halfway like annointed did ( i think his car looks great) or should I go all the way and get the bumper of an RS or a wings west kit one... the v6 replica.
Would mirrors really help the smaller tucked in ones... I have seen them around.... should I upgrade the bumper or no is the question should I go halfway like annointed did ( i think his car looks great) or should I go all the way and get the bumper of an RS or a wings west kit one... the v6 replica.
| stentorian | 09-06-2002 03:49 AM |
I would say that since you got plans to turbo your car, then get the RS bumper. I think you wouldn't notice the drag as much as with the tubro as when it's not turboed.
One of my friends has an RS that has turbo in it, and I sure as hell don't notice drag that much as when it was stock. Comparing it to my other friend who has a stock RS you can tell there is more drag, most likely because there is less power. Also the one with turbo does have suspension in it so it is lower to the ground as well.
If you were not to get a front mount intercooler you could keep the L bumper, but if you got a FMIC then get the RS bumper.
And if you get an RS hood you could always get the scoop so it is backwards for less drag ;)
-Joe
One of my friends has an RS that has turbo in it, and I sure as hell don't notice drag that much as when it was stock. Comparing it to my other friend who has a stock RS you can tell there is more drag, most likely because there is less power. Also the one with turbo does have suspension in it so it is lower to the ground as well.
If you were not to get a front mount intercooler you could keep the L bumper, but if you got a FMIC then get the RS bumper.
And if you get an RS hood you could always get the scoop so it is backwards for less drag ;)
-Joe
| Joncas | 09-06-2002 09:58 AM |
Double post - look below.
| Joncas | 09-06-2002 10:00 AM |
L - .32
RS (98-2001) - .35
WRX, RS (depending on wing option) - .34
RS (98-2001) - .35
WRX, RS (depending on wing option) - .34
| Julian | 09-06-2002 12:48 PM |
Wider tires of the RS also have an effect on drag. As does the RS wing (reference recent C&D story about wings versus drag versus downforce (and lack thereof)). The scoop adds to the drag as well. As does the RS front bumper - not so much because of how deep it is, but because of the bluff faces around the fog light areas. The car is a brick, compared to other modern cars without all the add-ons. People running top-speed events tape up everything, including body seams, to get the best aero effects.
But you can't tell a slippery shape just by looking at it. The old Datsun 240Z had a Cd of .43.
But you can't tell a slippery shape just by looking at it. The old Datsun 240Z had a Cd of .43.
| BOY | 09-06-2002 01:20 PM |
I think this link about sums it up...
[URL=http://www.autospeed.com/A_1055/page1.html]http://www.autospeed.com/A_1055/page1.html[/URL]
[URL=http://www.autospeed.com/A_1055/page1.html]http://www.autospeed.com/A_1055/page1.html[/URL]
| jkjersey | 09-06-2002 01:30 PM |
wow these are sum great replies now we are cooking.... I am definitely getting a gameplan in my head. I will start off with the hood with hood scoop and vents etc....... now there is a cusco giant hood scoop option even tho it is bigger dunno if it cuts thru air better. I have to ask Paul Eklund about that he is a cool dude he has hooked me up with sum great info esp about the 2.2 legacy turbo transplant I was considering (one being the strong ass block and two USA parts accessibility so say power steering breaks Im not stuck waiting for JDM parts). So first thing being compression test on my impreza 1.8L engine.... may get a leakdown test.... dunno yet.... if everything works out ok.... ill do the DIY subachad turbo with the top mount saab 900 intercooler since my boost wont be that high for drivetrain reasons and also for longetivity of engine reasons being that when I got my 1995 impreza L last year it already had 89K on it and now its at 110k. Subachad put his turbo on his 1.8L when his motor was 120k or so and was the guinea pig not having like say a S-AFC or good boost regulator from the get go so its ashame his engine went at 153k. So I think I will go that route turbo timer to get in the mid to low 6 sec range 0-60 that I want to be (being consertative with times) my car weighs less than a RS not as little as say a FWD Legacy L but with my weight being less that will show in handling and help with the power to weight ratio a little bit. I was thinking about engine transplant but in the mean time I figure why not do the custom turbo and drive the car now in the meantime with more ummphh and go.. then down the road I want more I put some of the parts say the turbo and uppipe and downpipe on I club cause there will be many other L owner that would be interested. Down the road if I want engine transplant I would do it and have the money saved up for the labor involved since I am not a mechanic which is a serious downside for me being involved in such a project. I have a dual tip stromung on the car already and did the silencer removal mod I noticed sum improvement on the highway so I was happy with that. When I get the turbo I'll get the midpipe 2.25 for now or a custom 2.5 but then my muffler is 2.25 so I dunno if that will mess up the backpressure airflow. I am purchasing H+R sport springs today with KYB AGXes new. So which brings me to my next mod my hood I want the RS/WRX hood without a doubt appearance wise and also turbo wise if I go top mount intercooler its a no lose situation from there I would go on the highway cruise 95 mph-110 or so for a decent while and get a feel if I really notice a difference. Then do the turbo... then drive again... then do the power side mirror mod Kostamojen was talking about they are pricey for power ones like 345 dollars I saw.. see if I notice difference.. then save the rs bumper for last if I really think my car looks incomplete without it.. ( I do love the look of rs / v6 wrx bumper tho) So thank you all for your help and sorry if I went on with my gameplan of performance mods in the dressup section. I just want your guys take on my plans please if you feel I should skip steps or do them in diff order or even scrap and go sum other route I didn't consider please feel free to add in... I mean I could get another car say an RS but then I have to sell this car lose out on the custom stereo install labor I had done etc.. tweeters near kick panels for imaging..etc... I mean I got my car for $5400 through NADA dealer only auction so at least Im not in the hole for money in it already. The new wrxes are dope esp if you want the new ride feel and all but I dont like the way cars handle in extreme situations over the 3,000 lbs mark.. except say if its an M3 :) i mean awd or chassis wise strength wise soup ups or not weight is weight.. they can mask it and do physics to compensate for it. I will say however wrxes for the usa market was the best thing for subaru and aftermarket. They are bad ass machines truly sick ass.. black ones with the sti lights do make them look much more aggresive and meaner when you get rid of those oval clear white headlights and your at a light and the young honduh kiddies with there cars not done clean are thinkin twice about stepping on the gas cause they r like dammm that wrx will prob stomp me like paulbunyan would rip out a oak tree.
Damm long post i need to get going peace, jay K
Damm long post i need to get going peace, jay K
| John2.5RS | 09-06-2002 01:44 PM |
how do you say, "Rambling"? :o J/K
| jkjersey | 09-06-2002 01:47 PM |
:eek: :cool: :D
| Keiho | 09-06-2002 01:49 PM |
Get a fmic and reverse the scoop for better aerodynamics if you're really that concerned. A lot of Japanese tuners also offer tiny sideview mirrors for better flow as well.
| JC | 09-06-2002 07:04 PM |
What about a body kit like Prova? Should be better than stock.
JC
JC
| Kostamojen | 09-07-2002 01:16 AM |
[QUOTE][i]Originally posted by Joncas [/i]
[B]L - .32
RS (98-2001) - .35
WRX, RS (depending on wing option) - .34 [/B][/QUOTE]
That sounds about right...
I dont think any kit could get better aerodynamics than the older L's from looking at the bumper design and all.
Lower it a little for less under-body flow, stick some sort of lip on there to get rid of the flow some more (maybe something like Gary-sheehans racecar :lol:) and fix the sideview mirrors and the CD might get a little lower even...
[B]L - .32
RS (98-2001) - .35
WRX, RS (depending on wing option) - .34 [/B][/QUOTE]
That sounds about right...
I dont think any kit could get better aerodynamics than the older L's from looking at the bumper design and all.
Lower it a little for less under-body flow, stick some sort of lip on there to get rid of the flow some more (maybe something like Gary-sheehans racecar :lol:) and fix the sideview mirrors and the CD might get a little lower even...
| MagicMT | 09-07-2002 01:22 AM |
1. slam it to the ground
2. get a custom chop-top
3. get a huge aluminum spoiler
That should help a lot.
2. get a custom chop-top
3. get a huge aluminum spoiler
That should help a lot.
| subachad | 09-07-2002 02:21 AM |
Hm... I have some of this info on my site. :)
[url]http://www.uniquemotorsports.com/tech_articles/calculator.htm[/url]
Chad
1.8T
[url]http://www.uniquemotorsports.com/tech_articles/calculator.htm[/url]
Chad
1.8T
| JC | 09-07-2002 02:42 AM |
[QUOTE][i]Originally posted by Kostamojen [/i]
[B]
That sounds about right...
I dont think any kit could get better aerodynamics than the older L's from looking at the bumper design and all.[/B][/QUOTE]
What aspects of the design are you refering to? Feel free to get technical, I'm a Junior studying Aerospace.
JC
[B]
That sounds about right...
I dont think any kit could get better aerodynamics than the older L's from looking at the bumper design and all.[/B][/QUOTE]
What aspects of the design are you refering to? Feel free to get technical, I'm a Junior studying Aerospace.
JC
| Kostamojen | 09-08-2002 02:21 AM |
1 Attachment(s)
Well its just a visual thing... Take a look and see: (this bumper looks much more aerodynamicly friendly):
| JC | 09-08-2002 12:23 PM |
Doesn't really looks that much more friendly to me. On the RS, your biggest problems are gonna be the fogs, which could be solved with covers. Keep in mind the big opening in the middle is open. Air flows through it into the radiator. While you may add some drag, you are getting better air flow. IMHO, cover the fogs, remove or reverse the scoop and open up the hoodvents and the RS would be more aerodynamic and stable than the L.
JC
JC
| stever | 09-08-2002 01:03 PM |
The ducts outboard of the fogs are pretty bad too, but there's not much you can do about that. If you really want to improve front end aero and cooling efficiency, make a proper duct to the radiator. Seal it to the front end and the radiator so all of the air that goes in has to pass through the rad. The duct should also expand in area so that the velocity at the radiator face is lower than the freestream velocity. Drag increases with velocity squared and by doing this, you reduce the drag of the radiator and increase it's cooling because the air has more time in contact with the rad, so it transfers more heat.
Anyway, the front of the GC8 isn't really the problem, it's the rear. The rear window is pretty steep and causes a lot of turbulence and therefore drag. You could put vortex generators (those little triangular things) at the top of the rear window and that would help keep the flow attached. They look pretty bad though and the molding over the rear window should really be flush to make it work.
Best and easiest improvement in my opinion is to make the bottom flat ... including the engine compartmnt. Just as long as you don't keep too much heat in or start fires. A good place to dump the high pressure air from the engine compartment is behind the front wheels where the natural low pressure will help suck it out.
Ramble ramble. Anyone wanna build a GC8 race car?
-Steve
[email][email protected][/email]
Anyway, the front of the GC8 isn't really the problem, it's the rear. The rear window is pretty steep and causes a lot of turbulence and therefore drag. You could put vortex generators (those little triangular things) at the top of the rear window and that would help keep the flow attached. They look pretty bad though and the molding over the rear window should really be flush to make it work.
Best and easiest improvement in my opinion is to make the bottom flat ... including the engine compartmnt. Just as long as you don't keep too much heat in or start fires. A good place to dump the high pressure air from the engine compartment is behind the front wheels where the natural low pressure will help suck it out.
Ramble ramble. Anyone wanna build a GC8 race car?
-Steve
[email][email protected][/email]
| stentorian | 09-08-2002 05:50 PM |
stever: Ok so what about the rear of a pre 02 wagon, is there a lot of drag there? And then to answer your question about building a race car, sure as long as I don't have to put the funds out ;)
-Joe
-Joe
| Kostamojen | 09-08-2002 07:28 PM |
[QUOTE][i]Originally posted by stever [/i]
[B]
Ramble ramble. Anyone wanna build a GC8 race car?
[/B][/QUOTE]
Well that is my long term goal for this car :p I'd need a daily driver to replace it, and the $$$ to spend on it :)
[B]
Ramble ramble. Anyone wanna build a GC8 race car?
[/B][/QUOTE]
Well that is my long term goal for this car :p I'd need a daily driver to replace it, and the $$$ to spend on it :)
| JC | 09-08-2002 11:36 PM |
[QUOTE][i]Originally posted by stever [/i]
[B]The ducts outboard of the fogs are pretty bad too, but there's not much you can do about that.
-Steve
[email][email protected][/email] [/B][/QUOTE]
Ya, I was gonna say something about that. I figure you could fiberglass over them and the signals, then make the turns in the corners. Hey Steve, need an intern this summer? Cuz I need an internship. :D
JC
[B]The ducts outboard of the fogs are pretty bad too, but there's not much you can do about that.
-Steve
[email][email protected][/email] [/B][/QUOTE]
Ya, I was gonna say something about that. I figure you could fiberglass over them and the signals, then make the turns in the corners. Hey Steve, need an intern this summer? Cuz I need an internship. :D
JC
| markus | 09-09-2002 12:00 AM |
[QUOTE][i]Originally posted by stever [/i]
[B]The duct should also expand in area so that the velocity at the radiator face is lower than the freestream velocity.[/B][/QUOTE]
Are you saying the duct area should expand as it gets nearer to the rad, or the area should be larger at the front of the car and norrows as it moves towards the rad. :confused:
[B]The duct should also expand in area so that the velocity at the radiator face is lower than the freestream velocity.[/B][/QUOTE]
Are you saying the duct area should expand as it gets nearer to the rad, or the area should be larger at the front of the car and norrows as it moves towards the rad. :confused:
| stever | 09-09-2002 01:20 AM |
Yeah, tons of drag from the back of the wagon. Not much you can do about that. But on the positive side, a rear wing on the top has pretty clean flow as long as there's no roof rack. Probably has better weight distribution than the coupe too.
I'm all for building race cars, but I can't sponsor anyone ... I've got no cash :(
You could glass over the vents, but unless you're trying for some land speed record, I'd just leave it alone. Screw it ... it's a rally car. It goes slow and needs lots of cooling air.
As for internships, I can't offer anything. But I work at Swift Engineering and who knows what next Summer may bring. We have a 50% scale rolling road wind tunnel here as well as the CFD stuff that I do.
As for ducting ... yes, you want the duct to be bigger at the face of the radiator than the opening in the front of the car. Most of that stuff was perfected in the 40's with WW2 airplanes. There are equations for the expansion that keep the air from separating from the duct walls. If it separates, then the flow becomes turbulent and that's really bad when you're trying to force it through a radiator. If you look at some race cars (particularly F1 and prototypes), you'll see that the inlets are pretty small and the radiator is usally angled, so it's actually bigger than it seems.
-Steve
[email][email protected][/email]
I'm all for building race cars, but I can't sponsor anyone ... I've got no cash :(
You could glass over the vents, but unless you're trying for some land speed record, I'd just leave it alone. Screw it ... it's a rally car. It goes slow and needs lots of cooling air.
As for internships, I can't offer anything. But I work at Swift Engineering and who knows what next Summer may bring. We have a 50% scale rolling road wind tunnel here as well as the CFD stuff that I do.
As for ducting ... yes, you want the duct to be bigger at the face of the radiator than the opening in the front of the car. Most of that stuff was perfected in the 40's with WW2 airplanes. There are equations for the expansion that keep the air from separating from the duct walls. If it separates, then the flow becomes turbulent and that's really bad when you're trying to force it through a radiator. If you look at some race cars (particularly F1 and prototypes), you'll see that the inlets are pretty small and the radiator is usally angled, so it's actually bigger than it seems.
-Steve
[email][email protected][/email]
Không có nhận xét nào:
Đăng nhận xét