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Old 01-09-2013, 01:27 AM   #1
tino
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Default How to prep subaru for 0-1000m event

Hig guys

i have decided to enter the Subaru in this coming event.

Its a 0-1000m timed event and for top speed.




a standard 2007 STI does 0-1000m with a top speed of 200 kph


My car makes 614 whp @1.9bar on E85 with still a heap of room to make some more power.


In my old subaru setup (575whp) i hit 134mph @11.3 down 400 m in 5th gear = 218 kph so with another 600 m should get deep into the 250-280kph at 8,500rpm in 6th gear?

Any suggestions in how i should prep the car, i.e suspension, aero, tyres, power etc?


This is the car:

Brief run down:

Built 2.5ltr sleeved, CD.
Low mount turbo BW EFR8374
V-mount
Corsa veloce intake

Ohlins suspension
MSI rear sub frame links arms etc

265 rcomps on a 10.5 inch wheel

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Old 01-09-2013, 08:57 AM   #2
Aceyduce
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Try the proven power bragging section. They're more straight line oriented and have a few that have done similar events. Best of luck!
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Old 01-09-2013, 10:15 AM   #3
Leafy
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Add all the power, remove all the drag.

More serious.
Make all the power
Small splitter maybe 3 inches out from the bumper with air dam that comes straight down from the end of the bumper
full under tray
side skirts, use the thick bristled brush stuff from 70-80 era F1 and amateur formula cars
Fenders completely cover rear wheels
Remove the hood scoop and add blockout plate
Remove that wing, add a long spoiler off the back at a very low angle of attack
Is that a roof scoop? Remove
Remove side mirrors
Tires, already on R comps? Might consider switching from A6s to R6s for a bit less rolling drag, drag slicks might get better off the line but I would be worried about how terrifying they would be in that long of a race
Tune the springs and dampers for the launch
LOTS of caster, get ALL the caster
Zero toe IF the car is stable like that, if not you'll have to add some toe in, but the more you do the more rolling resistance you add

Extra question, does the 6 speed have 6th gear high rpm oiling issues like the T56 in camaro/corvette/viper/etc?

Thats how I would theoretically go about prepping that car for a standing 1k.
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Old 01-09-2013, 10:41 AM   #4
3MI Racing
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^^^pretty much covered it. Taping all of your joints will well with drag as well.

I wouldn't put too much emphasis on the suspension set up for launch versus stability at 200 mph. A soft rear with low roll resistance could end up being you chasing your tail at speed.
Along the same note, talking with standing mile guys; they say that they don't net anymore speed with a good launch versus a slow launch. Which dynamically doesn't make much sense. My only thought is that with a good launch, they're eating up track at a faster rate than blasting the tires off first, second...third? and getting wheel speed up in a shorter distance (kind of like drag racing a Honda).
So basically distance versus wheel speed in the early gears, leaving more track to stretch the taller gears.

^^^complete BS guess as to why. Maybe I just got feedback from a few guys


Full undertray will further reduce drag too. It'll net you some downforce. How much depends on how well it's designed.

Do you have a trans cooler on your car, Tino?

Last edited by 3MI Racing; 01-09-2013 at 10:46 AM.
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Old 01-09-2013, 05:45 PM   #5
Patrick Olsen
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Quote:
Originally Posted by 3MI Racing View Post
Along the same note, talking with standing mile guys; they say that they don't net anymore speed with a good launch versus a slow launch. Which dynamically doesn't make much sense.

^^^complete BS guess as to why. Maybe I just got feedback from a few guys
The same is true even in a 1/4mi - your trap speed with a crappy 60' time is going to be pretty much exactly the same as it will be with a good 60' time.

How many runs are you going to get, tino? If you have multiple runs, perhaps you can experiment with some of the aero. For instance, at those sorts of speeds you'll be getting tons of airflow through your various coolers, so maybe you can close off some of the grille and lower bumper opening. Less air that's getting crammed through there means less drag.

Lower the car more if you can, and get the air dam that Leafy mentioned down close to the ground to minimize air under the car.
How well "tucked" are the front tires behind the front bumper? Maybe consider little wicker bills on the leading edge of the front wheel wells to push air out around the tires. (C6 Z06 and ZR1 have these - example here.)
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Old 01-10-2013, 09:30 PM   #6
tino
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Join Date: Sep 2003
Location: Down Under
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2004 GT40R-built 2.5
604 whp @1.8 BAR on VP109

Default

Quote:
Originally Posted by Leafy View Post
Add all the power, remove all the drag.

More serious.
Make all the power
Small splitter maybe 3 inches out from the bumper with air dam that comes straight down from the end of the bumper
full under tray
side skirts, use the thick bristled brush stuff from 70-80 era F1 and amateur formula cars
Fenders completely cover rear wheels
Remove the hood scoop and add blockout plate
Remove that wing, add a long spoiler off the back at a very low angle of attack
Is that a roof scoop? Remove
Remove side mirrors
Tires, already on R comps? Might consider switching from A6s to R6s for a bit less rolling drag, drag slicks might get better off the line but I would be worried about how terrifying they would be in that long of a race
Tune the springs and dampers for the launch
LOTS of caster, get ALL the caster
Zero toe IF the car is stable like that, if not you'll have to add some toe in, but the more you do the more rolling resistance you add

Extra question, does the 6 speed have 6th gear high rpm oiling issues like the T56 in camaro/corvette/viper/etc?

Thats how I would theoretically go about prepping that car for a standing 1k.
Thanks mate. Yes this is probaly what ill be looking at doing. I dont think ill add another spoiler on though just leave it as it is for a lil down force.

I havent heard much about oiling issues of the gearbox.

The 0-1000m is on an air strip so i think grip off the line will be at a minimum so id rather loose a bit off the launch to have a bit more grip. my r-comps are ad050s soft compound so should heat up nicely with a decent launch and give me some grip at higher speeds.

I need to work out what the max speed will be with my 2005 JDM STI DCCD 6speed box. I have access to a modena 6speed sequential box similar to what is used in andy forrests car, so may borrow that if the ratios wont be long enough with the standard box.

I am going to run this prova bumper which has a full undertray that covers the engine so this should help a bit in sticking the car to the ground. May even look at putting a flat bottom undertray to meet up to the rear diffuser.









Quote:
Originally Posted by 3MI Racing View Post
^^^pretty much covered it. Taping all of your joints will well with drag as well.

I wouldn't put too much emphasis on the suspension set up for launch versus stability at 200 mph. A soft rear with low roll resistance could end up being you chasing your tail at speed.
Along the same note, talking with standing mile guys; they say that they don't net anymore speed with a good launch versus a slow launch. Which dynamically doesn't make much sense. My only thought is that with a good launch, they're eating up track at a faster rate than blasting the tires off first, second...third? and getting wheel speed up in a shorter distance (kind of like drag racing a Honda).
So basically distance versus wheel speed in the early gears, leaving more track to stretch the taller gears.

^^^complete BS guess as to why. Maybe I just got feedback from a few guys


Full undertray will further reduce drag too. It'll net you some downforce. How much depends on how well it's designed.

Do you have a trans cooler on your car, Tino?
thanks Micah.. Yeh kind of makes sense that u are using up tarmac spinning gears. I will give both goes a try and see if there is a reflected difference.

I am thinking about putting in an undertray to meet up with my prova front undertray and rear hks diffuser.

I am going to try and win the subaru vs evo class in this event.

in regards to suspension settings im not sure i will do too much, id rather have it on the harder side so i have more control over the car at speed. But will need to speak to a few more ppl about this.

No i dont have a trans cooler, do u think this would be an issue over 30-40sec sprints?

Quote:
Originally Posted by Patrick Olsen View Post
The same is true even in a 1/4mi - your trap speed with a crappy 60' time is going to be pretty much exactly the same as it will be with a good 60' time.

How many runs are you going to get, tino? If you have multiple runs, perhaps you can experiment with some of the aero. For instance, at those sorts of speeds you'll be getting tons of airflow through your various coolers, so maybe you can close off some of the grille and lower bumper opening. Less air that's getting crammed through there means less drag.

Lower the car more if you can, and get the air dam that Leafy mentioned down close to the ground to minimize air under the car.
How well "tucked" are the front tires behind the front bumper? Maybe consider little wicker bills on the leading edge of the front wheel wells to push air out around the tires. (C6 Z06 and ZR1 have these - example here.)


I think we are going to build up to the 1000m and cars will need to qualify or show that they can go the distance. i.e probaly 1/8, 1/4, 600 m then 1000m. Id say maybe 5-10 runs in total so not a huge amount of experimentation will occur. There will be 200 entrants for this event so time will be limiting.

The front tyres will have to have camber to fit the gaurds so will stick out a lil. I could always put smaller rims on the car with skinnier rubber and see how it goes. That would probaly be a good idea actually.

The car can go lower so will do that as well, as blocking off and taping the front end.
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Old 01-10-2013, 10:47 PM   #7
Leafy
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Dont sacrifice too much suspension travel getting low. You need some travel to be able to soak up the bumps at that speed. Camber wont necessarily be bad, at lot will though since it can cause the car to follow any lines in the road surface.

Things to consider for the under tray. Trans and diff cooling, trapping of exhaust heat, and collection of leaked fluids.
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Old 01-11-2013, 10:43 AM   #8
Patrick Olsen
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Quote:
Originally Posted by Leafy View Post
Dont sacrifice too much suspension travel getting low. You need some travel to be able to soak up the bumps at that speed.
That's a good point. Don't want to be crashing off the bump stops @ 175mph!

Quote:
Originally Posted by Leafy View Post
Things to consider for the under tray. Trans and diff cooling, trapping of exhaust heat, and collection of leaked fluids.
Turn in Concepts posted in just the last day or two about having issues with all of that when they put a flat bottom on their time attack car. Obviously, that's running for longer than 30 or 40sec at a time, but even for a sprint I think you're right to mention it, Leafy.

Quote:
Originally Posted by tino View Post
The front tyres will have to have camber to fit the gaurds so will stick out a lil. I could always put smaller rims on the car with skinnier rubber and see how it goes. That would probaly be a good idea actually.
I almost suggested narrower tires, as my understanding is that tires are one of the biggest sources of drag. But I didn't suggest it because I was thinking that you don't want to go too narrow, as that contact patch is what's keeping you glued to road at speed. Then again, speed trial cars on the salt flats all run narrow tires, and they're running on a surface with much less available grip to begin with. They have the benefit of pushers to give them a rolling start, whereas you have to worry about getting off the line. Somewhere there's a balance of grip vs. high speed stability vs. aero drag, but I have no idea what the right answer is. Swapping wheels doesn't take that long - maybe bring along a set of wheels with 245s or 225s or something like that?

Last edited by Patrick Olsen; 01-11-2013 at 10:48 AM.
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Old 01-11-2013, 03:04 PM   #9
3MI Racing
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skinnier tires (I'd run 225 and check for speed rating) and sink those wheels into the fenders. Hellafunctional in reducing drag.

Hellaflush = fail
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Old 01-21-2013, 05:52 AM   #10
page2334
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question for top speed runs, since our gears are short would it be safe running a taller side wall tire? like 225/55/17 on sti bbs, Dunlop's SP Sport Maxx TT tires for the high speed rating, by my gear calculations with stock sti 6 speed gears you can net 202 mph or 325 kmph at 7500 rpms
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