Question for the Subaru Guys

Question for the Subaru Guys

Postby Terry.Murphy » Tue Nov 29, 2011 8:49 am

Hey All,

I started the 2.5L build for the RS and am curious as to which turbos you guys are running with them. I seem to think I remember reading a GT30 is a popular turbo for the hill cars but could be wrong. I will be building the car for more than just hillclimbs which will include an occasional autocross and some track days (I want to get my SCCA license next year). I have a source for a full vf37 twin scroll kit at a very affordable price and am thinking that might be the route I go to start. The only thing is is the price and required change of parts for the kit. It comes will all I need in the turbo, headers, downpipe, and uppipe. I already have a few spare turboback exhausts for standard turbo setups and in the interest in putting more money into the pistons, cams, valves, etc I may stay with a standard turbo setup, but I am torn. If anyone has suggestions or ideas based off of your much longer time on the hills with these cars that would be great. For now I intend on sticking with the 5 speed that is in it (Legact GT) and once that says goodbye, putting the RA gears into the original RS trans or going with the 6 speed swap. Thanks a lot and have a good one.


Murph
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2001 Impreza RS - Project Autox/Hillclimb/Track Car
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Re: Question for the Subaru Guys

Postby 3rdgendennis » Tue Nov 29, 2011 12:25 pm

Not Subaru-specific, but dont go too big...You are on and off the gas a lot in hillclimbing, so you don't want to be at the end of the straight before your turbo is spooled up. Joey K actually swapped his turbo overnight a couple years ago because the one he had was too big (this was at Philo, the smallest of the hills)
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Re: Question for the Subaru Guys

Postby STI NICK » Thu Dec 01, 2011 10:04 pm

I currently have a 3071 on my STI. It does pretty good on the hills. I dont think I would want anything bigger. The lag isnt to bad, but it does take a little planning on some of the tighter turns. Great mid and top end power. not so great for autoX. doable, but not great. Works great for track.

My mount washington setup uses a vf48 turbo with a restrictor. That gives fantastic low and mid range power, and chokes in the top end.
If you can manage the twin scroll I dont think you will regret it. I am hoping to do a twin scroll set up soon. Give Joey at Kales Custom a call. I know he has a bunch of twin scroll stuff in stock.

I would also recommend doing the 6 speed. extra gears are always fun, and the cases are stronger. the RA gear sets while stronger you are still putting them in a weak 5 speed case. if you are thinking of putting a 30R turbo in your car and beating on it at various car events the 5 speeds wont hold up. There are a couple people on here that have tried the 5 speed route, and now have a 6 speed after going through a few 5 speeds.

Have fun with the build and hope to see you at the hills.
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Re: Question for the Subaru Guys

Postby walterclark » Fri Dec 02, 2011 7:02 am

What about anti-lag to keep a big turbo spooled? Anyone tried it for hillclimb? Seems to be the norm for stage rally - where it is permitted such as in the open classes.
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Re: Question for the Subaru Guys

Postby BugEyeRex » Fri Dec 02, 2011 8:34 am

NIck is right about the transmission. I went chewed through 3rd gear 3 times on my 5 speed transmission before I got a 6 speed. My 2.5l with 2.0l heads has a TD-04 turbo on it. The turbo is really too small for the engine. I love the instant torque down low (all of it available at 2000rpm) but there is little power mid to the top end. Great autox set up. I'm also trying to figure out what the next turbo will be while I'm saving up funds.
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Re: Question for the Subaru Guys

Postby sachilles » Fri Dec 02, 2011 10:44 am

walterclark wrote:What about anti-lag to keep a big turbo spooled? Anyone tried it for hillclimb? Seems to be the norm for stage rally - where it is permitted such as in the open classes.

I was under the impression that it isn't great for the longevity of the turbo. Being that we tend to be a more frugal bunch, I can see it being a more wallet based decision.

I also got to say riding in Nick's car at Burke with the restricted vf48 setup was darn nice. Had a tough time wiping the grin off my face. Wonder how it would be "unrestricted" in Nick's car.

Joey put a vf48 in my new to me Legacy, which I've yet to get tuned. I've had the tune dialed back while the motor breaks in. Even as it sits now, it will wipe the floor with my 2.0l wrx, which has a turbo back exhaust and a good tune. The VF48 seems to be pretty reasonable in terms of price for lightly used ones(why I bought it in the first place).
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Re: Question for the Subaru Guys

Postby Terry.Murphy » Fri Dec 02, 2011 9:10 pm

Thanks everyone. I haven't even thought of the vf48, I forgot they make them for the 02-07 model years as well and I think it's one worth looking into. The RS currently sits a hair over 2500 lbs and I plan to get another 50-100 or so out of it this winter. With the turbo swap I believe it offsets that loss and I am also adding some more roll cage to it as well so I am thinking the car will be in the 2600lb range, which I would think puts it 500-600 lb lighter than the STI's you guys run. I would think that the power needed wont be as high as what you guys are running just due to the weight difference which is why I was ruling out anything bigger than a gt30.

Chris, do you have interior in your RS? I forgot as I only caught a few peeks at it. I have td-04 experience as well, my daily driver is an 06 WRX sedan and I understand that top end loss. I have a vf39 in it now with the usual supporting mods and its running 300whp/310tq which seems to be perfect for a DD. I have even thought that a vf43 would be sufficient but I almost feel both of those turbos would drop off too quickly at hills and track days.

After some more thought, I think I am in between the vf37 kit, hta68, evoIII16g, and a vf48. I would love to run a 6 speed but my budget is nowhere near where it needs to be to swap over to one. I suppose its not much more than rebuilding with the 5 speed RA gears, however.

Thanks for all the thoughts again. It's tough making a choice sometimes so the extra set of heads really helps me move closer and closer everytime! I am really looking forward to running with you all again. I had my first hillclimb driving experience at Ascutney 2 this year and fell for it! Have a good holiday.

Cheers
Murph
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1996 Legacy Outback Wagon - Winter Beater
2001 Impreza RS - Project Autox/Hillclimb/Track Car
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Re: Question for the Subaru Guys

Postby BugEyeRex » Sat Dec 03, 2011 3:28 pm

My Subaru is actually an L and not an RS. I have an 02 wrx interior in the front half of the car. The door panels are from the L. The passanger seat is a wrx one and the driver seat is a Sparco Evo2 seat. Behind the front seats is gutted. I have never had a chance to weigh her and there are a few more things I can do to lighten her.

I hear you on the cost of the 6 speed swap. The cost along with weight saving made me stubbornly stay with the 5 speed until I was sick of spending money replacing it. I did consider upgrading the gearset until I read a lot of raced Subarus would still strip gears. There are many people that have had success with a 5 speed, but after researching what those owners' definitions of a hard driven car I decided not to risk it. The funniest part of my research was being told that I was shredding 3rd gear because I can't drive...little did they know I also would race my 02 wrx (with the "glass" transmission) and the gearbox has never failed. Plus the gearbox always broke when someone else was driving it! :lol:
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Re: Question for the Subaru Guys

Postby Rabbit Farmer » Sat Dec 03, 2011 5:35 pm

My car is not a Subaru, but I also held on to the cheaper 5-speed for years... I think I broke 2nd and then 3rd in one year. Went to the 6-speed the following year (6-speed boxes in the VW world are also a lot stronger than the 5 speed) and never had a problem. It was worth the expense and the effort.
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Re: Question for the Subaru Guys

Postby agrabau » Sun Mar 25, 2012 3:05 pm

I would skip the VF37 and the expensive hardware needed to run it. Go with another VF turbo and run high boost/race gas and save money for a transmission like others are saying.

If you wanted to spend more get a GTX3071. Much better spool up than a GT3071 and not so big that it would be detrimental to your performance at a hillclimb. For autox you'd need ALS or a smaller turbo though.

I use antilag on my Evo for hillcilmb. It helps a lot. Turbo should last a long time given that we only drive about 30 minutes a weekend at best. Probably 3 years between swapping turbos depending on the intensity of the system and how much boost you want to make off-throttle.

If it were my car I'd try to find someone's STI takeoffs and get a water injection kit or use race gas and save for a 6 speed and R180 rear end.
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