Looking for some turbo advice... SM2 FC
 

I am in the process of a rebuild of my 88, and have been giving some thought to going standalone and a bigger turbo. I have been doing a lot of research, but am just not grasping the info that I need either due to a lack of comprehension, or it just isn't being shared.

Anywho, I am trying to come up with the best turbo choice that is suited for autocross. I am not looking for earth shattering numbers here, though if I am gonna put the money into it, I would at least like to see ~300hp at the wheels with as fat a curve as possible. I would love to figure out the best turbo to make this happen with the sweet spot from 3K~3.5K rpms to redline... I know.. I want the moon.

Anyone here willing to share what has worked best for them? Anyone know what the O'Blenes are running in their B-Prepared TII that keeps kicking butts at nationals?

The car will seldom see drag, will get some street use, but not daily driven. The most important thing to me in this build is autocross. The 80 has earned its retirement from CSP, so it is the 88's time to shine. Someone throw me a clue.

Thanks,
James

I was running a .81 P trim TO4S, Instant boost, 325-350rwhp, full boost at ~3200rpm spins 235-40-17 R compounds thru 1st, and 2nd gears. Probably cost ~650 new, that's my recomendation. Regards, Carl

That was with a 4" exhaust, and an E6K...

For the moment, I would probably adapt the RB turbo back system to whatever I go to as it is already on the car. Looking at e6k or e6x due to the large amount of support available. Also have a set of REW rotors and counterweights in route to have a small bump in compression in an attempt to quell as much lag as possible. Do you mind talking any specifics? What psi were you running to make the 325rwhp? What size injectors did you go with and what kind of duty cycle were you seeing. Any major fuel mods? Bigger pump than walbro? Rising rate regulator?

Sorry to pump for so much info, but your input is greatly appreciated. Thanks again, James.

Follow this link, then go to "modifications" the list is long.
http://www.teamfc3s.org/forum/member...iew&car_id=562

Spinning tires through 2 gears is bad news in AutoX.

Try a slightly smaller T-04. I just discovered something neat. I ran a couple of Autocrosses without any boost control just a heavy Wastegate spring. It was amazing how much faster the car was. No more wasting time counter stterring all the tire spin.

I actually took the tip from Cameron at Pettit. He said they tested the GT - FD's and they were faster without a boost controller. I like it a lot. Makes for a smoother run.

The ability to spin the tires was only mentioned to relate the availability of full boost at very low RPMs. I can assure you that to use anything smaller than a .81 P trim TO4 would do nothing but create large amounts of heat. I am willing to bet that there are NO competitive single turbo AX cars running a smaller turbo.
On the topic of boost control, you are simply loosing boost response, and the ability to hold boost near redline by eliminating an electronic controller. If this made you faster, it was because your driving ability did not allow you to utilize all the power you had available with the controller. A smoother run is certainly easier with a lower powered car, but if you learn to utilize the higher powered car you will be faster, all other aspects of the car being equal. There is substantially more time to be made up on straight aways than turns, this is a basic premise of racing. I know this sounds harsh, but slower response, and less power are not benefits.
As for Pettit's GT cars using a wastgate, and no controller, the only reason to do that would be for reliability.
To continue, since you stated that you ran on a spring only, you can still benefit from the controller, simply turn your boost down to the level you realized with the spring. This way, you will get the benefit of faster spool-up, and the ability to hold boost longer while still keeping your power down to a level you are comfortable with.
Regards, Carl Byck

Pettit specifically told me to loosemy boost controler for a couple of events and tell him what I though. He told me they experimented at Moroso West Palm Beach on a tuning day with removing the controller and letting the wastegate do the job and he cars were faster. It was not an issue of reliability it was a matter of experimenting and doing something others would not dream of doing and finding out it just might be better.

You prefer to have a lot of power come on really fast.

I like a lot of power to come on progressively.

I will be at the Rotary Revolution and have a AVCR in now. Running 1 bar on a T04E - 0.57 Trim 0.84 AR. I am heading to the dyno this afternoon to fart with this blasted AVCR and try to get it to do what I want.

With my old Profec B the boost would come on so strong even at half throttle it would break loose the tires in second gear pointing straight. (These are 10" wide Hoosier Slicks BTW) I would find myself driving around the course at 1/4 throttle constantly feathering it to keep the rear tires planted. Total waste of time. I prefer to concentrate on actually driving the course not feeling for my back tires spinning.

I bought this AVC-r in hopes of programming it to bring to boost on slower and more progressive. This way I am not sacrificing top end but I am getting better drivability on the low end.

I might just bite the bullet and get a Motec Ignition pack so I can free up an output and run a motec Controller. It has the ability to boost what I want when I want it. I just dont feel like re-wiring my entire ignition again.

BTW - I totally understand Straightaway speed will win races but unflortunatly this is Autocrossing it is rare to see a long straightaway. I saw one a few weeks ago unfortunately it had a 1st gear turn before and after it.
Gotta love it when your course designer drives a FWD low HP car.

Besides your telling me that my car boosting 1 bar with a boost controller is faster than it boosting 1 bar without?

The only difference I have seen is that I am able to get back on the gas sooner without it and let it accelerate out of a turn by the time I have me wheels back straight I am at full boost. So instead of feathering my right foot and pussy footing out of the turn trying to keep her from swapping ends I am pulling out nice and strong with awesome traction and screaming down the straight to the next turn.

"
The AVCR can easily perform that function as noted above. How does the Motec control boost? If it does not control a solenoid, it cannot modify boost via the wastegate. If you want to limit power output for purposes of maintaining traction, the RaceLogic traction control would be a far less expensive option to the Motec. RaceLogic is cockpit adjustable, it is fully programable, and can be set to engage as gradually, or as abruptly as you desire at whatever % wheelspin, RPM or combination of the two you desire.
Unfortunately it is difficult to completely, and accurately explain all the theory, and facts here. If you like, call me anytime at 707-696-2705, and I would be happy to discuss this all in greater detail.
Have fun, Carl

RX6
 

Single turbo, great boost response, very linear in power, will not overload your rear too soon but will build very fast.