anyone with a single turbo auto-x??? for all those who have, I have a question, do you guys think single turbo or twin turbo is better for auto-xing?? Ever since I switched to single, I seem to be getting slower lap times...

 

Auto-x is like 70% driver and 30% car. Chances are, you're just not "tuned in" with the single's power band. There are a couple MR2 guys in our club who run pretty competitive times. There is also one FD owner who runs the Apex'i RX6 turbo ... but, he's not a very smooth driver, so his times are not that fast.

But, running in BP or SM2 sucks because you're giving up so much torque down low to the competitors ... where torque matters the most in auto-x. I'm kinda straddling the fence on this one ... sorry. On one hand, it could be that you need to improve as a driver. On the other hand, it could be that the turbo lag/lack of low-end power is costing you on your lap times.

 

Twinn turbo is better for auto-X because you less lag. A single turbo will shine in the straight away on a autocross course but how many of those do you really have. For quick power at lower rpm's stock twins are the way to go.

 

There are quick-spooling singles that will suffice on an auto-x course. Local guy's Supra is running a small single and he runs VERY competitive times. Likewise, the Apex'i RX6 turbo spools up very fast ... I just don't personally know how well that translates on course.

 

I have a TO4S/E6K FC, and it kicks *** at the autocross. A T78, or some other large turbo would be hard to drive do to the power curve, and spool time. The TO4S on the other hand is fine. Full boost by 3500rpm. Spool time/lag can be easily mitigated on the track by intelligent driving. If you utilize left foot braking you can almost always be at full boost. As always, autocross is about the driver first, and the car second. Best regards, Carl

 

if you read the latest SPORTSCAR magazine you can see the details of a yellow and orange 2nd gen rx-7 that has won the B Prepared national championships 2 years running. steve o'blenes is the driver from la. it uses a single turbo upgrade too so it is possible to have a single turbo autocross demon. it would take a hell of a lot of know how to tune it for the autocross course though and would put you in a prepared or street modified class. it might be good for street mod 2 if you are really serious about it.

 

Its quite difficult to figur out exactly which gear to stay in with a single turbo FD in an auto x... Sometimes it make me wonder if it is worth for me to shift for this part of the track or not.
Sometimes shifting will cost more time, and i will fall out of my power band.... but not shifting I am going to be too slow for that section of the track...
It gets quite confusing. I think it helps to run with a smaller diameter wheel & tire combo for this situation...

 

It would be sweet to be able to change your final drive fast and easy.

 

some auto crosser brings two sets of wheels faster than changing the final drive...

 

Sometimes it helps using adjustable engine rev limiter.
Setting the rev limit higher sometimes helps staying within the powerband if you can shift later. (not exceeding the engine's capability)

 

The "not-so-smooth driver" would be me . Well, either me or my father-in-law, but we're running within one ten-thousandth of a second of each other, so take your pick. We're a distant 5 seconds from the top FD. Cut me mild slack for having to run against Dan Pedroza and the Strelnieks' though.

And he's (RR1 - Is that you D.?) right. It's so much about driver. My RX6 has no difficulty staying in the powerband when I need it to. I rode along with another driver with twins this past event and noticed very little difference in shift points or powerband issues. All differences in turn-in, throttle application, hitting apexes and so on.

Practice makes perfect, regardless of turbo (small turbo anyway).

-E

 

Sequential is faster coming out of the corners. On an open track the single is great but for most auto x's the sequential will win.

Yes BP does have a very fast 2nd gen. However the car is also stripped and probably close to min weight.

I will either be in his class or AP next year.

Anyway stay with sequential setup for autox or you will be to slow coming out of corners.

 

Sequential is much faster in most autox courses. Yes on a very fast course the non or single may be better but I also said may.

You want to come out of the corners as fast as possible and not wait for the turbos to spool.

Yes in BP the 2nd gen is very fast and the driver is very good. However keep this in mind when comparing to a 3rd gen in SS or ASP. You cannot strip your car, you cannot change your rear end gear ratio, and you cannot run slicks. All of which the 2nd gen has.

So stay sequential in autox if you want to do well.

 

I'll reiterate that with my RX6 the spool up is almost identical to the twins. Probably 150 rpm difference.

-E

 

well, who autocrosses at 2000rpm?
as long as you got boost at 3500rpm its probably all the same...

 

My point exactly.

-E

 

a high HP single is going to be harder to drive, plus it does lag more. But...on the nationals course at Forbes Field in Topeka KS, it is WIDE OPEN and I think give advantages to the higher HP cars.

 

with the right suspension, a high HP cars can definetly benifit more. Usually a autocross car can have the suspension set on the stiffer side. With stiffer settings it is not always the best way to plant the power down.
I often have traction problem and resulting difficulties to be able to "full throttle"

 

Yep. I hear that. Even w/ only ~280rwhp, I have my adjustables on the lowest setting. I'm still adjusting, and I'll probably end up somewhere in the middle, but the hardest settings present a real problem out there.

The car was all over the place with the stiffest suspension. Things were *much* better on the softer setting.

-E