chrisw

iTrader: (2)

I am not sure what the compression ratio is off the top of my head... I do run cosie M2 cams, and they have an awesome torque curve that is very effective within the "autocrossing limits". After researching the gains on MIVEC engines using the same M2 cams, I really do think there are significant gains to be made with the MIVEC head over a ported & polished EVO8 head. Is it worth the cost of the head, wiring harness & ECU? sure why not?

With the turbo and cam combination I run, I have not run out of boost yet this season, but I am not running a 285 sized tire either so I don't have that change in gearing. I have not tried to bump the rev limits yet, or push the limits of the motor since I can't afford to replace it if it decides to chuck a rod through the block... I would like to try a 8800rpm rev limit, but my tuner will freak out and call me crazy since I would be overrunning the turbo at that engine speed...

overall I am very satisfied with my usable power band that I have. I could use more power to compete against the likes of EVOlutionary's beast, but sadly, my 3 year old Ohlins road & tracks are crapping out and getting harder to rebuild. At this point I need a more effective suspension setup to utilize the power I have available... (Yo! zzyzxmotorsports you listening??? )


I like the power setup I have now because it appears to be well balenced for my driving style. I need more power, a better suspension, and new 18" rims, to compete nationally but that's coming, albit at a much slower pace than I want...

hokiruu

iTrader: (19)

I think Gricev meant that he is almost always IN boost, not vacuum, during a run, not "running out of boost" in the sense of the turbo being unable to deliver in the upper RPM.

chrisw

iTrader: (2)

if he is talking about the effiecency of the turbo at high RPM, then I agree with what his is saying. The gearing advantage you gain with the 285 sized tire will put you in the upper rpm range faster than with what I run, a 275. The EVO 9 turbo (and fpgreen) will be in their maximum effiecency range at a higher RPM than with my TME turbo at the same rpm.

Either way, the differnce in performance from the different tire sizes and the gearing advantage you have with the 285 sized tire plays a much bigger role then the difference between the turbochargers.

griceiv

iTrader: (2)

I wasn't talking about efficiency, just rpm. My main point was we never are waiting for turbo lag or waiting for the turbo to spool....ever. So if i could trade away some of the low rpm performance in exchange for better topspeed in 2nd gear i would.

I think fitting bigger tires would be of more benefit then more power though. We'd probably end up in XP though trying to get the 335's to fit.

prostcj

iTrader: (17)

Bringing this topic back from the dead. I'm going to give a 2.3 a shot for next year's season. I'm going to run a 8K redline and stock gearing on 285/30's. If this setup keeps me on the limiter too much I will either try higher gearing or switching to a 275/40 set up. Another advantage of the 275/40 set up would be my weight limit would move down 200 lbs.
Anyone try running the 295/30 A6's on 9.5 in rims? I'm guessing it could fit on the rim since some are running 285s on 8" rims. The issue would be clearance in the rear since the the 285 A6's barely fit as is.

Robevo RS

iTrader: (16)

2.2 cosworth stroker with a proper cams/ i think 264's are good , RS stock turbo, that set up will make you happy at low and mid range . Also, stock or stock type manifold , no tubular; full TBE but no 3 inch. 2.5 is perfect, etc.
And most importantly a good tuner, who understands it is not for drag , and not just saying it, actually he does understands it.

garageGT

iTrader: (1)

our solution is;
2.3L stroker, tomei typeR cams, 3076R w/OE exh.manifold,
6spd OE transmission w/carbonetic carbon blade clutch,
Throttle position based fuel & boost maps on AEM EMS

this combo seems to work for tight and high speed courses, not perfect, but as close as you can get without doing too many changes for specific tracks..

buttonwillow video (using 3rd-4th-5th gears)
http://www.youtube.com/watch?v=jDRx0Q7jJnI

prostcj

iTrader: (17)

I'll be using Tamer for the tuning. I've had good luck with him in the past. The engine is a BR 2.3 that I've already obtained. A 2.2 probably would have been better but I took this engine in trade and was a much cheaper route for me.
My rev limit last year was 8250 and on the local courses (central Il) I would find that limit typically once per course fo less than a second.
Seems like the key will be having the best transient response possible, gaining speed coming out of slow speed corners seems like it will be worth more time than the end of fast sections. We'll see.
I am about 1.5 seconds off national winning pace on a 50 second course by my approximation so I'm guessing if I can ever find that extra speed I will be on the the rev limiter more.

Dallas J

iTrader: (1)

Pretty much anything mitsubishi can be run in SM. Want a v6 3000gt motor, by all means squish one in

My opinion on this is to have the most torque where you spend the most amount of time. Power falling off up top is ok if you get in that range maybe once on course. But think about this, are you slowed more waiting for lag on slow turns or cause you're power isn't pulling as hard up top?

At all the venues I race at, I have had to shift to third at one event and hit the 2nd rev limiter at one other (in 6 years, and I race a lot). I was running a 2.4l with an EvoIII and 2nd topped out at around 70. I spend most of the time around 3500-6500 rpms and that was perfect for what I made. If I got stuck slower no big deal, I had 20psi at 2500rpms.

My personal experience showed me that I was faster overall with more grunt down low than peak power up top.

kekek

iTrader: (22)

The 295 A6's are taller than the 285, but not wider. Should be no issue at all fitting them on a 9.5" wheel. I would think the extra height might lead to more rubbing in the front fenders.

John

prostcj

iTrader: (17)

Should equate to taller effective gearing then. This may be the route to o over the more expensive 4.11 gearing.
I can't for see an issue with height on my fronts. My rear had issues with rubbing until I went to a 12K spring rate.

fsmtnbiker

If you're running at a National level, you'll need 4.11 final drives to keep the RPMs reasonable. Even with the rev limiter at 8800+ rpm we were running out of speed in 2nd gear in the SM Evo I drove this year... And the 4G63 will not rev that high very many times before something bad happens. I think a 2.3 with 4.11's and a moderate turbo (BBK Full-ish)at about 30psi would be ideal for autocross. This should give you 70+ mph at less than 8000 rpm in 2nd gear, and full boost around 3200-3500 rpm in 2nd gear. Great powerband.

kekek

iTrader: (22)

You do any engine/head work to get to 8800 rpm?

fsmtnbiker

Supertech dual valve springs. Had Cosworth and Kelford cams at various times.

Like I said, there is a finite number of times the stock motor will rev that high; it's a pretty low number. I wouldn't recommend going over 8000 rpm with stock valvesprings, and maybe 82-8400 with aftermarket springs. The piston speeds get really high and things get very warm.