smg944

iTrader: (34)

ok looking to run race fuel, now i have a few questions. what afr can i tune it to? right now at 93 oct. i run 11:1 afr. at 11.5psi. i have 2 choices of fuel 100 unleaded and 110 leaded. i want to run about 16-18 psi. also do i still need to retard the timing for the extra boost? mods are in the sig. i have a race comming up and i am not going to lose

rynberg

I have a feeling I already know the answer but has your PFC been tuned for your single turbo?

smg944

iTrader: (34)

yes its been tuned for a single... i want to safely run higher boost, i have herd of people running 12.5 afr's and 16+ psi with pump gas but i dont want to risk anything.

tookwik

With the 100 octane you will need to retard your timing if you want 16 psi. Maybe not with the leaded 110 though.

smg944

iTrader: (34)

the only thing i am worried about with 110 leaded is burning out my plx wideband o2 sensor. if i run 100 how much timing do i need to bring back. right now i am 2 deg. retarded from p13 up.

rynberg

If it's been tuned, then what are you worried about? What octane was it tuned on and at what boost level?

I don't know who you've heard about that is running 12.5 AF at 16 psi on pump gas, but if that's true, it would certainly explain all the blown motors around here.

I can in no way see you needing to run over 100 octane at only 16 psi.

Snook

iTrader: (12)

with just 1200s you aren't going to be able to make more than about 380rwhp safely = not a definate win if you're racing a decent car

I used to run 16psi all the time with the old setup on pump gas. Had the water/alc injection on though. I was told by Steve Kan that 15psi should be the max for safety on 93.

Fatman0203

BTW I was reading your mods, didnt notice an ignition amp you may want to look into one for leaded gas. I put 100LL mix 50/50 with my car and I get some high end break up sometimes.

Trevor

I'd run 11.5-11.6 on 100 octane...maybe 11.7-11.8 on the best leaded fuels. 12.5 is the leanest you want to go on a piston motor...I wouldn't touch that with a 10' pole on a rotary.

On a side note...if you're going to bother running leaded find some VP brand C16 fuel. You'll thank me later.

smg944

iTrader: (34)

well my car is tuned at 93 octane at 11.5psi boost. my afr's right now are at 11:1 and 10.5:1 close to redline. i thought with race fuels you could lean it out alot more. if i was to just dump in 110 leaded into the tank and not change the boost would my afr's still be the same? also i have a crane hi-6 ign. amp.

rynberg

Yes, your AFRs would essentially be the same.

This is a very simple problem, but I think you're looking for validation for something you know is a bad idea.

You are tuned for 12 psi. Anything above that is not tuned. If you run above 12 psi, you are risking a blown motor. Is it really worth blowing your motor just to try to win a street race?

Solution:

a) get tuned for 15-16 psi
b) run untuned at 15-16 psi, you may survive or you may blow the motor

It's that simple. And I wouldn't tune specifically for 100 octane, although I would run it for tuning (ie, leave a safety factor in timing).

adam c

iTrader: (2)

What are you going to race against?

smg944

iTrader: (34)

yea thats why i posted , i wasnt to sure about race fuels and how they were used. i do not want to risk damgaging my motor. i know my car now has about 310-320whp but i want to be close to 400whp. the race is against an evo8 , not positive on the mods yet but i will find out. if i dont race my buddy with a 99 cobra supercharged will shut him up. he has around 450whp. the only reason i even want to race is because he talks alot and he says he has never lost and blah blah. i seen him run against a stock sti , he was only about 1 car length ahead of the sti by 80-90mph. i can tear a stock sti apart. i think my fd with the 11.5 psi boost will beat the evo but i dont know by how much. i wanted to make it a kill . this evo8 is "claiming" 400 all whp. i been on the evo forum for about a year now and to get anywhere near that takes a ton of mods. will update later today with a list of his mods. thanks for all the responces.

adam c

iTrader: (2)

I beat a stock EVO fairly easily with less HP than you have. You will be at a disadvantange if you race from a stop.

Good luck

smg944

iTrader: (34)

ok the evo has full exh. intake with pipe, up-pipe, 272 cams, cam gears, and 20psi constant. i seen a dyno sheet in his shop for 331 whp. so that sounds about right for his mods. i need more hp before i would race him. i think we are pretty close right now considering my fd weighs less.

tcb100

I run 17-18 on 103 octane. Timing comes back one or two degrees from my setting for 93 octane, but with a lot more fuel.

Rynberg already gave you the right answer. Run what you are tuned on or pull the o2 sensors and get the car tuned for c-16. Trying to guess the amount of timing to pull out does not seem sensible unless you have spare motors.

GoodfellaFD3S

iTrader: (213)

at 14-15 psi you should crush him, just *do not* race him from a dead stop, no matter what boost you are running. trust me.

F0RSAKEN

lmao yeah, if you race from a dead stop you guys better be going real far, cause he'll kill you on the launch, and you'd need time to catch back up.

I beat a stock evo with my FD on the freeway, all I had was a DP, so virtually stock for stock.

cripsR6

Not to hijack, but have you had some bad experience with Sunoco's 116? Also, I dont suggest modding/tuning your car for the sake of shutting some dude up. Gas is expensive nowadays; let your Cobra friend waste his money on the evo. .02

Trevor

I've run Sunoco Maximal and a bunch of other leaded's from various sources in my Stealth. Of course they're almost all designed for bracket racers with large motors turning 5500-6500 rpm. That's the race fuel manufacturer's main customer so most of the leadeds you can easily aquire are formulated for that type of motor. The other leadeds made my Stealth lay down around town. You could tell you were running a leaded race fuel...no question. I assumed it was just because I was "over-octaning" the car and there was nothing I could do about it. Then I bothered to track down some C16 and give it a shot. The difference was immediate. It's truly transparent...the car is still peppy and responsive with pure C16 in the tank. On top of that you can run more boost and make more power than any other race fuel (except maybe $16-19/gallon VP Import). I've run a hair over 30 psi with C16 at the track...no problem. I've even accidentally made a pass at 13.5-13.6:1 and 25 psi. No knock...but the car was surging a little. The stuff is awesome. I'll never waste my time with any other leaded fuel again.

Of course the disclaimer is...
- Its a complete waste of money if you don't turn up the boost and tune for it (if you just want some extra knock overhead for a special event find some 100-103 unleaded)
- Don't even try to run it with cats in the car
- Be prepared for about 1/7th the O2 sensor life (according to a Bosch wideband white-sheet)