#54052, "I think 15 psi is the most we can run on 91 octane"
I've been messing with my car lately and found that on our California poop ass 91 octane gas my car can run 15 pounds of boost without detonation. I've been running 17-18 pounds lately but I have to pull out too much timing to get the car to not experience detonation. I'm almost sure that the amount of timing I have to pull out is sucking more power than the 2 psi of boost is giving me. I've been messing with the programmable dis2 alot lately and with my 02 voltages at around .96-.98 at WOT I have to pull like 6 or more degrees before the detonation goes away. I also noticed that the more timing I pulled the richer my o2's were. I pulled like 9 degrees and my o2's went up to 1.02v. Now I am back to 4 degrees at 17 psi and I still get very minor detonation at times, not alot, but a spattering here and there. It appears to mostly happen when the weather is hot and humid. Anyone else run into this wall with this shit gas we have in Ca.
#54068, "RE: I think 15 psi is the most we can run on 91 octane" In response to Reply # 0
Hehe, can't give up yet... take a look at some WRX forums. Those guys are crazy! They have tried so many different turbos. You gotta get some colder air man... maybe you're at the point where you have to start looking at different turbos, could just be spewing too hot of air. Ever datalogged your intake temps?
1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/ Mark Galyan - Greenwood, Indiana
#54069, "RE: I think 15 psi is the most we can run on 91 octane" In response to Reply # 1
i've been testing on 18psi daily lately and it feels like my car can handle it with no problems. but then again here in Florida the gas is 93 octane so it helps me a bit even on hot days. i feel like i can even push it to 20psi, my EGT's and a/f is still right where it needs to be before 1550. i'm pretty sure i need to datalog it, but i don't hear any knock or pinging.
#54072, "RE: I think 15 psi is the most we can run on 91 octane" In response to Reply # 1
Well James, Colorado has the poopoo gas too. The only difference in my case and yours is going to be the elevation. You being at sea level or close to it and me being at ~6000 ft above sea level. My situation is kind of close to yours only I run into the same issues at about 19-20psi. I also don't need to pull quite as much timing as you, only about 2-4 deg max to get the audible detonation to stop. In the winter I can run 20psi w/ no timing pulled all day long and the car has absolutely no detonation. Again this has to do w/ my altitude and the scorching hot winter days of 45 deg.
I think a colder charge would help you out a little but it probably has more to do w/ the fuel then the charge temp.
What a/f ratio are you running? I try and keep mine at 11.5:1
#54090, "RE: I think 15 psi is the most we can run on 91 octane" In response to Reply # 1
I am probably getting the coldest air into my engine. I have an hrc FMIC and a 3inch cold air intake feeding the turbo. so, i don't think blowing hot air is an issue. i've decided that it is strictly the shit gas. At 17 psi of boost I usually do not get any detonation if i start pulling timing. what I have found is that I have been making less power at 17 psi of boost than I was at 15 psi because of the timing I had to pull. I zero'd my timing curve and made timing start to retard at about 7 psi of boost and go to 3 degrees at 17 psi. I am also pulling some timing on the rpm map, basically a straight line from 0-7500 rpm going from 0degrees at idle to 2 degrees at 7500 rpm. so that would give me like a 5 degree retard at 7200 rpm and 17 psi of boost. With this setup i still get a little det at higher boost. my 02's are a little rich(.98) and my egt's never reach past 825 at wot in 3rd gear. This leads me to believe that my fuel setup is okay. its just a timing issue now, but everytime i adjust timing, the 02's go off again. hehe i guess i should expect this, but it is frustrating when you gotta deal with 91 octane.
#54101, "RE: I think 15 psi is the most we can run on 91 octane" In response to Reply # 4
Im currently running 17psi daily....no detonation in sight, and the EGTs/AF are, if anything, TOO rich. but i like it safe. im in TN, so we get 93 octane. must suck to have to settle for 91, i feel for you guys. 1997 Silver RS Wiseco 8.8:1 Pistons(back to low compression!) Eagle Rods T3/T4 Turbo Custom FMIC Greddy Exhaust 440's Most current 1/8th mile time: 8.3@90mph 2.015 60'(Nitto Drag radials, i suck)
Search
Printer-friendly copy
0 Users in Chat
