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Discussion Starter #1
Alright, this past weekend I took my dawg to the dyno. I ran it on pump 91 octane. To my suprise on all three pulls there was detonation! I ordered my EGR block plates, Apexi AFC, new plugs, and plan to run a higher ocatane fuel. My question is, is there anything else I can do to ensure I won't get detonation again? Thanks!!
 
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Discussion Starter #2
PictureMeRollin said:
Alright, this past weekend I took my dawg to the dyno. I ran it on pump 91 octane. To my suprise on all three pulls there was detonation! I ordered my EGR block plates, Apexi AFC, new plugs, and plan to run a higher ocatane fuel. My question is, is there anything else I can do to ensure I won't get detonation again? Thanks!!
my question is why you would run it on 91 anways? can afford a supra but not 92 or 93 octane fuel ;)
 
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Discussion Starter #3
91 is the highest octane I have found in AZ.
 
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What ecxactly is detonation???? what does it feel like??? i know this is dumb but i just want to know if my car had the same problem. thanks
 
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Correct me if I'm wrong guys, I believe detonation occurs when the octane rating of the fuel isn't high enough to handle the heat and pressure. Instead of a single flame front forming when the fuel is ignited, multiple flame fronts form spontaneously throughout the combustion chamber. When these collide, the shock waves make a pinging noise and the piston receives a hammer-like blow.
 
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Discussion Starter #6
did you do the EGR mod before or after the detonation...

also, how much boost were you running??
 
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Discussion Starter #7
I dynoed without my EGR mod, i ordered it after. I was running 15lbs of boost. For some unknown reason I can't get anymore. My hoses are pulled, and I have checked for vaccum leakes, but cant find any. There has to be one somewhere though...
 

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I had problems with our great 'premium' here in Colorado with anything more than 15psi. 101 unleaded is your friend.

Now that the car is running a single, I can run 18psi on pump gas and the car runs well.

FWIW. Add some octane, and not octane booster - real octane (race gas).
 

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Suprahaha, you can't feel detonation, but you can detect its effects. When the car detonates, the computer pulls timing which raises EGTs and slows the car down. If its really bad, you can hear a 'ping' sound come from the engine. It can also show up on spark plugs as aluminum deposits (ex-piston metal) or sometimes melt the plug off completely.
 
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Discussion Starter #10
Damn 91 octane!

It seems that the new lower octane gas(91 octane is the best you can buy in California now)is causing detonation in alot of pressurized cars these days.

Just tonight, i felt the computer pulling back timing on my Supra while making a few hard runs through the gears, and my car is stock! I use the highest octane you can get now(91 octane),but it's just not cutting it. My friend, who works for Dinan R&D, was riding along with me and said their supercharged cars have been experiencing the same sort of problems with the new 91 octane gas.

Time to stock up on some barrels of race gas i guess.......
 

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You can get 101 octane at Saad Saads mobil station on 44st and Chandler Ave. Its close to Firebird so its conveniant.
 

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1) Yeah you might have to do that. Make sure your a/f is right also. Some people have had FPRs go bad.

2) The GReddy sidemount was tested by Reg Reimer. He says its not as good as the stocker. A better solution would be to remove the PCV hose going to the intake and clean out the oil of the stock IC. This prevents the oil mist from being sucked into your engine and lowering octane, and restores the effeciency of the IC. I promise your car will see more timing advance than with a dirty IC. 15-16 psi still seems kinda low.

3) Easier said than done on a Supra. Fortunately the stock ECU is very good about taking out timing in small pieces instead of all at once, IME. It seems to take a while to give the timing back though.

Yeah, what he said. Audible pinging is VERY BAD and usually doesn't happen on BPUs, even with very high boost. Well at least mine never has, regardless of the boost on 93 octane. I'd imagine it would take another problem or two for it to be audible.
 
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Discussion Starter #13
How do you guys go about ordering a drum of race gas? I'm interested in doing so, but have no clue how.

Grant, do you want to get in on this? :)
 
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