ghost Posted January 6, 2011 Share Posted January 6, 2011 Went today for the first fill up of my new 87 turbo GL. Took 35 bucks from almost empty. Started driving away before I realized I put 87 octane in it. When i first got it i was under the impression the EA82T requires Premium correct? All EA82's has that recommended i think (obviously more important on the turbo one). Oh well, should be fine to go through a tank of 87 right? Then Ill switch to 91 or 93 or whatever the standard is around, im not sure. I did notice while Ive been driving it a bit so far the engine seems to have a miss right when the turbo reaches boost, Im going to attribute that almost entirely to the lower fuel octane. Would i be mostly correct in that assumption? Link to comment Share on other sites More sharing options...
naru Posted January 6, 2011 Share Posted January 6, 2011 Probably. Always buy the best gas you can afford w/a turbo. One tank of 87 will be OK.Just don`t use heavy throttle. Link to comment Share on other sites More sharing options...
CHIM Posted January 6, 2011 Share Posted January 6, 2011 (edited) Went today for the first fill up of my new 87 turbo GL. Took 35 bucks from almost empty. Started driving away before I realized I put 87 octane in it. When i first got it i was under the impression the EA82T requires Premium correct? All EA82's has that recommended i think (obviously more important on the turbo one). Oh well, should be fine to go through a tank of 87 right? Then Ill switch to 91 or 93 or whatever the standard is around, im not sure. I did notice while Ive been driving it a bit so far the engine seems to have a miss right when the turbo reaches boost, Im going to attribute that almost entirely to the lower fuel octane. Would i be mostly correct in that assumption? That wouldn't cause it to missfire, if anything it would miss more on higher octane fuel. octain is a catalyst and the more of it you have in your fuel the less flamable the fuel will be. Thus why it's used in performance vehicles that have very high compression. running a low octain fuel in a high compression vehicle causes pre detination or "ping" wich is the sound of the fuel detinating before it should. Think of Diesel, not very flamable by itself but apply alot of compression and heat and it becomes very flamable. Edited January 6, 2011 by CHIM Link to comment Share on other sites More sharing options...
NorthWet Posted January 6, 2011 Share Posted January 6, 2011 I don't thiknk that I have ever used anything other than "regular" in my EA82Ts. Not necessarily something to brag about, just that unless you abuse it you will probably be just fine. The knock sensor (if it is working properly) should be able to deal with the lower octane under most conditions. You may experience a little less power and/or a little poorer gas mileage if you are using boost a lot. What do you consider a "miss"? It is possible that you are having abnormal combustion (detonation or pre-ignition) which would feel like a drop in power... or it could just be that your ignition system is not up to the task of igniting the mixture at higher boost pressures. Link to comment Share on other sites More sharing options...
ghost Posted January 6, 2011 Author Share Posted January 6, 2011 Well i guess "miss" is a bad word. It hesitates and bucks every now and then. The worst ive done to it is close to 4k rpm shifts but i dont think over the course of a tank i'll cause any real damage as long as im careful right? (i know around the 4-5k rpm mark is the normal shift point for these anyway) Heck my sister stupidly ran her 1990 Eclipse GSX on 87 octane for 3 years and nothing bad happened to that thing and it had double the power. Link to comment Share on other sites More sharing options...
CHIM Posted January 6, 2011 Share Posted January 6, 2011 im currenly running 14 psi boost on a stock ea81 and have no trouble running regular, given it did run better before they forced the ethinal junk, running super does seem to give a little better milage, other than that i don't notice much difference. Link to comment Share on other sites More sharing options...
Numbchux Posted January 6, 2011 Share Posted January 6, 2011 stock turbo compression, and stock boost on an EA82t does not require high octane. The biggest factor is ignition timing. Higher octane fuel burns slower. so if you're tuned for 87, and run 91, it'll burn later, which can be a problem (and vice versa). So no, do not just run the "best" available. Use what it's designed to use. As far as I know, stock timing is designed for low octane, but I'm not 100% sure. The FSM has separate specifications for all engine types that year (SPFI, MPFI, MPFI Turbo), but only one section for fuel, where it says 87. Link to comment Share on other sites More sharing options...
naru Posted January 6, 2011 Share Posted January 6, 2011 That wouldn't cause it to missfire, if anything it would miss more on higher octane fuel. octain is a catalyst and the more of it you have in your fuel the less flamable the fuel will be. Thus why it's used in performance vehicles that have very high compression. running a low octain fuel in a high compression vehicle causes pre detination or "ping" wich is the sound of the fuel detinating before it should. Think of Diesel, not very flamable by itself but apply alot of compression and heat and it becomes very flamable. Nah. The octane # is a measure of detonation resistance under specified conditions not actual octane content. Link to comment Share on other sites More sharing options...
naru Posted January 6, 2011 Share Posted January 6, 2011 stock turbo compression, and stock boost on an EA82t does not require high octane. The biggest factor is ignition timing. Higher octane fuel burns slower. so if you're tuned for 87, and run 91, it'll burn later, which can be a problem (and vice versa). So no, do not just run the "best" available. Use what it's designed to use. As far as I know, stock timing is designed for low octane, but I'm not 100% sure. The FSM has separate specifications for all engine types that year (SPFI, MPFI, MPFI Turbo), but only one section for fuel, where it says 87. Higher octane fuel doesn`t burn slower. Octane rating has nothing to do w/flame speed,just detonation resistance. You should read the gasoline FAQ. http://www.faqs.org/faqs/autos/gasoline-faq/part1/ Link to comment Share on other sites More sharing options...
naru Posted January 6, 2011 Share Posted January 6, 2011 I don't thiknk that I have ever used anything other than "regular" in my EA82Ts. Not necessarily something to brag about, just that unless you abuse it you will probably be just fine. The knock sensor (if it is working properly) should be able to deal with the lower octane under most conditions. You may experience a little less power and/or a little poorer gas mileage if you are using boost a lot. What do you consider a "miss"? It is possible that you are having abnormal combustion (detonation or pre-ignition) which would feel like a drop in power... or it could just be that your ignition system is not up to the task of igniting the mixture at higher boost pressures. Knock sensor can only react to detonation that is already happening. Link to comment Share on other sites More sharing options...
CHIM Posted January 6, 2011 Share Posted January 6, 2011 Nah.The octane # is a measure of detonation resistance under specified conditions not actual octane content. absolutly, but they obtain higher resistance by adding more octane. Link to comment Share on other sites More sharing options...
naru Posted January 6, 2011 Share Posted January 6, 2011 im currenly running 14 psi boost on a stock ea81 and have no trouble running regular, given it did run better before they forced the ethinal junk, running super does seem to give a little better milage, other than that i don't notice much difference. Probably because you are activating the knock sensor even w/super at 14psi. Easy enough to tell by monitoring the phase control signal voltage from the knock control computer while driving.(BY wire on the ignition module) Link to comment Share on other sites More sharing options...
CHIM Posted January 6, 2011 Share Posted January 6, 2011 Probably because you are activating the knock sensor even w/super at 14psi. Easy enough to tell by monitoring the phase control signal voltage from the knock control computer while driving.(BY wire on the ignition module) nope, that knock sensor hasn't been plugged in since the motor swap like 6 years ago, plug is all messed up and have been lazy about fixing it:lol: Link to comment Share on other sites More sharing options...
kanurys Posted January 6, 2011 Share Posted January 6, 2011 Ya, just keep it slow for this tank of gas. I have a naturally aspirated ea82 with decked heads to raise the compression. Even it pings like a bastard without premium fuel. A little pinging won't hurt anybody's feelings or the engine, as long as it's not long term. Maybe it's because I have the timing advanced so far, but I like low end torque for nerding around in the forest. Link to comment Share on other sites More sharing options...
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