Buck531 Posted August 23, 2008 Report Share Posted August 23, 2008 Like it states. Is there much difference between 92 and 93/94 octane? I'm fighting some weird KR issues with my car and I"m wondering if 92 is worse than 93/94.. Can it really be THAT big of a difference? Quote Link to comment Share on other sites More sharing options...
Sparky Posted August 23, 2008 Report Share Posted August 23, 2008 3 octane points Quote Link to comment Share on other sites More sharing options...
OSUGT Posted August 23, 2008 Report Share Posted August 23, 2008 3 octane points 94-92=3? I'm no expert on ocatane points but... Quote Link to comment Share on other sites More sharing options...
phil Posted August 23, 2008 Report Share Posted August 23, 2008 10 cents Quote Link to comment Share on other sites More sharing options...
Ramsey Posted August 23, 2008 Report Share Posted August 23, 2008 vpower>speedway Quote Link to comment Share on other sites More sharing options...
Draco-REX Posted August 23, 2008 Report Share Posted August 23, 2008 92 is pig swill. Honestly, octane points count. It's a direct measure, so 92 will be less stable than 93 or 94. If you're having knock issues, just run a coupel tanks of 94 though the car and see if the issue clears up. On a 10 gal fill it'll cost you, what.. $2 more per tank? Quote Link to comment Share on other sites More sharing options...
rmezz13 Posted August 23, 2008 Report Share Posted August 23, 2008 something like the higher the octane the more boost you can create safely... something about higher octane keeps it from leaning out too much... i don't know i've never understood it because i never really cared to look into it - only have had N/A.... hopefully someone who knows will chime in Quote Link to comment Share on other sites More sharing options...
Draco-REX Posted August 23, 2008 Report Share Posted August 23, 2008 something like the higher the octane the more boost you can create safely.... hopefully someone who knows will chime in If we're talking about the funciton of octane, then you're close. He was just asking if there was a difference. Octane is an actual molecule. It's very stable (doens't burn easily). The Octane rating of a fuel is a way to judge how much of that molecule is in a specific volume of the fuel. THe point of it is to make the fuel more stable. During the compression stroke in an engine the air/fuel mixture heats up. Couple this heating with the temperature of the cylinder itself and there's a risk the fuel will prematurely detonate. This uncontrolled detonation is bad for a gasoline engine. One way to combat this (and maintain the timing and AFR you want) is to use a more stable fuel (i.e. higher octane). Now when you boost an engine, you're increasing those pressures drasticly. This, obviously, increases the chance of detonation. So higher octane fuel is even more important for forced induction applications. WHereas most N/A applications that are tuned for low octane fuel wont' see a benefit from higher octane (and can sometimes run *worse*). Forced induction engines can always benefit from high octane. So ultimately, if you have a turbocharged or supercharged engine you want the highest pump octane you can get. (Custom applications of both forced induction and normal aspiration can require stupidly high octane, hence race fuel.) Quote Link to comment Share on other sites More sharing options...
kenny Posted August 23, 2008 Report Share Posted August 23, 2008 I don't know what type of boost levels you're running but I'll give you an example... My frist Regal I always had the boost set at 21psi with 94 octane in the car. Any time I would put 92 in it I would have to lower the boost a pound or two or it would pull timing in 3rd gear. So yes, there is a difference, and what Draco said is correct and what I am too lazy to type. Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted August 23, 2008 Report Share Posted August 23, 2008 Torco race fuel additive. I always run 94, but had to run 93 today due to a limited selection of stations by Trails. This stuff is amazing. Quote Link to comment Share on other sites More sharing options...
SRTurbo04 Posted August 23, 2008 Report Share Posted August 23, 2008 I run nothing but 94 threw my car an bike.... if I ever have to put 92 in it it runs like cra0p an the a/f is off a bit....its a cheap inshurance ... Quote Link to comment Share on other sites More sharing options...
Rotarded1647545491 Posted August 23, 2008 Report Share Posted August 23, 2008 I understand these principals with regard to high performance/high boost vehicles, but dropping an octane point or two on a boosted grocery getter has never presented a problem for me In my A4 1.8T, which "required" 91 octane, I ran 89 octane with no problem/knock. I would knock like hell under hard accel with 87 octane. The Kompressor runs flawlessly on 89 octane as well. Of course this from a guy who wouldn't run under 94 octane in the FD. something like the higher the octane the more boost you can create safely... something about higher octane keeps it from leaning out too much... i don't know i've never understood it because i never really cared to look into it - only have had N/A.... hopefully someone who knows will chime in -rep for posting crap like this and wasting space...wasting space where reliable information could have been used. Pot, meet kettle. Quote Link to comment Share on other sites More sharing options...
sol740 Posted August 23, 2008 Report Share Posted August 23, 2008 93+ only in the EVO, but in my DD's its cheapie, and a fill up w/ premium every 8-10 fill-ups. The way it was explained to me was boosted vehicles need high octane to burn evenly and thoroughly to prevent possible detonation. That it helped n/a engines with high compression, or high revving engines. Or for non performance cars, just to clean em out every now and than. This is just what I was told so don't quote me. Quote Link to comment Share on other sites More sharing options...
Buck531 Posted August 23, 2008 Author Report Share Posted August 23, 2008 Yes i know Boosted apps need higher octane, that's why I always put premium in it. I see about 8-10 PSI on the s/c now. I put on headers and the KR still hasn't gone down much if any. That's why I was wondering would I see a difference going from 92 octane to 93/94. Quote Link to comment Share on other sites More sharing options...
GonneVille Posted August 24, 2008 Report Share Posted August 24, 2008 Yeah, you should see a difference, IF you're getting real KR. If your torque management is pulling timing, it will show up under the KR meaurement for whatever reason. Also, is it constant when you're on the throttle, or is it something that appears and fades quickly? If running 94 doesn't fix it, run it by Dyno Brian. Quote Link to comment Share on other sites More sharing options...
Scotty2Hotty Posted August 24, 2008 Report Share Posted August 24, 2008 Sunoco 94 > Quote Link to comment Share on other sites More sharing options...
Miller Posted August 24, 2008 Report Share Posted August 24, 2008 Sunoco 94 > Shibam. Quote Link to comment Share on other sites More sharing options...
Draco-REX Posted August 24, 2008 Report Share Posted August 24, 2008 I don't know how sensitive the knock sensor is on your car. But a friend of mine was having a lot of timing pulled on his subaru, and a good portion of the knock that was being detected turned out to be a loose heatshield on his exhaust. Another guy was having knock issues and it turned out to be a bolt a mechanic dropped that was sitting on top of the knock sensor.. Just a couple random thoughts if the 94 doesn't solve the issue. Quote Link to comment Share on other sites More sharing options...
Sparky Posted August 24, 2008 Report Share Posted August 24, 2008 Shell or Sunoco FTW Quote Link to comment Share on other sites More sharing options...
kenny Posted August 24, 2008 Report Share Posted August 24, 2008 Yes i know Boosted apps need higher octane, that's why I always put premium in it. I see about 8-10 PSI on the s/c now. I put on headers and the KR still hasn't gone down much if any. That's why I was wondering would I see a difference going from 92 octane to 93/94. That doesn't sound like enough boost to be getting knock. Are you sure it isn't false knock? You could have a FUBAR motor mount or something equally as stupid. Quote Link to comment Share on other sites More sharing options...
Draco-REX Posted August 24, 2008 Report Share Posted August 24, 2008 That doesn't sound like enough boost to be getting knock. Are you sure it isn't false knock? You could have a FUBAR motor mount or something equally as stupid. Boost alone isn't enough to guage how knock prone it should be.. In an STI, 9-10psi wouldn't be an issue at all for 87octane because the compression is 8.2:1 or so. But if his engine is already at 10:1 compression, 9-10 psi would definately need 93+. Quote Link to comment Share on other sites More sharing options...
Buck531 Posted August 24, 2008 Author Report Share Posted August 24, 2008 That doesn't sound like enough boost to be getting knock. Are you sure it isn't false knock? You could have a FUBAR motor mount or something equally as stupid. Heh, I think I figured out what it was. My o2's were pegged to 1000+ when going wot. I figured shit.. I have an extra denso O2 sensor in the garage that I'll put in. Climb under the car and the o2 sensor is not even hand tight. so I change it anyways. Now the o2's are down to normal range and when I went around last night and scanned I wasn't getting any knock. I still need to lean it out a little but for now this will do. Quote Link to comment Share on other sites More sharing options...
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