87 Octane in a GT

mrsamwong · Post by **mrsamwong** » Sun Oct 12, 2003 9:29 am

Hi everyone, I'm new to this site and have a question. I just bought my Vibe GT at the end of the summer and I've been putting 87 octane in it. I haven't noticed any knocking or anything yet. How or will the lower octane fuel damage my engine? Sam

ragingfish · Post by **ragingfish** » Sun Oct 12, 2003 9:38 am

You don't hear knocking because the engine has a knock sensor. If it detects an inferior octane gasoline in the engine, it retards the timing to prevent knocking.Your results: poor performance, and over an extended time, possible engine damage.The engine is NOT designed to run on regular fuel. You must use premium, or any fuel 91 octane or higher. While you notice no ill effects now, you CAN damage the engine in the long term...Read this thread for more on this topic: http://forums.genvibe.com/zerothread?id=3421

goodvibe · Post by **goodvibe** » Sun Oct 12, 2003 11:12 am

The poorer fuel mileage you're getting with the timing retarded will help offset the extra cost of premium. Was this by accident or for savings?

Flip-Side · Post by **Flip-Side** » Sun Oct 12, 2003 11:30 am

quote:I haven't noticed any knocking or anything yet. How or will the lower octane fuel damage my engine? Its a good question Sam, so don't get put off by our responses. YET, is the key word here though bro. As the others have said, 87 octane isn't good for the GT. I didn't understand why the higher octane was needed at first either. But once I learned more of how the GT engine worked, it made more sense. The GT has higher compression (crushes a larger amount of air and fuel) than a normal vibe. Low octane gasoline can detonate at the wrong time, from the high compression alone and not the spark. That is why 92 octane is needed. If you dont hear knocking, I assure you that you are still suffering from hesitation, lower hp and torque, worse fuel economy, and shortened engine life. Simply put, if you use cheaper low-octane gas, it won't detonate correctly in your GT engine.

coratz · Post by **coratz** » Mon Oct 13, 2003 2:56 am

boy are you in for a preformance gain when you splurge on the good gas!!!!! as soon as your on empty go to sunocco and get some 94!!!!!!!!!!!! AND REV HER TO 8200!!!!

TopObject · Post by **TopObject** » Mon Oct 13, 2003 9:27 am

You're lucky to have 94. Here in Minnesota its 91 or 92.And our gas is 10% corncobs too. Doh!

LavaMyVibe · Post by **LavaMyVibe** » Mon Oct 13, 2003 10:46 am

quote:Hi everyone, I'm new to this site and have a question. I just bought my Vibe GT at the end of the summer and I've been putting 87 octane in it. I haven't noticed any knocking or anything yet. How or will the lower octane fuel damage my engine? SamWithout 92 octane, I do not believe that is possible to hit lift. So you're missing out on one of the best thrills you can have in this car (while driving that is )

saking2002 · Post by **saking2002** » Mon Oct 13, 2003 12:10 pm

When I got my Gt I look into the owners manual and its says that you have to use 91 or higher or it will damage the engine in the long run

Roadpig · Post by **Roadpig** » Wed Oct 15, 2003 4:01 am

Sunoco has 94? I'm gonna check it out tomorrow...so far it's been 93 for me.

coratz · Post by **coratz** » Wed Oct 15, 2003 5:25 am

for you technojunkies out there..... do you think mrsamwongs pcm will re learn his fuel/air/knock mix right away? seeing that he did this 87 octane thing since his car was new for a few months? maybe a battery disconect after a proper octane fill up???

mrsamwong · Post by **mrsamwong** » Wed Oct 15, 2003 5:32 am

Hi, thanks for everyone's input. Really appreciate it. And yes, you can hit lift on 87 octane I'll have to look into that ECU issue. Thanks for the thought.Sam

87 Octane in a GT

87 Octane in a GT

Re: 87 Octane in a GT (mrsamwong)

Re: 87 Octane in a GT (mrsamwong)

Re: 87 Octane in a GT (mrsamwong)

Re: 87 Octane in a GT (Flip-Side)

Re: 87 Octane in a GT (coratz)

Re: 87 Octane in a GT (mrsamwong)

Re: 87 Octane in a GT (mrsamwong)

Re: 87 Octane in a GT (saking2002)

Re: 87 Octane in a GT (Roadpig)

Re: 87 Octane in a GT (coratz)