can i run REGULAR unleaded for short stint?

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04-12-2006, 06:17 PM

#41

JasonU

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Quote:

Originally Posted by Wisconsin S2k,Apr 12 2006, 09:56 AM

because no matter WHAT CAR you drive, DETONATION HAS THE POSSIBLITY OF CAUSING DAMAGE!

[QUOTE]this is an incorrect assumption.

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04-12-2006, 06:52 PM

#42

Wisconsin S2k

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Quote:

Originally Posted by JasonU,Apr 12 2006, 08:17 PM

This is true, detonation is bad, I agree. However, detonation is NOT an all or nothing proposition. It doens't just go from fine to BOOM. If this was true, everyone who's ever tuned timing by making the engine ping and then dialing back would have destroyed their engines. One instance of detonation is not going to melt your engine. The ECU will catch it the moment it begins to happen, and will compensate.

Are the chances of damage ocurring likely? No. But not impossible. And it HAS happened. Even to users of this very forum.

Quote:

For some reason I doubt there is any actual proof of this. Didn't you just imply above that ANY detonation can destroy your engine? If what you say above is true, that our cars detonate on a REGULAR BASIS, even with ultra-premium fuel, how come our cars haven't all self-destructed? And I suppose since the highest octane I can get at the pump is 91, I'm just totally screwed?

re-read what I said above. it causes very slight preignition detonation on a regular day even with 94 octane. so if you take that and dump in 85 octane, you've just exacerbated the detonation. you're onto a higher degree of detonation. and while it's rare, it COULD cause damage. it has happened.

also, yes there is proof of this. hook up a bone stock S2000 to a dyno, with a device that can hook into the knock sensors. make a dyno run and watch it pick up slight detonation, and then watch the ECU pull timing. many have done it, including some of the most knowledgeable people on this forum. I myself have even seen it first hand.

Quote:

I agree, using high octane fuel IS the right thing to do, and your engine will run correctly because of it. Do not use regular gas on a recurring basis! HOWEVER, using regular unleaded in an emergency is feasable, and will not cause your engine to instantly destroy itself. There are many more factors than just octane, such as engine load, humidity, temperature, and altitude, that will make your engine knock. Put some regular in, drive lightly and easily, and get to the next gas station that has Premium.

Another point to add to this would be is that if you must use regular, keep it below 4000rpms and no heavy acceleration. then you're definitely asking for trouble!