Higher octane gasoline bad for OZ?
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Joined: Aug 2002
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Originally posted by diesel_fan
There shouldn't be anything but an occassional light ping or spark knock from the engine once in a while, unless the place you fill up from has crap for gas.
There shouldn't be anything but an occassional light ping or spark knock from the engine once in a while, unless the place you fill up from has crap for gas.
A stock motor utilizing the octane recommended by the manufacturer should not ping or knock. Ever. Doing so is a sign of incomplete combustion or pre-detonation. Both are problems, and both are bad.
-M
i notice a difference in my car with 87 and 92 oct gas with 92 i get smoother faster acceleration 87 isnt as great and is slower but i do get better gas millage on teh same trip with 87 and im not trying to start some fight that is just how it is with my car
Evolving Member
Joined: Aug 2002
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From: Raynham, MA
So you'll NEVER ping on recommended octane - hmmm....
Take the car filled with 87 octane to Houston in the middle of summer. Drive through stop and go traffic on the I-10 freeway at afternoon rush hour in July or August.
You'll get pinging since the baked asphalt and heat coming off cars around you elevates the intake temp to about 115 deg F. The air temp is elevated enough that the 87 will ping in an engine without a knock sensor and mechanism to retard the ignition timing. If your car does have an ECU that can adjust, you'll notice how doglike acceleration will be since the ignition timing will be retarded to whatever is the maximum allowed by mfg design in an attempt to eliminate spark knock.
While living there for two years with a different "new" car it was immediatelty noticable - hell it was so hot a few times that even on 93 octane it would ping lightly under such circumstances.
Constant pinging is bad, but not a once in a while thing, for the reasons described here.
A useful link:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
Take the car filled with 87 octane to Houston in the middle of summer. Drive through stop and go traffic on the I-10 freeway at afternoon rush hour in July or August.
You'll get pinging since the baked asphalt and heat coming off cars around you elevates the intake temp to about 115 deg F. The air temp is elevated enough that the 87 will ping in an engine without a knock sensor and mechanism to retard the ignition timing. If your car does have an ECU that can adjust, you'll notice how doglike acceleration will be since the ignition timing will be retarded to whatever is the maximum allowed by mfg design in an attempt to eliminate spark knock.
While living there for two years with a different "new" car it was immediatelty noticable - hell it was so hot a few times that even on 93 octane it would ping lightly under such circumstances.
Constant pinging is bad, but not a once in a while thing, for the reasons described here.
A useful link:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
Last edited by diesel_fan; Aug 10, 2002 at 08:37 AM.
Newbie
Joined: Aug 2002
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Okay, point taken. Under normal operating circumstances, your car should never ping using the recommended octane. 115F is not normal... Though, we had a 112F day here about a month ago, and my OZ was just fine, even with the AC on full blast, using Chevron 87.
-M
-M
Evolving Member
Joined: May 2002
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Originally posted by ryancb
i notice a difference in my car with 87 and 92 oct gas with 92 i get smoother faster acceleration 87 isnt as great and is slower but i do get better gas millage on teh same trip with 87 and im not trying to start some fight that is just how it is with my car
i notice a difference in my car with 87 and 92 oct gas with 92 i get smoother faster acceleration 87 isnt as great and is slower but i do get better gas millage on teh same trip with 87 and im not trying to start some fight that is just how it is with my car
Newbie
Joined: Jun 2002
Posts: 21
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From: CT- the land of cops, potholes, and never ending construction projects
Maybe we should dyno cars with different grades of gas in them just to see if there is a difference... It could just be all in your heads, kind of like that thing when CD's first got popular, where if you drew a line around the outside edge with a green marker, it would improve the quality of the sound. I'm curious to see what the dynos say, because, theoretically, the grade of gas should make no difference at all in the performance of the car.
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