[Z06] Octane Question
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Melting Slicks
Joined: Mar 2003
Posts: 2,898
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From: Oklahoma City Oklahoma
Octane Question
Here in Oklahoma, 93 octane gas is getting harder to find, so many of us are now using 91 octane. Switching to 91 octane in my C4 has not brought on any noticeable performance changes, however, a good friend of mine with an 02 Z06 insists that running anything less than 93 octane in his car will put his PCM into "Low Octane" mode, therefore causing a noticeable "Seat of the pants" performance drop. Personally, I think he's nuts, but I may be wrong. Can somebody please clarify for me, is 2 stinkin octane points going to make a drastic performance difference on a Z06? TIA 
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Joined: Feb 2005
Posts: 61
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From: Clearwater Florida
octane
It's been some time since I read my owners manual for my 01Z, but I do recall it saying the car can be run on less octane. But the trade off would be less perf. My vote is he is correct!
Drifting
Joined: Jul 2004
Posts: 1,756
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From: Gulf of Mexico Florida West Coast
I Run 94 and feel the difference from running 93. Only out of the hole, not on a roll. Your friend is correct octane is power. 94 is rear here in Jersey. So I try and be safe not to get to low. Otherwise 93 Amoco or Mobile.
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From: King George VA
Originally Posted by CMYC4GO
... a good friend of mine with an 02 Z06 insists that running anything less than 93 octane in his car will put his PCM into "Low Octane" mode, therefore causing a noticeable "Seat of the pants" performance drop...
But... the car has two knock sensors nestled in the V of the engine. These knock sensors sense the inception of knock which causes the PCM to withdraw timing slightly to prevent knock. As timing is withdrawn, the HP goes down. But, I really don't think the PCM withdraws timing all the time on 91 octane, only when the knock sensors sense incepent knock, which may under conditions such as very hot weather, hard accelaration.
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Last edited by C66 Racing; Feb 13, 2006 at 03:25 PM.
Drifting
Joined: Mar 2003
Posts: 1,533
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From: Oklahoma City OK
You talking about Frisky's car? If so I would think since his car is tuned it would be even more so correct.
Yea.... finding "real" 93 around here is a bitch but if I am tuning or going to the track I hit up the 101 pump for about a 1/4 tank and 91 the rest.
Yea.... finding "real" 93 around here is a bitch but if I am tuning or going to the track I hit up the 101 pump for about a 1/4 tank and 91 the rest.
Melting Slicks
Joined: Dec 2003
Posts: 2,334
Likes: 11
From: las vegas nv.
Originally Posted by Subdriver
Your friend is only partially correct. I forget the octane that the Z06 goes into "low octane" tables (maybe someone with LS1 edit can chim in), but it is low. I believe as low as 87.
But... the car has two knock sensors nestled in the V of the engine. These knock sensors sense the inception of knock which causes the PCM to withdraw timing slightly to prevent knock. As timing is withdrawn, the HP goes down. But, I really don't think the PCM withdraws timing all the time on 91 octane, only when the knock sensors sense incepent knock, which may under conditions such as very hot weather, hard accelaration.
But... the car has two knock sensors nestled in the V of the engine. These knock sensors sense the inception of knock which causes the PCM to withdraw timing slightly to prevent knock. As timing is withdrawn, the HP goes down. But, I really don't think the PCM withdraws timing all the time on 91 octane, only when the knock sensors sense incepent knock, which may under conditions such as very hot weather, hard accelaration.
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Drifting
Joined: Jun 2005
Posts: 1,824
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From: Middleboro Massachusetts
I forget what the compression ratio is on a C4, maybe in the 9.5:1-10:1 range. 91 should be fine in that range so you shouldn't have any problems. Your friends Z however has 10.5:1 compression, and I personally would not run anything less than 91. Around here, I can find 93 quite easily and never had anything less in my tank. You never know when you really need fuel and the only offer might be 91, so you can use it without any adverse effects other than your pcm compensating for it, looking up a different fuel table to avoid pinging. Premium fuel for the Z is what you need, but I imagine it would still run on 89 if you had no other choice, but don't make a habit of it would be my thought.
Melting Slicks
Joined: Oct 2000
Posts: 2,524
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From: Stamford CT.
Originally Posted by VetteZ16
I Run 94 and feel the difference from running 93. Only out of the hole, not on a roll. Your friend is correct octane is power. 94 is rear here in Jersey. So I try and be safe not to get to low. Otherwise 93 Amoco or Mobile.
Ric
