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Oct 11, 2004 | 07:58 PM

jasonshurnas

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Intermediate

Joined: Jul 2004

Posts: 32

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From: winters ca

ping?

has anyone noticed that there is a pinging sound under a load??

i have had my c6 for several weeks now any only use supreme unleaded however when i hit the throttle sometimes i hear what sound like detonation ?? has any one noticed this??
maybe i should use an octane booster

Oct 11, 2004 | 08:01 PM

Donovan 572

Pro

Joined: Mar 2004

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Try using a different gas station first.

Oct 11, 2004 | 08:02 PM

David Lasic

Burning Brakes

Joined: Aug 2004

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From: Folsom Ca

Not surprised. We live in California where the best octane gas you can get is rated 91. Read your manual. It states that 93 is optimal.

This is because of the very high, for today, compression ratio of 10.9:1

That is extreme for this octance gas (91) even with all aluminum engine materials. The computer will back out a lot of timing due to this.

Other than expensive octane boosters like Torco, there's not much you can or should do.

Oct 11, 2004 | 08:58 PM

lager99

Team Owner

Joined: Jul 2003

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From: [Enter Unoffensive Comment Here]

Cruise-In VI Veteran

Cruise-In VII Veteran

St. Jude Donor '06

All I use in my ZO6 is 91. Shouldn't need to use a booster.

Oct 11, 2004 | 09:06 PM

David Lasic

Burning Brakes

Joined: Aug 2004

Posts: 1,110

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From: Folsom Ca

Quote:

Originally Posted by lager99

All I use in my ZO6 is 91. Shouldn't need to use a booster.

I've been following Andy's posts, A&A, on his work on the C6. He says the LS2 uses the Z06 heads without ANY change. So, a bigger bore with quench area unchanged from the LS6. Not only is there a power potential by opening up the combustion chamber to unshroud the valves, but a slight reduction in compression would not hurt. This would allow the computer to keep extra timing in there.

I also understand that Chevy uses a much more sensitive knock sensor mounted differently to accomodate this compression.

Add to this the 91 octane fuel in California, an oxygenated one at that, and you will have more susceptablility to ping.

I suspect that is another reason for the fat air fuel ratios to help keep combustion chamber temps down. Just my humble opinion. Although I have assembled many a high performance street small and big block, I have never been inside the LS2 or LS6.

Oct 11, 2004 | 10:38 PM

mlbz28

Instructor

Joined: Jun 2004

Posts: 107

Likes: 7

From: Ramona CA

What about adding a little 105 octane vp racing fuel to boost up the octane. My 69 Z28 has 11:1 compression. I add about 3 gallon to each tank and it works pretty good.

Oct 11, 2004 | 10:49 PM

David Lasic

Burning Brakes

Joined: Aug 2004

Posts: 1,110

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From: Folsom Ca

Remember the catalytic converters. Is this racing gas unleaded? That's not a consideration on your '69

Oct 11, 2004 | 11:03 PM

mlbz28

Instructor

Joined: Jun 2004

Posts: 107

Likes: 7

From: Ramona CA

Quote:

Originally Posted by David Lasic

Remember the catalytic converters. Is this racing gas unleaded? That's not a consideration on your '69

VP does make unleaded fuels legal in most states and according to their website (www.vpracingfuels.com) they are ok for cat converters. The problem would be availability. One station near me carries it but I haven't seen it to many places.