Have you thought about water/methanol injection? Also, I don't know which Cometic head gasket you are thinking of, but the MLS Cometic gaskets I used on my 347 stroker were actually thinner than a standard gasket, thus increasing compression.

Another thing that could be causing your engine to not take alot of spark could be hot spots in the combustion chambers or hot spots on the piston faces. Have you tried using a colder plug?

I asked the plug question on my first post.

Ben, I'm not trying to break your balls:nutkick:. Take out the spark plugs or bet this someone that has a code scanner (i.e. enkievette) and see which cylinders are having issues. Chances are it's not all of them. Check the plugs for fouling signs of excessive heat and carbon buid-up. If you can identify the problem cylinders then do an inspection of all the fuel and spark components on those cylinder. Check the plug wires and spark packs with a multimeter. Try swapping out the fuel injectors with some that you know work fine or switch them with ones from another cylinder and see what happens. If you can find anything wrong then get the car retuned. check your fuel filter also. If it;'se clogged it might work fine under partial flow conditions, but might have enough of a clog to prevent sufficient fuel at WOT.

I had considered alcohol injection, but on an NA motor that seems pretty gay. Cometic has a specific model for lowering comp by almost a full point on an LS motor. At least that's what I've heard.

I ran water injection on my Vette for 20 years. Once I tighted up the quench and cleaned the chambers smooth (and a little reshaping) and smoothed all sharp areas off the pistions, I could then do away with the water injection.

This was WITH Iron Heads and a true static compression of 11:1.

There has to be a reason you are pinging with such little full advance. Did you have the heads off this motor before you put it in your Vette? There could be some issues with the chambers and maybe a LOT of carbon build up. Just throwing thoughts around. I like BADASSC6 ideas though. :drink:

When the heads were off, they weren't particularly carboned up and I did a Sea Foam treatment (which has worked wonders on other cars I've done it to but nothing came out on the Vette, my guess is they're pretty darn clean).

My guess is this.
- Compression is perhaps higher than the advertised 11.1:1
- I'm getting fairly hot air. The intake is in the engine compartment and basically rests against the rad hose, not exactly ideal.
- Stock manifolds might be a bit restrictive causing unnecessarily high cylinder pressure/temp :huh:

It only pings if I'm on 91, on a hottish day and under load. Still though . . .

Fuel system (except injectors), plugs and wires were new and only have 7,000 miles on them now. Coil packs were older. I've done fully logged high speed heavy load runs the systems are all working as expected, no misfires, injector duty cycles are well within norms, no codes, nothing.

Bottom line, the combustion process needs to cool down or octane go up so I can put some real timing in. This is the basis of my original question, will an oil cooler actually cool the combustion chambers, or is it just to keep oil from breaking down?

Anywho, it's not like 391WHP is weak sauce and putting in a little Torco for safety now and then ain't such a big deal. But the idea some potentially meaningful power is only some timing away is alluring. I will get it retuned when I get some headers sometime next year. I'd love to get to 440WHP on my little NA 346.

Two things to consider 1) oil needs to get to a certain temp to rid itself of moisture. So it needs to get to about 180/190 degrees.
2) Cold oil does not flow well.

So first question; Are you planing getting your engine temp below or at 160 degrees?

So on compression, give me all your specs on bore and stroke, chamber size, type of pistons and dish or popup size. Don't forget gasket thickness. Do you have any idea of the piston depth at TDC below deck?

Lets see what's up.:huh:

How about FULL cam specs, if possible. If not what you do have on the cam.

I figured out how to get 91 octane to work with 11:1 with iron heads in the 80s.
Your engine will be simpler to figure out.\


Hold the phone-(another thought)--is your EGR valve working? If it isn't it can cause your engine to ping.

I don't think so. Stock (190 I think) thermostat for now.

Bore, Stroke, Piston Type and Gasket thickness are all bone stock LS1. I'm running the OEM MLS gasket. I can look up the numbers, but don't remember off the top of my head.

The heads are 4.8L Truck heads that have been milled and massively ported. 66cc chambers as I recall.


Un, no.

I'm pretty sure it was a comp cams. I don't have the cam card, but might have a receipt for model from the original owner . . .

224/224 114 LSA .566 Lift

Hold the phone-(another thought)--is your EGR valve working? If it isn't it can cause your engine to ping. That valve ACTUALLY helps keep combustion temps down.

The EGR valve thing could be a factor. That will need to be cheched
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"I don't think so. Stock (190 I think) thermostat for now."

We may want to lower that if possible. Computer uses temp to regulate a number of functions. Don't know if lowering the therm temp is possible on this year with out major Computer changes. Any one???

"Bore, Stroke, Piston Type and Gasket thickness are all bone stock LS1. I'm running the OEM MLS gasket. I can look up the numbers, but don't remember off the top of my head."

Ok, I'll work with that, but it would HELP to have gasket thickness.

"The heads are 4.8L Truck heads that have been milled and massively ported. 66cc chambers as I recall."

Ok, being milled is going to be a BIG factor. How much was milled? We really will need to know this. Or, is the 66 cc after milling?


"I'm pretty sure it was a comp cams. I don't have the cam card, but might have a receipt for model from the original owner . . ."


What I was hoping for was the intake lobe center line.

Don't gots one on my motor. I think 2000 was the last year and mine is setup like a 2001.