LT1 Head Coolant Modification ?

[240Z-DET]

I was looking at my LT1 on the stand and studied the factory coolant feed tubes in the rear of the heads. The whole thought process behind the reverse cooling was to be able to raise the compression while keeping detonation in check. So my question is, has anyone ever retapped the rear entry of the heads to any degree to allow more coolant flow to the heads and use larger AN stainless braided lines to feed them? In this could work, in theory the engine would run cooler and allow more aggressive timing. Am I off base here or on to something?

[jbc3]

Hmmm, interesting idea. Since I have never seen or done it, I won't say it will not give any gains, but if you are looking to run more timing you may be off base.

The LT1's tend to show performance gains when the timing is backed off a little on the high end of the RPM range. This is based on both my observations on the dyno and track performance. They like timing in the lower/mid range. I have as much as 50 degrees in the 3000 RPM range and back off to 35-33 or so over 5500 to my 6800 rev limit. I have seen this in both stockish motors as well as heavily modified motors. Some of the heavily modified numbers like 30 degrees on the big end. These motors are not detonating at the higher timing numbers, so it may not be a heat factor. I've tried up to 40-42 degrees of timing on the big end with no detonation, but the mph was down ~1 - 1.5mph. The car will MPH better at the track with the lower timing.

You may be able to get away with a higher compression ratio with more cooling volume... but with a 160 thermostat I rarely see the temp needle go above 180 except in traffic. Now that is in my 3800 lb F-body. When I get this same motor in my 280, things may change. ( currently 10.4 Compression, .040 over 385 stroker, 224/236-114 ) Going to 236/242-110 ( I think ) in the same motor when it goes into the 280.

[80LS1T]

I dont actually think it will help out much if at all. Im sure it wont hurt it. Those lines coming off the back of the head are not really there for cooling purposes but to releive any "steam"/ air that gets trapped in the heads. This way you dont get hotspots in the heads that could cause detonation.

 

Guy