My 340 build
OK, thanks. I've yet to go down that road... if I ever will.
FWIW, it actually has lower heat conduction than a standard AF-water mix so will run a bit hotter. But the fact that it has a much higher boiling point is probably of value in keeping the chambers a tad cooler when you push things hard.
Exactly. Even though water has better heat conduction, it also steams off quicker. That's how you get localized steam pockets and lose cooling effectiveness.
I found a website that had some testing of straight water coolant. It was interesting what they found. Essentially, they found that the more steam pockets that formed, the lower the system pressure became, effectively lowering the boiling point of the water, and then you get more steam pockets. It was a vicious circle.
I printed that all off but it either went with the W5 heads when I sold them, or Ive lost them. I'll never forget the year...it was 2000 and I was just starting out with the W5 stuff. I wasn't going to pull coolant from in between the exhaust valves on the intake side of the heads like the W5's are drilled to do.
Then I found that article and I did it. It was a ROYAL PITA to make the hosed clear my throttle linkage for the tunnel ram. But I did it because the article stated that on cylinder heads with side by side exhaust valves (SBC, SBM, BBM etc) that's where the first steam pockets formed. Then it was at the number 7 exhaust valve area because it fired right after number 5 (another reason to use the 2-3 4-7 swap firing order) and then I forget what happened.
A lot of good info has been lost over the years because it just gets ate up in the interweb somewhere. Somewhere there is a video of a dyno session of a 408 I did that went 545 HP at 5200. Have no idea where that went of how to find it.