<VV> Re: head temp VS HP

[djtcz@comcast.net]

> Folks, 
> What are your thoughts on how much horsepower a Corvair head can 
> take, heat wise, without shrouds, headers, properly de-flashed, etc? 
> Normally aspirated, no water cooling, .040 over SCCA GT3 legal or D Prod  legal bore and stroke, carbs on each plenum in road racing configuration.  Figure WOT for 15-20 sec on longest straights. 
> 
> Since I want to know what my limits are with all this horsepower I 
> would like to be making... . 
> 
> Equations appreciated and Guidance also helps. 
> 
> Thanks, 
> 
> Chuck S 
 
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That former Chevy engineer who spoke at a Corsa meeting several years ago (I think) said the first Turbo motors simply overpowered their stock cooling systems' capabilities, but mentioned it was OK for a while for practically all street use. So I think he was referring to steady-state full power conditions.  As the first Turbo was rated an optimistic 150 SAE gross, I guess the "limit" lies below that.  I thought it was pretty smart of Chrysler to put some kind of a time delay on their Turbo cars, so you could use more boost for frantic antics, but were limited to something more reasonable for cruisin'.
I ran my un-muffled 180 Turbo with a mild Crane cam and 140 heads without lower shrouds for several years through the 70s and recall the head temp being a lot lower than it had been stock. That combination seemed real sensitive to weather conditions. It had very good and very bad days. I figured on a good day it might be making nearly the stock 180 HP rating. But I could drive it up near the red zone (when I woul back off) pretty high pretty fast by driving real fast on the highway.  I think I only tripped the hi-temp buzzer one time when I was driving it with no fan belt in very short bursts to a place I could get off the road better.
As far as hurting the heads, I think it is possible to wreck them with stock power with carb and ignition settings. Here is a link to an article by the late, great, Gordon Jennings about the real issues (tain't the color) of reading spark plugs in hard working air-cooled engines - www.strappe.com/plugs.html.