Mandelon,
"What temp should I be running?..."
Not as clear as some may think. Unless of course you're predisposed to accepting whatever expert's post you want to believe.
"I'm surprised the existing thermostat have issues at 120 hours"
I ran w/o a thermostat (INLET valve controlling both temp and pressure) for two years on the Dragn, then a Rex thermostat kit (and valve on INLET to control pressure) for about 9 years after. This on a 400-425 hp engine. After a total of eleven years, the engine still ran strong to 5k (with many a NOS burst to 5.5k) So no family cruiser. On tear-down my builder said little wear.
I know splitting hairs. That's why you'll see many different opinions, 'cause more than one solution works just fine. But if you're looking for a pro with the simple answer, well then skip on by this post.
Me? I'm always interested in the very best solution for an application, and as hp goes up, so does the sensitivity to the "right solution" Not always posted here.
So I continue to question.
Floored, I understand the temperature vs. clearance issue you mention. My point, do you really know what that temperature is? I'm guessing most mfg's are keyed to car blocks. And what little block wear info there is for car blocks. Even if Mandelon's block or most jetter's blocks are bored and honed with hot water circulation? I'm guessing probably not.
But even if? How does the mean metal temperature and resulting cylinder shape and piston clearance match conditions at the lake? A big unknown, especially considering oil temperature (not water temperature) may be the driver. So the obvious question is, does "low" coolant temperature and "high" oil temperature result in lower or higher mean block temperature? Even if someone could define "low" coolant temperature. Nobody I know has the answer...
Besides clearances, there's the issue of contaminate burn-off and wear. For that you need "reasonable" oil temperature. But I'm thinking "reasonable" oil temperature, if well-defined, may be driven from something other than "normal" coolant temperature for a car than a boat? In other words, if 190 is reasonable oil temperature, does that take 120 or 160 degree coolant exit temperature to get that 190 oil temperature in a boat?
Then there's the question of cylinder compression ratio and engine timing and how they're influenced by head temperature and cooling flow.
Bottom line? We can all post what we think about ideal coolant exit temperature, or our experiences with valves and thermostats. I can tell you a Rex thermostat adjusted to 190 degree idle temp and a valve regulated inlet pressure worked just fine for me.
In the end, there's still a lot to be known about what is the best for each application. That's why I ask those questions in my post above.
jer
[ June 29, 2003, 01:55 AM: Message edited by: LVjetboy ]