I put a pair of electric fans on the aluminum cross flow radiator I have on my slant, and let it idle for 30 minutes in my garage. It reached 205 degrees, and stayed. Is this too high? I have the fan set to come on at 180 degrees, and the engine has a 195 thermostat. I could lower either one, but have heard many times that engines operate more efficiently, and wear better at the higher temperatures. It's just that the turbo puts out alot of heat under the hood, and I don;t want to get too carried away with the high temp thing. The temp gauge is mechanical, and the sending unit is installed in the drain plug hole in the block back by the oil filter. This temp then would be the coolant in the block early in it's flow, not at the head. I could hook up the lap top computer and check the head temp I suppose, as that is where the EFI temp sender is located now. Any thoughts here? Thanks.

For me the key would be that the temp STAYED at 205. Thats good. I would be suspicious that the head temp was much higher. Although I use a 195 thermostat for winter...my summer thermostat is 180. I dont use a fan at all.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Vader,

205 is not too hot, as long as you stay away from detonation. I try to run my cars around 210 for best mileage and wear, and I think this is where most new cars run. I usually don't turn on my elec fan until temp is above 210.

Try plugging in the laptop and reading the head temp too (and do more tuning! ). I'll bet the head's around 210-215.

Lou

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Home of Slant6-powered fun machines since 1988

Check the head temp. as suggested... the water in the block runs about 10 - 15 degrees cooler.

Many new cars run at 210 degrees, engine damage can start in the 240-250 degree zone. (the oil you use has a big influance on this)

You should be ok at 205 degrees, as long as it does not go higher. My 66 Dart runs at 200 to 210 degrees during prolonged WOT with the AC on, never had an engine problem with it.
DD

Thanks to all for your thoughtfull replies. I will relax and just watch it. I will also hook up the laptop to tune, and check the temp at the head. The fan had not come on as I drove home from work, but came on only in the garage after I had pulled in. It is a short drive to be sure, but I suspect that the engine is likely to run a little hotter sitting the enclosed air space of a garage than it would outside in the "fresh" air. Thanks again.

I know exactly where you have the temp sensor. If you follow the coolant flow, you'll see that it travels across your sensor up to the head and across all six cylinders. The head is what transmits most of the heat to the coolant. At the bottom of the block, your sensor reads one of the coolest points available. I would be much more comfortable reading temp at the front of the head just before the water outlet. You'll never really be able to calculate the delta T between where you have the sensor now and what your max temp will be as the coolant leaves the head. It could be much higher than what your gauge is telling you based on your current sensor location.

Mitch