How hot is too hot? - Team Camaro Tech
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post #1 of 7 (permalink) Old Jul 19th, 02, 10:44 AM Thread Starter
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I'm sure this has been covered many, many times, but one of the hot topics(pun intended) seems to always be about overheating. Can someone qualified give some factual expert advice on what really is too hot? Is 210 too hot for brief stop and go cruises through town? What about 210 for extended periods? I'm sure lots of fellow enthusiasts would like to know if they don't already. Especially young inexperienced guys. Thanks & happy motoring!
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post #2 of 7 (permalink) Old Jul 19th, 02, 10:53 AM
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Late model cars often run 220-225 with no problems.

My personal opinion on older cars is about 210 max.

I don't like to see much above 200.

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post #3 of 7 (permalink) Old Jul 19th, 02, 11:00 AM
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The temp in modern engines is designed to be between 195-220. Older systems I would say should be around 160-195. If I had an electric fan that was capable of dropping the temp down I would say 210 is not too hot. In my current set up if the temp runs up to 210 I start to get concerned, at 230 I'm a little nervous, at 250 Iam very concerned. Keep in mind that with a sealed system as pressure rises so does boiling point. If you have a slight leak there goes the pressure and here comes overheat. I like to see my car around 165-180 from a performance standpoint. From a standpoint of keeping it running clean Its probably better at 180-210. I would say use your thermostat as a set point. If you vary more than 20 degrees higher, look for problems.

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post #4 of 7 (permalink) Old Jul 19th, 02, 03:58 PM
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As both have suggested, a BBC will run hotter than normal, i.e., run on the thermostat. Todays engines do run hotter,

As long as the coolant doesn't punk on the asphalt, you should be okay.

There is a 22 lb radiator cap to help. Other help is a pusher fan in front of radiator to help.

I'm sure you have look elsewhere for the obvious problems, rodded the radiator, checked to see the correct pulley sizes are in place, water pump works correctly, and have a high-flow thermostat installed. Also, a 30/70 ratio of antifreeze to water installed.

Make sure the fan clutch is working and belts are in good shape.

Keep a recovery system in place to help on cool down.

Engine could be set alittle lean on fuel, leaner engines do run alittle hotter.

Hope this helps....

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post #5 of 7 (permalink) Old Jul 20th, 02, 02:43 AM
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TOO HOT FOR WHAT? Should be the question. There's efficiency issues, hot, then there is hot-hot until I worry about damage, HOT!

Today's cars are designed for higher temperatures due to the emission issues, lubricant operating ranges and generally the WHOLE system is designed to run in a higher range. The emission side dictates certain tailpipe emissions that have to have hotter engine temperatures and work very efficiently there.

Yesterday's technology does not like to work in the over 200 catagory for efficiency issues due to the whole engine block and heads are designed with differing cooling capacities and flows (making for different peak combustion temperatures), plus clearances are different also. From a practical standpoint, the older technology etal likes 175 to 195 temperature ranges (actual coolant temperatures..remember, you can taint temperature readings on the heads by sensing temperaturet there...hotter).

Today's lubricants are a leap in technology with respect to temperature range and really like 175 or above for proper lubricating properties. I would highly suggest for those of you out there that are running synthetic oils to get your temps up in the 185 range for best oil performance. 160 is too low, optimumly speaking. It won't hurt anyting, but you may be losing some lubrication qualities at that temperature.

Okay...on to the what's too hot for damage. As one poster brilliantly pointed out, as long as you are NOT losing coolant and are stabilized, don't fret! GM specs in the 60s called for ranges as high as 235 degrees operating range. I have seen many a cooling system show 240 accurately, holding coolant, and have no ill affects for years!...oh yeah...with aluminum heads too.

So, the key is accurate sensing, holding the coolant, and about 240ish and stable in my book. If it keeps going...then something is amiss. And, actually, you can be losing coolant at an indicated 200 and have hot spots occuring internally due to trapped air, insufficient flow, low pressure etc. that are far more potentially damaging than just 250 degrees!

Did I make sense?

ps....don't confuse engine operating temperatures with the old "to make hp you have to make heat" thing. Yes, hp requires heat in terms of peak combustion temperatures, but these combustion temperatures don't necessarily translate to engine operating temps. It's far more complicated than that!

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post #6 of 7 (permalink) Old Jul 20th, 02, 03:38 AM
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"Running an engine at 180 degrees will drop the overall horsepower by 2-3%. For max power the coolant temperature should be at least 200 degrees, and you should have at least 25 pounds of pressure in the system. Actually, a racing engine like the smallblock Chevy will produce more horsepower as the operating temperature is increased, all the way up to a maximum limit of about 220 degrees.".... "for maximum power output, the coolant temperature in a racing engine should be in the 200-210 degree range, measured at the point where the coolant is returned to the radiator."
But then, what did Smokey Yunick know....

[This message has been edited by sunocospecial (edited 07-20-2002).]

[This message has been edited by sunocospecial (edited 07-20-2002).]
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post #7 of 7 (permalink) Old Jul 20th, 02, 05:19 PM
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Posts: 917 make a good point and Smokey was certainly the king of hp, but coolant temperatures, per se as we measure them, are NOT indicative of internal metal temperatures, so coolant measurements without relative calibrations to other anomolies are useless in so far as precise power statements are concerned. Smokey had a handle on coolant temperatures at certain flow rates and taken at definitive distances from the metal and certain burns. We do not. Fuel composition can play a part too.

While general statements about power and peak combustion temperatures can be made however.

Racing parts, specs, issues do not translate well to stock, street, or even most high performance applications. It's a different science really if you understand it well.

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[This message has been edited by HOTRODSRJ (edited 07-20-2002).]
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