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Question on engine temp. How hot is too hot?

Wookie316

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I have a 400 bored and stroked to 512. I have a 3 core Aluminum rad with dual 10” pushers and a 18” puller, so lots of air flow to help cool. Perhaps this is a non-issue, but being I have a few $’s in this engine I don’t want to burn it up. I have been concerned because the heat gauge is much higher than any other dodge I have ever owned. So not wanting to trust a 42 year old gauge I have been checking with my heat gun different parts of the engine and the rad to see the temp it shows. Here are my findings.
Rad, top tank 80-90, core 180-190, top hose 185-195, bottom hose 160-170, Aluminum heads 170-175. Those numbers all seem good and I am not really worried, but the water pump housing and thermostat area range anywhere from the 220-240 range! Is that normal? I have changed the thermostat as I did think it was sticking. The new stat registers the same and it is actually a hotter stat I have in the car now. I guess my worry is that these tests have been done after 15-20 minute drives, not working the car hard and relatively cool days. Yesterday was the warmest day thus far and it was still only mid 20’s Celsius. I am worried with this heat at the water pump housing already, what’s it going to be like on an extended drive or on a real hot day? Perhaps this is normal though? I have never done extensive heat testing before, but I am really looking for opinions, suggestions and experiences on what’s too much heat? Thx in advance for your help. Much appreciated.

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Is this a fresh engine? If so expect it to run hot for a few hundred miles. All I can say for that is make a lot of short trips and don't let it get hot. By hot I mean much over 200F. A well broke in engine, provided the piston to wall clearance is adequate, can deal with as high as 220 if it's full of water but problems start when the oil temps approach 300F. If you have 4000 series alloy pistons they will tend to follow the iron block pretty well as temps rise but the 2000 series might outgrow the clearance if things get too hot.
 
Why not install a mechanical temp gauge in it? Also, what is your mix of antifreeze that you are using? You know straight water actually removes heat better than a mix, right? I've run straight water before and add in a water pump lube and rust inhibitors with good results but for the most part, I run a mix of 60/40 or less water to antifreeze in summertime. As for new engines running hotter than normal....I've seen it happen but I've also seen them not do that. Your discharge being around 240 sounds a bit high and that's the same area as your sensor should be in and I would think your factory gauge would be leaning over towards the right side.....? Are you picking up any rust particles in the radiator? Depending on how the block was cleaned, it might have some scale built up inside of it which will slow down the flow by the cylinders. Btw, nice looking Bee!!
 
No the coolant was nice and clean when I drained it. Not sure what the mixture ratio is though. I have thought about putting a mechanical gauge in as well, but my priority is to get the heat on this beast tamed. It only has 100 miles on the engine not including the initial dyno time.
Also when I'm on the highway and have good air flow, the gauge runs nice and cool. Only in town is where temp creeps up.
 
I've never seen any specs on what temperatures should be, taken with a heat gun. Don't know if they exist. As has been said, before pulling your hair out, install a mechanical gauge, even if temporary, to monitor the actual coolant temperature. Also remember that a system with a proper 16 lb. radiator cap won't boil over till 265*F. , not that you should let it get near this temperature. The fact that the temperature drops when on the highway indicates that the cooling system is adequate, but that the fans aren't pulling (pushing)enough at low speed, if indeed the mechanical gauge confirms the 'hot' readings. The reason you saw so many aftermarket gauges below the dash in the 60s &70s is because the factory gauges were notoriously inaccurate. Let us know what the new gauge shows.
 
I usually get some contradictions from the new car crowd but running over 210 is not healthy for an old mopar. Ideal is between 180 to 190...220+ is suicide.
 
I was wondering the same thing about engine temp. My car will run 160 with 160 thermostat and 180 with a 180 thermostat. I have noticed the car does run better with 160. I know everybody sais 180 is where you want it but I say the cooler the better. I run my car at 160 and it runs great. I think older classsics just dont like the heat.
 
The effects of running too cool of temp is faster cylinder wear. The oil runs cool for a longer period of time and a cooler running engine will produce condensate for a longer period. Getting to operating temp quickly is important for the engine and the oil. If you do some research on the effects of moisture in an engine, then you will understand why running too cool isn't so good.
 
I was wondering the same thing about engine temp. My car will run 160 with 160 thermostat and 180 with a 180 thermostat. I have noticed the car does run better with 160. I know everybody sais 180 is where you want it but I say the cooler the better. I run my car at 160 and it runs great. I think older classsics just dont like the heat.

I agree..been running 160 stat for , well since the early 60's. Old iron does not like heat. On a simpler example, ask the driver's at a track what type weather they like to run...hot weather or mild....cars lose performance at high temps(old iron,not the new junk that runs at 210 +)
 
I used to run my old Ford 289's at 160 and they did run better at the track but none of my Mopars did. They always ran a better ET when at a solid 180 degrees. Also, running too cold can promote faster cylinder wear. What makes old iron different than new iron? 'Mom' used a good quality cast iron in her engine building....much better than GM and Ford. If you ever hung around an auto machine shop when a block was being bored, you can actually hear the difference in the sound the cutter makes on each brand.
 
I agree..been running 160 stat for , well since the early 60's. Old iron does not like heat. On a simpler example, ask the driver's at a track what type weather they like to run...hot weather or mild....cars lose performance at high temps(old iron,not the new junk that runs at 210 +)
Only if they're not tuned for it. The big issue with old iron at that temp is fuel! Having a carb, you'll be boiling fuel and the carb won't like it. Add EFI with injectors, run it at 230 degrees and have at it! As Cranky says, too cold means more wear. Most new iron runs at 200-230 but it's all EFI. If mine gets above 200, the carbs start having fuel percolation issues.
 
I agree..been running 160 stat for , well since the early 60's. Old iron does not like heat. On a simpler example, ask the driver's at a track what type weather they like to run...hot weather or mild....cars lose performance at high temps(old iron,not the new junk that runs at 210 +)

I disagree for the reasons stated by Cranky and Hemirunner. We always warmed our race motors to 180* before making a pass. What you DO want is cool, dry weather for the intake charge (air/fuel) as the motor will make more horsepower.
 
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Here are a few photos of engine sitting in the car.

It has an MSD distributor and ignition since this photo.

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Newer photo of the engine.

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The effects of running too cool of temp is faster cylinder wear. The oil runs cool for a longer period of time and a cooler running engine will produce condensate for a longer period. Getting to operating temp quickly is important for the engine and the oil. If you do some research on the effects of moisture in an engine, then you will understand why running too cool isn't so good.
well i have tried to do research but really have not seen any facts just opinions. I do live in ca so maybe the warm year round climate has a effect. I have yet to see any water or moisture in my oil either. I am only stating what i have learned from my own testing. I ran a 195,180,160 and tge cooler the better. Heres what i found more power better oil preasure less detonation with our crappy gas. Wear is no a issue in my book because i drive it only around town and short distances. I think i will need to repint before i need a new motor. I would love to see real facts done on older motors not new iron. Just my opinion guys.
 
I disagree for the reasons stated by Cranky and Hemirunner. We always warmed our race motors to 180* before making a pass. What you DO want is cool, dry weather for the intake charge (air/fuel) as the motor will make more horsepower.

I agree, you do not want 160 stats in anything, thats just making a motor thats gonna fall off long before and need rebuilding long before it should....

You want the block and all internals at temp, that means a oil temp gauge also because the water temp will get to it's op area long before the oil does (unless you make a n2o pass then it gets temp quickly)... When the oil is at temp, then it's fast... and all the oil not just the motor's oil.
Then what you want is COLD fuel entering the carb, so you want a return system going thru a heat sink that uses whatever you like to keep the fuel cold, and then you will make your best passes.
Getting that part worked out is your dilemma, i have run my fuel cold enough that you would have thought the car was running in -30 air and that doesn't make the best pass, gotta get it just right.

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well i have tried to do research but really have not seen any facts just opinions. I do live in ca so maybe the warm year round climate has a effect. I have yet to see any water or moisture in my oil either. I am only stating what i have learned from my own testing. I ran a 195,180,160 and tge cooler the better. Heres what i found more power better oil preasure less detonation with our crappy gas. Wear is no a issue in my book because i drive it only around town and short distances. I think i will need to repint before i need a new motor. I would love to see real facts done on older motors not new iron. Just my opinion guys.

That's all the worst things you can do to a motor, how many miles do you have with such experience that this is good?
You have ran the car at different mileage issues to see it's slowed and lost power, found guides worn prematurely early from the short run use, loss of good seal...
You might not ever see water, you need to look at other things to see traces of the issues from condensation in hoses and breathers and pcv and covers, intake trays and areas that are the Water..
Saying i never seen it and you aren't running the car to test it and see the same numbers you did 2 years ago, not trying to see if it can or doesn't are where you find the facts of the running short trips and lower motor temps.
. Every motor i played with keeping cold lost seal and other issues long before it should have, all because it was running to cold.
 
Not sure what others think but I used "Water Wetter" in my 422 Stroker fresh build stock fan and shroud and ran 192° all day, 85° temp out side mostly city driving.
just my experience. Oh yeah, I did run it at the track so just water and no coolant was added.
 
180 Napa superstat. Green coolant. 26 inch copper w/clutch fan. Ma Mopar KNEW how to cool these motors. Shroud. Over 205 is too high. I do use Royal Purple Ice for surface tension. I idle for hours at 107 degrees when I have to. AC stays on. **** fuel with ethonal vaporizing is another story. One inch phenal. Love that PCP Charger!
 
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