Whats the optimal engine coolant temperature to make most HP? - Chevelle Tech
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  #1  
Old Sep 9th, 08, 11:36 PM
Dave427 Dave427 is offline
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Default Whats the optimal engine coolant temperature to make most HP?

Some guys swear that their engine makes the most horsepower when their engine is cool @ 160, and some say they make the best horsepower when their engine is hot @ 195. Whats best?

Dave
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Old Sep 9th, 08, 11:53 PM
BowtieAaron BowtieAaron is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

ive always had good luck with a 180 in my sb's.

aaron
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  #3  
Old Sep 10th, 08, 1:22 AM
Bomber '67 Bomber '67 is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

There is not just one "best" temperature - it depends on how the engine was built and where you are measuring the coolant temperature: at the head or the intake manifold? For a street car you will experience the best oil life and engine longentivity when your coolant is 200 to 205 degrees. Oil life is shorter when the engine is run cooler because there needs to be a sufficient engine temperature to burn off the atmospheric contaminants that are attracted to oil - oil is hydroscopic. Max effort later model computerized fuel injected engine tuners shoot for lower temperatures (~ 160 to 170) because they are fighting the dreaded knock sensors that will pull out serious amounts of timing if they perceive any detonation (knock sensors are not perfect).

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  #4  
Old Sep 10th, 08, 2:19 AM
kirkwoodken kirkwoodken is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

Whatever coolant temp you have, you want oil temp at least 220 to boil off water and acids. Head temps can be 300 F. degrees without problems. Air cooled two strokes get pretty warm. Ideally, you want intake air cold, head temp hot so as not to absorb combustion heat. More criteria that is hard to meet. It is a heat engine, made to run hot. You don't want to suck too much heat out of it by way of cooling system.
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Old Sep 10th, 08, 7:43 AM
SWHEATON SWHEATON is offline
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Smile Re: Whats the optimal engine coolant temperature to make most HP?

For Our 30-40 Yr Old Sbc/bbc Motor Design Approx 180-190 Deg F With Most Setups.

Todays Motors Are A Different Story,hotter Is The Norm.

Scott
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Old Sep 10th, 08, 7:48 AM
onovakind67 onovakind67 is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

For example an NHRA Pro Stock engine makes over 1,400 HP and uses a 0W-5 weight engine oil. A NASCAR Nextel Cup Engine only makes 850 hp but uses a 5W-20 weight oil. How can a more powerful drag motor use a lighter weight oil? The NHRA Pro Stock motor runs at a cool 100 degrees F. A NASCAR Nextel Cup engine runs around 220 degrees F. Our Joe Gibbs Driven XP0 racing oil is 11.5 Centistokes at 100 degrees F, and the XP0 oil is popular with the NHRA drag racers. Joe Gibbs Racing uses the XP1 in our un-restricted NASCAR Nextel Cup engines, and the XP1 is 9.5 Centistokes at 212 degrees F. As you can see, the operating viscosity of the 5W-20 XP1 oil is lighter than the operating viscosity of the 0W-5 XP0 oil due to the difference in operating temperature.
http://www.joegibbsracingoil.com/tra...er/082106.html

It depends on the application.
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Old Sep 10th, 08, 9:10 PM
ironhead ironhead is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

Quote:
Originally Posted by Dave427 View Post
Some guys swear that their engine makes the most horsepower when their engine is cool @ 160, and some say they make the best horsepower when their engine is hot @ 195. Whats best?

Dave
I would swing towards the 195 F and a cold air induction.The 160F guys are sucking heat energy away from the piston top thru the cool cyl walls.A cool head and a hot block is more desireable for a street deal imo.The combustion chamber can be coated so as to not tranfer heat energy into the coolant..and still allow the valves to transfer heat thru the guides and seats.Now if we could come up with reverse cooling on our 60,s era engines..I would get on board in a heart beat.
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Old Sep 10th, 08, 10:12 PM
boldm boldm is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

With the correct tune up the cooler engine (coolant temp) should always make more HP.
Any heads up racers, pro stock etc who make a better living by winning, or class racers, like super stock set on kill, trying to set national et records etc, they don't run 200 degree water temps,,, more like 120-140 on the starting line.

With the appropriate tuneup, I always ET quicker with a cooler running engine!
An added benefit would be to maintain hotter oil temp, less fluid friction.
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Old Sep 11th, 08, 9:56 AM
mirage2991 mirage2991 is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

knock sensors isn't the problem, you can detune them, matter fact I had to detune mine on the Goat as I was picking up some "false knock".
I think mose new engine are set to run hoter due to emission constraints. I do believe a hoter engine has less emission and has cleaner oil (like one stated: hot oil burns off the impurities like water).
They are also ran hoter for the Cats. Cats need to be at a certain operating temp to "work" like they are suposed too, so I would assume keeping the engine "hot" insure that the exh. gas are at the appropriate temp.
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Old Sep 11th, 08, 11:01 AM
Highway Star Highway Star is online now
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Default Re: Whats the optimal engine coolant temperature to make most HP?

i can attest to the newer vehicles liking higher temps. the newer 3800 gm motors have 205 thermostats, they like it hot for a cleaner burn, for less emissions gases and actually have a coolant bypass line plumbed into the water pump and manifold that purposefully heats up the intake right at start up to warm it quick and cut more emissions.
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Old Sep 11th, 08, 11:47 AM
SWHEATON SWHEATON is offline
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Smile Re: Whats the optimal engine coolant temperature to make most HP?

FYI,SOME MORE INFO ON OPTIMAL ENGINE TEMPS FROM COBRA VALLEY PERFORMANCE.

This is why is suggest 180 deg for best street perf temps.

SCOTT
================================================== =================

However, there is a "middle ground" where both optimum performance as well as minimal wear share similar characteristics. That "magic" number lies in the 175-180 degree range, which requires a 180 degree thermostat.

The all too commonly used 160 degree thermostat is way too low to be considered for performance or engine longevity. Engine wear increased by double at 160, than at 185 degrees. So then, why do the 160's exist in the first place? The 160's were commonly used in older, open loop cooling systems where only 6 pound radiator caps were used, and low 212 degree boiling points were experienced. In contrast, modern cooling systems can see upwards of 260 degrees in coolant temperature with radiator pressures exceeding 45 pounds. Many early hot rodders found the 160's to be better performing than the 190's, however, the in between "180" appears to satisfy both ends of the spectrum. The correct water temperature is required for the cylinders to achieve a minimum specific temperature in order to allow a fully homogenized Air/Fuel mixture to combust efficiently. Guess what the minimum number is… right! 180 degrees. Even so, you might see some still recommending the lower 160's, for no other reason than to possibly get that last drop of horsepower out, at the high price of dramatically reducing the life of the engine and it's internal components.
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Old Sep 11th, 08, 11:51 AM
Dave427 Dave427 is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

Sounds good, 180 is where its at. With the 160 stat the engine seems to run at 170 a long time. But when in traffic it stays at 180.

Dave
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Old Sep 11th, 08, 1:11 PM
onovakind67 onovakind67 is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

Ol' Smokey thought that 200° was the lower limit for making serious power. It's about the conservation of engine heat, turning it into power instead of dissipating it through the cooling system.
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Old Sep 11th, 08, 1:39 PM
Schurkey Schurkey is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

Quote:
Originally Posted by ironhead View Post
I would swing towards the 195 F and a cold air induction.
I agree. Keep the ENGINE hot; and the incoming air/fuel cold. There can be power gains with a "cold" engine, but it's not because the engine itself is cold, it's because they're not transferring as much heat to the air/fuel charge.

There were a lot of aftermarket PROMs sold for early computer-controlled vehicles; and it was recommended that a 160 thermostat should be used with them--the colder thermostat helped "fool" the computer into thinking the engine wasn't fully warmed-up, and so the computer was adding extra fuel as if the engine still needed "choke". So, yeah, the power went up--not because the engine was cool, but because it was getting a more advantageous air/fuel ratio.

It's not the cool engine temperature that's responsible for improved power.

Quote:
Originally Posted by ironhead View Post
The 160F guys are sucking heat energy away from the piston top thru the cool cyl walls.A cool head and a hot block is more desireable for a street deal imo.The combustion chamber can be coated so as to not tranfer heat energy into the coolant..and still allow the valves to transfer heat thru the guides and seats.
Don't forget applying thermal barrier coating to the intake ports, to reduce heating of the intake charge.

Quote:
Originally Posted by ironhead View Post
Now if we could come up with reverse cooling on our 60,s era engines..I would get on board in a heart beat.
1955--1959 Pontiac "Gusher" cooling. That doesn't quite make the "'60's era" cutoff, though.

Quote:
Originally Posted by onovakind67 View Post
Ol' Smokey thought that 200° was the lower limit for making serious power. It's about the conservation of engine heat, turning it into power instead of dissipating it through the cooling system.
I agree. Make the heat do actual work instead of inviting it to dissipate through the radiator.
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  #15  
Old Sep 11th, 08, 5:48 PM
boldm boldm is offline
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Default Re: Whats the optimal engine coolant temperature to make most HP?

I stand by my original response.
What Dave427 is asking is whats engine temp is best for making the most horsepower.
I don't see anywhere in his question anything about engine longevity.
I agree, the hotter coolant temps will reduce cylinder wear.
saying that,
my engine in sig is in it's 6th year,
400 + passes,
20,000 miles,
160 stat it's whole life.
why 160, because this is where it ET the best.,,,leaving the starting line at 160-165F, crossing at 170-175F.
and believe me it's not worn out.
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Last edited by boldm; Sep 11th, 08 at 6:25 PM.
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