Why Would My Car Make more power with Hotter Cooland Temp?
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My Car has an open loop tune and puts down seat of the pants power with a 200 degree coolant temp vs. 170-180.My OLFA is the same at these temps and my PE is the same as well.So what would make it have more power at Hotter temps?Thanks
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For some reason ive seen these cars run much better at "operating" temp then in "colder" conditions. Remember these cars come factory to run at 210* and 220 as well in hotter conditions. Stock fans etc dont turn on till about 220-225* so yea thats hot. lol and yes its weird ive experienced them running better when they're warmed up, more than one actually
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I've had a couple guys tell me not to run the lower temp thermostat because they are aluminum block motors. I forget exactly the reason, but because I design & built metal tools for oil wells, I'm just taking a guess, maybe it has something to do with the rate of expansion of the different types of metal.
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Colder weather & colder coolant temps are not the same though. Colder weather you will get cooler/denser air & make more power. Colder weather may affect engine temps a little, but probably not much. At least at the race track, now if you are cruising on the highway, yeah, all the cold air flowing thru the radiator will cool the motor more....but I guess it's all relative to if you are talking about at the track or dyno, or just more power cruising down the road.
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Colder weather & colder coolant temps are not the same though. Colder weather you will get cooler/denser air & make more power. Colder weather may affect engine temps a little, but probably not much. At least at the race track, now if you are cruising on the highway, yeah, all the cold air flowing thru the radiator will cool the motor more....but I guess it's all relative to if you are talking about at the track or dyno, or just more power cruising down the road.
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Don't tell the 160 stat people this or they will beat you up. I believe the STOCK motor was designed from the ground up for that op temp. This includes seals, rings, the spec'ed spacing, bearings, everything in the motor. Remember that AL has a larger change in size with change of heat than FE does. I could be wrong though. I am an electrical and not mechanical.
This means that the lower op temps affects an AL motor more than FE. Plus, most people running gen i engines probably have aftermarket crate engine optimized for a lower temp. Also, I do believe older cars were also designed for a lower temp.
To get the whole story, we need to also dive into thermodynamic cycles. Perhaps we could also find answers there. A larger difference in heat reservous usually makes more efficiency.
This means that the lower op temps affects an AL motor more than FE. Plus, most people running gen i engines probably have aftermarket crate engine optimized for a lower temp. Also, I do believe older cars were also designed for a lower temp.
To get the whole story, we need to also dive into thermodynamic cycles. Perhaps we could also find answers there. A larger difference in heat reservous usually makes more efficiency.
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I've never seen an all aluminium, normally aspirated engine that didn't make more power above 180 degrees. Put a blower on one and it is usually a different story. Iron blocks and forced induction engines normally like warm oil and cool water. 160' stats in a normally aspirated aluminium block LSX engine is usually a mistake. Properly tuned they normally make the most power between 180 and 210 degrees F. I think many guys do things because they hear it's the thing to do, and don't bother to test.
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"Indicated thermal efficiency" is one of the four fundamental efficiencies of an engine. It's the measure of how much of the thermal energy (from combustion) performs useful work on the top of the piston. When you burn the air/fuel mix, the goal is to use as much of the resulting heat as possible to drive the piston down in the cylinder. What do you think happens when your cooling system pulls some of this heat out? Result: less efficiency and less power output. The goal is to run the engine as hot as possible (without destoying it!) to keep from "stealing" the heat energy from doing valuable work and keeping the intake air as cool and dense as possible to get as much a/f into the engine as possible (for greatest VE, another fundamental engine efficiency).
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[QUOTE=dan@masportspeedshop;9556914]The above quote is right on the money. The engine was built and machined for those operating temps. If you machine the engine to run at lower temps, you won't lose as much power, BUT...you lose "thermal efficiency".
[QUOTE]
Even "built" normally aspirated aluminium engines make more power above 180 degrees. I see it every day. Many guys seem to assume they like to run colder and never warm them up real well to find out. I re-tune them all the time that have never been tested at higher temps. Put a blower on one, or an iron block, and they will make more power cooler. My old World of Outlaws sprint car made more power around 200 degrees, but back then I thought that was the methanol, not the alumium block. When the LS1 came out I was suprised they were the same way. Then I found the iron block 6.0L trucks prefered cooler water temps. LS1 strokers built with iron 6.0L blocks like cooler water also. All aluminium water cooled motor cycle engines they run in Mini-Sprint cars around here also like to run around 180/190. I would never use colder than a 180 'stat in an NA all alumium LS1 myself.
[QUOTE]
Even "built" normally aspirated aluminium engines make more power above 180 degrees. I see it every day. Many guys seem to assume they like to run colder and never warm them up real well to find out. I re-tune them all the time that have never been tested at higher temps. Put a blower on one, or an iron block, and they will make more power cooler. My old World of Outlaws sprint car made more power around 200 degrees, but back then I thought that was the methanol, not the alumium block. When the LS1 came out I was suprised they were the same way. Then I found the iron block 6.0L trucks prefered cooler water temps. LS1 strokers built with iron 6.0L blocks like cooler water also. All aluminium water cooled motor cycle engines they run in Mini-Sprint cars around here also like to run around 180/190. I would never use colder than a 180 'stat in an NA all alumium LS1 myself.
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I guaranty that I can make the same amount of power at 160° or 200°! ![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
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I guaranty that I can make the same amount of power at 160° or 200°! ![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
#18
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I guaranty that I can make the same amount of power at 160° or 200°! ![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
![Engarde](https://ls1tech.com/forums/images/smilies3/engarde.gif)
The engine will have a much shorter life span at 160°
I can tune it for 160°, but the parts are not setup for 160° and will not live.
Have you ever wondered why the car will not down shift at the same speed when it is really cold out (30° to 40°) vs warmer out?
If it is a NA all aluminium LS1, I'll garuantee you I can make more power above 180. If it is a very high compression engine (over 13-1), the difference will be smaller. We are talking coolant temps, not intake air, right? The air outside is a different subject.
#19
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You may have a coolant or intake air temp sensor with calibration issues. I have seen them stick, and not indicate lower temps. That is similar to the choke not working on an old carb. Might hook a scan tool to it before a cold start to verify the coolant and IAT temps shown are about the same as ambient.
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You can work a Cal program to target 160°, but the engine wasn't designed for it and will increase wear.
The Zone 190° to 220° and maybe up to 225°, but you need to cool the air charge a lot more.
I will load some datalogs
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Last edited by CalEditor; 06-17-2008 at 04:24 PM.