Horsepower and water temperature

[bigjoe1]

I had a nice 347 Ford engine on the dyno the other day, and I made some pulls at colder than normal water temps , to see what the power did== At 160 , the HP was 474-475 at 61-6200. torque was 454 at 4700==When I lowered the water temp to 110-113, the HP went up to 480 at 6100, and torque went up to 461 at 4700. It was not as much difference as I would have thought it might be== All the tests were with the OIL TEMP at 190 to 200== Just some food for thought


JOE SHERMAN RACING ENGINES

[Troy Patterson]

I've seen a 20 horsepower swing with an aluminum headed 440 + cid / 700 ish hp Chrysler when the engine was allowed to cool for twenty minutes versus back to back pulls where the engine was heat soaked from the successive pulls. Water temp was 140 bringing the engine block, heads, oil and all down during the 20 minute colling period.

Troy Patterson blog tmpcarbs.blogspot website TMPCarbs.net Engine Professionals Magazine's TMP Tuning article, pg. 44

[PackardV8]

Yes, cool is good for horsepower. My guess is improved ring seal and denser A/F charge has a lot to do with it. What are your opinions as to the cause of the increase?

However, as we all know, dynos, boats and street-driven in-car installations are very different animals. On a dyno or a marine installation, it is possible to hold the coolant temp at a very low point. Thus the tune can be much more aggressive than in a real-world in-car installation. The same tune which will make max horsepower in a 100-140 degree dyno/boat will quickly melt down in the car on a 100-degree day. It takes a huge radiator and huge fan to pull out enough heat to keep a big engine under 230. Add an automatic transmission and an AC and the build/tune has to be pretty mild to survive. FWIW, I like the Dodge Viper fan and a separate transmission cooler for street-driven cars.

jack vines

[bigjoe1]

I have not seen that big of a deal Jack.I tell them get the biggest radiator you can find, and keep it as cold as you can==


JOE SHERMAN RACING

[BlitzA64]

If you were planning on running the coolant temp in the 120-140 range on your build, would you increase the piston clearance a tad due to less block growth?

[bigjoe1]

YES


JOE SHERMAN RACING

[Travis Horton]

I stage both of my engines (548 bbc and 461 bbc) at 120 degrees. Both engines run about .06 quicker than staging at 160 degrees. Oil temp always between 185-195 degrees. On a different note, when staged at 170 degrees, ET is no different than staging at 160! Piston clearance on both is .005.

[grease monkey]

ive read to watch dyno people on this one they show a horse power increase that way letting engine cool some , and charge you big bucks.

[la360]

Comp Eliminator and Pro Stock racers keep their engines as cool as possible for good reason! 120-140 degrees would be on the high side for that style of racer. It takes alot of work to run the temperatures they run though.
Despite all that, there is no point tuning an engine to run at an engine temp you can't maintain in the car.

[mike walsh]

What about F.I. motors??? Just let them run open loop? And thanks for the post Joe, always curious what makes more power.

[beaker60]

Thanks Joe,,I have printed this thread,,not to post somewhere else,,,but to end an argument that I have been in the middle of for about a year now.I've been telling several local guys that this is what happens and they all argue that,,,,hotter temps create more HP,,,and my argument has been,,"you're out of your mind".Just the fact that,a colder engine creates a densor charge is enough,,,but they are under the impression that the hotter the engine,the more complete the burn,,,I've even brought up running a looser engine,,,but they won't listen,,,anyway,,,thanks again,,also,,to everyone else that posted,,hopefully this will end the disagreement.

[Matt Gruber]

some circle track racers claim more power hotter.
i think they block off the radiator and the car goes faster but the speed gain is from aerodynamics, less drag. but they say it makes more power when it is hot because of the faster laps.
it is fun to dyno race, but winning on the track can be another story. i wonder what drag racers would see for times if they reduced radiator drag until they crossed the finish line at say 220F ? Do u want to make more HP or win?

[bigjoe1]

This seems to be a very interesting topic. Anyone can try the colder water for himself to see if your engine combo will respond.In testing I have been involved with , every car made a major improvement in performance ( all at the drag strip )Here is what you should do. get the engine warmed up as usual, then make a run as usual.Next, drain all the hot water out of the cooling system, and flush cold water from a hose until the temp is down to 90 degrees or less.Tow or push the car up to the starting line. do your normal routeen ( burnout, whatever )as quickly as possible before the run. This will have the oil temp pretty warm, but the water temp will be much lower than before.. I have seen at least a .15 E T improvement every time I have ever tried this. Every car setup is going to be slightly different, but almost every car will get a pretty good improvement. In tghe good old days, this was a very common procedure that all hot cars followed. Now days, many tracks do not even have a water source to cool down the cars between runs. TOO BAD

[Matt Gruber]

bigjoe1
sounds good, i'm asking has anyone gone 1 step more and taped over the body/rad air grille to reduce drag? some old cars are like bricks, but how about the newer more aero cars? Back when i drag raced i didn't think of this, but i did hose down the rad and ice the intake. and it did work.

[W. Tripp]

What about F.I. motors??? Just let them run open loop?

This depends on the mapping. If the engine is mapped correctly, cooler water temps, and warmer oil temps make best power. But if the engine is mapped so that the engine temp compensates incorrectly, it doesn't work. Many stock engines are calibrated to operate within a specific window for engine temp. Outside this window, the engine management will alter fueling and ignition advance. In many cases, this can be recalibrated, but not always.

With aluminum engines running Nikasil bores, the engine needs to be warm enough run whatever bore clearance you have it set up for. Warmer or cooler, and things can change.