To Keep engine heat or not to keep engine heat ......

**RedPearl** · 10-30-2011, 07:46 AM

I know weve allways kept good heat in the motor before we go up to the holding rope. But recently going to NHRA drag races. You now see the pro stock guys running coolant through the motor between rounds. John Mills and myself talked to jerry eckman about this. He said they want the motor as cold as possible when going to the lanes. They have proven it makes the most power cold. He said by the time they do a burnout and stage the motor is about 90deg's. If you think about it. we build these motors with room temperature clearances. Ive also heard all i should worry about is oil temp and thats it. Its a little battle between old school and new school. Im still riding the fence on this.....

**billet racing** · 10-30-2011, 08:38 AM

You may machine it cold, but to taget heat requirements.

And I agree with warm oil.

Jerry

**RedPearl** · 10-30-2011, 08:46 AM

I heard a little trick the pro stock guys are doing. Is getting Blocks up to running temp when they do the machine work on engines. Love the innovative tech on pro stock engines....

**Red Rocket** · 10-30-2011, 09:37 AM

The engine will make more power with low coolant temp and hot oil temp. See it on the dyno all the time. If you have a water temp guage where you can see it look at it after you start the boat on the rope, by the time you get the solid yellow lite your eng temp is less than 100 degrees in a jet boat. They cool off very quick in the cool water.

When you are having you machine work done the shop should be aware of the fact the engine temp will low so they can adjust the clearnces accordingly.

**steelcomp** · 10-30-2011, 11:28 AM

X2 on what Mike said. At the boat races, warm-ups and the effort you see to keep heat in the engines in the starting lanes is purely for the oil. Cold or even "cooler" oil is a power robber. You're circulating pretty cool water through the engine almost instantly when you start on the ropes. They don't have that advantage at the car races. Oil temps and weights are definitely a consideration when setting bearing clearances.

**RedPearl** · 10-30-2011, 11:51 AM

good to know on the cold coolant. i was wondering if a closed coolant system in the boat would be beneficial to holding cylinder temp. Oil temp definitely has been the new focus since we got the dry sump. ive been logging oil temp trying to get a good ideal of were its optimum. we take a lot of precaution warming up the motor. i just got my hands on a heating element so i can warm the water up to 100 plus degs. then circulate the water to get engine temp up along with the oil heater. We prime the oil once the oil is hot. Thanks for comments guys. I think I got a better handle on engine temps....... Robb

**Gearhead** · 10-30-2011, 02:27 PM

The reason an engine makes more power when run from a cooler temperature is physics. The more temperature change that can take place in a combustion chamber during the combustion process will result in a higher power level.

In regards to the oil, an engine will make more power with a thin or heated oil up until the point of metal to metal contact, then the power drops quickly.

Both of these processes can be easily tested/seen on the dyno.

The oil viscosity one may use depends much on the temperature the engine will be run and the clearances in the engine.

Many of the Pro Stockers are running "0" weight and even thinner oils when operating the engines at 100 degrees.

The studies of oil viscosities is very interesting. Back in the late late 80's I found that a 5w30 motor oil is as thick at approx 170 degrees as a 50 wt oil is at 230 degrees. (Approximate numbers) Bottom line, our drag car at the time never exceeded 170 degrees temp and the bearings and components were lubricated as well at that temp as was a circle car running 50 wt oil and exceeding 230 degrees temp and the performance more consistent from of the trailer to full temp.

The oil weight needs to match the application. I run a thin oil in the race boat and a much heavier oil in the lake boat.

**RedPearl** · 10-30-2011, 02:40 PM

Thanks buddy, thats great information right there.. Ive kinda went away from doing the dry ice in the fuel tank. figured id wait till I got the hardware figured out first. have you ever compared the dry iced fuel on the dyno compared to room tempature fuel Steven?

**TNYoungblood** · 10-30-2011, 03:24 PM

Great Thread guys

What do yal use to warm your oil while in the pits at the races?

**stix818** · 10-30-2011, 03:41 PM

We run a closed cooling system which helps keep temps consistant. We make sure oil is around 180 and we warm the motor up to 130 before we leave for the lanes. Run 30w oil.

**stix818** · 10-30-2011, 03:42 PM

Originally Posted by TNYoungblood

Great Thread guys

What do yal use to warm your oil while in the pits at the races?

Most dry dumps have a heater. Not sure about wet sump systems..

**steelcomp** · 10-30-2011, 03:51 PM

There's lots of good info on fuel temp and related power. Basically, from what I read fuel temp has little effect on power. Not to say it has no effect, but going to a lot of trouble to control it is probably time/effort better spent in other places.
JMO

**Shaun** · 10-30-2011, 04:22 PM

One thing that has me surprised is how fast oil cools.

Some of you racers, you warm up in the pits, run a pan warmer, or whatever. Whats your oil temps look like by the time you get on the ropes and lite her up???

**RedPearl** · 10-30-2011, 04:53 PM

Originally Posted by stix818

We run a closed cooling system which helps keep temps consistant. We make sure oil is around 180 and we warm the motor up to 130 before we leave for the lanes. Run 30w oil.

Hey bud, are you getting oil temp with your data of a gage? Ive been checking mine with the inferred heat gun, I want to get a sensor for temp right away so i can monitor it by data...

and Yes the dry sumps have a heating element in them for warming oil in pits.

I got the oil temp up to 92deg and the heads 104deg in the pits.....

Right after the pass oil was at 98deg's and heads were 113deg's

Im getting this reading on the bottom of the drysump tank with inferred gun.

steelcomp, Yeah never found much with the dry ice. kinda put attention in other areas...

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To Keep engine heat or not to keep engine heat ......

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