I go down to the local track from time to time and alot of the cars have big blocks with special electric water pumps to cool the engine in between runs to cool it off b/c cooler = better performance. A buddy of mine was running multiple laps hot and was getting better times with each run on his nissan. From what I under stand if the engine is cooler you get slightly better performance? I was running hot laps and getting slightly better times but it was getting late and the air was cooling down so I am not sure? What I want to know is are you guys noticing better times when you let your engine cool off or are you getting better times running hot? I searched but couldn't find.. hope this has not already been discussed

 

I never went to a track, but I did notice harder pulls when cold. Some people put dry ice on their intake before a run. You might want to try that. Make sure you take it off before you run though, or make sure it's held down tight if you run with it.

 

This is true to a degree.. If the engine is too cold you'll end up either loosing some time or hurting the engine. You don't want it overheated, but you want it warmed up, if that makes sense.

 

yeah but my time was improving running hot through the evening... so was another guy that was running hot with an import. but everybody else try to cool their engines in between runs to get better times.. I am asking if anybody else has noticed if our engines run better hot or when they cool down... I know if we have cooler air it will perform better that is why we have CAI. I am asking about engine temp

 

the rule is generally that an engine will run better cool not cold. I am curious if anybody has left their engine running between runs and has seen better times

 

In drag racing and road courses, I don't let the car run between runs, but that's because it's usually 30-75 minutes between runs. For autocross, I often leave the car running for the 5 min between runs, but that's more because multiple starts wil be hard on the engine. I honestly don't see much of a difference between "cold" and "hot" as the engine (once warmed up) seems to run at around the same temp no matter how long it's left running.

As for the V8s, my experience with them (at least the ones more than 10 years old) is that they tend to get hotter than desired when idling for too long. My Trans Am was always just under the red (about 240 degrees) when I got stuck in traffic or let it sit running for more than 5 minutes. Maybe that's why they try to cool their engines, because they're running too hot.

 

I have a friend with a duster and a corvette and he installed the electric water pump on both of them because it improves 1/4 mile time when the engine is cooler- not cold... and it also improves consistancy when running bracket racing because the engine will be the same temp each time.. however that is on big blocks that they are getting better times. this same friend raced his wifes nissan and was getting better times running hot (not letting the engine cool down before next race). I was getting slightly better times when I ran hot.. this would not agree with what I understand about how an engine should perform. I just wanted to see if anybody has any #'s or if they saw a similiar thing on their cars

 

Oh, as for numbers, my 1/4 mile times got worse through the night (even as the temp got colder) when i was at teh track. I did turn the car off between runs because it was over an hour each time! However, once we got in line again, I still spent a good 5-15 minutes idling in line. Take that as you will, but despite getting better reaction and 60' times going into the night, my 1/4 times got worse.

 

hmmm... ok cool. that is strange. I wonder what acounts for our times getting better running hot? thanks man anybody else noticed one way or the other?

 

Is it possible the engine temp had nothing to do with it? Maybe your runs got better as the air outside got cooler. Cooler intake charge = more performance. It sounds probable that the engine was running w/in its normal temp operating range and that it didn't effect the performance either way. The cooler air would be the reason for your faster runs.

P.S. Never been to a track - just my theory

 

yeah that is what I thought the first night I noticed that... however one saturday we went down to race mid day and as it got hotter my #'s stayed the same even though it was 90 when we started and over 100 by early afternoon and our times stayed the same... usuallt time would get worse because of the heat.. but it stayed the same

 

anybody else?

 

cool day out idle the engine for about 5 minutes or so thats my 2 cents

 

the reason is probably because of your tires. multiple runs closer together keep your tires warm and a little stickier. as opposed to a run every hour or so where you get up to the line with cold tires.