Thermostat or restrictor?

[shwah]

The only reason to slow down the speed of the water pump is to reduce cavitation....period! It's a band-aid.

The other reason is because you have a good enough heat exchanger, and good enough airflow management to not NEED as much flow - so you slow it down to reduce parasitic losses, and free .5hp to get to the wheels.

I run a much smaller crank pully, and somwhat larger water pump pully. My water temperatures stays right at 180 in almost all conditions. My oil cooler holds temps at 220 consistently. I don't know why folks shy away from proper air ducting here - it takes $25 of parts from Home Racing Depot and a day to make it right.

[Greg Gauper]

I agree Chris. I was trying to counter the arguement that reducing the water pump speed to reduce the coolant flow was beneficial. My statement was based on the assumption that one did not have enough cooling capacity. You are correct regarding the 'free' horsepower from reducing the flow assuming you have excess cooling capacity.

Taken a step farther, you also shouldn't run a radiator bigger than necessary due to the added weight up front. Run the smallest, lightest radiator that does the job. As you indicated, by paying attention to the shrouding and air management, you can improve the cooling effeciency further.

That's one of the reasons why I posted a link to the open wheel site BTW. Excess weight and drag are so important to those guys, and they go to great extremes to get the cooling system as efficient/light/streamlined as possible.

One final comment...last month I had my Prod car on the dyno at King Motorsports to prepare for the June Sprints. It was quite an eye opener to discover how critical proper coolant temps were to making the best horsepower. It turned out I was running the car too cool by 10-15 degrees. Every engine is different, but there is an optimum temperature at which you will make the most power. Don't assume cooler is better!

BTW Chris, how did you do on Sunday? I stopped by to chat on Saturday during my off sessions from flagging, but you were never around.

[shwah]

Greg - you are dead on. I considered going with a smaller radiator in my car, but the prospect of a triple digit race weekend keeps me running the big one.

Sorry that I missed you at the track. I was talking to one of the other ITB guys that was solving a problem at the time. What corner were you working?

I ended up 2nd both days. Car was still down on power, but we made headway with it on Sunday, and expect to be back up to speed for the next event. It's a shame that the Miata smashed the right side of the car up so badly on lap one, but it appears that he earned a discussion with the BFS during the race for it...

[Greg Gauper]

I was at turn 2 in the morning for qualifying and turn 3 (Carousel) in the afternoon for the race. It looked kinda crowded out there

[shwah]

That is was, but in the end it was a fun race - well as fun as 2nd place can be.