Timing retard

What are the advantages of retarding the timing at high rpm's. Example a roots car turning 9000 max would it be an advantage to pull timing out 3-5 degrees over 7500rpm?
Thanks

 

I agree with Mike that pulling out timing costs horsepower during the run and is not a good thing unless you are trying to control tire slip or hitting the tires too hard at a shift. I read on this site a while back that some racers take out timing in high gear to let the motor run a little "free-er" thus making for some higher mph. I never did understand that concept.

 

Thank you, Mike and TAD I had heard about freeing up the motor on the top end. Just wanted to learn more.

 

Then if I add 10 degrees we will get 1000 more HP?

 

I've heard of gains on the dyno above 9k on a roots BAE. I've tried it on my screw combo and didn't see much but im not sure I run enough base timing to begin with. Some guys run extreme timing for parts of the run.
Your results may vary as always.

 

I can see where it may help on a Roots deal since even the high dollar Pro Mod blowers typically fall on their face somewhere above 9K at Pro Mod OD's. Don't have the blower falling off issue with a screw. Also depends a lot on your compression ratio, cam and fuel. If cam, blower and CR don't support making more horsepower above 9K, then the combination you're using below 9k becomes inefficient above it.

 

Most every pro boost or Nhra blown car is shifting a over 10,000. Going thru the lights at 9700. My old m5 with a broken case would go to 9800 all day.

 

You typically don't see it in the car because the motor is still accelerating, but you do on a dyno. Still making power, but you're making more power at 9,000 than you are at 9,800. That's what I mean by it falling on it's face.

If you're running more timing than the motor needs for optimum horsepower for most of the lap, you'll get a short burst of more power, but if you're squashing bearings, that's a pretty good sign that the motor is fighting itself and you're losing power by comparison. Same reason Pro Stock guys don't just put another degree in it to go faster. That's what I'm referring to, situations where there is already too much timing in the motor.