Rotational Weight Question

[Ed Carpenter]

I asked this before. I was told to spend my money under the hood. All that crap isn't worth .05

[james schaechter]

I think if you have the car flogged out, tuned out and drive it perfectly every time, buy that stuff. I do think it can help over time,but it is never one thing, it is all of the things. If there is no more HP to be had, start there. If you can't make minimum weight and you can save unsprung weight why not?( expensive though) You need the good stuff though. I have heard of guys trying some aluminum spools and the deflection hurt more than any weight savings. If you are not hampered by any pesky performance rules, just hop up the bullet. I agree, very small gains for big money. Walk the Comp pits.mthose guys know.

[Alan Roehrich]

You buy the lightweight stuff when you are building to begin with, or you need new parts. Then it is worth the money. If you're replacing perfectly good reasonably light stuff that is working now, with high dollar trick lightweight stuff, most often it is a waste of money better spent elsewhere.

The lower the power of the engine, the more it has to gain from light parts, as it has no "surplus" power.

Too many people go spend meg dollars on trick stuff long before they've mastered the basics, and maximized the rest of their combination. These are the people who have rarely if ever rented a track or spent days at test and tune sessions.

To the original question, the only way to know what it is worth is to test back to back on a given combination, with serious A-B-A testing. Most people who spend the time and money to do that are understandably quite reluctant to share that hard learned data with anyone, save a few people that share with them.

Some of the very fastest cars have none of the trick stuff in them, not even in the engine. One engine builder responsible for the legendary performance of a certain Stock Eliminator car once told me, while we were discussing dyno parts, that his "shop was filled with camshafts and headers the engine and car did not like", and "the secret to it being fast was not so much knowing what the car liked, but more a matter of learning everything it didn't like".

[FED 387]

to answer your question look for a book by Herb Adams on chassis--- he explains in great detail the difference between rotational and static weights and the ET/MPH/HP advantages in going to lighter weight items versus a heavier weight item ---performance wise he breaks it down into static weight-- rotational engine weight-- and rear axle rotational weight ---and the performance gains that can be achieved by using lighter weight components ---This should answer any questions you might have--- educational reading--FED 387

[Myron Piatek]

The laws of physics says any reduction in rotating weight has to be beneficial. But the variables associated with the comparison runs themselves can vary more than the benefits.