[slakjak1215]

So, from an engineering stand point, what decided how fast an engine will rev down after being revved up? I noticed that if I rev my engine past 5k RPM it takes a bit for it to come back down. I only ask because if i'm driving and i punch it in second past 5 close to 6 and I don't wanna punch it in 3rd, I gotta wait a bit for it to come back down before letting the clutch back in so it doesn't jerk. Just curious thanks.

[Russell James]

A lot of things. Mainly mass, compression, cam overlap...

A heavy rotating assembly, heavy flywheel, heavy clutch... takes a bit to slow back down. It's inertia from spinning mass.

Really high compression and a light rotating assembly... will be a quick revver and de revver.

Snap the throttle on a Pro Stock motor.

[slakjak1215]

Awesome thank you!

[DivineStrike]

Agreed of things outside the motor the largest contributor would be the flywheel. Pretty sure most clutches/pressure plate assemblies are made of pretty light materials already. Not familiar with what you could change inside the motor that would be worth your time without compromising strength and reliability.

Definitely both pro's and cons of a lightweight vs heavier flywheel. This is purely an assumption since I don't know much about drag racing but I would assume a heavier flywheel would help get you a harder launch. Or are the advantages there pretty negligible?

[kevint]

Originally Posted by Russell James

A lot of things. Mainly mass, compression, cam overlap...

A heavy rotating assembly, heavy flywheel, heavy clutch... takes a bit to slow back down. It's inertia from spinning mass.

Really high compression and a light rotating assembly... will be a quick revver and de revver.

Snap the throttle on a Pro Stock motor.

Pro Stock motors also have very short strokes, but that is tied into the reduced inertia.

Originally Posted by DivineStrike

Agreed of things outside the motor the largest contributor would be the flywheel. Pretty sure most clutches/pressure plate assemblies are made of pretty light materials already. Not familiar with what you could change inside the motor that would be worth your time without compromising strength and reliability.

Definitely both pro's and cons of a lightweight vs heavier flywheel. This is purely an assumption since I don't know much about drag racing but I would assume a heavier flywheel would help get you a harder launch. Or are the advantages there pretty negligible?

They sell heavier flywheels for this purpose.