[Full_Tilt]

I consider a lightweight flywheel to be one of the best bang-for-the-buck mods, so Id say it is certainly worth it.

Im not a drag racer, and I understand that people say a heavier flywheel helps you get off the line, but its going to slow you down for the rest of that quarter mile. So I dont think that argument really holds any water, and I still think its a good mod.

If this heavy flywheel theory is true, why would a Funny Car flywheel look like this?

 

[Full_Tilt]

I'm not sure what all this "falling out of boost" business is.
Don't tell me you're letting out of the throttle to shift...

 

[Full_Tilt]

You dont need a clutch switch to flat-shift. You just need to do it close to the rev limiter and do it fast.
Ive never actually driven a car with no-lift-shift enabled with the clutch switch.

Here is a reeeally old datalog of Tw34k driving his Turbo, Vitara, I beam, D16Z6 '97 HX. This car has a disabled cluth switch, so definitely no flat-shifting enabled in the tune:

As you can see, the first shift he doesnt even let all the way out, the TPS is still reading quarter throttle, and the second shift he kept his foot flat on the floor. Even when partial throttle shifting the MAP sensor never read any vacuum, and when flat shifting the car stayed basically at full boost. That dip is tiny, and only lasted for a fraction of a second.

This log would look the same with a lightweight flywheel, only the shifts could have been even faster because of the rpms dropping faster, and the car would just be overall faster due to less rotating inertia.

 

[Full_Tilt]

But what about for daily driving? He says that he drives the car a lot during the week in addition to drag racing. The amount the revs would drop would annoy me while stree driving. Also, any performance gains still need to be worth the $165 that he'd spend on the lightweight flywheel. What's the typical E.T. differences between lightweight and stock?

I can totally understand preferring a heavier flywheel, especially on a street car.
But I do not agree that a heavier flywheel is going to be better for performance in any way. It is a matter of comfort and practicality, not performance.

Like I said, Im no drag racer, but Im almost certain that you can launch just as well with a light flywheel. It may be more difficult, and possibly too difficult for some people to master.


Ive always considered a light flywheel to be a very good bang-for-the-buck mod, and thats talking about typical flywheel prices, not the extraordinary low prices Honda guys pay. Even at $300 bucks its one hell of an improvement.
In "Chassis Engineering" by Herb Adams, he shows an example where 15 pounds removed from the driveline at engine speed (flywheel, crank, etc.) Resulted in an improvement in acceleration that would be equal to a 32 hp increase in power.