Rotational Weight VS Ignition Timing

[Krewlkid]

So we all know Ignition Timing is 15* for the SR, but my theory is in a vehicle with reduced rotation weight should timing be Advanced to compensate?

My Theory: Advance timing allows for better low end and more Torque, lose out a bit on top end. Decreased rotational weight also helps low end, and turbo is all top end. Advancing the ignition would allow for the best power band.

reason for my theory is: i recently put a ACT 10.4 lb flywheel and Aluminum drive shaft on my car.

Discuss...

[di-devol]

I would n't, once the edu adds timing up top with advanced overall timing, you're gonna detonate. That's the point of getting tuned.

[MadScientist]

OK this is a bit more tech than you think... but they don't match up.

By dropping weight your also changing the center of gravity.
When talking about rotational mass your biggest scavenger (other than the Diff.) is the Tires, Rims, and Rotors because they are larger and carry more inertia.
Unless your dropping weight in every section from the flywheel to the tires, only then are you gaining power to the point of contact.

The Drive Shaft is interesting because this rotation effect all aspects including CoG. I changed the DS on my EVO and figured it would just help being less mass... I was palying around one day at the track and realized... My corner speeds are slightly higher and the car felt lighter in the corner. This was because the rotating mass of steel has more inertia then the lighter aluminum rotating mass.

Advancing timing is Tuning not weight reduction... when you lose weight you get faster and the power can stay the same... the only thing that has changed is the weight restrictions.

If you drop to much weight in the drive line you will have a very reactive, almost crack addict like, twitchy car.

Aluminum DS = reduced weight, reduced rotational mass
LDS = you will gain or match weight only.
Axel Stubs = reduced weight, reduced rotational mass
Rotors = Bigger means more weight and roational mass ususally causing loss of WHP. GiyroDisk makes light weight but lack life span, and mainly track only.
Rims/ Tires = lighter is not always better as road conditions become hazards, but heavyer will mean loss of WHP.

[Def]

Sounds like a good way to make some holes in your pistons. Where did you come up with this stuff?