are there any downsides to one?

 

They usually cost more but "you get what you pay for" right? Other than cost, the only other downside I can think of is if the car is already undergeared for it's low end torque. A seriously lightened assembly can have an effect similar to a light flywheel.

 

does that mean a lightweight assembbly will make less torque?

 

No, it means that less rotational mass will retain less kinetic (stored) energy than would a heavier assembly. While it could "feel" like less torque, measurable torque would still be the same. I didn't mean to scare or discourage you. IMO, the benefits of a lighter assemblty far outweigh the negatives. In order for the effects of the lighter assmebly to be a negative the car would need to be already "torque challenged" for it's gearing, weight, etc..

 

Actually, if the weight of the rotating assembly doesn't store enough potential energy for a good launch, that weight can be made up by a heavier flywheel. Lighter components, accelerate and decelerate more quickly and use less energy. Internal loads, such as on the crank and bearings are reduced. Unless the parts are lightened to the point of compromising their strength, the ONLY disadvantage, is the cost.

RACE ON!!!

 

Not wanting to steal the post, but I'd like to throw this out there. My question concerns the streetability of an aluminum flywheel on a semi-daily driver with the following combination. I currently drive my car to work 2-3 times/week 80 miles round trip in L.A. traffic, and plan to continue to do so once I put my rebuilt engine in.

I'm building a 377" engine using a 1959 283 with a 4.00" bore and a 3.75" stroke. The crank is a 4340 forged crank with 350 mains turned down to fit the early block, the rods are 6.00" I beam and the pistons are Probe forged dish.

I'll be running the stock #550 heads with 1.90" I and 1.60 E valves. The heads will be fully ported; the porter is expecting 240 cfm @ .500" I and about 70-75% of that for the E (I will have flow numbers this week). The cam is still undecided, but it will likely be a fairly mild solid. For the short term, the intake will be either a '68 Z/28 or a RPM (currently on car); I have both. Ultimately the car will be ran through a modified '61 FI unit, or possibly the original 2 * 4 set-up. The cam will be kept mild to work with the FI; I was told the engine needed 3" of cranking vacuum.

Currently the trans is the original T-10, but will be eventually swapped for a wide ratio Super T-10 or a 5 spd. Rear is currently a 3.25 geared Ford, but it will eventually be replaced with a Corvette rearend, and the final gearing will be determined once I choose the transmission. The engine builder recomended I run an aluminum flywheel and said that my engine would have no problem on the street in L.A. traffic. Does this sound correct? Your opinions would be appreciated. TIA

 

wesmigletz - I've been running an aluminum flywheel for @10 years now. I have a pretty hot 355 ci with a sollid cam.

I have 3.55 rear end gears and it's just knowing how to drive a stick car. I can take of at idle if I want to. Your larger motor with a longer stroke would even be easier.

 

LT1er, thank you for the reply.

Wes