Flywheel or Flexplate

swampfox44 said:

I'm building a 383 SBC for my newly acquired 16' Cheetah jet. It had a Flywheel on it and my question is,do I go back with a flywheel or a flexplate? Are there any pro's and con's to both? Thanks

Click to expand...

Anything you can do to lighten the rotating assembly weight is beneficial. Unless you run a clutch, there's no real reason to run a flywheel. I'd go with a flexplate.

I'd go with flexplate to allow it to rev quicker.

Flexplate

If you want quick engine accceleration, run a flex plate. If you want to try and maintain some rotational inertia and help the engine, run a flywheel. The middle ground would be an aluminum flywheel. Also depends on your balancing. Make sure if your 383 is external balance that you match the weight.

swampfox44 said:

I'm building a 383 SBC for my newly acquired 16' Cheetah jet. It had a Flywheel on it and my question is,do I go back with a flywheel or a flexplate? Are there any pro's and con's to both? Thanks

Click to expand...

Bottom line is either will work without problems.

If you have a flywheel and change, you ARE going to spend money/time on a new coupler or, at minimum, a spacer for the existing one (thickness difference).

You already have a runnable setup, so, you don't HAVE to change anything unless you just want to.

Quicker rev is true, but, how true (ie, how noticable) is the thing to keep in mind. A jet drive has VERY LITTLE resistance to turning at low to moderate rpm's (low to modreate pump back-pressures) so throttle response to full RPM is very fast any way it goes, unlike a prop (or a car).

Good luck with it, whichever way you go.

The difference in rotating weight in a LAKE jet is negligable, at the throttle hit, the engine will be at or near max revs before the boat even starts to move. In a drag boat the weight difference will change which number you leave on by a few hundredths of a second, the engine will stay at max revs till the finish line unless you have some sort of blocker grate to starve the pump for water to get the revs higher at the "Big end". We allways use SFI flexplates because they are thicker and allow less starter drive deflection front to back, but are much lighter than a flywheel. The dif on a LAKE boat is primarily weight savings for dead weight only. On our max perf. stuff, I use a thinned aluminum flywheel, it is more rigid than an SFI flexplate yet. Go to a car parts swap meet and buy an outdated SFI flexplate, and don't pay much for it because the racers can't use it if out of date. Just make sure that the teeth are OK. TIMINATOR

Thanks for the input Timinator. It is going to be a Lake jet,it's a 1668 16' Cheetah,383 Stroker w/Aluminum heads,XM278 Cam,Performer RPM Air Gap intake,750 Vac Sec Holley,long tube headers and two IMCO 13 gallon S/S tanks,one battery,maybe two,not sure yet.Setup as a two seater now.Berkeley 12JA pump with "B" impeller,split bowl and place diverter.

Thanks