Anyone have any thoughts about using a light weight crankshaft on the street? I'm thinking of the Scat Q-Lite at 40 pounds or the Superlite at 44 pounds.

 

compstar comet

 

Thanks Dwayne I will look into them.

 

im running eagles lightweight crank and i love it. it revs so much quicker, this is in my daily driver

 

Thanks for the reply. I did think there would be any problem running a lightweight crank on the street as long as it was balanced properly. That is good to hear.

 

I read a post about them freeing up lots of hp??? True?
Something about a light weight rotating assembly will produce more power??

 

I don't think it produces more power but does allow the motor to rev up faster. Less rotating mass for the toque to overcome.

 

You end up with more HP at the flywheel, because less HP is consumed in acceleratiing the mass of the rotating assembly. How much HP you gain on a dyno will depend on the engine rev rate, in RPM/sec.

 

I am actually looking at a 3.750 crank from Ohio Crankshaft, weighs 44 lbs. and about $550 I believe.. Thats less weight for a little under the price of the 52 lb eagle or scat.. I still have the Eagle H-Beams that weigh 630g, so dunno if it will do me any good? Any opinions?

 

Run far and fast. Those ohio cranks are all over the friggen place on tolorences last time I saw somebody try to use one it woulda cost 3x what he paid to actually get it in shape for use.

You wont notice a lighter crank unless you're road racing and matching revs is really important. In that case a light crank and flywheel is where its at you can get the engine where you need it a bit faster than the heavy crank.

The only other thing is, the energy your crank soaks up instead of sending it to the drive wheels is put back into the car at a different time. The inertia is given back to the car when you shift and the engine speed slows down... thats the surge of speed or the little bump you get during a shift at wot or anytime really.

If the price difference of the light stuff is insignificant then by all means go for it. If its going to cost more my opinion on that is, every dollar you put into the heads is worth three dollars anywhere else.

I would not lose sleep over my crank being 10lbs heavier than it coulda been. Also keep your eye on the target bobwieghts of the cranks you're thinkig of buying.

 

ahh I got ya, well if I can get a Eagle 4340 Crank for $200 plus shipping with 1800 miles on it, would it be wise and cost effective to buy it?

 

Assuming theres nothing wrong with it, by all means. I would at the least have it polished and checked for cracks and runout though, figure that into your bill.

 

Stay away from Ohio Crankshaft.

Rich

 

Rich, I hate to disagree with you but they are great to work with. I've had them "correct" several cranks supplied by thier competitors (Eagle especially, scat, and etc) and for very reasonable costs.

I've bought cranks from them and if they had any run-out or straightness issues they gladly corrected the problems, no questions asked.

 

Their service may be good, but there are plenty of horror stories about their import cranks.

Rich