Not entirely true. THe Scat crank is 10 lbs lighter than the stock crank. Well i know the cast Eagle crank is and the scat 9000 is the same weight 49lbs as the eagle. So rotation mass is reduced which will free up some power..
Also if u go lighter pistons and rods that'll help too. Thats 1 reason why people opt SRP or Diamond pistons over Speed Pro which are twice as heavy.

The gains probably wont be much but every little bit counts.

 

actually. lighter rotating mass wont gain power, but it will let the motor rev faster.

 

Well, no and yes.

If you dyno at steady state rpm steps (no engine acceleration) rotating mass (or part weight) doesn't really effect hp at the flywheel. That's how OEMs rate engines. However, if you measure the flywheel output during engine acceleration, typically 300 rpm/second or 600 rpm/second, there will be less flywheel hp with the heavier parts because some of it is used to spin up the rotating mass. That's the 'no' part.

The 'yes' part is that the engine produced the same "indicated" power, before friction and pumping losses. Of course it's "brake power" or power that actually gets to the flywheel and eventually to the drive wheels that does the job.

Bottom line is that lower weight rotating/reciprocating parts will help increase flywheel (and rearwheel) power whenever the car is accelerating. Some of the very few race engines that run wide open throttle at max power but don't vary rpm much are NASCAR engines at Daytona and Talladega. A couple hundred rpm max. Watch this weekend. Of course they are using very lightweight parts also, but for other reasons, like friction, durability, and the only times they do accelerate: after pit stops and yellow flags.

My $.02

 

The only SCAT cranks ten pounds lighter are definitely more expensive but they do make some SBC cranks and stroker cranks etc that are even up to 12 pounds lighter. I have a 43 pound 3.750 right now but it's more like a 1000.00 crank and the regular Eagle stuff is half that.

 

Well... seing these threads make me worry a bit.. I hope my crank doesn't break at 6400rpm and 700rwhp...

I know intimd8 did 775rwhp with his eagle crank no problems... My engine builder found none with my crank though...

we'll see how it holds up... I have eagle forged rods... anyways.. I do hope they hold and if they dont, lunati bottom end...

I always thought the first thing that went where pistons, if you had good pistons and a "street" car you wont likely break it...

I HOPE and I will see