Hahaha.. ok so the verdict is out or maybe just 1/2 way in It's probably pretty close to the speed pro pistons though.

I'll have some more stock pistons here in a week or two & will get 'em weighed when I bring my block in.

 

Mahle has been the OEM for most manufactures for a long time, they are the largest piston producer in the world. They made the pistons for LT1, LT5, 4.6/5.4L, etc.

 

Ok....

Now how about a quick lesson in the physics of engine building.

Using the simple Force = mass x acceleration (F=ma)

To use it in this we have to use Kg for the mass, piston G's for the RPM, stroke and rod length and then mulitply that by gravity and then convert to lbs of force. So to find the Force on the Rod and Crank


F = Kg x Piston G's x 9.81m/s^2 x .2248

Stock Piston

@ 6500rpm = .532 Kg x 2720 g's x 9.81 m/s^2 x .2248 = 3191 lbs of F
@ 7000rpm = .532 Kg x 3160 g's x 9.81 m/s^2 x .2248 = 3707 lbs of F

Now switching to a Mahle 4.030 stock replacement piston (5.7" Rod)

@ 6500rpm = .464 Kg x 2720 g's x 9.81 m/s^2 x .2248 = 2783 lbs of F
@ 7000rpm = .464 Kg x 3160 g's x 9.81 m/s^2 x .2248 = 3233 lbs of F

Now going to the 6.0" Mahle piston

@ 6500rpm = .429 Kg x 2690 g's x 9.81 m/s^2 x .2248 = 2544 lbs of F
@ 7000rpm = .429 Kg x 3120 g's x 9.81 m/S^2 x .2248 = 2951 lbs of F


So you can see how just taking that mass out of the piston lets you load the crank and rod about the same amount 500rpm higher, and when you go even lighter it loads them even less. You can get crazy and get the Force down to 2400 lbs @ 7000rpm by going to really light weight pistons. That would be equal to about 5600rpm on the stock pistons, a gain of 1400rpm.

Bret

 

Now we should calculate out effects from valve weights stock vs manley street SS, ferrera 6000, hollow stem etc, Ti retainers, ...

 

do it, I'll read it.
-b

 

Hmmm.... actually the only thing that would be any use would be the spintron tests of all of them. Actually unless you are running a hollow stem valve the difference isin't huge. The spring mass and retainer mass have more effect on the valve control than the difference between a Ferrea or a Stock valve, but usually if you go to a aftermarket valve you have more mass to control but better springs to control it with.

Bret

 

What kind of performance valves are you using in the LS1's? I'm curious about the valve weight difference there because the stockers are damn light...

 

Ferrea stuff... LS6 stuff if it's there or Hollow Stem Ferrea's if there is the need and $$$ for it.

It's all 8mm 5/16 stuff so it's light anyways.

Bret

 

What about stock rod weight?

 

what? no one knows?

 

I just weighed them today...

Stock LT4 PM rod - 603.5g/ 422 big end
Stock GM forged - 604g/ 422 big end

so they weigh exactly the same.

 

I doubt it will help you but i shipped a set of 8 pistons, rods, and rod bolts (all stock) and it was between 25 and 26 pounds with a box and packing peanuts.

 

I have been trying to rebuild my engine and just getting back into it and I figure I need good rods and it was mentioned that some forged are light and the formula shown showed a big diff in some app and was wandering would you get the same effect with rods. Stronger and light sounds like a great combo.