what rods and pistons to use?

nickleman60

Registered User
I just got my motor torn down and I plan on adding some major mods so i'm looking for some imput on what rods and pistons to purchase. The items I've already purchased or already have are:

1. mpx with coated gtp rotors
2. 25% overdrive
3. 60lb injectors
4. .520 lift comp cam
5. mildly ported and polished heads
6. 85mm throttle body
7. 80mm c&l maf
8. custom fmic
9. mp raised top
10. ported '94 manifolds
11. cloned scp "big dog" exhaust
12. 2.25" cat-delete downtubes
13. zex wet nitrous kit 55-75 hp
14. 2 program sct chip from d. dalke
15. scorpion 1.73 roller rockers
16. 255lph high pressure fuel pump

since I'm running nitrous I figure It'd be good to go with the forged stuff, any suggestions would are welcome.
 
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I have been kicking around the idea of a billit crank. I think that would be a good way to have a smaller rod journal and a longer stroke with a 6.2 Chebby rod. Of course with that it will require custom pistons but from what I understand, all forged pistons are custom for the SC so the price will still be close to a grand (for the pistons) with the rings and bearings.

Chris
 
See if Dalke has anything on the shelf for rods, then order the appropriate pistons for them. i went with longer rods, but to be honest the numbers don't really show that it's gonna matter. So any decent 351w rod with custom forged pistons will fit the bill. since you're getting a chip from him I'd talk to him about the pistons and rods.
 
See if Dalke has anything on the shelf for rods, then order the appropriate pistons for them. i went with longer rods, but to be honest the numbers don't really show that it's gonna matter. So any decent 351w rod with custom forged pistons will fit the bill. since you're getting a chip from him I'd talk to him about the pistons and rods.

i bought my chip,cam,rockers,tb,inj. and maf from dave d. after lettin him know my mods and future mods so maybe i'll give him a pm to get some info, thanks
 
If it was me I would go with an Eagle rod and a Wiseco Piston. It would be a flat top, Pro Tru piston, .039" back cut chrome top ring with gas porting, and a Total Seal second ring. If no gas porting then I would run an .031" dyke top ring. It would definitely be coated, too.

There isn't a reason for running a longer rod. It's heavier and produces more sideload on a piston.
 
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Heavier rod, lighter piston. The SCAT H-beam rods at a 6.125" length and the bushed pin were still lighter than the factory length stock rod and pressed pin.
 
It's heavier and produces more sideload on a piston.

How do you figure that? Im not trying to be an @$$ but the longer the moment arm the shorter the angle. I thought I could picture it but I just can not see it since the piston will carry the weight if the rod does not, and the piston will stay further in the bore, thus having a shorter angle off of the rod and staying parked longer at TDC...right?

Chris
 
He has a valid point on the side loading. To fit the larger rod you have to move the point of connection to the piston higher in the piston.

The main thing to consider is that the longer rod isn't substantially longer in our application. Going from the stock length to the 6.2 length (about the max you can fit and keep the pin out of the 3rd ring land) creates such a small change in piston velocity and duration, that I can't imagine the side loading is any more significant.

Certainly I'll always recommend a moly skirt coating on any non-stock piston, and while you're at it throw in a ceramic coating for the piston top. The silicone content of the stock pistons is so great that they created as little wear as possible in a cylinder bore. Factory hone patterns are clearly visible in motors that have been running for over 120k miles. Forged aluminum pistons will not have that same slippery surface and thus can benefit from the moly skirt coating.
 
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