Piston to cylinder wall clearance...

[Anonymous]

Has anyone here put forged pistons into a blown/turbocharged 300? I'm wondering what clearance is about optimum..... I was figuring a thousandth or two maybe over what the manufacturer recomended for the fact that the piston would likely be running a trifle warmer?

 

[Anonymous]

i believe thats right...Forged pistons expand more than cast so the lcearance should be a little more...dont quiote me on this but im sure your right on...about a thousandth or two...i think its 2 thousandths...

 

[MustangSix]

Depends on the bore size. On a 4" bore 302, i've run .004", about .002" more than cast. But on a 200/250 with a smaller bore, .003" might be more appropriate.

 

[Crosley]

On a forced induction situation or nitrous the ring land area of the piston can be reduced in size slightly or tapered. this will offset the growth of the piston under higher temps & loads.

The top ring end gap must adjusted also, so the extra heat does not cause the ring to grow so much that the ring ends touch. If ring ends touch the sealing can be lost & the ring can break

 

[Anonymous]

with forged pistons and a 4" bore .005-.006 isn't uncommon. I've seen forged pistons with a .004 gap sieze in the bores the first time an engine was worked hard. This is the main reason why OEM manufactures NEVER use forged pistons, they make quite a bit of noise from piston slap when they are cold.

 

[Anonymous]

I figure I'll go a thousandth over just to be sure.... It's nice to see a fellow megasquirter hanging around the board!

 

[Anonymous]

I figure I'll go a thousandth over just to be sure....

A thousandth over stock, or a couple thousandths? :

 

[Anonymous]

Only one...They're not really a performance type piston, more of a withstand the holocaust type piston....Seems to be doing ok so far... Haven't gone much over 8 pounds for boost yet though. Trying to break it in gently, so to speak...

 

[Anonymous]

They're not really a performance type piston, more of a withstand the holocaust type piston....

Funny!

Haven't gone much over 8 pounds

What kind of performance are you getting at 8 psi?

 

[Anonymous]

Before I smoked one of the cast pistons in the original high mileage motor I could work the neighbours dually pretty hard, it has a fairly fresh 454 in it.

The new motor feels quite a bit stonger. I'm not really sure how much torque it's making, but it's plenty enough for me... I'm just getting concerned about driveline parts those poor dana diffs were having axle *problems* before I rebuilt it...