Just wondering if there are any off the shelf forged pistons with a -31cc dish for a 6 inch rod, 4.030, 3.75. Need to handle up to 20psi.
If not, how long does it usually take to get a set of the custom ones made?

Thanks
Marcin

 

Diamond's custom pistons usually take 7-10 days.

 

Why not change the rods and run the JE or SRP's?

If not just call a Diamond dealer and have them get you a set with that change to them, it's cheaper than a custom set.

Bret

 

i would change the rods, but they are the nice and expensive oliver rods

 

More cases than not a simple job change to a piston isn't a huge deal. For example turning down the OD, or cutting the lock groove to accept a round wire or something of the like is more common and easy to do.

When you design a custom piston to stand up for big power, the skirt profile changes, the ring pack moves down, valve pocket/piston crown design changes extensively, etc. Much more than a simple job change would do for you.

Case in point, if a shelf stock boost piston comes with a .200 down top ring and you intend to run 20psi boost or more, you would want to move the ring pack down to roughly .275-.300 down from the piston crown. Moving of the ring package down like this to make for a thicker top land isn't something a simple job change would take care of, it requires engineering of a different piston. In a situation like this doing a custom 2618 piston is the best route to travel. In a case like this it is often common to change ring selection which will often have a different radial thickness and thus require a different ring groove depth to have sufficient back clearance of the ring.

Ok off my soap box, just offering my opinion on custom v.s. shelf pistons and when to do so.

 

I recall wanting to go with the 6" rods, but opted out due to the potential loss of material that is essential for durablility of the piston skirt, lands and the repositioning of the pin.

You're dealing with very small areas for milling and it could possibly affect your durablility. Also, there has been some other discussions about rod length and how the net power difference is extremely negligible.

I recommend checking your dimensions in greater detail.

PS: I have just passed over 40,000 miles on my P1SC 383 build. Drove up to Garberville, CA from Santa Rosa on 101 on Friday, got over 20 MPG. Wow, what a drive, wide sweepers at 85 mph. Unequaled vistas and.... very little traffic. Redwood forest...

 

Call your piston manfacturer of choice and discuss with them. Nothing OTS that I know of.

Rich

 

20 psi ..that is allot of boost...How are you going to make that ????

 

Call Probe Industries. They can make ya a set in about a week,if they don't have them on the shelf.
They will make whatever ya want.

 

D1 procharger

 

LOL ........i don't think you will see that kind off boost....1standgoal only made 18lbs......just a heads up

 

i know, i bought his set up believe me it will hit right at 20 psi with a less restrictive intake.
Adding some AFRs and lowering the compression so i can hit that 20psi with pump gas, hopefully it will work....

 

LOL....very very nice cool.......

 

Your car is going to be bad

 

yeah put down 640/595 with 14psi so hopefully it will be in the 700s with 18-20 psi.....i hope lowering the compression wont cost me too much power