I am building a boosted 355, looking for 700+ RWHP. It will be Procharged at 15+ lbs, LE trick flows, cam and intake. I am using 5.85 rods. It looks like any shelf piston is going to have me in low to mid 9s as far as compression ratio. I was planning on going with 10 to 10.5:1 CR. So, I was looking for suggestions on what to ask for as far as custom pistons. I just want to make sure I dont miss something that would be beneficial for this build.

 

Why such a high static CR?

 

I was under the impression that low CR is not necessary with boost anymore.

 

Probe pistons
JE pistons
Diamond
Ross
Weisco
All have a great selection of boost friendly pistons. As for compression i would be no higher than 10:1 supercharged or 9.5 turbod

 

LS stuff tends to do better with high compression. I run 10.8:1 on 93 octane/meth @ 16psi on stock bottom LS3 making close to 900rwhp.

Ona LTx I would stick to 9.5-10.0CR, but I am sure some people have run higher static CR and have had cams that bring down the dynamic CR.

 

I reckon it depends on what type of fuel you want to use.

 

Sounds like there is no need to go full custom piston then. I believe they can move the wrist pin in a shelf piston to accommodate the 5.85 rod. This will be cheaper than a full custom piston and give me around 9.2-9.5:1 CR.

 

They still make them. You have to be creative in how you look them up.

 

Hi RM72, I sell RacTec Pistons with prices of a shelf piston, they have a 10% sale price at this time, a factory discount.

The Forded Piston is machined in the original JE HB plant, same CNC's and still owned by Wayne Brooks the founder of JE Pistons.

A size of +.004" COULD save $200.00 for a bore job NOT required, just a hone.

Would you like my help ?

Lance

 

Im no expert just talking here and if I missed it I apologize but why are you using a 5.85 rod instead of a 6 in I thought even mahle had a shelf piston d dish -16cc to put you into boost friendly cr using a 6 in rod for a 383 or 396 setup....i thought I read that even if you were building a higher rev 355 the longer rods were prefered to keep the piston ch short and thus the piston itself lightweight upgrade the wrist pins and boost away

 

I wanted a longer than 5.7 rod to help with the side loading, but didn't want to go 6.0 and lose some of the strength of the Piston by having the wrist pin so close to the top. Figured the 5.85 is the best of both worlds.

 

You are not giving up any strength in the piston by going to a 6.000" rod in a 355.

The 6.000" rod is going to be a lighter and overall better combination.

The only time I would use a 5.850" rod would be in a 3.875 or 4.000" stroke combo with heavy nitrous use.

 

Hi RM72, the R/L is increased, becomes LARGER as the rod is made longer, the WORST POSSIBLE thing for a HC turbo engine AND will cause a LOWER Knock Rating.

As no concern for my piston engineering is asked, I will that "add" tech.

USE an "offset" pin boss position, OEM side AND the piston will MOVE faster AWAY from TDC.
This will ALSO lower the skirt Side Loading.

I LIKE the 5.850" rod as the piston has less weight, thus best of both worlds with an "offset pin boss" style piston.

Mahle does not offer this shelf item.

Lance

 

I sent you a PM

 

I can get away with 17:1 on methanol in a 605 BBC, but I wouldn't run near stock compression with boost.

I have ran Wiesco, JE, and Diamond, but I would look around to see if maybe there was a alternative like SRP that was off the shelf. Really need to call around since they don't have everything listed online.

 

JE pistons out of their catalog here. No complaints.