hi, i already have a 355 shortblock I got for cheap, just trying to figure out what compresion i'll end up with, my goal is 400rwhp. I will be using LE1 or LE2 heads.
car has full bolt on's and true duals.

355
diamond forged pistons part 11401 -12cc
scat 5.7 rods
stock crank

le custom cam

@ .050 230/240 lobe lift I .3770 E .3750 on 107.0

will be using 1.6rr

heres a link to the pistons

Diamond Pistons from RPM Machine

 

Short answer - too low. There is absolutely no reason to used a dished piston on a N/A build. You should target compression around the ~11.7-12.0 area. The -12ccs will pull your compression down close to stock (assuming a .028" gasket) - not necessarily ideal for a 400whp performance build.

 

Going to need deck height or how far the pistons are in the hole, then head gasket specs and head combustion chamber volume.

Dished pistons in a LT1 N/A build is basically taking 2 steps backward. The great advantage these cars have is the ability to run high compression. Look at Joe and I, we're both around 12.5:1 and run pump gas. Hell I'm at a toasty 4000 feet and with junk southwest fuel.

With a super small combustion chamber [50-52cc] .026 head gasket, plus pistons .010 in the hole you're barely at 11.3. Pretty much what you'd want for a stout Hotcam build.

-Dustin-

 

ok, so looks like i'm going to change the pistons. so I have some more questions

I already have the scat 5.7 rods, whats a good flat top piston I can run?

can i just take these pistons out and hone it, the asssemble with the new pistons? the build only has 10k on it and the cly walls look nice.

 

Well the shortblock isn't so cheap when it is wrong.

Was it built for mild boost?

I wouldn't do a 5.700 rod for an NA motor, longer rod makes for a lighter piston which is good for durability.

 

With a 4.030 bore 3.48 stroke, fel-pro 1074 head gasket,stock 54cc heads,block 0 decked and a 5cc relief flat top your looking at 11.7to1

 

It might be less work just to put this together then later on boost it.

would the cam I have work for boost??

 

I highly doubt it.

-Dustin-

 

Lloyd would be the person to discuss that. He recommended a 224/230@.050. 576/570 and a 114 l.s.a.
I currently have a xfi280 c.a.m which is. A 230/236@.050 576/570 lift on a 113 l.s.a .he stated my current c.a.m had too much overlap for boost. Fyi if its gonna take a long time too get a f.I system in the car just realize it will not perform very well with a lack of compression n/a

 

can I just change the pistons to flat tops and hone?? which pistons shoould I get?

 

Is the ad in question even an LT1?

 

I would assume it is since the le1/le2 heads will only work with our motors as long as the o.p knows what motor he has.

 

Mr. Elliott does in fact port heads other than LT1 and LT4...

-Dustin-

 

yes its a lt1

 

I believe what Joe was asking is are these engines the OP keeps looking at LT1s. Not is he looking to mod an LT1.