lsxfoxbody93

Found deal on some 3.903 -30 cc weisco pistons. What would my cr be with these and 243 heads? Any help would be greatly. I fear they may drop the cr too low for my setup.

A.R. Shale Targa

iTrader: (2)

The compression height must indicate that they are for a 4" stroke (383)application and a boost friendly 9 to one.
I dont see where they would be for a 347 as the comp would be 6 or 7 to one

96capricemgr

iTrader: (1)

Pistons are just one part of the compression equation, but -30cc will have no place in an NA ls variant.

lsxfoxbody93

The part # is ls3ut2id and the compression height is 1.0605. Starting to sound like not such a good deal.

A.R. Shale Targa

iTrader: (2)

Only 2 combos I could figure for you is a 3.9 K1 crank with a 6.25" rod, .060" gaskets as the pistons will be roughly .020" out of the hole and with 58cc chamber TF205 or CNC 5.3 heads it will be a 9:1 374 inch
Also a 4.125" stroke with a 6.125" rod with .045" gaskets and the same 58cc heads makes a 9.5 to one 395 inch. Problem with that combo is the pistons rock hard on directional change and are also pulling out the bottom of the sleeves so they tend to use/burn oil in fairly short order. That is why most people stick to a four inch stroke or less and prefer to use a LS2 or 3 block which has slightly longer cylinder sleeves.
IIWY I'd build the 374 and either cam it small to maintain some cylinder pressure & possible spray every now and again or turbo it and keep the rpms under 6500.

lsxfoxbody93

Thats interesting. I have never seen a 3.9 stroke crank b4. I think ill just pass up the deal and buy some new pistons. Its a twin turbo e85 build and i already have the turbonetics 66m turbos and a bunch of other junk. Would rather have my cr at or around 10.0/1. Trying to put 900+ to the wheels.