CharlieC

iTrader: (5)

Need to buy the pistons for my LSX-440 engine. I've seen Pistons designated for 4.000 Stroke and 4.125 Stroke, big price difference between the two... I'm guessing I can't, but can you use 4.000 Stroke Pistons on a 4.125 Stroke-Crank? Assume same connecting rod.

What's the difference between the two pistons? Is it the distance from the centerline of the pin to the top ring land or something like that?

Charlie

NemeSS

iTrader: (127)

its called compression height
any compression height piston, con rod, stroke can be manipulated to achieve a specific ci engine.
what crank do u plan on using,pistons?

CharlieC

iTrader: (5)

I've got a Callies 4.125 Crank, and 6.125 Rods. TSP L92 Heads. Plan is for a 10.5'ish compression ratio motor. No racing, just want lot's of torque.

The LSX Block is new, plans were to bore it to 4.125 to leave room for future expansion if needed.

I've got a lead on a new set of 4.125 Bore/4.000 Stroke Diamond PN 11522 Pistons/Rings for $500, so I'm real interested to understand if they could work, just not familiar with all the variables of what can/can't work. Getting it done at a shop here in the D/FW area, but it is time for pistons.

Thanks for the help...

Charlie

OneQuickCoupe

iTrader: (1)

This should answer your question. Give Brian Nutter a call. He'll take care of your engine.

https://ls1tech.com/forums/showthrea...ht=lsx+pistons

LSX

CharlieC

iTrader: (5)

Thanks for the reply... I had read that thread previously, but it was more of a why Diamond vs Wiseco. Good to know, but I'm just trying to understand the 4.0 vs 4.125 piston question.

Charlie

ScottyRocket

Given the same deck height... you would need .125" shorter compression height(distance from wrist pin centerline to the fire deck of the piston) with the 4.125" stroke using the same rod.

Deck height is measured from crank centerline to the top of the deck. Then take the rod length add 1/2 the stroke and subtract that from the deck height to get compression height needed on your pistons. Some guys run the pistons a little above the block's deck..."Out of the hole".

Here is what i get for your setup.... This assumes that you want it even with the block's deck....
Deck Height: 9.240 LS
Stroke: 4.125
Rod Length: 6.125
Compression Hgt: 1.053 inches

So basically, no you can't use the 4" stroke pistons on the 4.125" stock crank using the same rods cause the 4" pistons will have a taller compression height and be sticking out of the hole by .125" when using the 4.125" crank.

Sales2@Texas-speed

iTrader: (5)

He got it! With the crank, rods, pistons you've got your pistons will be out of the hole .0725" on a standard 9.24" deck height block. That's not good! The easy way will be a difference piston