Hi Guys,

I'm trying to put together a motor and I'm keeping the stock stroke. With that in mind my calculated compression height is 1.331". Do the pistons have to have that exact compression height or can I go with a 1.34" or a 1.105"? What would happen if I went with the 1.105'? This will be the first lsx motor that I have built and I just want to make sure it is done right the first time.

Thanks in advance!

 

If the compression height is shorter than what you calculate it out to be, the piston will be that much under the deck (assuming zero deck) It will not work correctly unless you address the piston CH with the correct length rod.

In easy terms it goes like this
stock stroke, stock rod length (6.100) your CH is (roughly) 1.340
stock stroke, 6.125 rod length your CH is (roughly) 1.315
The math works out. But these are all assumptions with CR based on zero deck and not a normal "out of the hole" experience.

They math will get you close, but real world measurements will tell the truth. FYI LS pistons normally stick above the deck .004-.012. That is a huge margin from GM.

Also when looking at all of your piston choices and such, make sure to get the correct size pin as well.

 

Thanks!

 

No kidding..... .004 to .012 above deck.

What a contrast to Gen I motors where the pistons were well below deck from the factory.