AmnSF

iTrader: (12)

Wanting to turn my current LQ9 into a 408.. However, I'm a little confused on the rotating assembly (tad new to the engine building). Really stuck on piston sizes.. TSP offers a bunch of different sizes. Seeing as the bore would be 4.030, what size piston would be needed? They offer 4.010, 4.03, and so forth. Looking for some guidance for a NA setup.

KCS

iTrader: (20)

4.030" will get you 408ci with a 4" stroke. More and more guys are taking the 6.0L blocks out to 4.065", myself included, but I wouldn't do that with any sort of power adder.

Sales2@Texas-speed

iTrader: (5)

In order to make a 408 you would need to have a 4.030 bore. However you will make very similar power with a 402-404.

redtan

iTrader: (5)

If you buy it from them as a package, it will be a 4.030 piston.

If you're doing it yourself, you should be buying 4.030 pistons and boring out the block based on their exact measured sizes. Don't do the bore first to 4.030 and then try and stuff in those pistons.

ss performance

iTrader: (17)

You should decide what bore is best for you, with the assistance and advice of a reputable machine shop. When you order a set of pistons, or rotating assembly let them know what your bore is and they will know which diameter pistons you will need. The actual diameter of the pistons is smaller than the diameter of the cylinder bore.

Most machine shops prefer to bore the minimum amount required to achieve a proper cylinder condition (round & smooth). Unless your cylinders are damaged you might choose to stay with a stock bore.

Good luck.