Which DOHC pistons to use in my '01 Magnum?

supertrick_05 · Post by **supertrick_05** » Mon Aug 27, 2012 10:48 pm

Next Spring, EJ and I are doing a slight performance rebuild on my '01 R/T's Magnum motor and I'm trying to figure out which pistons to use. I'm for sure going with Sealed Power pistons, but I don't know if I get the standard size or what? Here's the link of all the options to choose from: Click Me!

Any help would be greatly appreciated. Thanks!

Edited link size: O.D.

Edited link syle: Dante

stdlystdmufn · Post by **stdlystdmufn** » Tue Aug 28, 2012 12:46 am

you have to measure your cylinders before you order your pistons. or you could go .020 over and just take your block to a machine shop and have the bore fit your pistons.

JeffB#2 · Post by **JeffB#2** » Tue Aug 28, 2012 6:57 am

If you buy anything bigger than stock bore you drop the piston and block off at your machine shop. You ALWAYS bore the block to fit the pistons and ALWAYS have the pistons there at the time. With high miles on the block, the bores are most likely no longer straight and round even if they "appear" to be.

supertrick_05 · Post by **supertrick_05** » Tue Aug 28, 2012 8:11 am

So if I get the stock size I should be good to go?

Post by **occasional demons** » Tue Aug 28, 2012 8:15 am

There is one benefit to a high mileage block tho: It is likely completely stress relieved. Or "Well Seasoned" as the old school racers called them. In short, it will hold it's bores straighter after it has been machined.

Not sure on our engines, but do they also require a honing plate when bored/honed? I know a lot of newer thin wall blocks do. Also anything that bolts to the block should be in place, and properly torqued.

Maybe overkill, but you want the stresses on the block when machined to be the same as they will be in use.

supertrick_05 wrote:So if I get the stock size I should be good to go?

That ultimately depends on the actual measurements of the bores, if they are still good enough for a stock size. If they are too loose after honing, you are going to have piston slap. And possibly ring issues, if they are too far out of the ring lands. (snapped rings)

Your best bet, is to have the block inspected at a reputable machine shop, and go with what they recommend.

A few hundred more will be cheaper, less disappointing in the long run. (If you get a good machine shop. :/ )

Heck, even on a brand new block, the piston clearances should be checked for each bore. You never know which side of the tolerance each part is on. Never take for granted they are all exactly the same.

ZeroChad · Post by **ZeroChad** » Wed Dec 05, 2012 2:54 am

supertrick_05 wrote:So if I get the stock size I should be good to go?

old post, but no. What Jeff was saying is the block most likely needs to be bored out since the cylinders are most likely out of round.

That said, you could pull a Chad, buy stock size, use a dingleberry hone on your 120k block while torn apart in your apartment parking lot and cross your fingers. Ended up working well for me.