Piston Differences

[DunderXJ91]

Hi there! My name is Danny and I'm from Fort Wayne Indiana, getting ready to tear into my first stroker. I found a 4 weight crank from an 88 yj locally and it's in fantastic shape for the build so I'm good there. My question is can I use 91-95 pistons in my 98 block for the build? The earlier model pistons seem to have a thicker skirt to them and to me look stronger. Or would a piston set for my 98 engine suffice?

[Russ Pottenger]

The 2229 Silvolite is the earlier piston with the thicker skirt.

You might consider the advantages of my Forged Piston that will allow you to run the longer and more desirable 4.0 rod. You'll have a choice of any cc dish, zero deck with no machining of the block.

Shoot me a email if you're interested in more information on my Pistons and stroker kits.

Thanks,
Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
(626) 673-2203
Email/PayPal: [email protected]

[Cheromaniac]

My question is can I use 91-95 pistons in my 98 block for the build? The earlier model pistons seem to have a thicker skirt to them and to me look stronger.

You could use those pistons but only with the shorter, less desirable 4.2L rods. You'd then need to have the piston dishes machined to a larger volume, and have the block decked, to achieve a desirable combination of compression ratio & quench height.
You're much better off getting a custom set of pistons from Russ and using them with your existing 4.0L rods. The cost will end up being about the same, but you'll avoid the headache of the extra machine shop work and having to look for a matched set of 4.2L rods (which might need to be reconditioned anyway).

[DunderXJ91]

My end goal was to build a 4.2 just because I don't see many of them around. I have a 88 yj 4.2 engine lined up for my crank just haven't torn into it yet to see if its in good enough shape for my
build. Why are 4.2 rods less desirable? And if I use Russ' kit with 4.0 rods how to I achieve the lessened stroke? With a shorter piston?

[Russ Pottenger]

My end goal was to build a 4.2 just because I don't see many of them around. I have a 88 yj 4.2 engine lined up for my crank just haven't torn into it yet to see if its in good enough shape for my
build. Why are 4.2 rods less desirable? And if I use Russ' kit with 4.0 rods how to I achieve the lessened stroke? With a shorter piston?

If at all possible you would be way ahead of the game if you built your stroker from a 4.0 platform building a 4.6/4.7.

There's a good reason you don't see a lot of people building 258 engines. Two of the most obvious reasons is because of their relatively small bore and poor flowing cylinder head.

The short answer to your connecting rod question is as a general rule of thumb you want to put as long of a connecting rod in an engine as practical because of the lesser angle and therefore less force exerted on the piston and piston skirt.
The other negative is that the short rod in a 4.0/242 block in conjunction with the 3.895 stroke, the piston skirt comes farther out of the bottom of the cylinder.

Lastly the length of the rod doesn't affect or change the cubic inches of a cylinder or Engine.