Piston dishing

[oletshot]

I get this question on almost every request for piston dishing, "How many cc's can I get out my pistons?". When you break it down, there are 2 manufacturers of "off the shelf" 4.0 pistons, Federal and Silvolite. Both make cast and hypereutectic pistons, and as far as dishing goes there is no difference between manufacturers. Piston construction type is available in the FAQ piston page. Find your part # in the list of pistons and it tells you cast or hypereutectic. So for an easy rule of thumb:
Cast pistons (2228, 2229, 677) can be dished to 30cc's

Hypereutectic (3241, 802, 825) can only be dished to 20cc's

I have not had a chance to machine/measure a set of KB 944's so I can't comment on dishing them as of yet.

If one of the moderators could move this to the FAQ piston section, I would appreciate it. Thanks MoFo for suggesting this.

[GoMopar440]

I've decided to go with a long rod build and am going to buy a set of 944's (+.060 for a 4.7L) at the begining of next month when I get paid. I was planning on PMing you soon to get a shipping address when I saw this thread. If you want I can leave them with you for a while to take some detailed measurements and work up a good machining setup. I'll need to get all the build parts together by mid April so I can send the block, crank, rods, pistons and head off to the machine shop. That would give you about 1.5 months to play around with the 944's. Would that work for you and your schedule?

The current build plan is to try to get all the rest of the parts finish machined and back to me by the end of the semester in mid May so I can start building the 4.7 over the summer break.

I was previously planning on using 677's dished to 30cc use in a zero decked block. However, I decided that it's early enough in the build to switch that plan and see what kind of CC's I can get out of the 944's and set the deck height to get the desired DCR from there. Even if you can't get them past the factory dish depth, I can still work with that, and everyone else will aslo benefit from the results of whatever you find out.

FWIW: As for the reason I'm switching from 677's to 944's? I just can't shake the idea of putting a turbo on this engine sometime in the future. Cast pistons and turbos just don't mix well for long term reliability.

[Antifreeze2]

I just got my set of KB 944's and I am not sure if you can really dish them out more. The point of these pistons is to lower the pin height, having less material between the pin and the top of the piston. This is why Icon website has a maximum compression of 9.5:1 for the 944's, and 10:1 on the smaller dished pistons. You could take some of the material from the quench side of the piston, but that is designed to reduce heat in the combustion chamber. You may need custom forged pistons.

[montelibre]

Is possible to get custom forged pistons with about 34 cc of dish (or features that you need: dish, pin height, bore, rings, etc.), with same price than forged pistons, less than 430 dollars from bulltear, for example. I bought six of these for my jeep last year.

[GoMopar440]

Well, I may have to go back to the original plan of using the 4.2 rods and 677's. My 02 WJ DD grenaded the transfer case and I'll have to be throwing money at it first. The XJ is back on DD duty for a while which really sucks (35"tires + 4.10 gears + stock 4.0L = 11MPG).

[ohho92]

Oleshot are you still doing custom dish volume on pistons? I've seen your name metioned on a few topics with great feedback.

[Muad'Dib]

Best to contact him via Private Message with questions like that.