Pelican Parts Forums - deck height, dome volume and compression ratio

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Josh, my understanding is that there are only two versons of the max moritz pistons... The 3.2 and the 3.4. But there are many different 3.2 and 3.4 variations that were not built for max moritz.

With the mahle reply, I am confident that I have what I think I have.

Quote:

Originally Posted by jkh2cpu (Post 8748763)

Josh, is that a busted stud on the lower right?

Yes it is, but that is not my engine.

Quote:

Originally Posted by gliding_serpent (Post 8748876)

I agree. Your's is a recent production and you have a current part number that you were able to cross reference with Mahle. There are other wedge dome Mahles, either of the 3.2 or 3.4 variety that don't have a recent, or any, part number engraved on them. Thats why it can't be said with confidence, without measuring, that all the 3.2 versions have a 28.4cc dome volume. In fact, I would guess that Max Moritz (the actual dealer/tuner) hasn't offered this upgrade in decades, yet for some reason, we continue to call them Max Moritz pistons. Porsche was the first to use this design in the 3.1L. Both Max Moritz and Ruf wanted to use the 97mm wedge pistons in their customer tuned cars, but Porsche said no. So, as I've read, Max Moritz had Mahle make them in 98mm with bored out cylinders to match. Both Ruf and Max Moritz used these.

Patrick Motorsport still offers both the 3.2 and 3.4 Mahle wedge P&C. They list the 3.4 set, like you have, as 9.8:1 CR. They list the 3.2 set as 10:1 CR. That would require a dome volume of around 38.5cc, yet Mahle says, according to others research, there are only two dome volumes of 35.4cc and 28.3cc. So who knows?

http://i906.photobucket.com/albums/a...ps2tvee7pj.jpg
http://i906.photobucket.com/albums/a...psuteudp0r.jpg

Quote:

Originally Posted by Josh D (Post 8749033)

Both Ruf and Max Moritz used these.

They list the 3.2 set as 10:1 CR. That would require a dome volume of around 38.5cc, yet Mahle says, according to others research, there are only two dome volumes of 35.4cc and 28.3cc. So who knows?

I guess my assumption that the 3.2 Max moritz pistons are 28.3cc assumes that the data given to the other member from Mahle was correct. As you say, best to run the numbers by Mahle, or measure.

I find the lack of consistent info quite frustrating actually. I am having similar issues with injector seal kits. So many variations and mis-information. Another thing to add complexity to the piston ID issue (including the Patrick Motorsports 10:1 3.2 pistons), is if PM had those 10:1 pistons custom made? EBS told me the Max Moritz 3.2 98mm pistons were no longer in production or available to them.