M96.03 Rebuild - 996 (3.6) and 997 (3.8) piston and rod compatibility

(I tried a search with no luck...if you know of a thread that helps to answer my question, please direct me to it and ignore this post, thanks) I am looking to use Mahle Motorsport pistons in my next "M96.03" rebuild with replacement ductile iron cylinders. My main reason for using these pistons is due to the "4032" alloy and the Mahle Grafal skirt coating. My preference is not to turn this into "what brand/type of piston or cylinder sleeve" thread, please feel to search the forums for the many threads that address those topics. Please let me know if you have any experience with using 99mm pistons from a 997 S 3.8 in a 996 "M96.03 96mm" rebuild. Pin height, deck height, and any other critical measurements need to be taken into consideration. The part numbers for the Connecting Rods (996 103 985 02) and Wrist Pin Bushings (996 103 111 51) appear to be the same between the 3.6 and the 3.8. For reference, here are the pistons available from Mahle: See page 5: http://www.us.mahle.com/media/usa/20...ap-guide-2.pdf PORSCHE 996 3.6L with replacement cast iron cylinder liner (not Nikasil) 96mm piston set with rings Mahle part number 197849180 PORSCHE 997 3.8L with replacement cast iron cylinder liner (not Nikasil) 99mm piston set with rings Mahle part number 197837098 Pictures below/attached are in order of the 96mm piston, 99mm piston, and both pistons (96mm on top, 99mm below):

I'd call or email LN engineering and talk to them about your project.

I haven't tried this particular set-up, but the only difference between 3.6 and 3.8 pistons is the diameter ( and a little weight difference). 96mm vs 99mm.

I have looked at these pistons too, they look like a great set-up. My concern, and I had discussed this with LN, was that the compression height was set for a stock motor and the pistons would not have the deck clearance they needed on a milled head. I never persued it any further, but I did wonder if Mahle would make a custom C.H. on these. I'm not familiar enough with how they operate, even though I have a set of MM pistons in my VW 1.8t.

Mahle will do custom,, but be prepared to wait especially in the winter,, This is when all the race teams are in full rebuild mode.. CNC tech being what it is I'd be surprised if its much of a change for them to change the build height to keep the CH in the zone. But its been many years since I bought Mahle's for anything.

YYC, can I suggest you contact our Sharon on [email removed] and request our technical article on our oversized engines by E-Mail. We provide a 3.9 conversion for the 3.6 engine by fitting aerospace full new ribbed Nikasil plated cylinders that convert the block to a closed deck and are not only supported at the top but also at the centre and bottom (i.e. full closed deck). The pistons already have all the right corrections for compression ratio and the rings are made to suit Nikasil. The results are slightly better performance than a std 3.8 without any other tuning (and a much better mid-range). We have fitted thousands of the cylinders without failures and have many very happy customers. Crankcases, bottom ends or complete engines (less auxiliaries) can be sent to us in the UK or we can sometimes find a set of cases to exchange. A remap makes the engines even smoother. She can also provide another technical report on the 4 main weaknesses in this engine range, one of which highlights some potential issues with ferrous liners that you might find of interest (and explains that true cause of bore scoring). Full technical details are available from Sharon and prices from Grant on [email removed] but although we can turn round such project in a few weeks - we are always busy and so even if you decide on an alternative solution - we are not trying o make out a case just to only come to us and you should find the contents of the report of interest (including photographs and tables) that helps you with your project one way or another. Our web site www.hartech.org also contains 2 videos that might be of added interest. Good luck. Baz

Thank you for the quick replies everyone, much appreciated. I expect to be tearing down two 3.6 engines in Dec/Jan and will double check deck height at that time, after having heads completed. I will update this thread with progress.

There will not be an issue with the deck height, the pistons are made to Factory deck height/compression height. The Factory recommends no machining of the block or heads because they made no provisions to correct an issue there. Due to any machining will cause slack in the chain drive, machining must be kept to only a couple thousandths to correct any unevenness of the block/head or surface finish. If only a couple of thousandths are removed there will not be an issue with deck height/compression height, if excessive machining is done, custom/thicker head gaskets will be necessary. There are companies that can make a custom head gasket of any thickness you want. The MLS head gaskets are three layers, the upper and lower are embossed with a coating on them, the middle layer/shim is flat stainless steel, they take the rivets out and separate the gasket, then make a new middle shim of any thickness, then reassemble/rivet the gasket back together.

Quotes source post: 16259311

He's the man--follow his advice

Thanks PorscheTech3, much appreciated. Looking forward to these builds!!