Porsche 944s2 engine

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yannisalex2000

New member
I want to build an IT legal engine for my 944s2.The problem is that one engine builder tells me that installing sleeves and boring the sleeves to .40 over is the way to go and another recommends boring the block to .40 and installing the pistons without the sleeves.So my question is to sleeve or not to sleeve?
 
I wouldn't sleeve it - just that you have to get the bores redone properly, given the Al/Si block. A 928 shop will have the technology. One of my crew guys had his S2 engine go through a total rebuild, track/street car... went with a mild overbore, new pistons and rings from Diamond, had a 928 shop out west bore the block (can't remember the name, will ask).

Biggest PITA in that thing was timing the cams. Ended up busting the teeth off one, as well as bending valves, due to the first (failed) attempt.

Anyway, he gave a stock piston to Diamond to pattern; much less expensive that JE, I'd recommend calling them. A spare set of rings with your order is a nice bonus! Standard with them, because they normally do V8 stuff. They should also be able to do the math, I think, to adjust the pistons for bore etc as needed.

So, who are you having build it, anyway? If anything, I'd suggest a 928 builder. If not - well, the engine's just too special to trust anywhere else IMO.
 
Back already with your info.

Turns out the 928 shop actually sent his block to US Chrome for Nikasil plating and honing:

US Chrome Corp of Wisconsin
650 Oak Park Ave
Fond du Lac, WI 54935​
(866) 922-5066

As for Diamond Racing:
Diamond Racing​
Ask for Nick ([email protected])​
+1 (877) 552-2112​
(OEM Replacement design should be on file)​

Hope that helps; feel free to email me direct if any further questions about the build...

We also found a very good machine shop in town, eventually, for the balancing etc... not sure where you're at, though - please add your location to your profile!!
​
 
I believe Porsche did treat those bores OEM.

Sounds like a very expensive rebuild.

Porsche...accept no substitute!
 
It would be legal to apply a Nikasil coating on an engine that came with the coating as OE. In that case, it would need to be identical to the original spec (try policing that).

As far as I know, the only cars currently listed that came with Nikasil coating were the ITR Porsche 911's.

The 944's came with Alusil blocks, which is an alloy, not a coating.
 
Definitely an expensive rebuild, either way you look at it! Yeah, pistons were around a grand or so for the set, IIRC. Best thing would be to talk to US Chrome about it, if not Jon Milledge.

Again, the car I reference was not an IT car, so coatings not a concern - but a good point.
 
GKR_17 said:
It would be legal to apply a Nikasil coating on an engine that came with the coating as OE.
Click to expand...

On second read, application or use of coatings are prohibited. It does not say except as stock.

So under a strict read of the rules, OE engines with Nikasil coatings are not legal. Clearly a stock engine should be legal, but it may be a very tough sell to say that this allows the coating to be reapplied if it is removed for some reason.
 
Per the factory manual. Actually, it's not really a coating in the '44 motor... but perhaps the 911 guys would still be at risk for some rules nerds.

I recall the Saturns having a similar problem with the stock piston skirt coating on their engines...
 
Back to the original question: to sleeve or not to sleeve.

Both have pros and cons. Sleeving (dry) is a common procedure that many good machine shops can handle. Cast iron sleeves are fairly inexpensive. Alusil honing on the other hand requires specialized equipment and knowledge. Most likely the block will need to be shipped to one of few shops that can do it. In the end honing will most likely cost more.

The risk with sleeving is that if it is not done properly, it will result in catastrophic failure. 3.0 blocks are expensive and are getting hard to find. If the engine builder and the machine shop have done sleeving on 944 engines before, I'd say go with it. If not, look elsewhere

Another thing to consider is timing. There is zero margin of error in these engines. Make sure that the builder knows how to set the timing after the compression change.
 
GKR_17 said:
Well, since the ITCS doesn't mention sleeving, it's not legal either.
Click to expand...

Oh, knock it off Mr. Big Chief No Fun! ;)

I would definitely not trust my block to a shop that hadn't already sleeved 944 blocks successfully (with references!!!)...
 
GKR_17 said:
So under a strict read of the rules, OE engines with Nikasil coatings are not legal. Clearly a stock engine should be legal, but it may be a very tough sell to say that this allows the coating to be reapplied if it is removed for some reason.
Click to expand...


I noticed that rules problem too. One of the ITR cars I considered has pistons that are coated from the factory. Now, of course you can buy OEM pistons and they will be coated too, so you don't have to apply coatings. And naturally the stock motor has pistons that are coated. But the rules say no coatings period.

Illegal car right out of the box.
 
There are coatings on every Mazda motor ever run, it is called chrome plate. The factory processes are not called out in the ITCS any more than every other stock part is specifically called out. It is still legal to use stock parts and processes. Many cams are nitrided from the factory, are they illegal too. Many more are parkerized, illegal?. It has always been legal to build or repair to factory spec and process. No different than the remote res shocks on the S2000, if it came factory it is legal. Alusil is actually a coating in that there is a special honing process to impregnate the surface and then the pistons are tin Plated to not gall up. So under a strict read the 944S2 would not be legal stock because of the coated piston skirt?:D
 
I agree, stock parts should be legal. The rule should be updated to allow stock coatings (I doubt you'd find any SOM's that would rule against stock parts like these, though I'm often surprised)
 
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