944er-teile.de

i heard about it, but also about good experiences… tried to figure out everything in detail and now we’ll see :-)

blade7

It seems the good experiences are no more, unless the pistons are old stock.

sherry66

Do you know anyone with old stock Woosner pistons then Blade ?

blade7

None with the coating that used to work in Alusil.

333pg333

Seems like there are a few of these builds about to run Wossners. Finger's crossed for all these guys.

blade7

From what I've read, it seems easier and cheaper to have the cylinders Nic plated in the US. As that was what Porsche did on the 968 S/RS and 911 turbo engines, it seems a no brainer in view of the benefits.

333pg333

Yes, certainly an option. I did consider that for the latest motor but have settled on MiD sleeves. Just need to change rings to suit. Ironically last motor did have Nic plating but just wanted to put this one together down here.

sherry66

Are you going to share details of this latest engine build Patrick ?
Always enjoyed your thread for some inspiration.

blade7

Yes, will be interesting to see whether he uses a 2.5 or 3.0 crank.

blade7

Could you have the sleeves plated, and the final finish done locally, after they were installed?

333pg333

Build is the same as the last motor. 3.2lt 16v. All I did was to buy a spare S2 block and use the internals from the last motor which had a catastrophic block failure. It was decided to source an engineer / builder down here. I did also source some high end studs which will be using a different type of sert from the last motor as we believe they were the probable cause of the numerous cracks. The crank is a modified 3lt stroker version. The material of the MiDs is a very hard ductile iron so I didn't consider having them plated.

blade7

Crank dampener, and balancer shafts this time?

333pg333

It's got the same ATi crank dampener as previously. No balance shafts. Definitely get some polarising views on balance shafts for race cars.

blade7

I don't pretend to be an authority on 944/68 race engines, but the benefits of deleting the balancer shafts seem to be fairly minimal. So if there's a possibility of them working as intended, why not leave them in place. I don't remember what treatment the crank had, was it just polished and not knifed the last time? Maybe offset grinding the crank for more stroke, has some effect on the engines harmonics. TurboTim didn't do much more than polish his crankshaft. Like Mike Tyson said, everyone has a plan until they get punched in the face. Or their engine blows up...

333pg333

The decision to delete b/shafts was made in concert with the previous builder. The thinking was that the dynamics of a race engine designed to be able to rev to 8800rpm would not benefit from b/shafts that are there for lower rpm harmonic issues. From my understanding you can't just add b/shafts and covers from another motor as they're paired for each motor individually? Hence we didn't consider retro fitting a set for the current build. I mean, given a choice again I'd probably opt for them however people who have run them on race motors have cited throwing belts as a negative. Also seen enough people run without them with no disadvantages.

The crank was modified for offset grind to try and get a little more tq than a 16v typically produces. Because we only have a factory 968 H pattern gearbox vs sequential gb that pretty much all our competitors have, we thought a bit more tq might be help close the gap. The old 3.1 8v had great low down tq which was a plus on the tracks we drive on. It was not knife edged though. Not going down that path again.