Chris White

As they say, "the devil is in the details". If the pistons are working fine for most others I would look at the block machining and clearances. Thats not a knock on your machine shop – I would guess that they have not used this exact process before (Tom C pistons and Alusil blocks). Piston manufacturers (and block manufactures) all have different expansion rates and clearances. You learn by experience.
That’s why I stopped selling the “install yourself” MID parts.
I normally wouldn’t toss in a pitch…but if Tom has stopped doing his pistons I do have another solution, I have been using the Wossner alusil coated pistons for almost two years, no problems. Custom sizing / compression ratios available.

951and944S

I have two non-factory coating engines up and running, no problems.

One is a 16V 944S daily driver with 1 year+ mileage and the other is a 944NA SP2 track car, also, no issues at all. As a matter of fact, engine #2 was over revved severely enough to float and bend a valve recently, so the head is off now for an exchange....still, no piston-cylinder issues.

Hotard Engines here in S. Louisiana is the machinist.....and a d@mned good one at that.

For others contemplating use of someone local, ask around at who does the German car dealer's work.
They will be more prone to have the necessary knowledge on fit and cylinder finish.

Chris - what is the highest compression ratio that can be reliably run in a 16V 2.5 for track use and are the Wossner's available in that configuration..?

Ski - top 'o the day....there's a PCA DE at Hallet soon that I'm contemplating......y'all up and running yet and will y'all be there...?

T

jacksonrw

Faerman Machine shop is one of the best in the nation specializing in the complicated way these Porswche blocks are bored out and polished

I am asking them a lot of questions as I hope to from Tom

I don't think anyone is really going to raise their hand up and say ME ME ME as the fault

but something terrible happened. I know the machine shop here well and their reputation outside of what I have experienced is very very strong amongst performance racing here.

Chris White

That depends more on fuel quality and tuning than the piston design!
Any compresison ratio you want - as it gets higher we will have to start talking about what cam you are using to make sure there is valve clearence.

Ski

Chris, the Wossner pistons, got any pics of those? You said Alusil coating so is it like for like or is it an iron based coating?

Terry, no, sad to say. Both of us have been too busy with work and home projects. He bought a shell of a home on the bay, been finishing that. I've been doing some home and landscape work that's just winding up. We're trying to find someone who wants some XMas cash to use Jim's truck and bring the car and trailer to me. We'd like to up by Hallett but we have to do paint as well. Running, yes - UP and running - NO.

BC

What are the wossner pistons in price? Do they get cheaper when you buy more than 4?

theedge

Heres the tops of Wossners

951and944S

Paint...., the track car....?
I asked Jason about y'all the other day when placing an order for Dr.Z.
Said he hadn't heard much from y'all lately.
Ah well, we'll sync up sooner or later, alot of DE action around the region for sure.

Chris....yeah....I meant mechanically possible, as far as interference with stock cam profile. Have a side project engine on the stand with perfect bores but one of the cam sprockets is toast so yes, I might be going with an other than stock profile there. Still accumulating the parts for a regular 8v NA track car conversion to 16V PCA class racer for my son but him parking it long enough between lapping days is the biggest problem...

OK, apologies to RW for the OT and I didn't intend to question anyone involved with your build, just offering up my experience per your opening post.

Good luck,

T

Ski

Well, the passenger side door to center of the rear section is in rust from the Paint being BURNED off from the oil fire, F*k'n A we have to paint it or sand the rest and just bring a rusty sheet metal track project to the track
I told you the fire ball filled the passenger and rear view mirror and you just thought I wanted to be Ricky Bobby.

jacksonrw

i wish my pistons still looked like that

Chris White

Basic pricing for pistons, rings, and DLC (Diamond Like Coated) wrist pins -
Stock configuration - $800
Custom Configuration - $1000
Quantity deals….we can talk!
BTW – the custom pistons include Wossner sending out engineering drawings for approval before manufacturing. Very detailed.

Chris White

With correctly designed valve pockets the limit on compression will be the tuning, not the pistons! if you really wanted I am sure we could make up some domed 15:1 pistons...

Chris White

[QUOTE=Ski;6086485]Chris, the Wossner pistons, got any pics of those? You said Alusil coating so is it like for like or is it an iron based coating?

[QUOTE]

The coating is designed for Alusil and the BWM equivalent, last time I met with Mr. Wossner he showed me a nice certificate form BWM approving of the use of the coating for BWM products.
Here is a picture of 10:1 NA piston I used in a DE instructors engine (good friend of mine). Interesting project – a low budget exercise, rebuild a stock engine for his DE instructing car. No engine mods other than higher compression pistons, not even a chip. He runs 93 octane street gas (except the time he added a gallon or two of diesel before he figured out what was in his gas can!). This car gets a LOT of track time, at least 30 days a year and he never misses a session. He picked up quite a bit of speed and had to rethink his shift and brake points!

Olli Snellman

So Wössner can offer pistons which works OK in our alusil blocks? I am asking this because quite many 3.0L projects going on and Mahle/Andial 104,5mm pistons will be available in six months and many of us needs to locate replacing item.

Ski

What's the recommended total clearance Chris; turbo just a bit more than NA due to heat? Nice looking skirt on that piston.