Flat6 Innovations

There's not a single fix for this, since the rod angle is so steep on the 3.6 and 3.8 engines, a piston won;t solve the problem alone.

This is one reason why I have shortened the strokes on my high speed engines, to allow for better geometry. Pistons can help, but the work I have done with piston offsets haven't made it into production parts. Its one of the tricks I'm retaining to keep my edge.

krombacher

Ok, that makes a lot of sense. Presumably the rod-to-cylinder wall angle is abnormally steep compared to typical production motors. I guess Porsche went to far in stroking the m96 engine to a 3.6. Was the 3.6 -> 3.8 a bore change or a stroke change? If a stroke change, that motor must have worse piston scoring issues.
Re: tricks - understood.
Re: LN Engineering- Awesome work, btw.

I'm getting a slight ticking on the passenger side of my engine occasionally when it's hot. Hopefully it's a loose sparkplug. But it might be worse.
Also may be loosing a tiny bit of coolant. I'll keep any eye on it. This was my motivation for my original post, and I don't have anywhere near the funds to get the engine rebuilt. I'm happy to make a winter engine tear down project though. I saw your online 101 class for $400 or so, but wife won't let me spend it (grrr!) she said I've spent enough on this car many times over. I want to stay married.
I do have a boroscope that I can check in the cylinder walls with, but I'm not sure what is acceptable and what is not. I've never seen pics of acceptable wear of stock 3.6 cylinders (2002 c2).

Water pump was replaced over a year go. No foreign debree or evidence of broken blades found. Engine never overheated. (Well did get to 215 coolant temp while in Toronto @ 39 degC., hopefully that didn't hurt it).

krombacher

Re: piston offset & scoring
I heard the vast majority of cylinder scoring occurs on bank 2. Is that true?

Flat6 Innovations

Yes, the side where the offset is essential backwards from the factory.

We see scoring all over these engine, Canadian engines often see all 6 cylinders effected at once.

m3driver

FYI, everyone who builds a high revving engine uses short strokes....everyone

Flat6 Innovations

including the one I finished this week for my own car.

996SPECticle

Flat Twelve Innovations! BBi FTW

craig001

Serious gearhead ****! Love it.

Torontoworker

And we are at the point up here that we don't even worry about IMS issues any longer as the cylinder scrubbing will get you sooner or later or... you park the car in late October and don't fire it up until April or whenever the outside temps are above 50F.

Its getting ridiculous that I know six owners with cly scoring and NONE with engine failures due to IMS. All of these cars are year round drivers.

The only theory I can think of is the people that drive their M96's during the winter months are suffering from some sort of super wear due to frozen surfaces, metal surfaces warm up and expand at different rates, heat shock of sudden combustion against -10 surfaces or just plain poor engineering on the part of Porsche. Its just silly but there is no fix for this - no preventative maintenance that can solve this issue other then make the car a three season car and buy a $5K winter 'beater' and save yourself this issue along with salt baths.

Apparently its not just a Canadian issue as northern US and northern UK M96's have suffered these failures as well.

AWDGuy

The LNE nickies will get a solid test from me here in Ottawa where we will see -40 Celsius.

And yeah, I share the same experience, some of the 996/boxtser owners I know have the same ticking I had in my engine. They just add oil and drive though.