Picked up a set of NOS pistons today w/another car bound for the crusher.
EXTREMELY light, appear to be forged. they are 94mm for the 2.0L
No rings or Pin retainers.
I did extensive searches but I cant find any info on them.
I need a set of rings and to figure out what if any special instructions might be necessary to install in a set of Mahle barrels.
Not sure if the stampings are part #'s or what?

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rich email the electro etched PN on the pin boss to Cosworth , they can help you.

light pins, what size? what size ring gaps? interesting gas porting

So I got ahold of Cosworth US in Torrence CA and got as much info as I could.
They were made for Robert Overby of Overby's Porsche service back in the 70's.
No longer available product but still in thier archive info.
Rings & circlips are still available.

1mm compression rings w/4.03 radial thickness
4mm one piece Goits type oil ring w/ 4.13 radial thickness.
37mm Squish Deck height

they told me that they still have a pretty consistent & loyal Aircooled cust. base that was managed by a guy that has now passed (died) shortly ago due to cancer so they no longer have the same level of knowledge or support they once did for this mrkt segment.

look like a short stroke, perhaps 66mm. I hope Jake chimes in.

Ahhh, so you are the guilty party.....maybe

http://forums.aircooledtechnology.com/show...35622#post35622

"when you call us asking us how to make Cosworth pistons work in your engine and we tell you that we won't answer that question."

.....

Sorry if I am wrong, the timing was just too funny....

Stu


BTW - those would fit my vintage race car nicely! I dont even want to ask what you would want for them ;-)

"Goits" is spelled "Goetze", FWIW

Thanks Cap'n Never heard that one before so I took a shot.

Rich wasn't a guilty party, more of a perfect example for that post..

When I start using Cosworth Pistons in my engines, I'll start selling Cosworth Pistons, then I'll field questions pertaining to them.

These do look nice, sorry that I don't know anything about integrating them into a TIV.

whatcha think of the gas porting on the rings?

So if it wasnt Rich, then that means these are fairly common???

As I remember, the advantage of Cosworth Pistons were the metallurgy. We used them (not Porsche or VW) in the race car. The metallurgy allowed for a lessened piston to cylinder wall clearance.

That's from my memory ... we quit racing in 1984.

considering they are about 35 yrs old 1.0mm compression rings are high performance today even, 4.0 oil ring probably because its a horizontal.

If you're referring to the ports below the oil ring, those aren't gas ports. I believe they are there to divert pressure and oil away from the oil control ring.

Gas ports are used to help force the top ring into the cylinder wall more aggressively.

Nice looking set of pistons!

Stick one pin into a stock piston and the cosworth piston (side by side) and compare the pin height.

or you could measure with calipers from top of piston to top of pin bore and add 12mm....that will give you the centerline of pin to top of piston.

Rich

I just did a quick search on Robert Overby. He was a 914 guy, among other cars as well.

http://www.racingsportscars.com/driver/pho...Overby-USA.html

Did he also race a Porsche 356 in SCCA events?

Definitely 71mm stoke.But the side by side Pin trick indicates they would be very HIGH compression.
Some deck height manipulation would be necessary.

which may mean serious cylinder shims.. Which complicates everything from pushrod tube length to valvetrain geometry to even fitting the stock cooling tin..

I thought the pin height looked large that's why I asked.

So exactly how much higher?

1-1.5mm guessing they are 0 deck