atb

BC wrote:

That's the idea. The stroker already uses an off the shelf chevy rod. It's not a stock dimension, but is a common aftermarket dimension. The porsche piston uses a wrist pin that is larger than the stock chevy, meaning that the small end of the chevy rod needs to be reamed and bushed to work with the porsche piston. I've never heard of this as a failure point for a connecting rod, but I'll tell ya this, there sure isn't very much meat left on the small end of the rods that I have had this process done.

I'm thinking if we can use a stock sized chevy piston with the "stock" sized chevy rods, it will bring down the cost quite a bit. The small end of the rods will not have to be machined to take the porsche wrist pin which would also saves some expense.

But yes, your on track with what I'm looking to do, basically use small block chevy components to keep costs down. We'll see if it works.

BC

Ah, but adam - I want to do this with a regular crank.

BC

Any update on this (or these?)

Jay Wellwood

Interesting discussion.

Just curious Adam, have you CC'd the heads yet? What did they turn out to be?

Still stuck in house building land at this writing, but should be able to start my own Stroker after the first of the year. For those who are trying to keep track of who's doing what with their project, I am using the 968 pistons with no other coatings per se. I too am using a 'spare' engine for the build up and using a 928 Stroker Crank witht he SBC rod design. Once the house is built and we're moved in, I get to start!

Vilhuer

Hi Brendan,

Visited local 928 parts dealer yesterday just to see and measure wall thickness on two S4 engines he has apart. Both had just above 11mm's. So making bore to 104mm would leave 9mm. I take this is enough as there are 6.5L strokers running around. As soon as I have GTS engine out of car and heads of engine will do same measurement on it.

Regards,

Erkka
1992 928 GTS with unknown cylinder wall thickness
Oak Green Metallic 22L
Classic Gray MX

BC

Thanks Erkka. I have my engine apart now, and I have planned to do the same.

But think of this: There is a gentleman here named John Anderson, Anderson Motorwerks, and he has a guy doing 106mm bore sleeves. So that has to be 1 o r 2mm thick at least. 106+2=108OD, maybe more.

Hmmm.

atb

No update on my project to date, other than I finally got my spare engine on the stand.

Ah, progress.

DoubleNutz

Double Ouch!

atb

Jay wrote:

Haven't pulled the heads yet Jay, soon I hope.

I'll definitely post as soon as I have the answers.

V-Fib

Just a side note. My block is sleeved, and one is migrating South, causing me head gasket problems every few thousand miles. In my case I bought another engine (M28.11) and am going that route. I seriously doubt anyone would want my old block, not even the aluminum recyclers due to the iron in the block. It will make a fine coffee table, however. Although I'm not modifying to the extent you guys are, My only experience with sleeves has not been a good one. If they can place them in such a manner as migration is not an issue, maybe. Very interesting thread.



Anthony Tate
79/928 Silver Metallic

atb

Hi Anthony,

Could you give us some details about the sleeving you had done? We're all out cylinders sleeved? Was any of the original sleeve retained or did they bore out the entire alusil cylinder? How long did it last until the sleeve(s) started shifting?

V-Fib

Adam, It was sleeved when I bought it (unknown to me). It had 116k on the clock and now 124k. The first gasket gave out about 118k and I replaced both gaskets. I was in a hurry and thought the discoloration of the #7 cylinder was due to the coolant/water that I found in the cylinder. At about 123k the #7 cylinder was leaking coolant again. I could see the coolant through the spark plug hole with the piston at BDC. I removed just the #5-#8 cylinder head (left) and discovered the sleeve with a magnet (with the help of some fellow Rennlisters). The sleeve had migrated south about 1/4 inch from the top of the cylinder casing. After reviewing the photo's I took of the first gasket change, #3 cylinder also has the same coloration, so it is sleeved too. I had the head checked at 2 different shops and both said it was within specs. The #3 cylinder sleeve is flush with the outside top of the cylinder casing. Sorry I can't give reliable information on when it was done. It looks as though the cylinders were bored to fit the sleeves into the casings. The PO bought it in MO. and brought it to Texas. By the title transfers He didn't own it long enough, < 1 year, to have a problem with it (or at least he said he never had a problem). When I install the other engine, I will be interested to tear it down and find out if they used the stock pistons and what it looks like from the bottom end.



Anthony Tate
79/928 Silver Metallic

Fastest928

Anthony,
If they put a lip on the sleeve at the top, it will REDUCE the head gasket failure rate, but not eliminate it.

In stock engines that must run in all climates, it is nexst to imposible to defy physics of CTE.

Try Bensons in S cal for block work...

Marc
DEVEK