Ski

I have heard that after a 951 is bored out, the cylinder walls are too soft and wear out fast. Not true in my experience

By people who really know for a fact and have or rebuilt a 951 personally!
Although heat is created when bored, the small amount is not enought to alter the metal according to the machine shop we've used 6 times. My engine is on the 6th year, friends 2.8 on the third year, 1 is on his second year and the track car lasted almost 4 but a rod broke.

What is the longevity of a 951 engine after a rebuild?
Depends on lots of things but mainly your maintenance and tuning. Track car - double duty on DE weekends - two owner partners, lasted almost 4 years until a rod broke; after tearing it down I'm convinced it would still be going this year and then some more.

A good machine shop, proper pistons with proper clearance are key.

cruise98

Tell us more about the CP pistons, and the rings available for them. Aluminum pistons will not survive in the alusil bore without some type of coating. What are they providing? Is their thermal expansion rate compatible with the clearances you are planning to run?

MAGK944

You could always have the scratches welded up, the Alusil replaced and the block would be like new allowing you to use stock pistons. This is not the cheapest option, 928 Motorsposrts can do this. (no affiliation)

Richgreenster

If I have a machine shop sleeve the block, what are some of the things I should look for to make sure they are doing it correctly? Also the only reason I am thinking of having it sleeved is so that I can reuse my pistons. Is this ok to do and if so will I need to get a certain type of ring for the sleeves?

pk951

frist get someone who knows these blocks who has done many of them. Here is a link give them a call see what they say.
http://www.customengineeredperforman.../services.html

cruise98

The problem with stock pistons is the lack of ring choices. I had a block nikasil plated for the stock
100mm pistons and now wish i had used a different diameter for aftermarket pistons with more ring choices. You CAN use the factory 964 100mm rings with nikasil, but they are $110 per hole and come in a set of six last time I checked into it.

If you sleeve it, make sure the sleeve/piston/ring combination is compatible, or you will have wasted your time and money. The machine shop that sleeves it, should provide the pistons, fitted rings and the final plateau honing as well!

If you stick with the stock alusil bores with either the 100 or 100.5mm bores, there are three pistons that have a track record of survival:
(1) factory of course; (2) Mahle/Ski Motorsport (3) Tom Charlesworth Arias.

Lindsey Racing has some Wiseco's that may work, but i am not too sure of the ring choices.

Ski has, as usual, given you sound advice.

Matt Sheppard

Ski,

<aside, for the record>

Would you use stock 951 rods again in a track motor build?

Ski

hmmm...hard question. No is my answer. The $890 - $1200 upgrade is worth the money, not that you can't have a failure there also. If budget was tight tight, I would at least send the stock ones out to be crack checked by someone proffessional in that field.

We lost a block, had to get new pistons, machine work, seals, gaskets, and we have to repaint from the passenger door to the driver rear from paint burned off AND buy a new WBO@sensor.