Yep, remember the Vega well. Seemed like such a good idea but GM sort of got it wrong. Really am old school afraid. Sleeved my block back to std. and used stock pistons and correct rings. Guess still holding a grudge on that whole Vega deal. Porsche got it 100% correct but old habits die hard. As for pal we were visiting last week and offered up "might" consider a early series water boxer 911 for a daily driver and ditch the super dependable and economical Acura (I'm old but still stupid). Asked how familiar with doing the L&N kit for RMS and IMS. His reply was sorry, my experience stops with air cooled and not going there. Old dogs, no new tricks!

 

Wow, form good ole boy work around to Vega...

I love RL..

 

I can offer you a couple of options –
Get your block refinished with a Nikasil coating – the block gets bored out and coated with a Nikasil finish and then bored and honed to original specs. Ball park cost is about $1k including shipping (the shipping adds up!) You can reuse your stock pistons but a different ring set is recommended.


Thank you all for your help.

Chris: Can you explain more about the above mentioned process. I have a set of aftermarket rings would I need a special brand? I am in CT how far away are you?

 

Sure –
Nikasil is an electrodeposited oleophilic nickel silicium carbide coating.
The Nikasil reconditioning is a process where the original cylinder is bored out to make it straight and true and then a Nikasil coating is applied (it can be up to .040” thick). The Nikasil is then bored and honed similar a steel cylinder except that a diamond hone is required due to the surface hadrness. The result is a very hard finish and cylinder dimensions are back to factory new. It is important to have this done correctly, a ‘bad’ job will result in the coating coming off. If done right the binding between eh coating and the Alusil is stronger than the Alusil.
Piston rings made for Alusil will work on a Nikasil (barrel shaped ring face).

As for location - I am near Syracuse. Shipping a bare 944 block can be easily and inexpensively done via UPS. A bare block weighs about 100lbs so it is not a ‘freight’ item. Once the studs are taken out it is easy to pack and ship without the risk of damage.

 

Chris- Thanks for explaining that to me. I was not aware of that option before.

 

Hey Chris, do you do house calls?

 

Depends on the house.....

 

Great advice, redo the block or find one that is not scratched. I spun the #2 at Daytona a couple of years ago. Pulled the motor apart and decided to put it back together with some minor scratches on the cylinder wall and an oversized bearings on #2. Long story short, I wish I'd had the advise you just got. Do it right. My rebuild lasted about 40 hours on the track. I recently got to do it all over with a different block.

Any input regarding using oversized bearings in this situation, especially for the track? Same thing happend to a friend and his mechanic advised not machining the crank for oversized bearings. Get a new crank. His, like mine is a dedicated track car.

 

Chris,

What determines whether or not the stock pistons can be used again?

 

Budget.




As long as there is no apparent damage to the skirts and crowns the only other reason is the ring lands. Most folks think about the cylinder walls as the sealing point of the rings – they also need to seal against the ring land or the gases will leak past the back side of the rings. Take a really good look at the ring lands and if any have been damage then toss ‘em.

Personally I would go with new pistons. The Wossners are about $1k for an alusil coated pistons and then are lighter than stock and come with new rings and piston pins. (A set of stock rings is about $200).

The only time I feel good about reusing a stock piston is if it goes back into the same bore and the bore and piston were both in really good condition (very uncommon!)