Alusil-->Nikasil replating durability?
 

I'm in the process of rebuilding my 3.0 top end with modified cams, heads, runners, etc. I am currently contemplating bumping up the compression ratio from stock to 9.8:1 with JE pistons. I have a good idea of what torque/hp the added CR will bring by talking with EBS, engine builder and folks from this BBS. See these threads for background.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/111591-x-compression-ratio-increase-x-hp-increase.html

http://forums.pelicanparts.com/porsche-911-technical-forum/111592-x-compression-ratio-increase-x-hp-increase.html

My question is....I currently have Alusil cylinders and the JE pistons are not compatible. My options are to wait for the 3.0 Mahle's or replate the Alucils to Nikasil which EBS farms out to USChrome. I've read in past threads that Andail (sp?) has had mixed results with the replating process. Does anyone have first hand knowledge or can anyone offer opinions, suggestions, comments regarding the durability of replated C's?

I'm teetering on the edge here. The top end is ready to ship and will need to decide if the Alusils should come back home for reassembly or have the shop send them to EBS for replating and JE's.

If it fails you have everything in your engine to lose.

The oil will be contaminated and perhaps you will have to toss both the re-plated cylinders and your screwed up pistons.

Maybe the crank bearing surfaces will need to be re-machined too?

Imho the replating process is cheap compared to a new set of cylinders,,, although a catastrophe like above makes a new set of cylinders appear the better bargain.

I would not risk re-plated cylinders in my motor.

Ted, I agreee. If it fails, I'm screwed. Apparently the process USChrome (they do work for the aerospace indusrty) uses is better than the process used by Mahle many moons ago. Just want some opinions from folks out there who have had this done, good or bad.

bump.....?

I would call USChrome directly. I heard guy on another site rave about them and their plating results.

I've talked to both EBS and USChrome and they say their plating process is superior to Mahle's and will hold up just as well. I have a feeling they would have a hard time telling me 'well, we've had a few C's come back due to.......". I'm not trying to call anyone's bluff or say anything negative about these two reputable businesses, just looking for an unbiased opinion either way.

I am going to do it when I rebuild next year. I talked to both of them as well. I want to use the higher compression pistons like you are and I figure If I buy the Mahles I would have to throw away a brand new pair of pistons. I appreciate what Ted is saying but his engines are alot higher dollar than mine. I also think that EBS is fairly reputable and they wouldnt mess with the replate if it wasnt OK. Just my feeling. No experience

Elombard,

BTW: EBS said the 3.0 Mahle's (P/C's) are out of stock and no word from Mahle when they will get more. If I go the JE piston route, I'll probably go for the replate. Just havent made up my mind if I'm going to do this yet......$1800 for just a bump in compression, no displacement increase

I think you can put in a short stroke 3.2 for the same money?? Tahts what I was planning. Ask EBS.

I have to replace one P@C anyway. I figured ~ $1000 for the bore out and replate and $1000 for the pistons.

A 3.2 with the 9.8:1 JE pistons are $2400 through EBS. Once you start increasing compression, displacement and flow (with cams, exhaust, porting, etc), the current CIS fuel curve will not be adequate, you'll start seeing the A/F mix lean out as the RPM's increase. Hopefully by keeping the displacement the same, I won't have too much trouble in this area. One way to alter the CIS fuel curve to better suit the mods is to use the Euro throttle body, and fuel distrib.

Right - sorry mine is a 73 so no emissions I was going to go with zeniths jetted properly and I guess I would need to do something with my distributor curve. I have had carburetted cars and the climate here in Atlanta is conducive. Plus I only drive it a couple of times per week.