951and944S

Jay, what options are you willing to consider...?

And what is the reason you even wanted to go down the sleeve route..?

Cheaper pistons, use of an otherwise unusable block..?

What blade7 was alluding to (kind of cryptic, I'm just guessing) is that KS offers Alusil sleeves and makes the process available in literature in a web PDF.

Millennium can repair, bore, hone and nikasil your block and as mentioned, you could have Alusil sleeves installed if you are looking to bring it back into a factory specification.

Sure, a lot of people, a lot of qualified people might argue but for me, steel sleeving (or whatever the metallurgy) is a step backward.
The surface roughness as measured by the profilmeter may even be close to finished steel sleeves but the exposed crystal surface of Alusil/Nikasil is extremely hard and as long as it's not contaminated by grit particles and the correct rings are used, it's very long lived.

T

Jay Wellwood

T-

Since you asked, I'm still working on the details for a build similar to what Shawn put together. I have accumulated a few parts over the past few years and its time to start getting the job done.

That said, using the formula Shawn and Syd came up with using the dry sleeves and SB Chevy pistons/rings and an offset grind 3L crank for building a stroker motor. As I've accumulated the parts now, I'm trying to figure out the detail for getting the block sleeved. Without going into to many details, I'm trying to find an alternate sleeve and machine shop option to finish the block. Looking at the wet sleeve option, I'm not ruling it out, but at the same time still investigating if I can find a dry sleeve option that is reasonable in both price and turn around time with the results I need (i.e., without complications as a result of poor or otherwise incorrect installation technique that results in rework).

951and944S

Ok then, clear now.

But with the SB piston so close to the 944 bore size, why can't you stay alusil or get new nikasil and have the pistons coated to run in either...?
Has somebody determined that increased stroke causes side loads on the skirt that makes either less reliable...?
All of the newer alu/nik compatible pistons can be had with/without coating, Wossner, CP, Arias, etc., it's just added, just as easily as you can have it added onto SB Chevy pistons.
If I order CP, they just recommend where I should send finished pistons for coating.

T

Voith

Alusil is most expensive and slow process to produce of all and is used in porsches of today.

blade7

Did a lot of research over the last 10 years, probably too much. Ideally I would use a nickel ceramic coating on Alusil, unfortunately I cant find an easy option to plate a 944 block in this country. I know iron dry liners can work, I'm just not comfortable with the different expansion, heat transfer and wear rates. And although people that know a lot more about engineering than I do, seem happy to glue/O-ring wet iron cylinders into alloy blocks, I still feel it's an option I wouldn't take unless I had no other choice.

V2Rocket

Issue is the +6mm stroke, have to move the pin to compensate.

can arias etc make a piston with alusil compatible coating?

951and944S

Agreed, I worked for GM in the mid 80's to early 90's and lived through the Cadillac HT4100 days....., didn't instill too much confidence in alu block with wet iron sleeves for me.

Did a few I6 tractor sized Cummins diesels in my day that work fine with cast block and wet sleeves but if the o'rings go and contaminate oil with coolant, you can wipe an engine out very quickly dude to stroke/torque on the rod bearings.

In those days, one of the largest tractor/truck companies, Mack, stuck to shrink fit dry sleeves.

Advantage with either, and a big plus in replaceable sleeves is intent of doing overhaul "block in frame" which is a big deal in large trucks.
It's so much work to get entire engine out, you can do an overhaul and have truck back up making money again in way less time with block still in truck.

Don't see a benefit to going this route in a street/race car that can sit idle until repair is made.

T

V2Rocket

Recall that alusil engines are the odd ones out, the uncomfortable option... that ALL other aluminum block engines use liners (99% dry).
GM, Subaru, Honda, everybody. Heat transfer is different but not really inferior, just have to get the right interference fit on the liners and open up the piston wall clearance vs alusil.

your valve seats and guides are other metals squeezed into the aluminium head, and carry heat out just fine...😁

951and944S

Of course Arias can.

Yup, another story....

In the 80's, I did a HiPo GM 2.8 liter V6.
Nobody had done.
It was such an interest, the GM teachers at the tech school got wind that I was doing and invited me to their table at lunch to discuss.

The 3.8 liter GM engine (Regal Turbo, etc) and the 4.3 liter (basically the 305/350cid with two less cylinders) already existed at the time but the new 2.8 liter had only 1 rod per journal and it interested me.
Very smooth engine.

So I used Arias way back then and was very impressed.
So much so, I was glass engraving as a hobby at the time and engraved the Arias "Flying A" logo center top of my windshield on this Firebird car.
An "A" with wings.

Anyway, many years later, I had done my first - last bore only step, polish then hone with +.xxx" Swain coating to build piston diameter to allow enough room to refresh 944 cylinder using stock 944 cast pistons.
I knew that it worked without upping $1200 for a new set of pistons.

So, sometime later, I figured "hey, I will get with Arias, go forged next time if they can do coating"
They assure me a moly coat will work.
As said, I have no reason to doubt, +++ experience with them already and I have proved the Swain Tech.

After initial discussions, they tell me to send them a piston.
I have a piston boxed up ready to ship in the back of my SUV but got busy for a few weeks and had to put it off.

I come to RL one day and sign on and find RL user Ski talking about some pistons being sold by Tom Charlesworth with coating that will work in Alusil.
Arias pistons.
Oh well.
Either they had the thought same time as me or Arias went ahead without me, I never knew.

The pistons were fine though, if you do a search with "arias" and maybe using Bret's username "Ski" to narrow, you might find those old threads.

Today, CP/Carillo will make you a 944 piston, but they only recommend where to send them as a go-between from finished piston out their door en route to you to a coating company.
Can't recall right now which one they recommended but I have the info at work.
I have only ever used Swain Tech Coatings.

T

951and944S

Don't know the first engine to use but almost certain that Chevy used Alusil before the 944.
Google the Chevy Vega.

I would have thought that Lokosil would have been the next great thing.
It had suspended fibers that were burned out through a heat step that really sped up the process and cut expensive steps of Alusil.
Don't even know if it's still a "thing"..?

T

blade7

True, and BMW resolved their Nikasil issues in the 90's by fitting ferrous liners, but we don't know how much those manufacturers spent and how many pistons/blocks they scrapped before they got the process right. AFAIK 911 turbos have always used plated alloy cylinders.

Penguinracer

There is the option of Aluminium Alloy Nikasil plated liners, but these would need to be thicker than the equivalent steel liner.

In the UK I talking this through with Laystall Engineering:

www.laystall.co.uk

Capricorn Automotive had nothing for the 100.5mm bore I require.

I too have concerns about differential expansion rates for Ductile Iron / Steel Liners for a fast road / track car.

Those materials may be fine in a racing car which is carefully warmed-up, runs flat-out and has no requirement to meet emissions standards at idle or be starting from cold
more often where the larger clearances & blow-by could lead to increased wear.

Tim

blade7

As 951and 944S mentioned, KS supply or used to Alusil liners. Someone I know had one fitted to his Turbo S years ago by Capricorn I believe. I'd be interested in the plated aluminium liners if they're plated before fitting?

Jay Wellwood

V2Rocket

Wow, i thought wossner (and mahle) were the only game in town for alusil.

if they can coat an SBC piston to work, that would cut 600$ or better out of a stroker build.