You are joking George -- right? If not -- I can't be the only one to see the irony here -- you really meant to say alusil not nikasil right?

-Dan C.

Could you post your research please? I don't know if the very early 944 motors ran Nikasil, but it was since phased out due to corrosion problems in the 928 by the 944's time. All the pictures of 944 motors I've ever seen show Alusil cylinders and the factory workshop manual describes re-boring for Alusil cylinders with no mention of Nikasil anywhere. You can't get the two mixed up.

FEI, Nikasil is an electroplated nickel silicon layer on the aluminum cylinder walls and is very different from Alusil, which is a hypereutectic high silicon aluminum alloy, that once cast and cooled at a controlled rate, precipitates silicon particles throughout the casting. Nikasil has crosshatch patterns from honing when new, and Alusil will have a very consistent, fine, rough surface from the microscopic silicon particles suspended in the aluminum exposed during final lapping. They wear smooth as the rings break in to the cylinder and form a very good seal that is also very durable. You cannot install new rings into a used Alusil cylinder without re-exposing new silicon particles and lapping the aluminum from between them to restore the roughness of a new cylinder.

Yep, a joke.

Still, the block has always been one piece of metal, starting with the 83 engines, all the way to the 968 engines.

Thats what I thought. :)

I think there is more than meets the "conventional wisdom" eye on how to handle these blocks. There is SO much misinformation it stuns me. The first step in getting there is for us to start really understanding what these blocks are all about. 944 and KS 911's are not the only engines that use it !!

You all should check HondaDustR's thread http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/487924-project-924-s-engine-replacement.htmlabout on how he prepped his alusil block. F'in Awesome thread. I bet a few 911 K&S guys would be interested in it too.

Also check out http://forums.pelicanparts.com/911-engine-rebuilding-forum/137346-re-ring-alusils.html. Read the whole thing and even though there is no satisfying ending -- it is informational.

HondadustR -- tell us more about the new hone pads?



-Dan C.

Read this article. It mentions the elastomeric substrate finishing stones towards the end.

Honing Options for Hypereutectic Aluminum Cylinder Bores - Sunnen

My cylinder reconditioning was extremely low tech compared to the stuff they're saying, but the motor still seems to run great, and I only spent maybe $75 plus time. I'm sure my cylinders did not have "excelent geometry" either, but it seemed to work pretty well and they looked to be in decent shape as far as abuse, scratches, and other indications that the geometry could be far off due to unusually excessive wear. If I wasn't in such a pinch for time, I probably should have had them measured at the shop before and after, as well as roughness measurements just to see how close it came out to the correct surface, how close each cylinder was to each other, and how much material was removed. I think part of it was I was afraid to find out the bores were shot, but... :o I have a feeling the cast iron Deves rings probably break in easier than OEM and gave me a little more wiggle room, at least if OEM was chromed, since the Deves are not. The endgaps were a little wide outside of spec, but they measured up the same top to bottom, before and after the honing/lapping, and easily half of what the old rings measured, but I was only measuring with a feeler guage. They also brag about their Swedish metalurgy that does some sort of thermal set to conform to the cylinder or something like that. I called it all "close enough", and I think it was. I guess the real test will be how it runs and how much oil it burns 100K miles from now, but at least it hauls @ss now...noticably stronger than the old motor that was burning 1 qt every 300 miles.
The other thing that made the project doable is it seemed to be difficult to impossible to over lap (also the basic consensus I got looking on the web), at least with the AN-30 paste and felt hone, so I just experimented with pre-lapping prep that would give way to a rough, almost chalkboard-like texture that also lost the reflectivity of the used bores once lapped with the felt and paste. I had my condemned block to freely experiment with, so that really helped, too.

It would be cool to have a block bored out and refinished by a really good shop that really knows these cylinders and see how much better it comes out. Maybe my old block will live again with that project years down the road.

So I bought the engine yesterday and I'm going to pick it up some time next weekend. I ended up getting a pretty good deal since the guy liked the idea of an 18 year old taking an interest in 944's. And he didn't have any use for them since he sold his a few years ago. Anyways he originally said he'd like to get $500 for it over an e-mail. I told him I didn't want to spend nearly that much on an engine that I'm going to rebuild anyways once I got there. So I told him $250 and he said $300 and I can take what ever else I wanted. So I got a new driver's side seat, the back part of the passenger's seat, a guage cluster (with over 400,000 miles on it :eek:) and a set of "15 phone dials. He wanted $150 extra for the wheels though. I'm happy with it though I think I got a decent deal on everything.

That's awesome! Just hope you don't have any "oh crap..." discoveries during disassembly. As long as the cylinders aren't gouged and the crank hasn't been destroyed by spun bearings, it should work out pretty well. Naturally, you can bore oversize, especially if you're getting custom pistons made anyway, and get the crank turned down and use undersize bearings, but it sucks to pay for extra machine work...and undersize bearings are freaking expensive. Just work with your machine shop to get good measurements of everything and help plan exactly what to do, since they've been through many of these projects and at least a good shop will steer you in the right directions. You just want to make sure you're dealing with someone who knows Alusil, since you'll definitely want to get the block bored and re-finished if you are going through the trouble and expense of new pistons. It shouldn't be too hard to find one, since aluminum cylinders are a bit more common in recent years than they were.

Just remember, no one may have the time and money to do it right, but everyone has the time and money to do it again. In other words, take your time, plan carefully, and ask if you're not sure. Good luck and keep us posted. Start a project thread and take pictures. I always like following epic projects, especially engine related. SmileWavy