Kwenak

Hey all,

Recently I decided to rebuild the engine on my '86 turbo. Now that i have it all apart, I noticed some groves in the cylinder walls. Most can't be felt but one or two I can feel with my finger. I was looking into getting this honed and I've gotten the following responses

"Sure I can hone it for $20." all the way to "Nope, you can't hone those things, have to send them somewhere in WI to get redone for about $2k."

So I was hoping you all might have some expert advice. I am planning on re-ringing it and have plans to purchase the Lindsey Racing "file to fit" rings.

Thanks in advance,
Rob

Scott H

The piston walls are alusil, which means they have silicon impregnated into the cylinder wall surface. When you hone the cylinders you will abrade/cut away that coating and it then has to be reapplied to the cylinder walls with a specific honing compound and technique. My bet is that the guy charging $20 thinks it's a normal block that you can just machine and hone and the guy charging $2k probably wants to sleeve the block, or at least I would hope so if he's charging you that much. If you sleeve the block then you can run any size piston you want, better rings, and it can be honed like normal iron cylinders.

To answer your question, yes, it can be done, but by a specialist. Lindsey Racing has prices on their website for engine machining, and it's much better than $2k.

BC

Alusil is not a coating. It is the block itself. You get Felt pads and use a special paste that wears away the aluminum on a microscopic level and allows the silicon to stay, which is what the pistons and rings ride on.

Scott H

Yeah, that. Got too many things vying for brain space right now

JBrown

talk to Lindsey racing my engine is there right now as we speak, depending on how bad they are scoured they can "hone" it and use some sort of chemical to put around the piston to fill in the space since the tolerance is very min. if you talk to mike he is very knowledgeable. if they are scoured where they can not do that process they do offer slightly bigger pistons witch are about $1000, but if you are going the route mine as well go a 2.8L like me only difference if the crank shaft!

Ski

Alusil as a hypereutectic aluminium-silicon alloy contains approximately 78% aluminium and 17% silicon. This alloy was created in 1927 by Schweizer & Fehrenbach of Baden-Baden Germany and further developed by Kolbenschmidt.

To do an oversize bore, you have to cut the cylinder walls and then there is a FINISHING PROCESS, which does include stones and paste and the last part is with felt pads and the paste. Kolbenschmidt, still work with companies today, including Audi and more...

You might find the whole process, cut - stones - felts and paste etc online; I have a copy at home but I'm traveling. We use Duffin Engine Service in San Antonio.


Our new block that we built for the track car. Clean block, remove head studs, finishing pass, cut/hone/finish to desired piston clearance +/- 600. Send your new piston with it so the shop can measure on the skirt.



two others done by Duffin for friends, one o-ringed

Darwantae951

You can also have the clyinders nikasil plated.

Ski

Any long term users of the Nikasil have reports? I know there was one a few years back that missed the wall to piston clearance and had a massive failure due to expansion rates of the piston but just curious of success stories.

lart951

Or for less than 400 bucks have a used block in excellent condition shipped to your door

Ski

LOL, so true. I'll be home a week and half, we need to talk bumper cover and that steering rack you have listed.

333pg333

This...

& This...

86 951 Driver

Sleeve it and do a hybrid build like blown 944

67King

Karl Poeltl of Racer's Edge nikasil's every one of his engines.

Also (directed at all, not you), FWIW, the technical term for what is done to the aluminum is "etching." The acid in the compound etches away the aluminum, leaving the hard silicon proud. The process also conveniently leaves features where oil can collect to better seal the cylinder, analogous to what cross hatching does. If you want to look up what is done, use the term "etch," not "hone," to get a better picture.

blade7

The OEM etched the cylinders but I dont know of any rebuilders that do it. Sunnen manufactures equipment to hone and lap Alusil.

Darwantae951

Ski, unfortunately I do not have any first hand experience with Nikasil. My engine is sleeved.