Carl Fausett

We are developing a wet wall sleeving process for the 928.

This will be a nice addition to our drywall sleeves and Nikasil plating that we already offer.

The new wet wall sleeving allows us to increase the range of available bores beyond what the block gives us. For example, using an 85/86 928 block to start with, we can bore and install drywall sleeves to build up to a 6.5L motor (with stroker crank)

That is as big as we feel we can safely go with standard drywall sleeving of the 928 block. However, with the new wet wall sleeve, larger bore sizes are possible. This one (in the pictures below) will be a 7.0L 928 engine (also with a stroker crank).

The old aluminum cylinder walls are completely removed, down to where the Siamese webbing begins between the two cylinders. I included a picture of our new ductile iron sleeve before it is installed.

The wide cylinder wall provides strength, cylinder stability (resisting out-of-round conditions) and a wide enough gasket surface that we can cut in o-rings if the customer requests it.

Carl Fausett

Here are a few pictures of one of our typical drywall sleeved 928 engines. This is what we have been building the most of.

The stock cylinder bore is honed out to the press-fit size of a full ductile iron liner, and the liner pressed in from the top.

Like the wet wall sleeve, the liner is captured (held in place) by the head at the top and the block at the bottom. The 928 is particularly well suited for this because the head studs reach well past the cylinder walls and all the way down into the cradle. Other engines with short head studs can experience cylinder wall migration in an operation like this, but in 10 years of sleeving these engines, that has never been a problem. More credit to the 928!

Note the ARP cylinder head studs. This engine was built for lots of boost!

Carl Fausett

Nikasil provides a very tough, scratch-resistant outer coating to the Alusil block. It's a nice upgrade, and now standard procedure on many Porsche, Audi, BMW and Mercedes models.

The Nikasil plating takes what is normally a shiny Alusil block and turns it a dull gray. It can't be helped.

For the customer who wants to re-use their stock pistons, Nikasil plating is a solid choice that can fill in all the minor scratches and restore the block to standard sizing.

The finished block is more scratch-resistant than stock, yet retains the core strength and characteristics of Alusil.

Special piston rings for Nikasil must be used. We have them.

TexasDude74

Wow, that's a pretty major development Carl; and this was posted yesterday? Yet not a single negative post, flame or bash! That in itself is awesome. Any estimates on pricing yet for the sleeves? Any other piston options other than low compression blower pistons? There are lots of us that would love a 7.4L 13.5/1 wet sleeved big block porsche.

123quattro

Since it's an iron sleeve you can use any piston you want. Custom pistons aren't that expensive to have made. Diamond Racing did a really nice set for me. With skirt and bowl coatings, spriral locks, total seal rings, and new lightweight wrist pins they were $220/piston.

Carl Fausett

The wetwall sleeves wont be that much more expensive than the drywall sleeves we have already been doing. A little more, but not a lot. The price to install them will be about $200 higher, owing to the additional machining to remove the OEM cylinder walls.

Our engine building options are here: http://www.928motorsports.com/parts/long_block.cfm
and you will see block boring and sleeving the 928 block is $2845

The 4.25" pistons to go into those sleeves were within a few dollars of the 4.125" pistons we put into the largest drywall sleeve.

Rings - no difference in price.

Below is a pic of the 4.25" piston for that 7.0L block.

Carl Fausett

You're right, I was just going to mention that. By getting out of the metric sizes and into standard US sizes, we get to take advantage of the economy of scale - as these pistons start to be made from the same billet as a SBC or BBC piston, our costs come down.

Carl Fausett

I'm expecting to be asked: "where will it end?" or "how big can the biggest motor be?"

The answer is "I am not sure yet". The limits as I see it are 1) the ability of the head to cover an ever-increasing cylinder bore without getting into water jackets and such; b) the distance that remains between the outside of the cylinder wall and the block so we can get adequate coolant flow; and 3) the increasing size of the flame front in the combustion chamber may prove counter-productive at some point. Only dyno testing will be able to tell me that.

That's why I am building a 7.0L now - we want to discover what we might encounter as we go forward with this build. We have checked a,b,c above on this motor and we think we're going to be OK.

TexasDude74

From the looks of that blower pistons height, isn't it time to reconsider the stroke limits as well? Looks like there's another half a liter being left on the table for a N/A build. Have you developed a port program yet for large non supercharged engines?

Tom in Austin

It's interesting that the siamesed webbing area has enough strength after the original cylinder walls are cut away to support all the forces acting on the sleeves ... as a layperson it just seems sort of counterintuitive.

Eplebnista

How many cubic dollars is 7 liters?

TexasDude74

Wet sleeved engines are not a new idea being pioneered by Carl, they've been around for many decades. Wet sleeved 928's are relatively new and rare, but the principle is sound. I have a couple 16L diesels that are built like this and they are putting 725 rwhp at 2000 rpm and 2400 rwtq at 1100 rpms. Cylinder pressures that far exceed any 928 engine ever built, and they go well past a million miles.

jeff spahn

So when my 928 engine finally dies I don't have to do an SBC? But I want a 6 speed corvette auto. 7 liter 928 engine, reprogrammed computer and a 6 speed corvette auto living in a 928 body. Sounds cool.

Carl Fausett

Absolutely true. Wetseeving is common to many motors, almost all rebuild-able commercial trucks, and every engine now in NASCAR. I am certainly not inventing it.

Whats new here is my application into the 928 Alusil block. I know of one or two private engines out there that were done as a one-of - I am trying to commercialize or standardize the process so I can offer it to all.

Carl Fausett

I actually have a "C5-C6 transaxle into a 928" project on the boards now. Ever since I started eating G28 transaxles every few races, I recognized the need to get a beefier gearbox in there. That project will not go fast - I am going to take my time with it.

We've looked at the broad brushstrokes of "how they did it" to the few that have been done, don't like the layout, making our own.