[verbeekb]

Pictures of a bare head:





Not my pictures, but they will help to illustrate.

It begins with the holes that go over the headstuds, the spacing is -almost- identical to stock Type 4, however, they are like tubes incoporated in the casting, and there is very little room to move them. If they break through to a coolant pocket there would be leakage issues. The tensioners are mounted on the head itself, so there is no need to fabricate custom brackets/plates for them, can use the stock parts, along with all the Ducati internals, covers, flanges etc.

For our engines we need to marry two heads per side. There are large roller bearings in the large holes to support the camshafts, here I will need to select the correct camshafts for each side, determine timing offset, and make a keyed or splined collar where the camshafts join. There is plenty of room here, and no one says I need to use stock Ducati bearings.

The heads will need to be decked a few mm between them so the combustion chambers will be centered over the cilinders, there is very little room to do this, I may have to leave them a little off center.

These heads are designed to work with the 66mm stroke that I am using, the Duc has the same stroke. Torque is a problem, the Duc reaches maximum torque at 8000 Rpm, obviously, this needs to come down by a lot, I want to accomplish this by keeping the exhaust runners to the merge-point as short as possible, and use smaller throttle valves than the Duc uses. Camshafts of a smaller Duc engine with the same head casting may help as well.

The coolant openings at the headgasket surface will be welded shut on a vibrating welding table. Then they need a spigot to locate them on the cilinders.

Ducati's have no redline. Motorcycle engines have very light rotating parts, it is hard to compare, but this set up would pull easily to or over 10K rpm. I will need to establish whether I would have to maintain a redline for this engine. The thing is that motorcycles use very small big end diameters to keep the bearing speeds down. I am using a whopping 55mm big end, so far I haven't found any data that will help determine how fast the bottom end can actually/safely turn without cavitation of the oil film in the bearings.

Desmo Animation

It's a lot less work when compared to fitting 911 heads where the camhousings need to be shortened and custom camshafts need to be fabricated. The 911 heads then still have valve springs.

Originally I was looking for aircooled heads ofcourse, but they are not easy to fit, two valve and hard to cool properly. I justify the air/watercooled combination by thinking of the 959 and 962 engines that used this combination. I will underdrive the cooling fan, I have the large cooling fan normally used on the '89 Turbo, but will probably go to an earlier smaller fan. I've actually tried to find the 959 parts (knowing that will be close to impossible, and the new parts are still available from Porsche but would set me back close to 4000 Euro, not counting the alternator), the 959 uses a unique really small cooling fan. Still, I've found the craziest parts in the craziest ways, so if anyone has a lead to 959 parts pls. let me know.

To cool the heads I want to use as few parts as possible, thought of thermo-siphon circulation by mounting radiators higher than the heads, perhaps a mechanically driven waterpump in the fanhousing against the alternator, or driven off of one of the camshafts on the transmission side.

Motorcycle radiators are often curved, perhaps I can find something that would fit in the VW rear fenders. I'm completely new to water cooling, I still have to do my homework on this.