Danomite

I didnt really pay much attention to the weight stamps since they have all been machined to the same weights and balanced. Jeff Bruce said the shaft is done and the housing mod almost complete, so hopefullly annother three weeks or so till it ships.

Jeff20B

Ah, that'll work.



It looks like the owner wants to take his time on this project (even if it takes 5 years). I only hope I don't forget all that I've learned before he's ready to take the project to the next level. He gets back from Maryland today so we'll discuss the project further once he's settled.

Jeff20B

We discussed the project further and it's still on. Pulled the gas tank, installed the driveshaft, raised the engine up a half inch to correct the tilt, saw how close the alt is to the hood. Just a little massaging of the hood brace and the alt will fit. Or perhaps an aftermarket carbon fiber or fiberglass hood. It's getting a widebody kit anyway so the hood isn't a big deal.



Danomite, since you're a couple steps ahead of us, can I pick your brain? I need to know how many front and rear rotors I'll need. I assume I'll need two fronts and two rears.



Three front stationary gears and one rear. Two intermediate plates are sent to Jeff Bruce for machining to fit two stationary gears; one front gear is used as a rear gear, but what is the topography? Also, how is a 4 rotor put together?



I believe rotors 1 and 2 are phased 180° apart just like any 2 rotor engine. Likewise rotors 3 and 4 are also phased 180° apart. Or am I incorrect about this? Are there any clear pictures of the shaft and where the bearing journals are located?

Danomite

I dont know what the diff is for 12a rotors, but I'm basing it off of a 13b so there is no diff in the rotors. To be on the safe side though I would ask Jeff bruce.



The modified stationary gears are fronts and the center intermediate housing is stock (two gears from the back, two from the front). i have'nt asked about the assembly yet but I assume it is similar to a 20b, just an extra lobe to install.



You are correct about the phasing, the firing order is 1,3,2,4. I had some decent pics from Kiwi but they nolonger have them posted and I cant seem to find the ones I had.

Jeff20B

Thanks for the reply. Here are some pictures of my progress.



The car is going to be CYM so we painted the engine bay first.

Jeff20B

As for the 4 rotor shaft, I think it's similar to the one pictured here from autotechmotorsports.



Here we can clearly see rotors 1 and 2 are 180° apart and 3 and 4 are 180° apart, with that funny 90° offset in the middle. If Jeff Bruce's shaft is like this, which I suspect it is (I think autotech copied Mr. Bruce's shaft), then we can get an idea of how it works and the topology of the journals and stationary gears.



Ok, we know the middle intermediate is not modified. Like any old 2 rotor engine, the middle of the shaft with its 180° offset, is inside the intermediate plate. Now working fore and aft from that position for our 4 rotor project, we can assume the stationary gears adjacent to the middle intermediate plate are going to point the same direction as a 2 rotor (with one front gear acting as a rear). In other words, one pointing forward and one pointing rearward. This makes sense as these gears are machined to fit in the two intermediate plates that Jeff Bruce modifies.



If the above assumptions are correct, from the middle intermediate's point of view, it will have one front rotor and one rear rotor just like a 2 rotor engine, except they will be offset 90° instead of 180°. The rest of the engine beyond the little sandwich of intermediate plates should have one more front rotor in front of the front intermediate plate, and one more rear rotor behind the rear intermediate plate. In other words, anyone building a 23A (4 rotor based on 12A stuff) will need two front rotors and two rear rotors. For 13B parts, as Danomite said, it doesn't matter.

Jeff20B

To build the 4 rotor engine, I think we would start with the front intermediate and mount it to an engine stand if possible. Plot down one front rotor (if 12A) and mesh it to the gear. Then one rotor housing. Lift the shaft and install the unmodified intermediate plate. A rear rotor and another housing. The rear intermediate plate. All like any 2 rotor engine and sorta similar to a 20B.



This is where it gets tricky. Assuming the front intermediate was attatched to an engine stand, and the currently built housings were all held together somehow, we could either keep going and add the rearmost rotor and then flip the assembly around, or add the rearmost rotor, don't flip the assembly, and somehow lift the front assembly (complete with rotor, apex seals, rotor housing etc already in place) up and start dropping tension studs into the holes. Hmm...



Or is it possible to start with the front plate and build rearward like any 2 rotor engine? I'm affraid you wouldn't be able to lift the shaft high enough to get the middle intermediate around the 90° offset in the shaft.

Danomite

Since the front and rear lobe slip onto the main shaft I think it will be feasable to start with the front iron and front lobe, then #1 rotor & hsg > front intermediate Iron > main shaft > #2 rotor & hsg > center intermediate housing (lifting the main shaft like normal) > and so on.



I will be emailing Jeff in the next day or two with my rotor weights and I'll ask him about assembly.

Danomite

Assembly order depends on whether you run the std ball and spring oilers or not in crank , if not and you fit a jet on its own then you can assemble from either end , ifyou run the std setup then you have to build the centre two rotors first then lock housings together with a plate or something so that engine can be turned over to complete one end then over again to do other end . This is all assuming you have a centre housing bolted to an engine stand.

regards jeff

Jeff20B

Now I'm confused. I'd think with the standard oilers the engine would go together more easily.