Ok so let me first explain what I am trying to do. I have a vw powered tube chassis sand rail (sometimes called a dune buggy) and I want to put a rotary engine in it. Now it would be just used offroad, so emissions aren't a problem (I would tear that stuff out) and I would only be using the engine itself, not the transmission, rear end, suspension, etc... I can buy an adapter plate to mount the rotary up to a vw transaxle.

Anyway, I have some general questions on the different rotary engines. I want a n/a motor, not turbo/blown or no2, and I also will be using a carb, NOT efi for reasons I won't get into here. I see that there is a 12a and a 13b, and the 13b comes in both 4 and 6 ports.

Someone mentioned that the 6 port has more torque than the 4 port? They also mentioned something about the 6 port having some kind of valve to close the ports depending on the rpm? If this is true, is it computer controlled or mechanical?

Is there a big weight or power difference between a 12a and a 13b?

I know they have a manifold adapter to convert an efi engine to carb, is there anything else besides the intake I would have to be concerned about? Like ignition, do these engines use a dizzy? I figure I will have to plug the injector holes.

Finally, if I am going to get a motor from a junkyard, is there any tips to getting a good motor vrs a thrashed one?

 

these are only my opinions based on somewhat limited experience . . . caveat emptor.


Yes it's true - I believe the 6 port actuators are controlled by exhaust back pressure but I'm not sure. I've read some discussions about people putting on free flowing exhaust and having their actuators stop working. I don't own a 6 port, so I don't know for sure, but a little searching on the 2nd Gen Forum or for GSL-SE specific info on 1st Gen Forum should get you some answers.


well, the bare "block" itself is probably only 5 to 10 pounds different if I had to guess (if that.) Accessories you add to the engine after that might change it a lot. I'm not sure about power changes either, but perhaps 10-20 HP, 20-30 ft/lbs torque. I'm guessing here, so don't quote me on this.

adapting throttle and choke linkage would be a concern of mine, as well as making sure the oil metering pump gets operated correctly with your setup. You can easily use a distributor - installing the "DLIDFIS" system would be recommended. You just need 3 coils and 3 GM HEI ignitors, a cap, rotor and set of plug wires. less than $100 I think.


the best thing to do in this scenario would be to pull the exhaust manifold of the engine and visually inspect all 6 apex seals on the engine. You can see them and use your finger to check if they have some "spring" to them. You should be able to easily rotate the engine by hand and check all 6 seals this way. You can also get a small view of the chrome surface that the apex seals travel on. if there was major engine damage from a broken seal, you'd be able to see it through the exhaust ports. Other than that, it's a dice roll . . .

 

double post . . .

 

Nix that. If its going in a sand rail then it will have a duty cycle like a racing RX-7. Lose the OMP and pre-mix your oil and gas.

Cooling is a big deal with rotaries, more so than a regular piston engine. Your VW motor was probably air cooled, nice and simple. The rotary will need a liquid cooling system AND an oil cooler in a place where they won't get gunked up.

 

i would suggest going with the 13b. parts are much easier to find when you break it.