Jeff20B

Thanks for the tip.



I've gotta redo the middle pipe. It'll gain me some clearance around the idler arm. It's currently too close and won't allow the header to come off the engine (if it were already all welded together). I'm glad I caught it before I went too far. Unequal pipe lengths are probably unavoidable with so little room.

Jeff20B

So do you guys think it'll have a weird sounding idle with unequal length pipes?



I'm so concerned about the sound that I'm still planning on using 13B for the inspection because I've got a 13B to rebuild, and a nice carb and exhaust manifold to use. I even have a down pipe from an RX-2 manifold that will probably fit the 13B manifold. I also have access to three Rotary engineering glasspacks. I want it to be quiet for the inspection for obvious reasons. Then the 20B, with its 120º exhaust pulses and unequal length pipes, can be as loud as I can stand.



It'll also give me a chance to test the cooling system so I don't overheat the 20B. Also, the 13B will have a heavy REPU flywheel. I'm going to keep the battery up front for the 13B and the exhaust manifold together ought to equal the weight of a 20B and then some.



Things on my list for right now include:



cutting and rewelding the 20B header



test fitting a radiator (it can be any style at this point)



test fitting the oil cooler and making custom oil lines



welding the tranny mount pieces of the U together (I don't trust the 10mm x 1.25 or 1.5 bolts I used)



street porting two sets of 13B rotor housings and one set of side plates



tearing down a 13B for cleaning and a rotor housing swap.

Racer X

What are the 13b parts for?????Unequal length pipes will work but if theres no other way to equal length them then you have to do what you have to do.IT'll work either way plus a 3 rotor sounds different from a 2 rotor anyways.

Jeff20B

The 13B parts are for the 13B that's going in it first.



I rerouted the rear pipe and started on the middle last night. The cool thing is I can remove and install the header so far. I'll see how it goes when the middle pipe is done.



Back when it had the 13B in it, the header was almost impossible to remove because it touched the idler arm. Good thing I have a manifold to use.

Racer X

Cool.Once you get it tacked where you want it heat it up and weld it good and solid.Rotaries put out a shitload of exhaust heat and the stronger the welds the better.

Jeff20B

I used a propane torch to heat it up. I made some seriously ugly welds on the flange at the rear pipe. It should be airtight; that's all I care about. I started getting nice looking welds by the time I had to stop. I finished the rear pipe and started on the front one. I'll probably tack the middle pipe today and finish it and the front pipe if I have time.

Jeff20B

The welds tend to clean up rather nicely. All those little metal ***** can be chipped off with a screwdriver or chisel. A little wire brushing later, and it's good to go.



The upper part of the middle pipe is tacked together. I'm going to test fit it in a few minutes.

Jeff20B

It looked good so I welded it all the way around. I used two 4mm or 5mm wide pieces as spacers between the two elbow pieces that make up the upper part of the middle pipe. The pieces were leftover from when I corrected the undercutting of the old 12A header's rear pipe.



For those that don't remember, I originally removed a 3cm long section of pipe because the distance between a 20B's front and middle rotors is 16cm. It's 13cm on a 13B from front to rear, and 12cm on a 12A. I'm using an old 12A header as a starting point in building my 20B header. I failed to realize that I should have cut 4cm of pipe instead of just 3cm. I corrected the error by slicing an extra 5mm from each side. The idler arm was still in the way so I cut the pipe below the idler arm and rerouted it to the rear rotor's exhaust port, and all was good.



I also tested the steering. It cranks both directions fine. It does hit the header when fully cranked to the right, but my truck is the same way. I'm not worried.



After checking the welds around the upper part of the middle pipe, and patching as necessary, I started tacking the middle pipe together from misc pieces laying around. I'll be adding a third pipe to where the two merge together at the collector. All I've got to do is to slice one of the scrap pieces lengthwise at an angle so it'll match the shape of the other two, and cut an opening in the collector. A die grinder would be nice, but a dremel will do.

Racer X

Are you merging all three pipes together?

Jeff20B

Sorta. I may merge the front and middle together where the front and rear also merge. It'll look like a mirror image of an L kinda like this .:



Or maybe I'll try something a bit more radical. I'll see how things work out.