Somebody please tell me why nobody has figured out how to use 13B parts to make a 3 rotor engine? Back in the day when I was a computer nerd and wanted something I couldn't afford or didn't exist, we made the ****. Some of you guys have mechanical engineering experience and should have the skills to do this. The first person to do this could make major dough by selling conversion kits.

 

I'm pretty sure that the only part that is very different is the eccentric shaft, but I may be wrong.

The hitman made his own 3 rotor out of 13B parts:http://www.hitman.hm/rx7.htm

 

The side housings are different according to alamo rotary

 

It would probably be cheaper to just buy a 3 rotor, unless the maker could sell alot of kits. Even if you get a motor there's still alot of work that needs to be done to install it and get it running.

 

I considered making one myself, but it would have ended up costing much more than the $4,000 USD going rate for a complete twin-turbo 20B. I don't think that this is expensive at all. The expensive parts are making it run and making it fit. The REALLY expensive part is making the car take all that torque, especially if you are an idiot like me and slap on a big turbo.

If you really want to make it yourself regardless of the cost, you can get most of the 20B-specific parts like side housings and e-shafts from Mazda Motorsports, use your own old 13B-REW rotor housings and whatnot, slap on a cheap ECU and there you go! OK, so it's not quite that easy, but you get the point. Even at the inflated Mazda pricing, I seriously doubt that you will find anyone in the US who turn a block of metal into a 20B component for less. However, you may be able to find some cheap labor overseas.

Here are some various part numbers and prices that I happen to have saved on my HD. The info may not be current because I took it from my old 97 catalog, but it will give you a rough estimate. Oh, and I'm giving you retail pricing because you would already know this info if you are factory sponsored.

Front Housing NF01-10-C00E $403.50
Intermediate Housing#1 NF01-10-D50D $556.45
Intermediate Housing#2 NF01-10-D00C $364.45
Rear Housing NF01-10-C50D $388.70
Eccentric Shaft NF01-11-D00C $994.85

 

talk to PFS....in the august? issue of car&driver with the supertuner shootout he said that the 20B in that RX-7 was a modified 13B

 

Ya in that same issue I believe they used 13B rotor housings, So I think the rotor housing are interchangeable but the plates and the shaft a different.

CJG

 

From the person that supplied parts for Hitman's 3 rotor:


precisin@ihug.co.nz

-------------------------------------

General Info on Rotary Kits

This is a general list of parts available to convert mazda 13b type
engines to 3 or 4 rotor variants ,only the modified parts are
listed as most others are mazda items or are easily fabricated
by a competent engine builder.
All prices are in NZ$ and are ex factory so no allowances for
shipping etc have been made .
NZ customers should note that gst is charged on top of these prices.

1. 3rotor crank assy NZ$2100
2. 4rotor crank assy NZ$3200 (includes rear c/weight)
3. 13b centre bearing kit NZ$1800
4. Centre housing modification for 3 or 4 rotor kits NZ$600 (2 req for 4 rotor)
5. Thru bolt set for 3 rotor NZ$175
6. Thru bolt set for 4 rotor NZ$195
7. Dowel set for 3 rotor kit NZ$110
8. Dowel set for 4 rotor kit NZ$130
9. Direct oil feed for 3/4 rotor kits centre housing NZ$250 (2 req for 4rotor)

note that the centre housing mod cost is only for the mod ,it does not include the cost of a std front gear or the housing ,these items esp the housings vary greatly in price depending on the year/type. They can be priced on submission of mazda part number of course.

 

The PFS car had 13B-REW rotor housings in a 20B. The REW housings have better exhaust ports, apparently. (Isn't that what die grinders are for?)

Sure you can make your own... just get the E-shaft, the front and #2 side plates, front cover, figure out an intake manifold and an exhaust manifold, oh yeah and a pair of 13B's to cannibalize... assuming you can get three good rotors and rotor housings out of 'em oops it would have been cheaper to just buy a used 20B in the first place.