Hey all,
A couple of us over in the 1st gen forum have been discussing the complications of building a 3-rotor engine based on a 12A.

Anyone have any input?
(Know anyone that's done it? Know of anyplace else out there offering the parts?)

Here's the thread from over there:
https://www.rx7club.com/forum/showth...09#post1967209



Thanks,

enigma32

 

intermediate plate, tension bolts, e-shaft, oiling system, all manifolds would all be a nightmare. The little big engine that could...

a three rotor, but it's a 13b...
http://www.hitman.hm/rx7.htm

these guys have a 4 rotor 12a...look under projects
http://www.autotechmotorsports.com/index.htm

that's all I got

 

Eamon Hurley made one back in the late 80's and put it in an 83 RX-7. He split the eccentric shaft, and added a taper & key to locate the add-on assembly, and fixed it in place with a tension bolt. The central intermediate housing was modified with a special planetary timing gear and bearing. A high-volume oil pump was added, and the timing was accomplished with a custom electronic distributor firing at 120 degree intervals. (Like all good drag racers, he tried and tried to make an ancient distributor work, but after breaking numerous caps, he finally gave in to modern technology, lol). He made a custom manifold for three 1.75" HIF SU carbs. The exhaust was a really cool custom unit with three exhaust tips poking out of the right rear of the car. The performance was 250bhp, 170 lb-ft torque, and 25mpg @ 70mph.

 

awesome, any pics of that car? Or is it long gone by now? Or just made before cameras old timer.....j/k lol

 

Good to know it's been done by at least somebody and seems to have worked quite well.

So I'm assuming you guys would recommend talking to autotech motorsports to see if they'd be interested in fabbing the parts, and for what price?

I'm thinking that if one was to go through the troubles of building one that the manifolds wouldn't be too much of a nightmare compared to the rest- the worst part would have to be engine internals.

Evil Aviator: By "split the eccentric shaft" I assume you mean that he basically made an add-on piece that fit on the end?

 

Precision Engineering in New Zealand make custom shafts for 3 and 4 rotor. The only details I have are on ones that are for 13B rotors, but I would think they can make 12A versions.
As a price point, they charge NZ$2100 for a 3 rotor e-shaft and $3200 for a 4-rotor one. They also make dowels, tension bolts and centre bearings to suit.
The Hitman in Australia uses one of their shafts in his 3 rotor.

Gary
New Zealand

 

I'll look around and see if I can find the article written on one of my scrolls that I keep back at the Dead Sea cave.

"I refuse to make my opponent's youth and inexperience an issue in this campaign." - Ronald Reagan (aka Ronaldus Magnus)

Woot!
http://story.news.yahoo.com/news?tmp.../uss_reagan_14

I'll see if I can find a picture, but I think the article is just text because pictures were not invented yet. BTW, can anybody read Aramaic?

I think you are better off having one of the el-cheapo labor countries like NZ make you a shaft. It's going to cost you a fortune in the US. The custom center housing may be even more difficult, so see if you can get one of those, too, and some ready-made tension bolts would sure help. The manifold and oil pan are easy, but based on my own experience as a non-mechanical engineer and non-mechanic, it is probably going to be cheaper and easier if you can find a package deal on a short block.

A good, used 20B-REW sells for about $4,000 in the US. Are you sure that you don't want to go the "easy" route, and get more torque while you are at it?

 

Hmm, Can't find Precision Engineering's website...
Anyone know if they have one? (Or if not, how to contact them?)

haha- pictures not invented yet...

We were looking into this option instead of the 20B due to the size of the 20B....
It's large enough that it apparently takes a bit of work to make it fit into the first gen... So it would appear that a 3-rotor 12A (which would be only slightly larger than a 13B?) would be easier to fit in the engine bay without major modifications.

And, again, because it's just so cool =)

 

No website, but here is their address and phone number:
Precision Engineering
9B Airborne Road
Albany
Auckland
New Zealand
Phone: +64 9 415 3264
Contact person is Jeff Bruce

Remember the time difference if you are going to phone.

Gary

 

I think I'll write a letter

I'll post back here once I hear back, just so the thread is complete.

Thanks for your help everybody,

enigma32

 

From the September 1989 issue of Rotary Rocket:

http://www.geocities.com/evilaviator/hurley

 

25MPG is Imperial gallons.

25 * 5/4 is 20mpg.

 

Yashiro Eng. in Japan makes a 12A 4 rotor ecc shaft as well.. and a 4 rotor engine actually , that's what's powering the 4 Rotor Scoot FD that's been in a few media clips here.. the last few issues of option2 mag have been showing more and more of this engine.. I'd like to find out how much their 4 rotor shaft is , maybe some of use here would be in for a GB.. I know I am.. I keep getting smoked by RB25DET swapped S13/14 's..

 

It looks like the Hurley RX-777 3-rotor 12A is still available, as well as their 4-rotor and 6-rotor engines.
http://www.hurleyrotary.com/

 

6 rotor motor..... 4 rotor would be just about as cool.

But I think for simplicity I'll stick with a 20b

BY the way I'm back anyone know of a cheap T2? I'm wheelless right now.

 

The distributor itself was mechanical with electronic ignition (as opposed to points).

 

JESUS!!! thats a LOT of cables to hook up!!!

But here's how I think you COULD make a 3-rotor 12a (18a) easily:


Fit an intermediate-plate in place of the end-plate

machine the statonary gear off the side of the intermediate plate you dont need

machine two e-shaft to fit into each-other (bore a hole into the ends, insert a hollow rod, dill holes into it from the sides, weld in several pins)

get some longer dowel bolts

get a dizzy from somewhere

 

250bhp and 170lb/ft? ****, i'd just go with a 13B with all the mods...

 

Wow, this thread is back from the dead....

 

it......IT'S ALIIIIIIVEE!!!!!!!!

 

I remember someone posted a video on either the first gen or the other rotary forum were somebody had a running 4 rotor 12a I tried a search to no avail

 

i remeber seeing a 4-rotor vid, was it the one in the fd with a REALLY weird bodykit?

 

http://sashishi.hp.infoseek.co.jp/4re_spl.mpg

Pure bad ***

 

hey I tried the link but it didn't work for me

 

yeah no workee