In the 13th issue of "RX7 Magazine" Japan, they have a few b&w pics of RE Amemiya's GT300 class FD. What's interesting is that it's a pretty much bare chassis with the engine installed using RE's custom intake runners and individual throttle bodies. I'm so interested in this as it looks like the entire setup is low enough that it would NOT require the cutting of the firewall to slide the engine back a bit. The intake setup itself is just as interesting IMHO.

For those not familiar with the GT racing series in Japan, there are two classes, 300 and 500. The numeric designation denotes the hp limit of the two classes, although the RE car appears to make a bit more than 300hp. Their car is also naturally aspirated. Wonder why they don't run in the 500 class? The turbocharged 3-rotors don't do well, mostly due to heat and reliability. Cost and complexity also plays a major roll which keeps him from running in that series. I've posted the pictures below.

Ok, now a few questions as these images have really started the wheels turning. I know there was a thread a while back that one could use 13b parts to make a 3-rotor with a custom E-shaft. If I remember correctly, going this route would provide a three rotor that was several inches shorter (3?). My question is this however. Are the 13b REW housings just as strong as the Cosmo 13b's or even the 20b's? Also, it's my understanding that the Cosmo 13b and 20b ports are quite a bit larger than the REW. Is it possible to make the REW ports just as large without running into the cooling passages?

My idea is to use the 13B REW parts, create a 20b using the custom shaft, use the RE intake system or fab one up myself, which would allow easier installation into an FD. I'd like to get the engine as far back as possible without cutting the firewall. Far enough back however that I can use a stock mount IC (not a stock IC!) instead of a front mount. I have the CWC which I may have to re-engineer a bit for it to fit.

If I go this route, would I still need a custom subframe or could I just do custom motor mounts? Enjoy the pics and I'd love some feedback on this. Thanks in advance.

 

Pic two, side view of the intake/TB system.
Michel

 

I think its pretty safe to say that engine will make sick HP

 

Does anyone know if the Cosmo 13B is identical externally (in terms of overall dimensions) to a 13B-REW out of the third gen? I have someone telling me that the ports are just so much larger, it'd be easier to start off with the Cosmo 13 as opposed to the REW if using those parts to make a 3-rotor. I hope it will make sick hp...at least a "bit" more torque than a 2-rotor :-) 450hp daily driven sounds pretty good to me. The Microtech guy can pretty much provide maps for just about any setup as well, saving me lots of time there as well.

I noticed that most of the 20B's run distributors too...it's possible to go with a distributorless ignition system using crank angle sensor, correct? I'm sure it depends on the computer in use.
Michel

 

I know the COSMO 20B ports are bigger. I dont know about the COSMO 13B, though. BUT when RE compared the 20B, 13B, and 12A, oh my god, the ports look like day and night.. I think the 20B port is too big, even if you port out the 13B-REW, I dont think you can get it that big, without bustin in on the water jacket..

What about just using the 20B housings, is this impossible?

 

....but the exhaust ports on the rotor housings need lots of grinding on either the 13B-RE, or the 20B. I plan to rebuild my 20B's with REW rotor housings only, since there is considerably less material to remove for a sizeable exhaust port. The intakes are nice though!
The dimensions of the 13B-RE and 13B-REW are similar, but the engine mounts are very different. Also, 20B's more commonly are equipped with the older FC style CAS pickups than distributors.

rx7tt95: interesting ideas you have there... let us know when you get started! I am convinced that there has to be a better way to install a 20B in an FD, so I plan on wasting at least a couple hundred hours welding my own cradle before I give up and buy a pettit!

 

LOL, Exit. Yes, I'm of the same opinion. There HAS to be a better way. Pettit, too far forward. PFS, too much hacking to the firewall. My goals are to eliminate as many one-off custom parts as possible which will greatly shorten the time from start to finish. I need to get in contact with Amemiyasan and find out what sort of drivetrain mods they are using (tranny, PPF, driveshaft) and see if this is something that can be purchased from them. If creative motormounts are needed, no biggie there. Microtech for engine management, pre programmed. The fuel system will have to be custom, along with the engine harness and turbo manifold/downpipe. I know it's a bit more complicated than this, but it really doesn't seem to be much of a larger step than a fully built, ceramic seal 2-rotor with a custom GT series turbo kit, no? I hope to figure most of this out before starting and go from there. Est. departure on this adventure isn't for six months however.
Michel

 

I think the term is used rather loosely when describing that the Cosmo engines have "bigger ports" than an FD 13B-REW engine.&nbsp The Cosmo engines do indeed have larger SECONDARY intake ports, but the Cosmo primary ports are SMALLER than the 13B-REW intake ports.&nbsp Overall, it might be that 13B-REW engine has larger intake ports overall of both primary and secondary intake ports over the Cosmo engines.

Yes, the engine dimesion are the same between Cosmo 13B and 20B engines - the only difference is the front/center housing on the 20B engine.



-Ted

 

Thanks for the info Ted. Appreciate it.

I think I'll stick to using readily available 13B parts...now if I can just find the link to the person producing the custom e-shafts :-)
michel

 

 

Don't 13B-based 3-rotors suffer from overheating problems?

I recall something about how because they use two 2-rotor's center plates, the middle rotor has no coolant flow except at the rotor housing (no coolant at one of the sides) and the sides get too hot.

If i'm wrong, let me know.

 

A "real" 20B uses a front/center housing that has a stat gear and bearing in it, so technically, it's not "two center housings".



-Ted

 

They probably do peejay. Good call. I've never read anything about overheating on the HITman's sight though.

 

Right RETed, I was trying to differentiate between a 20B, and a 3-rotor made up from 13B parts, which has a stationary gear adatped into a 2-rotor's intermediate housing, which is why they are shorter than a true 20B.

 

From comparing the cosmo 13B to the FD engine the ports look exactly the same size, the only diffrence is motor mount location and the front cover uses a distributor type pick up instead of a crank angle sensor...
also the lower and upper intake manifold runners are diffrent, the FD has small runners to the primarys and the secondary runners are larger.. on the cosmo 13B the primary and secondary intake manifold runners are the same size as the large secondary runners on the FD... other than that they are pretty much identical...

 

So if there isn't a cooling issue using 13b center housings, it'd be worthwhile to start with the 13B REW as a base and just port the intake manifold runners and optimize the intake/exhaust ports then, correct?
Michel

 

Dragon was talking about the 13B-RE vs. the 13B-REW - nothing about the 20B-REW

 

Right. I understand that. I'm concerned with all the variables and would obviously, like to make the right choice the first time and not wish I had done one thing versus another. If I can use readily available REW parts to create a three rotor, I'd much rather do that as opposed to using harder to find on short notice Cosmo parts or even a "real" 20B. At the same time, I don't want to give anything away in terms of intake/exhaust port design. If I can take REW parts and "optimize" them to the point that it's just as effective as "optimized Cosmo 13B parts, then I have what I would consider a viable option. Just need figure out the cooling issues.

Also, I'm assuming if one goes this route that I could use the stock FD clutch mechanisms (with upgraded hardware naturally) and reuse my lightweight flywheel. An ACT pressure plate with a Stage IV or V Clutchmasters disk would probably hold the power. If not, there's always a dual-plate, right? :-)
Michel

 

I havn't researched this at all so I may be wrong, but one problem I could see using the 13B parts to build a 20B would be using the 2 13B intermediat housings... the center rotor would be fed by two small primary ports, making it run way diffrent than the front and rear rotors, I'd be hell to ever get the fuel tunning right...
basicly I think if you want a 20B and you've got the $ it'd be better to get a 20B.. If you don't have that much $ it's probably better to just build the **** out of a good ol 13B and slap a huge turbo on it...

 

Actually it's not a money issue. It'd be a pretty safe bet that it would be cheaper for me to go with just a straight 20B in terms of engine buildup. The custom E-shaft alone is probably what, $1200 or so? Combine that with everything else that would have to be custom, it'd be cheaper for me to go with a 20B.

My main goal is to allow easier fitment into a third gen. By using the 13B parts, I can take a good chunk (maybe 3-4"?) off the length. If I can slide it back and design/purchase an intake that'll allow clearance of the firewall, I've solved two of the major issues.

I plan on doing something really unique with the front end air management, some of which has never been done before (as far as I know). It'll necessitate that there is as much room between the nose and the front of the engine as possible. The steering rack needs to stay just where it is too. Think PFS 20B conversion for 1/4 the price. There's always the RB aluminum housings as well. It'll save weight and help with the thermal expansion issues.

 

Ok, just returned from vacation. I think I just blew my 3-rotor piggy bank taking the niece and nephew to Disneyworld. Doh!

Anyhoo...I wrote to Pineapple and their reply was less than satisfactory. Rob's comment was someone paid him to do the "research" and it's now proprietary. Um...let's see...can I hand you a wad of bills to have you build me a "shorter" three rotor? Waiting on a response on that one. Come on.....so now I have to figure out who this is and pay them TWICE as much as it's really worth. No thanks. I'm sure there are other engine builders out there who are capable. I'm more than willing to pay someone for THEIR knowledge, but this whole proprietary "I paid someone else to build it for me and now you can't have it" belongs somewhere else besides here in the good ol' US of A. But I digress...

I did have a chance to pick apart a 13B and Dragon, you are right..wasn't clear to me until I assembled it. The primary ports can only be enlarged so much and they "probably" could not be made as large as the secondaries.

A few options I have left are some of the custom Racing Beat products made out of tasty aluminum. I don't have their catalog handy at the moment but I remember reading something about custom housings...Or to contact Spencer Racing who is now fielding a turbocharged three rotor. There's always the Aussie connection or heck, even my own creativity.
Michel

 

Looking at Hitman's 3-rotor, it's using a 12A center and there's a 13B pic with the stationary gear in it...What allows Hitman's 12A to work that wouldn't allow a 13B center to work? Also, what about 13G parts? According to my limited recollection, the G was smaller than the 20B. Racing Beat has aluminum G parts (I know, extremely expensive!) so perhaps a G center plate would work? Anyone?
Michel