I've made the initial plunge and ordered a Cosmo motor which arrived yesterday. The engine looked to be in great condition too.

After pulling off various ancillary items, I took a look at the ports. The intake side is absolutely huge. The exhaust is about the same as an FD until you peer in and it's a bit smaller but not by much. The actual port shape is different too.

The upper and lower intake manifold runners are again much larger than the FD counterparts. From the looks of it, the FD throttle body will bolt right up.

The first issue I've run into is that the Cosmo fuel injector setup uses side feed primaries and top feed secondaries. The FD secondary rail will not bolt up as the spacing is a bit different between injector bosses. This will require switching to 1600 secondaries. The secondary fuel rail on the Cosmo looks like the FC fuel rail which I may be able to modify and allow for the 1600's to fit.

The second issue is that the front plate will have to be exchanged for the stock FD front plate. not a big deal. The oil pan has to be swapped too. The FD motor mounts will bolt right up.

There are a few other minor details that require swapping of parts but again nothing too major at this point.

I'll post a few pics.

 

cosmo exhaust ports

 

Cosmo intake ports

 

lower intake manifold comparison, FD vs Cosmo (right), secondary runners.

 

Overall comparison of LIM FD (L) vs Cosmo (R). This is all I have for now. The engine will go in around Feb. 10, or at least that's when it'll start. Should take about 2-4 days to get it in and straighten everything out. It'll be interesting to see how this motor responds to a big single.
Michel

 

nice pix. i hope it all works out for you

 

I looked into doing this but seemed to be to much trouble. I did find out that you can change the Cosmo exhaust inserts for the 3rd gen ones. I am very interested in how you make out with this. So keep the info coming. :-)

While the stock throttle body should bolt up, did you measure the height of the Cozmo intake manifold? It seems to sit quite a bit higher than the stock 3rd gen one.

 

what kind of numbers are you expecting...in comparison to your fd motor?

 

What are the hp numbers for the cosmo engine stock?

R.K.

 

The Cosmo motor stock makes 25hp LESS than an FD motor of the same year, 230hp I believe. It does it at a lower boost level however.

Capt. Bill, how hard is it to get the exhaust ports out without opening up the engine? Is that even doable? If so, then this would be a tremendous upgrade although there aren't too many Cosmo motors out there. Is it a case of just unscrewing them and sliding them out? I wanted to give Mike a call to do this stuff but I'm too far away in Naples so Compact Car Performance is doing it (shop we were at for the SW Florida Rotorfest in Naples if you remember).

As far as the height of the intake manifold, it actually seems LOWER than the FD. We haven't had them side by side but if you look at a stock FD, there's about three inches between the top of the IM and the top of the firewall. I don't forsee that being an issue but time will tell!

I was a bit worried about the LIM and downpipe clearance. The curvature of the ports on the Cosmo LIM are much better than the FD. Not as abrupt and much larger of course. I know SOMEONE somewhere has done this before and I believe that Ray at SR told me he used the Cosmo block in their red project 93 FD, the one that made 321hp or whatever at 10psi with just a couple of bolt ons. Going off the top of my head on that one.
Michel

 

Oh and the stock Cosmo turbos..one is the same Hitachi unit found on the FD, the primary, and the secondary is a larger unit. I haven't pulled them apart to check their condition, but when I do, I'll see if they mate up to the FD manifold. Might be a nice affordable upgrade for someone running twins.

 

Michel,

Where did you get the motor from? Reason is, I'm in the market for a motor.

 

From Compact Car Performance...I'm not sure where they got it from but you may want to try www.soko.com as they have a shop in Cali. I believe it was called Japan Direct or something like that.

 

how are you mounting the engine? I thought that the cosmo motors used a diff style of motor mounts?

James

 

It does...you simply unbolt the Cosmo mounts and bolt the FD mounts on. No biggie. That's one of the reasons the oil pan needs to be swapped over. The other of course, is the lower brace/engine cradle. All the appropriate bolt holes are there for the FD mounts on a Cosmo motor.
Michel

 

Does the 2 rotor have more hp then the rx7 2 rotor? becuase why else would you waste you time.

 

he made this point already. read the post.

i had this idea as well a few months back, but was shot down by a couple of people. im pissed now!!!!!! hahaha, i really wanted to do it. oh well, i guess ill just stick with the fd motor till it decides to get stupid on me.

paul

 

LOL. Think of it this way...I get to go through all of the headaches for you! If I had been able to get a hold of a late model FD motor (like a 98 on up) for a similar price, I would have done it. But this engine was about $600 cheaper than a reman which are often of unknown quality.
Michel

 

Ok, I've done a bit more research and glancing over things. Here's what I've come up with so far...the fuel rail of the Cosmo and FC are not the same (according to K2RD). SR, rather than replacing the entire rail, bores out the rail a bit to allow aftermarket 1600 cc injectors to fit. But I'm getting ahead of myself a bit...

The primary rails are interchangeable. They're not identical, but the mounting bosses for the primary injectors is identical on both blocks so swapping injectors back and forth is not an issue on the primary side.

On to the intake manifold. The "length" of the cosmo intake is about 1" shorter than the FD intake. That means the throttle body will sit 1" closer to the center of the engine. Depending on which IC setup you have, there may be enough "fudge" room to allow the pipes to align up to a GReddy elbow.

The next issue with the intake manifold is fitment of the FD throttle body onto the Cosmo upper. It'll work, but it will require an adapter plate. Don't get me wrong...it all lines up. Problem is, there appears to be an idle air bypass channel on the bottom of the Cosmo UIM (see pics below) which is left uncovered when using the FD throttle body. One could use a 1" aluminum adapter or a sheet of aluminum to seal that channel up. Or you could just fill it (in the appropriate manner such as welding). It wouldn't be difficult.

With that said, I'll be using the FD upper and lower unfortunately. I have impending surgery coming up on the 10th and between working a day job and keeping my company afloat, I just don't have time to mess around with stuff. Which is a shame because the runners on the Cosmo IM are much larger (again, see pics). The secondaries on both manifolds look similar in size, but measuring with a set of calipers, the Cosmo is about 2mm in diameter larger. And you can definitely see the difference between the respective primaries.

 

here's a comparison of the UIM runners.

 

UIM inlet comparison

 

injector bungs and rails next...

 

FD injector holes...look familiar?

 

primary injector manifold

 

i have seen quite a few remans... they are pretty damn good for the money. i hope your jspec lasts a long time but i haven't had any luck with them