Good evening, I've always wondered why you see series 5 front covers on most custom setups such as billet engines, and most custom 3 and 4 rotor setups. Its probably extremely simple but just always wondered why wouldn't you use the FD front cover for the CAS aspect.

 

That is not an S5 cover, that is '85-earlier, cannot tell if 12A/4-port 13B or GSL-SE without seeing the MOP flange.

The why they do it is probably related to how you can tell the covers apart: FD and FC do not have motor mount bosses, RX-3/4/5/7 do.

 

its probably more to do with mounting the engine than anything else.
my friend is putting together a 20B P Port, and for the thin intermediate and rear housings we were just going to use FC housings, because he's got those, but then we end up with no way to mount the engine, because the Cosmo has the engine mounts there and the FC didn't.

 

on that note it would be neat if someone did a center iron that had FD ports, but FC mounts, so you could build an engine that bolted in an FC, but used FD intake. etc on it

 

Besides the ports, and the lack of the drilled/tapped holes for the engine mount, are there any other significant differences between FD & FC center irons? If there's nothing else substantial, I'm thinking a good machine shop should be able to take a set of FD center irons and drill/tap the FC style engine mount holes in them, which would get you exactly what you're suggesting.

 

So it sounds like it’s purely for the front engine mount capability’s? As someone who has never owned an FC (yet lol) I forgot they have the engine mounts drilled into the center iron, is it possible to use fd irons on a 3 rotor build so you can use the stock motor mount locations on the fd subframe or is that to much weight hanging forward since the mounts are all the way in the back on an fd?

 

i'm not convinced there is enough meat in the FD iron, but i think people have done it before

 

It's slightly more complicated that that (if I remember correctly). There is an FC with an REW swap local to me, and if I remember correctly, it was tap the passenger side of the housing for that mount, then use a custom adapter for the driver side mount. There was some finagling to get the FC oil pan to mate up, but I can't remember the particulars as to how that was resolved.

I was always concerned with this as well, but the car I know of that did this was done in the early 2000s and ran up until the owner pulled the engine to paint and refresh the entire car just a few years ago.

 

Meanwhile, I got a set of Turbo II engine housings super cheap because the intermediate was broken on the passenger side, split horizontally right above the motor mount, about in line with the top of the tension bolt that goes through there.

I globbed some Right Stuff over the crack and shipped it



It never seemed to get worse, although when I did first do the engine install it was with the same 12A front cover/GSL-SE oil pan/modified engine mount bracket that I used for the GSL-SE engine install. The FC front suspension swap came a year or two later. And even then, I originally did the subframe swap with a motor mount plate that strung out to the framerails from the 12A cover instead of trusting the intermediate housing to not break all the way apart...

 

My setup is FD BLOCK ported 2 Cosmo specs on a FC .Drilled and tapped the center iron and some bolt holes for the fc oil pan 2 fit,S4 front cover and COSMO upper and lower manis.On the driver mount i used a stock fc mount modified that also bolts 2 the bottom stud on the front cover and also 2 the center iron top bolt so it has 4 studs.10 years on that setup and it hasnt cracked the center plate