Wanted to post an update about my FC. I have a thread on here about a 4-rotor engine I once tried to build, but thought this car deserved it's own thread.
I bought an FC 2.5 years ago, and modified the engine by adding semi p-ports, and motorcycle throttle bodies. At that point the car looked like this:



With these ports and a very short intake the thing only had power at very high rpm, meaning above 6500rpm, rpm limiter was set at 10000. The transmission was a turbo 2 one, which didn't match the engine at all. It was kindoff fun in a special way for a little while, but after around a year or so I got bored with it. Also the car was multiple colours and some rust started appearing. So around christmas last year I emtpied the car out to a bare shell and spend a week welding / prepping and painting it. While welding I modified the front end of the chassis to convert the cooling to a v-mount type system:


.
And when the week was over:



With the shell painted I started focussing on the engine. I got tired of the semi-pp engine and wanted something more streetable, and decided to go the turbo-route.
I had a good pair of late S5 T2 iron's with rotor housings lying around so I used those. The rotors are S4 n/a 9.4:1 compression for now.
What I did not have was an intake. After looking for a little while and not finding anything local (with local meaning somewhere in europe) I tried "fitting" a 4-port RX-8 192hp intake.
With fitting I mean throwing away the entire lower intake manifold and only using the top part, as the runner diameters and fitment are way off.
This was some work, but I think it turned out pretty nice. I even included the SSV-valve:



CNC machining the SSV-valve housing:




I had two turbo2 transmissions, but damaged both of them with the semi-pp engine. I think the high rpm kills them. Took the least damaged one apart and rebuild it with new bearings and seals:



After this I started rebuilding the car, which took a few months, and I didn't take a lot of pictures in the process, but this is how the car is currently sitting:









Some specifications:

- S5 T2 irons and housings, stock ports.
- S4 9.4:1 rotors
- Some engine mods, solid dowels, oil loop line, FD oil pump / stat gears / bearings
- Custom lower intake, RX8 upper intake, 4 ID1000 injectors
- Exedy lightweight flywheel / clutch
- T2 transmission and diff. S4 clutch LSD with inceased preload
- MS3X ecu, LD performance canbus display, Canbus I/O extender ecu with lot's of sensors for monitoring / logging. 4x IGN-1A coils, 36-1 crank trigger with hall sensor.
- Custom radiator as big as I could fit, 24.5x20x1.75" core, with the biggest spal fan I could find. Universal ebay intercooler, Stock oil cooler using seperate ducting and fans.
- 1.75" dia 40" long primaries header into 3" exhaust into cheap ebay presilencer intp 2x 2.5" homemade mufflers. Sounds terrible, need to change this.
- Tein HA suspension, but I have a set of billstein's that I'm going to swap in, the tein's are too stiff on the street. Polyurethane suspension bushings.
- 4-pot brakes with DS2500 pads, rebuild calipers, braided ss hoses.
- 150a alternator (BMW 7 series), Electric power steering pump (Saxo)

So far I havent got around to fitting the turbo yet. After over 9 months of working a few evenings per week on the car I just wanted to get it up and running again.
I do already have the turbo lying around. It's a borg warner S300SXE, 61.44mm compressor, 76mm turbine with 0.91 housing and 2 tial wastegates.

I have driven the car daily for about a month now, getting the tune really dialed in. With the stock turbo ports and very long RX-8 intake it's a pretty torquey engine with all the power down low. It completely drops of a cliff over 6500rpm though. Kindoff curious as to what a dyno sheet with the car like this would look like.

 

Hi John, nice build! Kind of curious why you didn’t port the engine while you had it apart; looking for more low-end with the car?
Any plans to continue the 4 rotor?

 

that turned out quite nice!

 

Hey John,

Should have msgd me about the intakes, i do have pretty much everything But since u didnt, there is something new , which is always nice

 

Good to see you up to your old tricks again haha.definatly subbed

 

great build so far, subscribed

 

That's a super cool build.

How much do you have into the intake manifold?

 

You just couldn't do it the easy way lol! Cool build.

 

Yes, looking for some low-end power and a car that's nice to drive. With the turbo it will make enough power anyway, so no need for huge ports.
So far I like it, it's really torquey, drives nicely and the turbo 2 transmission (Which sucked coupled to a high rpm semi-pp engine) actually matches this engine well.
This is a view of my VE-table, which shows that the engine quickly builds efficiency, with the downside being that it drops off a cliff at 6000rpm.



Thanks! :-)


Next time I'll ask :-), but after seeing you putting all those RX-8 stuff on your FC I just had to do the same aswell. I might steal your idea about using the RX-8 diff though.
Currently running an S4 clutch LSD with increased preload, but it's a bit clunky.


Money-wise maybe $150-200 for materials and the cheap ebay 70mm throttlebody. It did take me some evenings and free sundays to build though.
I am pretty happy how it's working. I can open and close the SSV valve and see what difference it makes, and it really helps with tuning and mileage.
With the valve open at low RPM I need a ton of acceleration enrichment, and it's more difficult to keep a stable AFR.


So, right now I have put around 2000km's on the car, no issues yet, besides one flat tire because I ran over a screw, so I call that a win.
I did do some changes to the muffler as it was a bit loud and raspy. I was using 2x 2.5" straight through mufflers and a cheap 3" ebay resonator.
I removed one of the 2 rear mufflers, and changed from a stainless wool packing to this stuff called "Acousta-fil" which makes a huge difference, really knocked all the high frequencies off.
I also ordered a few vibrant ultra quiet resonators to replace the ebay one, curious to see if that helps.

 

Had some free time during christmas, so I started putting the turbo on the car :-).
First I CNC-ed out a pair of flanges and mocked up the turbo location. I wasn't able to mount it low next to the engine because of the RX-8 intake, so I had to move it up and forward a bit.






Didn't have all the parts for the turbo manifold yet, so I started on the rest of the exhaust.
I basically made 2 exhaust pipes, one for the turbo and a seperate one for the wastegates.
Both exhausts are 3" in size, and I fitted 2 vibrant ultra quiet resonators and a bottle resonator to the turbo exhaust to hopefully quiet it down a bit when not in boost.