SpAm@FC

iTrader: (4)

Hi guys!

I'm actually building up a drift car for the next couple of seasons... it will be my lovely FC3S TII (My first car i've got with 16, now im 25 it was my daily for 3 years)...
I was drifting BMW for years now (I'm located in Europe), also owned crazy things like a V8 E36 Coupe for 3 seasons... But ever since I'm in love with the FC3s handling characteristic (50:50, very low polar moment etc.). Rotarys are very rare over here, so everything is very expensive... But now i can afford an exotic race car like the RX

I have a perfect S4 TII engine laying around... 50.000 miles, very good compression etc. ... This will be the basis...

I want to have about 400hp with very good response... Therefore i want to use a set of FD Twins... Please DO NOT bitch around about the twins... i know the problems (UIM collision, downpipe routing, wastegate porting etc.) and the needed effort to make them work sequential (solenoids, vacuum hoses, wiring)... I'm using a Haltech P2000 and have a very good tuner at my hands (old DTM guy )

I know its a common problem on the s4 engines to crack the rear housings... therefore, i need at least a S5 TII housing with the thicker casting + rib... I will also stud the engine to increase torsional stiffness

So here is the first question: should i use only a s5 rear plate or is it better to use a complete Set of FD plates? (is the changed spark plug location of the FD housings really worth the extra money?

I'm also thinking about increasing the compression of the engine... the s4 TII engine only uses 8,5:1 CR... i want at least the FD CR... now, here we come to the biggest question mark in my head... i hope i can explain it good enough what i want to know (I'm not a native speaker, so please excuse my English )

I'm using FD twins, therefore I'm limited to their flow... will it be possible to run a high compression engine (lets say with s4 or s5 NA rotors...) with the FD twins?
I don't know if i have to retard the timing that much that i will not benefit anything in higher rpm ranges of the high compression rotors because of knocking danger...
I know, EVERYTHING depends on the tune, but there are physical limits...
So, will it be a gain in high rpm power to use high compression rotors with the limited FD twins? Of course it will be nice in the low and mid rpm (response, torque curve...)

Thanks in advance for your help
Patrick

barnett87rx7

iTrader: (1)

s4 housings don't crack its the rear plate that cracks at the top dowel pin thats why we search high and low for s5 rear plates because they fixed that problem

SpAm@FC

iTrader: (4)

with rear housing I've meant rear plate... sorry for confusion!

One sentence later i was talking about plates...

arghx

iTrader: (3)

FD twins won't make 400hp, not measured on a chassis dyno. you would need a 20B with stock twins for that.

SpAm@FC

iTrader: (4)

I've never talked about rwhp, did I?

sharingan 19

iTrader: (16)

lol, excuse the confusion, rwhp is all we use on this side of the pond.

There is a company (BNR) that makes hybrid FD twins using gt28 turbos that would be capable of 400 rwhp. Also there is a forum member that is running 13b-re twins and making over 400 rwhp, so it IS possible.

For my next build I was also contemplating using S4 N/A rotors (9.4:1) to give better off-boost response and run less boost for roughly the same power goals you have. It seems like high comp turbo builds for the most part are just people w/ tired n/a's slapping on a turbo until it blows or they save up enough for a turbo motor, so I haven't found much information.

I look forward to your build, please post results.

lastphaseofthis

iTrader: (8)

i'm also planning on an s5 N/a rotor'd fd twins setup, already have EVERYTHING. except the rotors, and i need a new turbo center iron. and some new apex seals. i'll let you know what i find with the clearance issues of the twins when its get warm in a week.

SpAm@FC

iTrader: (4)

will a s5 NA rear plate also work? Or does it have to be a s5 Turbo rear plate?

D Walker

iTrader: (1)

DO THIS. High-comp rotors are key if you want better response, and if you are using good fuel- 100 or better octane and have good engine cooling you will make good power as well.
One thing about the stock twins is they concentrate heat at the motor and really cook everything. Its not as bad in an FC bay as there is a couple inches more room, but still, its not good. I would definitely look into a BB GT35R which will give you terrific response and the power you are looking for.

Cheers,
Don

diabolical1

iTrader: (3)

my opinion ... and that's all it is, so do with it as you wish ....

i see two main avenues to travel, personally, i like Plan B best, but here they are:

Plan A
set the car up with what you have and start competing, getting everything else dialed in, and run it until you need a new engine ...

OR

Plan B
wait a bit and sell your S4 lump and get your hands on a S5 engine and be done with it. let's face it, you're not looking for stratospheric power and chances are if you do something to blow a S5 engine up at that level, then you'd probably have damaged an RE or REW, too. the S5 is the answer to most, if not all, of your concerns - the physical strength over the S4, the higher compression ... and perhaps most importantly, it bolts in.


i just found this bit hilarious! a world where Rx-"X"s are exotics? sounds like heaven to me ....

on a more serious note, if rotary parts are that expensive there, then you should make this as simple as possible and not try to build a composite (Frankenstein) engine using parts from all different generations and generational series. as far as i see it, spend the money for a good S5 13B-T and simplify the already tedious task you have ahead.