nekky

I was wondering if anyone here has done a S5 NA swap into their SE (or 12A car, for that matter). I'd be interested in knowing some details and the sort of difficulty level I'd be looking at. You can get S5 NA longblocks for under $1k, so it seems like it might be a good idea. They make 160HP stock, but with a header/free flow exhaust and a good intake, it should be up closer to 200, am I right? I think the most difficult part would be the ECU and 6 port sleeve actuation. The sleeves in the S5 blocks are activated by the air pump, right? Also, if I'd be getting an S5 block, and I'll be needing a new transmission soon anyway, why not pick up an S5 NA tranny too? To my knowledge, they'll bolt up to any 6-port engine. Would the shifter position be any different with the S5 tranny mated to EITHER a stock GSL-SE 13B, OR the S5 NA 13B?

Oh well, that's enough questions for now. ANY and ALL info is appreciated. Yes, I tried searching, but it's hard to when you can't search for S5 or NA because they're only 2 letters.

You'd think this subject would be more of a hot topic but geez, I don't think I've ever seen a 1st gen with an S5 block in it, aside from a turbo.

Thanks everyboooooody,

Zac

bouis

purple 82 has one. He has an aftermarket ECU and it gets 167 RWHP which is pretty darn good. If I ever do an engine swap that's the one I'll do.

I don't think I'd bother with the S5 tranny since you'd probably have to replace the shifter housing and cut and tap the shifting rod. The S5 block would just bolt up to an FB tranny and at stock 160hp it'd probably be okay.

bouis

Anyway, what would you need? I don't know if the GSL-SE manifold would bolt up or not, but you'd need a header with an oxygen sensor on it, the front cover, OMP, and oil pan from your SE, the ECU from the S5 and all that associated crap, an ignition from an S5 (or maybe you could use your GSL-SE one?). I'm sure I'm forgetting something.

bouis

Oh, yeah, a cone air filter.

enigma32

Me likey this.

bouis

Um yeah here's something else to think about. S5 block in an FB would give you much better gas mileage than a tricked out 12a or 13b with a carburetor and make plenty power. If you drove it 12k miles a year you'd probably save $4-500 on gas.

RacerX7fb

A friend of mine has done the swap and Im in the process ...doing some port matching and polishing of the intake manifold.
Yes nekky, youd figure this would be a hot topic but most people seem to be more interested in turbo swaps, whereas Im not ... this allows my car to remain in CSP for autocrossing, and a pretty quick HPDE track car with day to day reliability and good gas mileage.
IT-S FC racecars yield anywhere between 170 to 190 RWHP ... I like in my FB

enigma32

I'd be interested simply for the reliability-- I've gotta assume this would be more reliable than a turbo setup of the same cost?

purple82

Yup, I've done the swap. Actually, I had it done professionally mostly. I've got a local rotary guru that I fully trust with my baby.

If I had it to do over again, I'd just buy a junker S5 and take parts off it. You need so many little parts, especially if you still need to be emissions legal, that it's worth just having a car to pull it off. By the way, if you're not planning to be emissions legal, get ready for that pungent unburned hydrocarbon smell that the rotary makes so well. And you won't be making many friends at stop lights.

My ignition is controlled by my stock 12a distributor and an MSD direct fire setup on the leading plugs. I'm using my stock 12a transmission, which doesn't have any problem with 200hp, and a GSL limited slip rear end.

My engine is street ported with the secondary sleeves removed and the ports are slightly massaged. If you compare my dyno run with a stock S5, there's no low end torque loss in my engine. It just pulls alot harder as the revs rise. I attribute this mostly to the fact that I'm still using the S5 intake with it's long runners. The only driveability issue with the engine is that it's a bit grumpy at low RPM/low load. I've read that removing the sleeves can cause this. It's not bad at all, just noticeable compared to other cars.

The engine ends out making 167 hp at the rear wheels (uncorrected, in Denver, 5200 ft). The stock S5 puts about 130hp to the wheels, 20% drivetrain loss. Going by this, my car is making about 200 flywheel HP at altitude. I've got it tuned mostly for driveability, I've seen a very similar setup to this make 190 HP at the wheels, but midrange suffers somewhat.

purple82

One other thing, you'll certainly want to upgrade your exhaust. I'm running a Racing Beat header, a Bonez cat and a Racing Beat muffler with 2 1/2" tubing all the way. It's pretty loud, but people know not to screw with you. And when you can take out Boxters, they better not.

bouis

Do you have an oxygen sensor?

purple82

Yup, it runs in closed loop at cruise.

bouis

Where did you mount that o2 sensor? I have a RB "SP" exhaust that doesn't collect until the muffler, so I guess I'd have to tap one into the header?

purple82

I'm just tapped into one of the header runners. It's only monitoring one rotor. The MAP sensor on the intake is doing the same thing on the intake side.

enigma32

purple82, what was your estimated total cost?

bouis

If you get someone else to do it for you, way too much [I assume].

I've figured about $1600-2000 doing the work myself.

Edit: using a stock ECU and a lot of parts I already have.

purple82

Keep in mind, I did all this professionally, the person that did the porting normally only does SCCA racing cars, the exhaust is totally custom welded from mandrel bent segments and the Haltech was installed, wired and tuned by a pro. Engine and porting, $1500; intake and fuel parts, $600; Haltech, $900; exhaust and parts, $600, labor, $4000. Um, almost $8k.

So yeah, it's not cheap, but I spent alot of time looking at FDs before doing this, I think I looked at six of them. I just couldn't give up the solidity and build quality of the FB for the questionable reliabilty and obvious inferior quality of the FD. Also, this was spread out over about 2 years, so it wasn't as painful as it sounds.

bouis

What kind of fuel pump/filter did you use? What about the front cover and OMP? I'm really thinking about doing this as my "summer project."

purple82

The fuel pump is a Bosch unit from a Porsche 944 mounted in the stock location. The filter, I'm not sure and I'm not around the car. I'll take a look when I get a chance. The fuel injectors are stock S5 and I'm also using the stock pressure regulators without any issues. The front cover and OMP are from an SE.

I neglected to mention, the core engine was a NA S5 but it's actually made up from T2 housings for better exhaust porting and NA rotors and plates for intake porting. I guess the exhaust ports are easier to work with on the T2 housings.

purple82

I forgot, the 1st gen clutch is no match for 200hp so you'll need to upgrade these parts as well. I've got the Racing Beat street/strip disc and pressure plate. The pressure plate is VERY heavy and it's not for everyone but you definitely won't have any slipping problems.

nekky

Thanks for all the good info guys, keep it coming! Could we make a sticky out of this?

Zac