Haven't been around here much recently, but now that I have my life more in order and might have some money to play with, I've come seeking ideas.

Background on the car: 88 GXL chassis, self-built frankenstein motor. S5NA rotors, large street port S4NA front and rear plates, T2(don't know series) center plate and rotor housings. Big radiator, lightweight steel flywheel, RB catback.

The non-turbo motor, especially at altitude, just doesn't cut it. Don't get me wrong, she's super quick coming down the canyons, I just want a little more oomph going up. So I have come to the place most N/A owners end up, wanting a turbo. Nothing huge, I have no interest in rebuilding my motor (again), and ideally would like to keep the intake manifolds and all that. I have a friend with a pipe bender and a TIG so a custom exhaust manifold is a sure thing.

So with minimal limitations on the exhaust manifold shape, but working around the stock intake, what are some small turbos that could be fit in there? To make it more compact, I expect it will have to have an external wastegate. I can route that out the bottom somewhere. Maybe a little T3/T4? One of those could push 8 PSI, right? Like I said, just a little more oomph.

Of course, that's not even close to the only part involved. As for an intercooler, for the low pressure, I wouldn't need anything huge, but with the stock intake, inlet and outlet need to both be on the passenger side. I have no problem cutting holes to pass pipes through, but I would still like to keep the pipe size small, 2"-2.5".

For fueling and electronics, obviously all of that needs to be replaced. I'm going in with the expectation that the ECU will be the bulk of the cost for the project. IIRC, good ones run around $2500. If it comes with a harness and presets, it might just be worth it. But if the price gets too out of hand, I may look into the DIY one. I'm pretty electronics-savvy and could put together circuit boards without too much trouble. For sizing the fuel system, I figure aim for about a stock T2 level, since I should be aiming around that power level.

Thoughts? Ideas? Criticisms?

 

If your goal is ~200hp and have a budget of at least $2500 consider a swap. That out of the way it seems you're determined to to boost your N/A block, Although we are at altitude your tune has to be impeccable with those s5 rotors, a well sized intercooler (Consider water/Meth injection) and plenty of fuel.

Now as far as the turbo goes, stay away from small T3/t4, you'll get a boost spike and then choke your engine and run the turbo beyond capacity. Rotary requires a fairly big turbo. If price is a concern go with a stock S5 turbo or a BNR turbo (Same as stock but modified)

ECU wise Adaptronics came out with a plug n play ECU for our cars, full stand alone and about $1500.

What are you doing drive train wise? The N/A gearbox/ diff aren't the strongest, that being said just don't do any hard launches.

 

In my opinion, the S5 NA compression ratio of 9.7:1 is to high for reliable turbocharging with pump fuels available. Unless you make compromises by running very rich, pulling a lot of timing and/or running some sort of AI.

Maybe at your altitude things are a bit different.

"T3/T4" really doesn't describe anything but a class of turbos. Meaning a T4 compressor which has been combined with a T3 turbine. Very common in the piston world where they don't need as much exhaust flow. But can mean ANYTHING.

Best question at this point is: what is your power target?

MegaSquirt.

OK, so you are talking around TII power level. Well, that's easy. Use the stock turbo. True, it's a huge POS compared to anything you can buy today. But they are cheap and bolt right up when used with the TII intake manifolds. You will need to port match the TII manifolds to fit the NA block.

Porting The 4 Port Turbo II Lower Intake To Fit The 6 Port NA Block

 

back before the T2 came out, corky bell sold a turbo kit that fit a T4 turbo with the stock NA manifolds, they used a cast thing, it sort of looks like an S5 manifold. the point is that you CAN fit a proper turbo with the 6 ports, very few people do it, because its not an off the shelf thing.

i can also second the fact that the rotary needs a larger turbine side than a "normal" piston engine, the rotary flows a lot of air.

oh and i can second second the high compression thing, i've seen a dyno sheet where they did a 9.7 rotor vs 9.0 rotors, and the 9.7's need to be detuned so much that they were down 50hp over the 9.0's...

 

I hate to say it and now I'm "that guy" but it is a lot easier to just find a T2 than to turbo your NA. While I'm glad I went through the experience of learning everything - it'll be easier on your pocket to find a T2 or a T2 swap.

If you do go through with this, please add water injection or methanol injection. That should reduce your chance of detonation.

Aaron Cake has a great guide you can follow here: http://www.aaroncake.net/rx-7/naturbo.htm

Here is my thread, I did megasquirt, NA-T, the LIM modification etc. Info is a little more scattered than Aarons but I tried to take a good amount of photos. https://www.rx7club.com/build-thread...r-time-993003/

 

Yep!

In part 25 of my Cosmo I built a turbo manifold for the GT3076R which fit around the NA lower intake complete with functional aux port actuators. It was actually a bit easier than I had thought it would be but I'm starting with a completely empty engine bay.


The engine not only keeps the aux port actuators (with Atkins sleeves) but also the double throttle from the FD upper intake.

 

oh yeah, how did i forget about that?!

 

I wouldn't use a crush running bender for a manifold nor have I seen one made like that. I hope I don't

 

Hey I am also in Colorado and just bought a T2 swap for my S5. Be careful online if that's where you are going to get it. Mine was screwed up pretty bad and might need a rebuild.

Make sure you get some high cc fuel injectors, as you will have to replace them anyway. If you need any help I am in Colorado and can try to help you, I'm rebuilding my T2.

 

$2500 for a swap? For some reason I thought that would be more like $6k. I'll have to spend some more time looking around. I had figured the conversion would run $3-4k. If I can do a swap for less, that is definitely the way to go.

 

Uhhh 6k will get you a three rotor, but that's just the engine. Expect to pay $1500 to $2500 for a decent enough TII swap, remember there's a lot more to the swap than just engine/tranny though.

 

I spent about $1700 for my TII S5 engine with trans and ECU/wiring harness.
After a quick look at mine, it definitely needs some work, and possibly a re-build (which I was super pissed about)
After I got a little more into it, I decided it shouldn't need a rebuild.
I'm getting a custom driveshaft made for about $500, and I got a really good deal on an old racingbeat exhaust, and I also got a LSD.

Mine is coming out to about 3000-4000. And that's what I would expect for most.