RX-7 GSL-SE race car; easy power mods.

I'm trading the 323 for a RX-7 as I've put the driving a rally car dream on hold to concentrate on road racing. The car I'm swapping for will have a stock intake with a header and minimal exhaust.

Keeping with my KISS attitude for race cars, what fairly simple things can I do to get maximum power out of this puppy? The thing I love about the 323 in it's stock low power guise is that you go to the track, make sure you've got gas, oil, coolant, and brakes, turn the key, and race (OK, at the back of the pack, but still racing). How do I get more power in the RX while still keeping it reliable?

And finally, this will be my third rotary. I've actually not had the best luck with them (flooding, ignition, other issues) which mostly had to do with my ignorance. What do I need to know to keep this trouble free?

Thanks,

Jeff

Stick a v8 in it...

So you decided to go for it Jeff? Excellent - I have nothing to add. I know jack about rotaries, but I will be following this thread.

You and me both Dave. I'm depending on the kindness of strangers to get me through this. And yes, at some point in the future (next winter or the following) it will probably get a V8.

I'm not too familiar with FB's, but the standard intake, header and exhaust should work, as does a light flywheel. With FC's anyway, the 5.12 diff is popular for racing, but mostly because 3rd, 4th and 5th gears are closer together than 2nd, 3rd, 4th (at least with the GTUs 5th). The stock power kept going up from the FB to the S4 to the S5, which got an 8000 rpm redline, higher compression, lighter rotors and a more sophisticated intake. You could try swapping one of those in and it wouldn't necessarily cost that much, depending on how you source it. Maybe you can swap a later intake manifold on the existing engine for a bit of a boost too. Other suggestions are of course porting, but that means a rebuild, or a carburator setup (weber or holley) if you're willing to go that way. It all depends on how far you're willing to go with it.

I know a little about 1st gen 7'S, but I had a carbed GS model. Exhaust was restrictive. replace the header and mid pipe, no cats with a high flow muffler. But be ready for it to be loud.*edit...that part was covered teh reading is hard.

GSL-SE was the injected engine, so there must be some type of tuning that can happen. Raise the rev limiter as high as you dare. I've seen guys spinning 9-10k with em and not blow up....but I don't know how long that lasts. Dont know much about the intake side of the FI engine, or how restrictive it is. might look into that.
Ditching vac. line rats nest is a popular mod, there should be how to's a google search away. In my opinion, there is no such thing as a consistently reliable rotory...its always needing to be adjusted somehow.

Mazda kept improving the intake design over the years so swapping a later intake is a good step, if your class allows it. I'd also dump the 'flap door' air flow meter for the later 'torpedo' type, it's not hard to do and is worth a little more HP. 'Torpedo' style AFM:

These were used on 89-91 cars. Be sure to get the N326 which is for an NA car, the N370 is for the turbo cars and has a stronger internal spring among other differences. You'll also need the wiring plug, it's different from the flap door type. I happen to have an N326 I'm not using, but I don't have a spare wiring plug.

Some say to jack up the ignition timing, I say no because the apex seals are very sensitive to detonation and due to the design you have to really be listening hard to hear it.

On exhaust, 2 1/4" seems to be the magic number for diameter with an overall length somewhere in the 96" range. There are different headers out there, all are better than the stock manifold but the cheap Pacesetter header is not real good. Primary tube length should be in the 24-27" range.

The rev limiter is there mostly to keep it from throwing belts. There's a Gilmer belt out there but IMHO it's a lot of $ for not much gain. An underdrive pulley will help slow the water pump down and that helps with cooling at high RPM. I'm currently running a dual groove pulley set but am working on a slightly different setup which uses one belt from the E shaft to the water pump, then another from the water pump to the alternator. That's been a popular SBC setup for years, it keeps belts from flying off at high RPM. Like this:

only with a single belt. I need to get off my butt, order the underdrive pulley and then get some belts to test with. By the way, on that setup you install the belt by putting a stud in the water pump pulley flange, slip the belt around both pulleys then use a small pry bar to lift the water pump pulley into place. You then run another belt up to the alternator in the usual way.

I'd say open up the intake and exhaust and be sure you've got sufficient fuel for the extra air. Beyond that, porting, but depending on how aggressive the port job is, you can make the engine fragile and sacrifice driveability in pursuit of top-end power.

I think the best power adder for the rotary is a turbocharger, but I may be biased in that regard. Just remember to consider the whole system. I recall being disappointed with gains from my exhaust work, only to finally reap the benefits when I opened up the intake. And never go lean!

Well since nobody has asked, WHAT CLASS?

^ The most important question.

Intake and exhaust are the obvious ones, rotaries love to move air. One of the biggest gains I saw was from putting in a good, adjustable rising rate fuel pressure regulator and wideband O2. 1980s catalytic converters weren't as good as modern ones, and couldn't cope with the heat from rotary engines long enough for whatever the federally mandated length of time was (I think 60,000?)). To get around that, Mazda had to run them fairly rich to keep the exhaust temp cooler. You can gain a lot of mid range power by adjusting the fuel pressure to a happier AFR in the range you'll be running it.

I ended up going Megasquirt and that made it much happier throughout the entire rev range, but swapping the computer isn't legal in a lot of classes. Some times and sAFC is, though!

The AFM isn't really a restriction. People have made near 200hp with the GSL-SE AFM in place.

The intake manifold sucks. A S4 N/A ('86-88) is a near bolt in and worth every penny. It's the same design, just larger everywhere. You'll need to put a glob of steel putty under the primary ports to blank off the block's air injection port, but this is trivial.

Sorry for my delayed response, things have slowed on this, but hopefully it will be mine soon.

Class is open. It's open GT. At the last race a few weeks ago we had a full on stock car, a radical GT, numerous vettes-cameros-stangs and my 323.

Thanks.

Open up intake and exhaust and raise the rev limiter. Should make some good noises as well!

As others have mentioned intake and exhaust are good starting points. I also use an underdrive pulley on my FC, and removed most of the "rats nest" and had the ecu reflashed for better performance. There are a bunch of other mods that are reasonably inexpensive and don't effect reliability. I think rotaries like to be revved and make great track engines. I have been doing, TTs for 9 years and once I got away from junkyard engines I have been happy with longevity of the engines. Rebuilds run about $1500 and I got 5 seasons out of my first one and just finished my 3rd season on the 2nd rebuild. They are not the fastest but are lots of fun to drive. Good luck.

Fitzauto wrote: Open up intake and exhaust and raise the rev limiter. Should make some good noises as well!

GSL-SE don't have a rev limiter. Keep it under 8,000 if you want the engine to live.

Or take it apart, get a set of FC rotors and counterweights to replace that 3mm seal junk, skim .003" or so off of each side of the rotor near the tips, squish the oil pressure reguator until the nose is flat, teardrop the oil passages in the eccentric shaft, port the rough corners out of the oil passages into and out of the oil pump, make sure the apex seal slots have no more than .002" clearance, and then after a decent breakin your rev limit will be "I'm afraid of the clutch spinning at suborbital speeds right next to my ankles". Premix 2-stroke oil in the fuel at roughly 2oz/gallon.

Not that this hasn't been my engine since 2012 or anything.