Hey folks! I'm looking for some info on whether there were any performance upgrades from the factory for FCs? I have an 87 GXL, and I want to build it to be as close to "from the factory" as possible with my own personal twist. One of the big things I'm curious about are factory performance parts, not necessarily for horsepower though. Things like upgraded sway bars, braces, bushings etc... If they don't exist it's fine, I'll probably look for good aftermarket equivalents.
Thanks!

 

From Mazda there weren't a lot of performance options on these cars. The drivetrain was the same (for all intents and purposes) for Base/GTU/GXL, and whatever else. Mazda seemed to keep everything basically the same, and then try to "lighten" certain models to be sporty, but they were all within a couple hundred pounds of each other. The only OBVIOUS standout was the Turbo II, which had nearly everything tweaked towards the performance side, in some way.

Items that did vary... sway bars were beefier on Turbo II models, and are a direct swap.
The engine rotors themselves varied in weight/compression, but no enough to warrant a swap without a "build".
Some cars were equipped with a manual rack instead of power steering.
Some cars had "auto-sport" suspension that car controlled.
There were a couple rear differential combinations used between models.. a lot had a 3.90 or 4.10, with 4.30 being pretty rare. Then you had open and LSD.

The most common thing 7 owners swap for performance in NA cars is to typically go to a full T2 drivetrain, for the rear gear, bigger axles, and sway bars. Find a manual rack if you can, and an aluminum hood.

This all said, there is a ton of aftermarket support these days, and some companies like RacingBeat are synonymous with OE styled performance. I hope this helps. Ive had a ton of these cars so feel free to ask questions.

 

Thank you!
That's about exactly what I was looking for. I want to keep my car NA and as reliable as possible which is why I'm not interested in messing with the powertrain after my rebuild. I was thinking about sway bars and other forms of chassis bracing though, good to know that the tii is an upgrade. I'm also planning on keeping my aas as it sounded like it worked before I tore my car apart. I'd also like to modify it, or worst case find a similar aftermarket system to wire in to work similarly (who knows what the future will hold). I mostly just wanna treat this car as some chill fun, nothing too serious. The only performance mod I'd considered was putting the s5 na rotating assembly in, but I couldn't afford it, and higher compression means less reliability (or so I've been told).

Still new to these cars, so I'm always curious to know more about them.

 

Not at all. Typically you don't go high compression on boosted builds because you are already artificially adding more air.. there are some different schools of thought.. but generally in the rotary world, builders go low compression-high boost. For N/A going to 9.7 or 10:1 isn't any concern (look at the RX8). BUT does the end justify the expense? If its not a "full build" and just swapping 9.7 rotating assembly in, you've spent thousands to rebuild for 15-25hp..

Now if an engine already needed rebuilt and was going to stay NA, absolutely use high comp rotors, otherwise its not worth it #my2cents

 

OKok that's what I was thinking. My engine is apart for a rebuild right now, only problem is that the cheapest I can find an s5 na rotating assembly is 2.5k, which is far beyond what I have. So it's looking like I'm gonna keep the heavier 9.4s until the inevitable day that my motor has to come back out.

 

Honestly, best straight up performance "mod" would be finding an LSD. Powering both rear wheels, lower center of gravity and sticky tires will be night and day difference, imo.

 

As far as I know the only cars with 3.90 rear gearing was the automatic transmission equipped cars. All the rest had 4.10 except the '89-'90 GTUs that had the 4.3. All the U.S Turbo II cars were 4.10 so no advantage in swapping driveline as far as gearing is concerned. As to the TII driveline swap there are other advantages besides being beefier. There are more clutch and flywheel options for the TII and all TII's had LSD plus the Torsen from the FD bolts right in. That said IIRC the torsen from the early Miata's swaps into the N/A so may only be needed if you are going turbo to handle the extra power. I think the 87 GXL had a clutch type LSD though by now yours may need rebuilt. Not sure if the parts needed are still available. If so I would rebuild it and while I had it apart swap in 4.3 gears if you can find them.

 

IIRC the E-shaft is the same between S4 and S5, so you only need the S5 rotors and front counterweight and your S4 flywheel or a S5 rear counterweight and aftermarket lightweight flywheel.
Also, if it were me, I'd street port it while it's apart. You'll need to replace the n/a exhaust sleeves if you are re-using your rotor housing or use TII rotor housing if you are replacing them in order to street port the exhaust. You'll need to ditch the stock exhaust manifold and use a header to get the full benefits of the porting. No real downside to a header other than noise.