NA Specific Mods
 

I recently got an 88 Vert (NA), and I wanted to know what some of the basic HP mods for NAs are. I searched for awhile and haven't seen anything NA specific for someone that isn't looking for a whole lot of power and wants to keep their stock tranny or injectors. I remember reading that the stock injectors and s4 transmission can take up to 250HP, but that might've been for the turbos.

Basically, I'm only looking for like 190-210 HP if possible (porting isn't out of the question, but a turbo swap kinda is). What are some of the mods you can do and keep this thing relatively stock and street legal? Maybe we can make this an archive thread or something.

For starters, I know a new header, downpipe, and cat-back are all essential and basic, but what are the steps after that?

P.S. - Mods - I *almost* put this in the Tech & Performance section, so feel free to move it there if it fits better ;)

after intake and exhaust you may not reach that goal of around 200. Unless your talkin at the flywheel.

This has been a debated topic about reaching 200 on an n/a without the aid of a major power adder like a supercharger, turbo or spray.

I would check out the dyno numbers and drag times threads and see what people are making with certain mods and go from there.

You won't reach 200hp on an n/a without some moderate porting, a standalone and alot of tuning know-how. Check out the naturally aspirated performance section of this site. You won't reach it with bolt-ons only, you'll need to strap it to a dyno, hook up a wideband and tune.

https://www.rx7club.com/naturally-aspirated-performance-forum-220/

FULL TUNE UP!!!! every damn thing!!!

get some 4.10 gears/diff out of a base/se or 4.56 LSD diff out of a GXL, because i think verts have 3.96 gears or somthing, anyway higher then the rest so a gear reduction will help the acceliration of the car.

racing beat true duals or a header of some kind along with atleast 2.5" exhaust all the way back.

Make a CAI, the filters in the engine bay suck in hot air, killing N/A preformance.

MSD 6A or MSA 6AL (see fc3spro for instal)

SAFC and posibly AFPR of some kind, because (at least thats what they say here on the fourm) that the tune is quite crude and rich for the N/A needs.

bigger plug wires (OBX, racing beat, magnacore, etc...)

Lightweight flywheel (ACT, fanzia, RB, Mazdatrix, etc...)

make sure your 5th and 6th ports are working correctly!!!!

idk if this will get you to the 190hp mark, but it will make the car a blast to drive in combo with a good suspension package.

If you still want more power, go w/ wet shot of laughing gas. you'll already have the SAFC (and posibly the MSD 6AL) to tune a larger shot with, snag a higher volume fuel pump (TII/FD, twinturbo supra, twinturbo 300zx, walbro 190 or 255, etc...) and it will be much much cheaper and easier then the turbo or supercharger route.

You don't need bigger plug wires... The ngk's will do just fine. But you do need a port to reach 200hp.

I wouldn't recommend using the afc to tune with nitrous if your looking for a big shot.

This has been debated for awhile...

There is a huge thread on this in the archives with some great information...examples of not so great or questionable information...

A CAI is a VERY questionable "upgrade" on an NA...especially without any type of box built around it. The heat of a rotary is the reason why a cone filter tends to take away performance over the stock system.

This is the truth.

Thanks for all the replies guys!

Yeah, I thought 200 rwhp was a little much :)

Just gave it a tune-up, so the next step is new headers/exhaust and a CAI. Turns out some hackjob mechanic who worked on it before I got it forgot to hook up the boost sensor, and the water thermo sensor was rusted out (was getting a code 03), which made it run like 8% rich for god knows how long and kill the cats.

I didn't know that verts were geared differently, so that GXL diff sounds really good ;)

I also was just checking out some of the dyno times and most of the N/As are either stock or heavily modded. Time to do some more searching.

To put in an MSD and SAFC you have to port the engine first right? Isn't porting an N/A weird because of the 5th/6th ports? I've got no practical experience with that, so I'd probably have Pineapple Racing do it once I get some more money since they're just up the street. What kind of plugs would you run with that? B7/B9EGV's or stock? And a standalone is a little much for right now if that's avoidable. Honestly, I'd be more than happy with 175 rwhp.

I'd do a wet shot system too, but I'm no where near experienced enough for that (yet ;))

No. You do not need to port the engine when you install an aftermarket ignition (MSD) or a fuel controller (SAFC.) Those are two completely different areas of the engine. In my opinion porting the engine is the last step unless you need to rebuild the engine. If Pineapple Racing is right up the street from you go talk to them. They should be able to give you some advice.

LMAO, i actualy did know we had an N/A section till i re-read this thread (fail on me).

I'm sorry, i was not spicific enough with my CAI comment. when i say CAI, i mean byond a box built around a cone filter cuz how is that better then the stocker?? IF I WAS TO BUILD ONE; it would be removal of the window washer fluid bottle and run a filter down in that corner of the wheel well so the air being inhaled by the engine is entirely out of the engine bay like a true cold air intake (CAI), OR you could cut away a little bit of the rad support by the radiator and run it infront of the radiator (i've seen pictures of it done this way on here somewhere lol)

ignition is ignition, the stronger the spark the longer the plugs will last and more powa! (besides we all know how cleanly and efficently these motors burn right?

He has an 88 so as long as he has the AVC and the smog pump working they should work fine. (unlike stupid exhaust driven 86/87 :icon_tdow)

this all coming from a guy that has a turbo car lmao. but my close friend has a N/A we are building up and we also share some parts cars, so i learned while he learned.

[QUOTE=2slow4stock;9209708]I wouldn't recommend using the afc to tune with nitrous if your looking for a big shot.[QUOTE]


K, we need to define "big". I said bigger, meaning bigger then the 75shot jets you get in the universal wet kits, just guessing but maybe 125-150shot with SAFC and posibly MSD 6AL (the regular 6A is not tunable).

if its N/A, you dont have a boost sensor, its more like a vaccume or MAP sensor.

I like the way the racing beat true duals sound, but they cost $$$ so maybe just e-gay header and have some exhaust shop run you 2.5", 2.75", or 3" exhaust.

"NOS... one of the big bottles... actaully make it 2... 2 of the big ones.

Port, header, full exhaust, intake, light flywheel, Rtek to tune it.


That is about it without NOS or getting really expensive.

If you do port your motor, you don't want a true dual exhaust. A collected header with 'tuned length' primaries is important for serious n/a power. Again, check out the n/a performance section, there's a few threads in there with information about how to calculate proper header length and whatnot.

I don't completely understand how a SAFC works. I understand that it tricks the ECU into dumping more fuel into the engine via the mass airflow sensor, but without the added air of a port or forced induction, wouldn't this just make it run rich? And with a stronger spark, wouldn't you run the risk of detonation? Sorry for the lack of knowledge, not only is this my first rotary, but the first car I've every really worked on too :icon_tup:

Thanks again guys, getting some great ideas!

^^^ yes, the S-AFC is used to lean or add fuel to the mix by tricking with the AFM inout to the ECU. In a N/A car, not much is gained by adding fuel as they run pig rich, unless you have a ported motor. But with an safc in a N/A you can lean it out a bit, giving a little more power. With a turbo motor, you can "safely" control the fuel mix running larger injectors and adding more boost.

I dont understand why people are talking about diffs and flywheels when the subject at hand is about rear wheel numbers...

flywheels and etc... are for overall acceliration; remember seat of pants dyno is the KING!

I dont remember who, but someone told me 20hp (flywheel i assume) could be gaind by leaning out the motor (to 11.3:1 i think [that ratio has a special name]) with a SAFC/fuel control of some kind.

If you seriously call it the prosses or using nitrous oxside "NOS" i stamp RICE on your forhead, and for those of you trashing this thread with F&F bull, leave now befor i call REted, lmao.

hmm, I think 11.5:1 is supposed to be "rich best torque" according to piston engines.

And thank you for the "NOS" comment. I can't stand when people refer to it that way. There are so many much cooler terms for it. The technical " Nitrous Oxide", or "Nitrous" for short. Some of my favorites are " spray" or "juice" maybe "boost in a bottle."

ya i think thats what i was thinking of, but i thought it had a name like "absoulte somthing, i cant remember" i guess nvm on that.

From what i've read it breaks down like so:

6.0:1 Rich burn limit at full temp
11.5:1 rich best torque
12.2:1 safe best power
13.3:1 lean best torque
14.7:1 stoich
15.5:1 lean cruise

But this was in a book that mentioned nothing about rotaries so take it with a grain of salt.

Jesus christ... lots of misinformation in here.


For an NA car you want to adjust fueling to about 13:1 under load and it will be very close to perfect. At low load 14.7:1 or a little higher is where you want to be.

Forced induction cars you want to tune somewhere between 11:1 and 12:1 depending on the car, the setup, and a variety of other things.

And yes, you will physically see more HP on the dyno with a lightened flywheel.

If you want to get 200 Naturally Aspirated HP, my advice would be to only take advice from verified members of the N/A 200HP Club.:)

Not one of the bench-racers above are members. If they were, they would have told you.

Next best thing, look in the archive for this thread https://www.rx7club.com/2nd-gen-archive-72/how-make-beefy-n-need-your-recommendations-31410/

Time to throw my dog into this hunt...

The best thing about the NA rotary is it's reliability in stock form.
It's not that unusual to see (basically) stock cars with near 200K miles, still running fine.
Mine is approaching 190K and is an excellent daily driver.

IMO, attempting to hotrod the NA is almost a waste of time- you give up the longevity/reliability and still don't have much power...an extra 40-50 hp ain't much of a return for what it costs.

If you insist on more horses, go turbo or V-8.
Yeah, it's expensive but you'll actually notice the difference.

Should you decide to stay NA, invest in tires/suspension and brakes, then learn to drive the car on it's own terms.
A NA can be quite entertaining once you get up to speed because you can maintain the momentum using the RX's good handling.
Don't expect "neck snapping" acceleration, cause that's just not going to happen.

+1

You are right about the vert, and good luck finding a 4.56LSD in a GXL, not a single one came that way from the factory. You are probably thinking the GTUs, which are a pretty penny.

to add to the gtu-s the rear end is a 4.30 vlsd