So, whats the most hp wise can you get out of a S4 NA without turbo or throwing out emissions.... Id like to see around 250, but I still want it to be an everyday driver/legal. Is this possible w/out transplanting a TII? If so, can someone point me in the right direction? Anyone w/any experience w/this?

 

I'm gonna go with a no on this one. 250 is gonna be pretty high hp for NA, so street legal ain't gonna happen. However, most people on here run NA's, so perhaps someone could shed some light on what a street legal NA can do hp wise. I would suggest searching, reading, and looking at this thread in particular. Good luck.

https://www.rx7club.com/2nd-gen-archive-72/how-make-beefy-n-need-your-recommendations-31410/

 

Thanks gregk...I've done hours of reading on this, and the only thing I came up w/was porting which means no tags...or emissions passing (colorado emissions standards are high) or a switch to a TII. I'll check out that link though...

 

i think it's a question of logic. you want to increase power by nearly 80% without any major modifications, AND you want it to be a daily driver. think about what you're asking, and then look at buying a real daily driver and keeping this car as track car

 

I would say to put an intake, catback exhaust, light flywheel/aftermarket clutch combo for sure. I would think that people would recommend some sort of piggy back fuel computer as well. I hear NA's run pretty rich on the factory setup. Wheels and suspension tuning can make the car alot more fun to drive as well. All the little things can add up. If you don't mind switching exhaust for smog every year or two, you can get away with a little more. Just don't get busted by the cops. Plus dumping things you don't care about can drop weight and help overall performance. And of course...making sure everything is fixed and in good working order is what most people will recommend before doing mods. Not trying to lecture or anything...I hate when people do short little posts that don't have much to do with the poster's question. If you're gonna take the time to post, you should try to post factual info, and try to help out, right?

 

180 hp

Minor porting, rtek, intake, exhaust, flywheel, lighter wheels, suspension.

Those will make a fun car.

If you want a daily driver, restore as much of it as you can. Stuff goes bad when it is all over 20 years old.

Josh

 

out of everybody that has posted coxxoc is the closest to being correct.
180 hp is about all your gonna get out of an non-ported n/a motor that will pass smog. thats with everything is perfect shape, maybe port match the TB/UIM/LIM. rtek, flywheel etc. etc

DO NOT LISTEN TO ANYBODY who says to put an intake on your FC, the stock intake flows better and cooler than any little cone filter/aftermarket intake setup ever could. i have an intake Temp sensor installed after completely warming up it sits at about the same temperature as it is outside. with a cone filter on once the car wars up intake air temps are about 127 F consistantly.

IMHO theres no need for 200+ hp in an FC, it's not a drag car. and in the twisties i have no problems staying on an FD's ***, in my N/A

 

Thanks for the temp numbers. Assuming you did that when it was 70F outside, that translates to a 10% (15 HP) drop in power with a cone intake. i.e. the air is 10% less dense when it's 60 degrees warmer. If it was actually 100 F outside then it's only 5% lost. I think you do gain 2-3 HP from a cone, assuming you isolate it from engine bay air and let in cold air.

 

not saying no major mods...just street legal. surely this is possible.....But what do I know, this is my first rotary..... I'm interested in speed as well as reliability and being able to drive my car on the street....

 

Sounds doable... may just learn on the 86 NA, and then invest in a 13BT, find a good shop to drop it in s/transmission CPU etc...

thanks to all that helped, I'm new at this...I love how the rotary is designed...so I'm gonna stick w/it. I'm sure you guys have heard all these questions a million times...so thanks...

 

165.2hp

 

Don't rule out a mild street port for a daily driver. I had the motor in my '90 GTU rebuilt in 2000 and got a mild street port at the time. With a Bonez cat (and later a Random Technology cat), a downpipe eliminating the precats, and all other factory emissions equipment intact, the car easily passed Pennsylvania emissions and later Maryland emissions pretty easily. I never had it dynoed because the numbers weren't important to me, but it was a fun car with a noticeable increase in horsepower from stock.

I guess if Colorado strictly prohibits the removal of any stock emissions equipment then a high-flow cat might be out for you, though I'd be pretty surprised if the testers there know what a 20 year old RX-7 stock exhaust looked like...

 

Right; I'm just saying that a 250HP emissions-equipped N/A 2-rotor RX-7 doesn't exist.

I would say that 200HP would be the MAX you could be able to achieve, and really I'm not even sure that's possible. I think 180HP is going to be pushing it, and that's with a decent street-port and better (though still emissions-compliant) exhaust, as well as a piggy-back fuel controller/ecu (rtek, etc).

Now, with that said, a 180HP N/A S4 would be a blast to drive. You're talking about a car that's already pretty light (compared to today's standards, anyways), and has some of the best handling of any car during its time (it's still pretty darn good, IMO).

I'm not trying to discourage you from doing all the possible mods to your car as possible, though, because I'm having a ton of fun and learning a lot as I do my own mods. But, from all the work I've done, I've come to realize that HP isn't as important on these cars, because they're already quick little buggers.

 

Peripheral ported NA 13B's can make quite a bit of power and can be built to rev at 10k+, but it would cost you a lot, probably still couldn't pull off emissions and make 250+hp, and as a DD you might lose your hearing, too.

 

yeah I'm doing a big n/a build up and supposely I can't even get 200 from my setup. Look at my sig. Even with a lightened flywheel and a standalone it would still be hard to get 250.

Mazdatrix sells a 13B engine that is Peripheral ported and makes 300 to 350. Yet that has to do with

9lb Rotors
Balanced Engine Assembly
Peripheral Port Rotor Housings
Side Cut Rotors
Race Aluminum Pulley (eccentric only)
Hardened Stationary Gears
Front & Rear Counter Weights
3-Window Rear Bearing
Oil Pan & Baffle
Deep Grooved Rotor Bearings
New Eccentric Shaft
New Ribbed Tension Bolts
Large Oil pump w/Hardened Gears
Competition Pressure Valve
Test Run & Broken In

Add On:
Intake of your choice
Flywheel & Clutch
Water Pump & Housing
Alternator & Belts
Ignition System

 

How can a lightened flywheel change HP?

 

RWHP, mainly. Since there's less mass to spin around, especially with such a large radius, it frees up power to go to the wheels.

 

I think technically you're not changng the horsepower at all with a lighter flywheel. It may feel like it, but the HP will be the same. A lighter flywheel will only allow the engine to be more efficient at using the power it already produces. I know it sounds like were saying the same thing but what I mean is the HP the engine produces will not change with a lighter flywheel.

Brian

 

You're not changing the rwhp either. You're reducing the car's inertia, which improves the acceleration. It has the greatest effect in 1st gear. The lower the gear the greater the speed of the flywheel relative to the car/wheels. So it's similar to weight reduction, but the impact changes depending on what gear you're in.

Assuming most of the flywheel's mass is in the outer part of the flywheel, find (flyhweel weight saved) x (flywheel rpms) x (overall gear ratio). That's effectively how much weight you're saving. If the flywheel's mass is evenly distributed from the inner part to the outer part, then cut that in half. That doesn't include the little bit of static weight you save from making the flywheel lighter. The overall gear ratio is (gear ratio at tranny) x (final drive ratio). If the two flywheels distribute weight differently then you gotta figure out the rotational inertia for each and subtract.

 

I thought I was specific enough, but I guess not. I never said nor believed that a lighter flywheel allows the engine to make more power, only that the transfer to the wheels is more efficient. Using a lighter flywheel should yield more hp at the wheels because it costs power to accelerate that rotating mass. Granted, it may not be a lot, but it matters for serious racing.

 

interesting find w/some running a 13B NA everyday driver. https://www.rx7club.com/showthread.p...ight=remove+ac

Claim 200+ w/dyno to prove it...

 

i'm a little confused by what his list of mods is, because the two cars he has listed as owning are an FD and an 84 gsl-se w/ 13b-re.

not calling bs on him, because he has dyno's of something, but im sure those 6 things aren't his only mods to get those kind of #'s

 

From the same poster:

"I thought a solid rebuild w/ porting, exhaust upgrades and good tuning were pretty much taken as a given for n/a performance. With my 13b-re, nice street port, high compression rotors, decent exhaust, and haltech, it layed down 174rwhp/ 135rwtq. Know how I got it to 206rwhp/152rwtq from there? With those gimmicks listed above. I will continue to stick with them any time. And this is with a 1st gen distributer. Please dont take me as bragging, but I was simply trying to help others get a little more power. When you have n/a, there is no boost **** to just "turn it up". So its hard, small gains after the big chunk is made. "

 

Definetely do mods to intake and exhaust first.

I'm hoping to have around 250hp, when my car's complete. I'm thinking an extended port rebuild (new seals, polish etc...), new injectors, bigger fuel pump and an aftermarket ECU will make that.

I'm around 150hp at the moment, it's a very reliable daily driver, and has some ***** to stick it to other cars.

 

Cutting through all the BS, there is no way to get 250HP out of a "streetable" NA engine and still pass emissions.

You could do it with a bridgeport or peripheral port, but the engine will be LOUD and have no hope of passing emissions.

It just isn't going to happen.