I recently purchased a N/A 1991 Mazda RX-7 5 speed Convertible with new rotors, brakes, tires, clutch, and catalytic convertor, and a freshly rebuilt motor/ APEX Seal... It was very well kept outside of normal worn seats.

On my other RX-7( The one down below as my signature), it came equipt with a racing beat full header exhaust and the air pump removed... it also had the little valve/ port thingies zip tied open... I had taken the manual fan off and installed a electric cooling fan, did a small port and polish only on the intake, and removed the stock inlet air tubing and replacing the filter with a performance cone filter... It ran really good after all and I am not sure if I should attempt to do all this to the latest stock RX I just bought... I want it to run a faster and do the best mods possible without hurting it... Please if I could get some real Rotary heads recomendations I would appreciate it... Thankyou.

 

Put a free'er flowing exhaust on it, you can't port the engine at all without tearing the engine apart and the S5 NA intake setup is already very closely port matched from block to intake manifolds. Don't remove any of the emisions like the air pump because the S5 NA engine setup has whats called VDI (variable dynamic intake) and it runs off of the air pump to operate a diaphram to change the intake's air charge. (Its explained in the service manual) Its also controlled my the ecu to the solinoid pack on the dirver's side along with the secondary ports' solinoid. Reason there's to seperate solinoids is because the secondary ports open around 3500K and the VDI changes at 5K rpms. You could put a typical cone style filter off of the MAF but think about this... The engine bay emits hot air and the stock setup is drawing in cooler rammed air from between the front cowel. You could maybe loose power by changing out of a single cone filter in theory. ( I haven't dyno'd it to be sure) Only advantage is maybe it looks cooler idk. I will say that on a couple of my TII's I do run a cone filter off of my MAF cause I wanted the least amount of restriction possible. I do however leave the intake that sits over the radiator so it is still channeling colder air to the filter.

Don't put an electric fan on this NA cause again it will be more for show and it will actually tax your electrical system like your alternator from the draw the fan will be using. It has been dyno proven that an electric fan adds no hp increases and only helps a small bit in reving because there's a little less draw on the crank but this is only noticable in N.

Your best bet would maybe be to do something drastic and chip and/or tune the ECU like an Rtek setup and then you'll recieve a few extra hp, or get a matched lighter flywheel (however the electric fan principal applies here to and it does lighten the flywheel and can add a couple extra hp but I've heard you can loose a couple lb's of torque because of less inertia). Your easiest bet for getting extra hp without having to change something big or make really large mods is simple, give it a tune up. Then just drive the hell out of it and have fun

 

why throw money into an NA motor if speed is what you're looking for? TII swap!

 

I had a similar situation with whether I should mod my low mileage stock S5 vert. I modded the NA first with


Bonez cone filter intake
RB street header wrapped with heat temp tape
Bonez highflow cat
50mm HKS exhaust
Jacobs ignition box
10mm magnacor wires
Reduced ratio pulleys
New NGK plugs
Lightweight flywheel and RP street/strip clutch

It ran good until it started smoking around 126K miles.

I then decided to do a complete TII swap and believe me there is absolutely no comparison. If you have the cash and the where with all I highly recommend it.

 

Thankyou for the info, I appreciate it. I would love to just engine swap to the TII, but I will have to save a while for that... For now I will more than likely get a lighter flywheel, RB Header, and a tune/chip... I will play around with the filter to see if its worth keeping the stock setup.... I know that the more bends and tubing the air has to travel... adds the resistance to how easy the air enters the intake... Just trial and error I guess.

 

You can make a cold air box for your cone filter or buy one. I think Rotary Rocket has a DIY Cold air box thread around here somewhere and there's a company that makes them too (can't remember the name).

If I were you, I would save for a T2 engine swap because you already have a tuned N/A and in the end, you're not gonna see much of a difference in power (maybe more low end on the S5 due to higher compression).

 

I still have the HKS exhaust in excellent condition as well as the rotary performance lightweight flywheel and clutch with 20K miles on it if you are interested?

I could even meet you in Wichita Falls to avoid shipping.

Let me know

David

 

do u still haVE the flywheel?