RXinfini

Whats up guys. I just bought an 1987 RX-7 and planning to do put some mods on. I would like to know how much N/A potential does those engine have with all the mods: engine rebuild, intake, header, manifold, exhaust, ECU, IRTB?). Any information will be apreciated. Thanks =)

synesthete

Depends on if you do any porting with that rebuild or not.

JJohnston

DO a compression check then change all the fluids.

RXinfini

Thanks for replies! and yes I'm planning to port it.

FirstRotaryExp

iTrader: (3)

An na will not have the power potential of a tII, however we that chose to mod an NA find greater longevity in our builds, an NA lasting roughly twice as long as a turbo. Im not exactly certain what the most power one can squeeze out of an NA is, but good luck and we hope to see some nice numbers.

snowball

the most i have ever heard of is ~300whp for a 2 rotor NA

RXinfini

Thanks for the replies! The reliability is one of the reason I really like the na tuning. hmmm... ~300 whp for 2 rotors. Do you think I can hit the 200whp mark with 1 rotor engine?

FirstRotaryExp

iTrader: (3)

The standard 13b rotary is a 2 rotor design. 20b's are 3 rotors and then we have 26b 4 rotors. But 200 is a easily achievable goal even on pump gas.

RXinfini

Didn't know that the 13b was 2 rotary design.. Srry for being noob =( . But that means ~300whp can be possibly drawn out without engine swap to 20b? I gotta start searchin more

FirstRotaryExp

iTrader: (3)

Yes you are correct. Your first mods should be intake and exhaust, biggest ones outside of porting a rebuild, for power and performance. If your county/city doesnt do smog checks then you are free to remove all emissions and throw in a header and a presilencer in place of teh stock cats and manifold. if you have smog checks see what others are running on the forum in cali and youll get a good idea of what can be had. and how to cheat a bit.

RXinfini

I'm not sure about smog check in here cook county so gotta go check..

FirstRotaryExp

iTrader: (3)

Indeed. Be sure to download a copy of the Factory Service Manual from the FAQ as well as search for a specific question before posting, just warning you now, they love to eat roast noob.

RXinfini

Thank you so much for all the help, FirstRotaryExp!!

snowball

if you dont know about the smog im willing to bet you dont have any.

Stanello

iTrader: (1)

Sorry to rain on this parade, but getting over 200hp NA 13B will be hard, loud, and unpleasant to drive on the street.

As for the 20B... it all depends on money.

If I could do it all over again, I would just lightly mod the car while saving up for a TII swap.

fcdrifter13

Exhaust is a big thing on these cars, but remember that the 40hp increase on RacingBeat.com is talking about there turbo exaust, you might see half that number if you are lucky. Save you cash and get an SDJ header, and build a header back exhaust after that. I used to run a SDJ header, borla xr-1 muffler used as a presilencer, into a cheap ebay N1 style muffler, 2.5in piping all the way back, worked very well and sound AWSOME.

For an intake you can either drop in a high flow filter element with the stock ducting, or you can build a box and custom ducting that isolates the filter from the heat of the engine bay. Putting a cone filter on the end of the MAF will reduce your horse power because of heatsink.

A guy name Karen is working on a custom intake set up that is supposed gonna be great.

Depending on the extent of your mods you can go either stand alone($500 plug and play megasquirt), or you can do a piggy back fuel mangment computer like a SAFC II. The stand alone is a great deal, plug and play, and if you want to turbo your NA motor you already have one of the bigger obsticles out of the way.

FirstRotaryExp

iTrader: (3)

No problem, and like white87fc has pointed out, it will be a loud, depending on your exhaust setup and ports....but then again not many of us drive around on bridgeports....

snowball

ITB p-port FTW!

RXinfini

Thanks for the replies!! I know that the turbo have way more potential for hp but I really want to stick with na. I don't care about how loud unless it drones or loud enough for cops to take me down. Planning on visiting drift avenue this week to see what they can do for my car.

40hp increase for just exhaust.... thats insane!! too bad its for turbo though =(

FirstRotaryExp

iTrader: (3)

But an increase is an increase nonetheless. Though for the time being prepare yourself for the wallet draining, bank account killing goodness that comes from owning an Rx7, enjoy the ride

Dak

For the amount of money it it would take to get 300 hp out of a n/a you could turbocharge it. It will take a large bridge port or a Peripheral port to get those numbers and you end up with a car that won't idle below 1500rpm and is on it's face below 5000rpm. I think once you go to a bridge you lose longevity due to the bridge itself wearing out and issues with the water seals on the large or monster bridge ports. I'm not ******* the n/a but don't want you to get the idea that a daily driven 300hp n/a is really feasible. Sure they're out there but they are pure race cars or they're not the owner's sole means of transportation.

lupin

iTrader: (3)

I've spent about $5500 on my na engine rebuild right now. I got new housings and a master rebuilt kit. I also needed a new front plate and stuff like a koyo rad and new oil cooler lines, aluminum flywheel and a exedy organic clutch kit. I spent about $1100 on exhaust and I forget how much on suspension. I was gonna buy the 13bre engine and push nice hp numbers but I decided that I wanted to drive it for a long time or at least try to.

Sideways7

iTrader: (7)

About the most you can hope for in a reliable, daily driven NA is 200 to the wheels. Thats with a large street port, exhaust port, full exhaust, a standalone, and dyno tyme to tune it. 170-180 is a more realistic goal. But trust me, thats still a very fun car. I'm guestimating mine had in the low 160's, and it was still quite quick. It pulled strong past 100 (which is all you need on a street car) and could keep up with a Mustang GT if your a good driver.
The key to making NA RX-7s good cars is suspention. I can't emphasize this enough. If you get a good suspention setup these cars are incredibly fun, even if they car run in the 12's in the 1/4. I would take twisties over straight line performance any day.
FWIW, a full exhaust will run you around a grand, with a good suspention around 1000-1500. Intakes are about 200 or so. While its out, you can get an aluminum flywheel and a stiffer PP if you want.

RXinfini

So the 300whp can be possible but its not recommended for daily driven car. Instead I should go with somewhere around ~200whp? I do have pretty deep pocket... Can I aim little higher withouth sacraficing my reliability?? Lupin, that sounds like a great project!!

fcdrifter13

"with great power comes responsiblity", and that responsiblity is that your gonna have to buck-it-up chuck and realize that a motor making 300hp NA is not gonna last as long as one making 200HP NA, probably about half as long A 200hp NA is great fun, and if you lighten up your car alil bit it gets even funner.