I got this car about 2 months ago after my old piece of crap mirage kicked the bucket:

1990 (non-turbo) 5spd GXL RX-7

Now that I have everything pretty much working and in order I am going to start racing it out to compete with my friends cars and other cars around here. I was wondering what is the cheapest way of gaining horsepower and wherre I should start?

I will be getting it tuned up soon, so I was wondering if I should spend the money on performance spark plug wires and plugs. Also I keep hearing that the first thing I should do is change out my exhaust system. I would love to do it, but I am a college kid on not the most "lavish" of bugests :-) Besides, I do have other expenses (like my main hobby, guitars).

Right now I am a little dissapointed that my friends 95' honda civic (v-tec, 5spd) is beating my car in races, so any advice would help a bunch, thanks :-)

Mathieu Billeaudeaux

 

Weight reduction! It's free, and makes your car perform better in both the straight line and the twisties.

Some ideas of stuff to remove:

Spare tire/jack
Air Conditioning.. All of it.
Sound deadening undercoating under carpet
Thickass sound deadening mat under hatch area
Stereo
Passenger seat
Power windows/door locks
Power steering
Replace dual mufflers with one... or better: one PIPE
Replace 3 cats with one...or, a pipe
Replace exhaust manifold with a header
Remove airpump (mm....careful with this one..it may actually hurt you)
Remove sunroof motor, seal sunroof in
AAS strut actuators, AAS control module (light....but worthless)
GET LIGHTER RIMS!

Every 100 lbs you remove roughly makes you 0.1s faster in the 1/4. And every 100 lbs is BETTER than the previous 100 lbs.

And if you're absolutely insane:
Acid dip your car
Cut away metal you think is useless (it doors, under hood, etc)

-Tesla

 

Yeah, that would help out, but my car is not going to be *totally* for racing my friend. Like I won't remove the stereo or the spare tire, and I like my sunroof :-) Besides removing weight, any other ideas?

Mathieu Billeaudeaux

 

The only sure way to get HP is to spend cash.

Luckily, because our cars have no pistons (or a reason similar to that), we have incredible HP potential without much input. Exhaust is key in a 7. Ditch all that **** under there now and have a muffler shop make you some straight pipe. Maybe throw a muffler on for good measure, too. Ideally, you'd be able to buy a good, custom exhaust system from an aftermarket rx-7 retailer, but then the money factor skyrockets. Free up both ends (intake/exhaust) and you have one big ol', 1308 cc airpump.

The above may be difficult in CA, but it's worth it.

Good luck


Note: That civic shouldn't beat you unless he's a damn good driver and you are a bit sub-par. Learn the car and try it again.

 

im planning on doing most of those weight mods, ive already gotten the sound deading and stereo out. also, check your 6 ports, if they arent opening, thats a huge power loss. like what, 30-40 hp? ive got an 89, its almost the exact same. mine were frozen. also, check out doing the ATF trick. do a search for it under the 2nd gen forums. u could have weak compression and that should help a bit. and an exaust is not that expensive. i got a RB header for $180 and and a straight pipe for $50, its much more powerful now. good luck to you...

 

I was thinking about just putting a straight pipe, but I decided against that since it would be loud, and not very environmentally friendly (hey, I recycle). Anyways, I would like some price estimates on an exaust system I guess. Something street legal preferably, but anything you wanna put it fine.

Oh yeah, I was wondering if I have that 3800 RPM power stumble. I can get to about 35 on 1st gear, is that normal?

 

when the race starts,.. drive really fast.

 

Dont remove too much or the GF wont ride with you anymore. Plus its a pain in the a$$ to put back in with out breaking the brittle plastic.

Next best thing is exhaust its relatively cheap and will give any internal combustion engine more power. A 3" straight pipe would be the ultimate in performance but worst on noise so find a comprimise. (and cats wont let you throw flames).

 

There's lots of exhaust to choose from, since your looking for a exhaust that is not to loud, I recommend racing beat header,keep the main cat, and rp 50mm cat back. You can find a racing beat header at racing beat.com or mazdatrix.com try to find a header that will still open up your 5/6th ports. For the rp 50mm cat back go to rx7.com to find it. it will have a good deep sound untill you get into higher rpm's. You should be whooping the civc's a$$. hope this helps

91 na
intake,exhaust,S-AFC

 

I think you might have the wrong car to be a tree hugger Mine smokes at idle as it burns it's premix 2-stroke oil and has a NON-CARB legal turbo on it. MPG is around 9, and it shoots fire out the exhaust about 4-6' long on a nice cold day

I would recommend dumping the precats and replace the main with a high flow cat from RP. I have the Bonez main on my vert with a RB catback and the sound is nice and the power is good through the midrange. You do lose some higher end power than if you were to use an A'PEXi N1, but that is probably too loud for you. Or you could just buy the RP system. It is cheaper, and will tide you over until you can get some more cash. Like the others say...$$-HP

 

BAh... All you guys on the forum with your racing beat stuff.. and catback stuff..... Ive never seen a rx7 race car around where i live run that stuff ...for about 700 bucks less you could build a way better system !!! Just go to your local exhaust shop get them to weld some pipes from the header or exhaust manifold back... put a highflow cat if you really want one... And spend about 120bucks canadian and get a Dynomax Ultraflow (with a lifetime warranty included) This system is wicked, sounds good, and you get the most performance for you buck...

 

My N1 catback cost me $390 shipped to my door. My RB downpipe was $90 and the presilencer was $155. So that's $635 for a completely mandrel bent system that flows beautifully. The DP and silencer are constructed with 304 stainless steel piping. The N1 is high temp particle coated and sounds great. I doubt you are getting a mandrel bent system that is made with that type of piping for "$700" less than that.

 

well.. i was talking about the complete RB system but this setup is way cheaper.!!

Straight Pipe : 80 bucks canadian
Dynomax Ultraflow: 124 Canadian
Labor: maybe 40 bucks. max , or a case of beer depending who you take it too!....

total=Priceless


lol...
yah 200 bucks or so canadian youve got a wicked setup... whats that like 160 US ?? if that... This guy is looking for somethin affordable by the looks of the post... this is an effective alternative

 

if u wanna beat that civic learn how to shift better!!
he shouldnt be beating u by much.

 

Here are some reasonably cheap mods for you to do...some give more HP, some just make your car faster:
(I have done all these mods to my 86 GXL and I liked them)

-new tires($100 each)no HP gain, but definitly more control and faster off the line
-K&N filtercharger($90)(lifetime warranty) I heard this adds around 4-5 HP
-remove pre-cat/cats($130) 5-7 HP?

I got a new fuel filter too...didn't make my car faster, but idles smoother now and runs better. Removing A/C is also a good idea.

 

Do you know if that Dynomax muffler can handle the heat of a rotary? I mean our exhaust is like 2 or 3 times as hot. Might not last long. Thats why people go with what they know.