I know, I know... you'll all most likely say "bad bad bad" when I tell you that I attempted to take my car up to the limit on the beltway...

But, that's all I did... I tried.... The damn thing won't go past 105! I know, that is fast enough.... but I want to know why it couldn't do 135 like it's supposed to.

Been in a friends 7 and he took it up to that with me in the car. So I am wondering if there is a possible speed regulator on the car. See, it gets up to 100-105 and then it stays... the tach and speedometer waver up and down like it has high end power fade or something... but it is only running at 5500 rpm when it is that high....


any suggestions???

 

probialy your fuel pump, there is no "speed limiter" but with all the massive 101 hp i dont think your going to beable to do 135.

 

I think only GSL-SE in stock setup can go upto 135MPH, 12A should be around 124MPH.

 

Maybe that 101 horsepower is enought to get you to 135mph but ur gearing might be too short.(maybe thats whats cause the needle to wave)


i hit 135 all the time in my SE i even see 140 on a weekly basis

but in km/h tho

 

Rolling on the floor laughing! (ROFL)

Yeah I can do dat too... on a hourly basis.... but I am in the states, and we are MPH as you know...



Thanks anyways....

 

I am having the same problem. My engine has been rebult with new rotor housings and I cannot break 103. I think it is my Fuel pump as well.

 

it's quite possably fuel, but it could also be too much wind/rolling resistance.

The -SE struggles to break 119-ish in 4th, and 5th doesn't really pull much at all. Mazda claimed the -SE's top end was ~123MPH, which, if it was running 100%, I can believe.

A mildly modded 12A might get into the 110's but make sure you're not leaning out the motor too much under all that load.

--matt

 

I love the color of your car abeomid. Whats the official name of it? I always call it CD-R Blue.



Also, what kinda rims are those?

 

I've had my 83 GSL up to 110ish. once.

the 12a rx-7s are supposed to top out at 115.

you'd have to do some serious modding to bust 135 in a 12a.

 

The guys at the parts store don't think it is the fuel pump. Could someone PLEASE give me some assurance that it is. I don't like the idea of dropping my fuel tank, spending 100 bucks, and ending up at the same performance as before!

Please guys, if ANYONE has ANY thoughts on this... please reply!

 

You can get more speed out of it if you run it down a hill, with the wind at your back.

 

besides going down a hill with your wind to your back, your only option to hit 135 is more horsepower. 1st gen rx-7s aren't that incredibly fast.

 

i'm working on that just as soon as i can get 'er tuned, that is.

 

Suggested fuel pressure for a Stock 1976-1983 12a engine is 4.5 P.S.I. per Racing Beat.

The fuel pump is located forward of the fuel tank on the drivers side of the car near the fuel filter. The fuel pump is mounted outside of the fuel tank, so no need to drop the tank.

You may want to get your parts guy an RX7 manual so he can better identify the location of the components on your car.

Victoria British’s price for an electric fuel pump RX7 12A 83-85 is $79.95, reference p/n 56-011. You can probability locate one cheaper than that………

It would appear Jeremy didn’t like my earlier reply.

 

Don't bother with a stock fuel pump. It won't keep up at high RPM. My car will only go about 125 with the stock fuel pump and carb.

 

See! I told you it would work!

 

Well then.... I have a fuel pump ordered. It is not a Holley, but it is not the stock one either, so it puts a little more psi out of it...

I will be changing them sometime next week, so I will tell ya all how it went...


Thanks alot for all the help guys! Yes, even you POS Racer!

 

Just make sure you get a regulator on it as well, since excessive pressure may cause the fuel level in the carb. to rise and overflow.

What is the allowable fuel pressure to the carb on a 12a?

POS Out……………..

 

Why don't you guys with the 12a's and suspected fuel pump problems just put a pressure gauge in the supply line and hang it out of the hood and take her up to max speed and see what it reads??

 

Yeah really. you'll need it for a Holley regulator anyway.

 

I asked some people the same q at a local shop; they told me I was reaching the limit as far as how much my carb could shoot in gas (mixture of both pump and carb). Replacing with a high end pump and regulator can cause float probs. Sooo get a nice weber carb (power boost!) and an upgraded pump and reg. Uncork your exhaust, should be good for a few more mph!

91TII
83 GSL

 

Well, I dont know about you guys down in the states, but around here, a properly running stock 12A RX7 hits AT LEAST 120mph. I know this from having owned a couple of them, and having driven quite a few at this speed. True, the acceleration over 115mph is not spectacular, but 120 is definitely attainable. My car has a stock Nikki and a RB streetport exhaust, and I can hit 130+mph on a cool day.

Josepi, the gearing is the major problem, not the carb. I ran a Dellorto for years and in my opinion the Nikki provides a bit more top end mph. Sure, you can get there faster with a Dellorto, but you're still going to run out of power and revs (on a stock port) with whatever carb you have on. Street porting seems to me like the only effective way to gain substancial top end in a 12A RX7.