Okay so this is my first rotory. I went stright pipe from the header back to a 2 1/2 outlet. sounds good. deep, not ricey, my gas mileage sucks.... its like driving a v8! is that because I straight piped it? or are rotory's notorious for bad gas mileage? and I baby the car!

now, I know how hardcore you guys can get on people who are learning about rotory's..... so dont be too mean... just wondering.... thanks

 

I know nothing about your setup, I am guessing you have an NA and the aux ports don't open properly without some restriction in the exhaust. Dont qoute me on that never had an NA but I have seen this pop up enough

 

Yup, you're right. Without the backpressure of the cats, your 6 ports will not open. There are lots of fixes to this.

http://rotaryresurrection.com/2ndgen...elec6port.html

If you do have a NA you should be getting around 20 mpg with equal mixes of highway and stop-and-go traffic. I was getting around 22MPG before my rebuild.

 

Yeah if you have an 87 like you avatar says you have an s4, with exhaust driven aux ports, with that straight pipe your not opening them, killing your horsepower and sucking more gas in your higher rpms

 

okay your all saying that with my na s4 I would be better off just throwing a high flow cat on it. and get the better gas mileage and hp. ?? thanks you guys were a lot of help... The only people to talk to in hermiston is honda people.... haha

 

that makes a lot of since... I would drive to tri-cities its like 30 mile drive @ 70-75 mph and it killed on gas. Like I said it was like driving a v8....

 

The only reason people are "mean" on here is because people are lazy and don't SEARCH. If you would've searched you would've come up with your answer, but whatever. I don't care, I try to help people out cuz at one point I was just as lost as the newbs, not that I'm any more experienced than another person. I'm still learning things all the time.

 

I understand.... when I was getting the exhaust put on of course it was custom... so the guy here in hermiston took off the stock exhuast and just cut right through that tube that the article (A tube runs from the main cat back to the engine) and just tack welded it right back onto the new pipe so it would just hang... Your right If I would have done some research I wouldnt be spending more money and having to do it over again... thank you again.

 

Oh and btw, you should have only used about 1-1.5 gallons since it was highway mileage. I drove from Portland to Seattle and back on one tank of gas.

Don't un-do what you've done with the exhaust just fix your ports and you'll be good. Either way, if you upgraded your exhaust and eliminated the cat you would have had to fix that problem anyway.

 

dang I wish... thanks

 

i've known the rx7 to not save that much on gas, but i really wanted one no matter what anyone says. i'm still glad i got one, even though i know there's so much more i have to do, and want to do.

well, back to the subject... ports are stuck too, but i ignored having them fixed... but my car runs fine, and i get 23-25 mpg = 350 miles to the tank.

i'm satisfied

 

n/a always seem to run rich (headers make it run richer) make sure its tuned up (plugs/wires/o2 sensor/fuel filter/inj) i get around 22-24mpg on mine.

you could also look into a rtek ecu and a wideband

 

Hmm...my S4 na barely gets 200 to a full tank. Well it did the last time I checked. I still have to do a lot of maintenance to make sure everything is working correctly. But back to your car, if you keep your custom exhaust on your car there are a few ways to get your 5th and 6th ports working if they are stuck. Check the archives in the 2nd gen section. And the other guys are right, na's run rich so fixing that will def help with gas mileage.

 

I wish you would stop saying that. Every LS1 RX7 I've ever owned/driven has gotten 25-27mpgs. Those with stock motors have reported 30 on the highway.

 

okay I guess I wasnt giving enough info... it was like driving around in my buddies 5.0. that thang is a gas hog. and he was getting better milage on the highway than I was. but I have taken all the info you guys have given me into consideration and am going to do some RESEARCH because Im not sure what most of it means...lol I have had a fresh tune up as well. and I am not running rich.... im going to fix my ports( that is what im not sure on, i'll look it up) and see how much that fixes things..

 

I have a almost complete stock na 91 s5 with all emissions. i have a cat delete pipe and an apexi n1 exhaust and my rx7 is getting about 13 mpg. There is about 165000 miles on the clock and i think its got low compression. Apparently 13 mpg is much much lower than what you guys are getting for mpg. any suggestions?

 

see, this guy know's what im talking about. this is about what I am getting as well. 13- maybe 15 on the hw,

and all of this is happening because of the cat delete. right, it is causing no back presure which is causing the ports not to open.

 

any time you add a free flow exhaust its going to get rich either get a s-afc or a rtek and lean it out on the top end.

does it have new plugs/wires/o2 sensor/fuel fitler/clean air filter?

 

I dont know whats wrong with this guys, he has a series 5 second gen, which runs off of the airpump already. Again series 4 is 86-88 series 5 is 89-92. Series 4 runs off exhaust backpressure, series 5 already runs off the airpump. Try running some kind of injector cleaner through your car, and change your fuel filter in the engine bay.

 

I added a free flowing exhaust and some redline fuel cleaner and it went from 16mpg to 20-23 mpg.

 

On the highway, right?

 

I could be wrong, but wouldnt injector cleaner be bad for a rotary?

 

the OP has a 87 n/a thats who i was talking to

 

no i've been running the lucas stuff for years

 

it has everything new besides 02 sensor.. but wouldnt it throw a check ingine light if it were bad and needed replaced? does that really have an impact on milage?? hmmmm.