I know all FC's were engineered to run 87 (regular). I bought my car from a good friend of mine who is pretty knowledgeable about the rotaries. He told me he had been running premium in the car (since it has a nice street port and crane cams ignition)...i continued to run premium in the car and its been running like a champ....i did try regular recently and the engine didnt like it at all.....I couldnt rev past 2500rpm (as if i hit a super low rev limit).....Once i added more premium the problem slowly went away.....From what ive heard, the common consensus seems to be that with my mods, i should still be able to run 87 with no problems.....what else could be causing the engine to respond so poorly to regular?

 

This is something I have no real knowledge in, just something that sounds feasable...

If the timing is advanced/retarded enough, wouldn't the lower grade in gas affect it?

 

I was thinking the timing couldve been changed.....definitely something i'll look into. The engine was rebuilt recently...i guess the timing couldve not been calibrated correctly after the engine was reassembled.....Im assuming there's no real benefit in advancing the timing and running premium...if there was im sure alot more ppl would be doing it......thanx again for your input...hopefully someone else will chime in too

 

I dont think your mods allow you to run regular unleaded anymore, but you do have to retard the timing a little bit to see if you can get it to run on regular, but then the car might run like crap.

Its like a piston car changing cams and ignition systems- the car CAN run on regular, but to run great you need the timing and the premium fuel.

 

a very good mechanic told me if its efi always run premium doesnt matter what the car is. So i just run premium and never had a problem

 

Makes alot of sense...I completely understand what you're saying.....you hear so many different things on forums....its rediculous. thanx for your input

 

I ran my vert when it was NA on 87 octane for the entire 15 years I had it like that- never missed a beat. But it was basically stock, just exaust and K+N drop in filter. On a stock NA rotary its best to run regular.

Your friend with the thinking of running premium in all fuel injected cars is thinking like its 1985 again. Now they actually suggest you DONT run super unleaded in a car that can run on regular, the super burns slower and if you dont have the motor to burn it your not only wasting your money you are actually doing more harm then good for the engine.

 

Thats interesting...... There's also lots of ppl saying that you should always run the lowest "recommended octane" fuel for max gas mileage and overall engine performance. My car has run wonderfully on premium and crappy on regular...kinda disproves that general theory

 

my old jeeps cant run on regular, they ping and run like crap. I have to run premium in them. They both have aftermarket cams, intakes, carbs, etc..

When I used to play with piston cars I could get my car to run like a totally different car if I ran CAM2 race fuel- I would get out my wrench, loosen the distrubutor and advance the timing, adjust the idle and the car would run like it just got a turbo charger. When I could not afford that fuel anymore I would have to retard the timing and adjust the idle for super unleaded- could not even think about running regular unleaded in that car either.

 

yeah i had this other car once it wasnt a rotary but was efi and it was running but not at its full potetional and thats when he to use premium and told me all that and it when heaps better and never gone back and when i got the rotary i used premium and never had a problem with it miss firing or spitting or anything

 

you also have a turbo rotary- it requires premium fuel.

NA cars- save your money and run 87 octane!!!

 

i would never put regular in my rotary lol, i got an old pajero with a carb and i just run dirty old regular unleaded in it and it works fine wouldnt call it a preformance car but its gets me through the bush

 

I think Mazda recommends 87 for both stock N/A and turbo FC's (from what ive read, it recommended that modded turbo rotaries run high octane)....Im not sure if theres any noticeable difference in performance between the two types of fuel in a stock turbo car

 

I clearly remember a premium fuel sticker somewhere on my old TII- but maybe someone stuck that thing on there themselves at one time.

 

mine has a "rocket fuel only" sticker inside the fuel door....haha.

 

Turbos == premium. You need the knock resistance when you are running boost.

An NA should run fine on 87. Our compression just isn't that high, and we have big square pistons with lots of surface area to cover.

You very likely got a "bad" tank of gas. Probably had some water in it - not uncommon if the underground tank at the station is getting low, or if it was being filled by the tanker truck when you got your gas.

You may want to try it again, but this time get a half-tank of 87 from a reputable station. If it doesn't work out, top off with premium and see if that fixes it.

 

From what I know , running higher octane gas on NA Rotary will actually cause the car to have less horsepower, so something just doesnt seem right to me because it should actually run better on lower octane gas and not worse.

It could very well be like the last poster said, bad gas with water in it or like you said the timing could be out of adjustment from the normal stock.

I hope you do figure out the problem , I myself am having my own problem right now with my car as well but you still have to love the rx7's even though they are so tempormental.

 

I dont think its bad gas, I think its his ported motor demanding the premium based on where his timing is set, if he can adjust the timing and see no difference in performance on regular unleaded he should do it.

 

The gas station where i got the regular from is a place i go to frequently (i normally go to a Shell Gas Station down the street from my apartment), but i've never had a problem with this other gas station in the past...I'm assuming watered down premium would give me problems just as much as watered down regular.....I'm leaning toward the Port/timing being the issue......I wonder if the original owner tried running regular w/ the ported motor + factory timing and had issues then advanced the timing to get the engine to run better......why advance the timing just to run higher octane when u can retain factory timing and run regular?....I'm just probably gonna keep the current set up....Thanx for all the input guys

 

You can run regular in any stock FC, na or tii.

 

Hmm Read The Owners Manual If You Can Get Your Hands On One. Clearly States To Run Premium Unleaded Fuel Only

 

Wow, what's this on my desk? Could it be an owners manual for a 1991 RX-7? It is!!!! And on page 1-4, we read the following:
I think that's about as "clear" as you can get.

The interesting thing (which I didn't realize) is that they do not advocate a higher octane for the turbo model. But note that this is a stock turbo system they are talking about. I still advocate premium for anything above stock boost levels. In the FD owners manual (which I also have in front of me), Mazda advocated premium (91+), but indicated that the car would run "with slightly reduced performance" on 87-90 octane.


-b

 

didn't anbody notice that he mentioned that his engine is ported?

 

I noticed, others im not so sure

 

I don't know, I get better gas mileage with shell; but knock count increases as well. I think the poor condition is timing, if the guy is knowledgable as he seems he probably messed with the timing to compliment the street port.