Is it alright to run 89 in an 87 NA?

 

Yep but 87 is fine.

 

i try to use 92 or above

 

i use 89 in my NA with no problems

 

I don't know what's best, the question is too complex. Some octane boosters like alcohol cause the mixture to be leaner (because it already has some oxygen in it).

The "How to Modify Your Mazda Rx7" book actually says to use "comparitively" lower octane and "comparitively" conservative settings. They talk about some teams going to extremes by using unleaded gas but that's extreme only in comparison to race gas. They never actually give hard numbers.

I could say that my 87 NA gets better street gas mileage on 92 but that really says something only about my average throttle opening. It doesn't really say what my WOT requirements are. Until somebody does a dyno test on premium and regular gas we're really only guessing because I don't ever trust the butt dyno.

On the street I use 87 because the extra MPG doesn't pay the difference and at the track I use 92 but I have no definitive proof it's any better. To be honest the driver has a bigger difference on my car's performance than any fuel choice ever did.

ed

 

i only use chevron gas. mostly because my dad owns a chevron gas station, so therefore i dont pay for it. but it is the best gas to use because of its techron additive. and i use 87 for my n/a and 93 for the t2

 

damn you for getting free gas greg!! j/k

yeah i like chevron gas i try to get it when its cheap.

 

My baby only gets 87 octane 76. the big orange ball adds hp ya know....

Seriously tho, 76 means NO MTBE!!!! mebbe the ethanol in the 76 gas will clean out my injectors....

 

I use 87 on my car but it's not an rx-7 so ya. Still just letting you all know

 

when i first got my NA i was running 87 in it, it ran ok!! last year i started to run 93 just for the hell of it and it does run better, being that i have a full exhaust and intake on it!! maybe thats horseshit but it runs great, so i will keep putting 93 in!!

oh i do alot of high rpm driving so 93 works better on gas mileage also!!

 

i used to run 91 octane in my 90 N/A... but gas prices have forced me to use 87... and even thats expensive.

 

The amount of mis-information in this thread is grossly dissapointing.

All US spec FC's were designed to run on 87 octane gasoline, INCLUDING TII's. There are few instances when you should run higher than 87.

scenario A: You have a naturally aspirated engine but have changed the timing enough so that 87 octane is no longer sufficient.

scenario B: You have a forced induction engine that is running higher than STOCK boost.

scenario C: Your car is running poorly.
note-scenario C actually has nothing to do with octane. As someone stated previously in this thread, use the highest grade of SHELL gasoline. The actual octane in the gasoline is not what makes your car run better but the detergents that SHELL adds to their most expensive gas. The higher octane does absolutely nothing for your car.


In a TII with stock boost, 87 should be perfectly safe. I run 87 in my TII and drive it hard every day. I have never experienced even minor knocking. If you are using higher octane gasoline on a stock TII you are simply wasting your money (unless you need the detergents because your car is running poorly). On engines running higher than stock boost, you do not necessarily want the HIGHEST octane available. You actually want the LOWEST octane that you can run without knocking. In this case, it depends on your compression and how much boost you are running.

High Octane does not mean high performance, high safety, or high detergents. It means one thing: high cost.

unless you fit into one of those 3 scenarios, you have no reason to be pumping anything other than 87 into your FC.

 

93 in the AE, prices are getting rediculous though...

Every once in a while throw in some MMO too.

 

Actually, this is also misinformation which was unleashed on the American public for many years until the FTC cracked down on them. This is from the Shell website FAQ:

http://www.shellus.com/

Your example C sometimes does have to do with the octane rating. If the engine is in poor shape, or out of tune, a higher octane fuel can stop the knocking or the knock-sensing timing retard. Obviously, this is just a band-aid fix, but sometimes it does solve the knocking problem long enough until the car can get fixed properly.

A high octane rating just means a high anti-knock quality. The octane rating is not necessarily an indication of pricing, although in general the higher octane fuels are more expensive to produce, and therefore usually more expensive. However, you will probably find that cheap high-octane pump gas sometimes sells for less than better quality mid-grade or lower octane pump gas.

 

I use 98 octane. The lowest we have is 95 octane.

 

95

 

i use 93, its the best i can find, i wouldnt mind switching over to 87 in a month or so , but when i got the car it had been sitting for 2 years . I figure after about 3 months of running higher octane and fuel cleaners that any of that old nasty stuff will be outta there and i can start saving the wallet agian.

Bone stock 86 FC

 

I'm kinda partial to Alcohol. Although it creates almost half as much energy as traditional gasoline. Methel alcohol naturally has an innate octaine rating of around 114 and burns at 100-150 degrees cooler than gasoline. Another nice property of alcohol is the amount of deposits left behind or the lack thereof. Not that it would ever be needed for a rotory, but the octaine can be increased by adding a certain amount of water. I've run it in a couple of cars and the results vary, largly on the injecton systems ability to compensate for the increased amount of fuel needed. I've never run any in the rx it seems that the fuel injecton is just adequate for stock or slightly modified. It's not cost efficiant to run on the street, as much as i wish it was, it does make a good track (drag or auto x) fuel because the time between tear downs is reduced. But, there's alot of rules and regulations concerning the use of alchol as a fuel in racing. Plus it's enviromentaly frendly

I wonder about the effects from running sunoco cam2 or NOS supreme in a rotory. These, along with other race fuels contain lead. Im curious if this will cause problems. I know it will screw catalytic converters first hand.

Hehe, my favorite stuff is model aircraft fuel. I ran a tank of 35% (35% nitro-methane, 65% oil) through an old yamaha YZ 125 and holy crap, it was just scary. I wouldnt recomend it in anything you wanna keep

Just for the record I run 93 in my t2, heh I wont even run 87 in lawnmowers, it just makes me feel better inside. BTW I really hate the gas pumps that only have one nozzle and the grade selector buttons. I just know the first gallon is probibly 87 from the previous person. I'm just weird.

-E

 

On my TII I only use 93. Anything else would be uncivilized.

 

87....

....I too am a broke ***!

 

I'm gonna run 87 from now on in my vert, I use to put 93 in there, it's only 12 more cents a gallon. It wouldn't hurt your car to run 93 on your na, but it could hurt your pocket, 18.3 gallons is alot.

 

What kind of rims are those on your car JPA? Does anyone know if they still make dori dori...heard somewhere that they don't make em anymore

 

so... uh.... whats the concensus on the best company? or does the land its stored in matter more?

because there is a shell and a chevron down the road, right across from eachother

I want to know which is best.

 

from the canadian manual

"Your new Mazda is Designed to obtain maximum performance with UNLEADED GASONLINE of 91 Reasearch Octane "(RON+MON)/2=87" or higher when the engine is adhysted to factory recommemnded specifications"

i still use 89-92 though.. depending how rich i am that day

 

here is a question

a lot of ppl say higher octane fuels burn slower

but yet looking into some cars (piston motors) it seems the heads that have the most resistance to detonation have the fastest burn rates
ie one motor I saw was a 502 running 87 octane on 12.3:1 compression but the heads had a very FAST burn rate

also with fuels that burn slower you have a chance of getting two flame fronts correct?

so wouldn't a faster burning flame be better to detonation ressitnace