Mazda90RX7

Hey, I have 1990 Mazda RX7 (no turbo) bought it not to long ago, and I was wondering is it safe to put 93 octane gas instead 87?


Thomas

Slow Rotor

Yeah of course it is, the higher octane isn't going to hurt anything

Mazda90RX7

Thanks for quick reply! Ill just wait till gas price drops little then run 93 octane. ($3.69 for 87, $3.91 for 93) Plus i love Rotary engine.

mazdaverx713b

iTrader: (91)

it is safe, however, there is no benefit to running 93 over 87.

The Shaolin

iTrader: (5)

lol, it's weight reduction. (it lightens your wallet)

Other than that, there's really no benefit. Don't be a stupid n00b, it's not going to give your car magical powers.

93rx74lyfe

iTrader: (1)

As long as you plan on staying NA, then the cheap stuff is fine.

Force Fed

I think that the first time I've ever seen that asked lol. Higher octane allows you to do thing to increase power, like increase timing or boost, but doesn't give any more power in and of itself.

wrankin

I run 87 in my NA track car, spending mosts of it's life between 5k-8k rpms.

It may be an urban legend, but some claim that 87 has a hair more power density (how much power you get per cc of fuel) and thus is better to run. The only thing that 93 gives you is resistance to detonation which is not needed in an NA rotary (at least not an RX-7). I do run 93 in my FD, for the exactly the same reason.

Bottom line - run 87 in your car. You won't magically "find power" by going to 93.

ecko

iTrader: (57)

i run 89 in my car and wow some cheap gas over there(3.91 for 93)93 over here is 4.29.

K-Tune

iTrader: (26)

you will actually hurt performance and longevity by running higher octane than 87 in an N/A.

SDrotary-FC

i wish they made a lower cheaper octane i could run, yea you will not make any more power with 93 oct.

Funkspectrum

iTrader: (5)

all your are doing by running higher octane fuel in an NA is wasting money.

K-Tune

iTrader: (26)

and decreasing power...and increasing the amount of carbon in the motor...and hurting MPG...and making it harder to start...

ecko

iTrader: (57)

good too know.

SDrotary-FC

mine likes this stuff

NCross

iTrader: (18)

Mazda recommends we run 87 octane NA or turbo, unless your boosting.

Evil Aviator

That is true more often than not, but it depends on the formulation. For example, Chevron actually reports a 0.5% higher energy content for its high octane test fuel than it does for its mid-grade.

The performance is based on energy content, and that will depend on the formulas used by a particular manufacturer. Assuming that pump fuel is made of only octane and heptane (which it is not), lower octane would have a higher energy content. Assuming that the higher octane gets its higher numbers from aromatics, then it may have a higher energy content than the lower octane grade. Regardless, they will be pretty close to each other, usually within 1%.

The octane rating will have absolutely no effect on the longevity of a typical street car.

That is not necessarily true. When comparing the various grades of pump fuel sold in the US, there is no significant difference in any of those items. Detonation resistance and price are the major factors.

K-Tune

iTrader: (26)

even small numbers add up over time. filling up with 93 octane for 60,000 miles will have a different effect compared to filling up with 87 for 60,000 miles.

Evil Aviator

The problem is that you do not know which brand or grade of gasoline makes those small numbers go up or down. Contrary to deceptive advertising and auto enthusiast urban legends, those numbers have absolutely nothing to do with the octane rating.

Yes, it will affect your wallet by about $600-1,200. That's it.

http://en.wikipedia.org/wiki/Pemex

Mr.FC3s

I remember back in my first months of owning my 7 someone told me I actually lose power by putting in 93. I cant remember the convo but something to do that the motor actually never completes the burn and the explosion is continued well into the manifold or the headers.

ecko

iTrader: (57)

i always went too how much mods you have in your car...thats how i see what octane to use.

NCross

iTrader: (18)

A stock RX-7 in average condition will not burn all of the fuel anyway so there is no need for anything over 87 without large boost or porting etc. A rotary engine is fairly wasteful with fuel. That is why you see them shooting flames when straight piped. The unburned fuel is sent out through the exhaust and ignites there.

REDFC3S86

Is it still ok to run 87 on a street ported N/A?

Icemark

You want to run the lowest octane that your car will run without detonation (or pre-ignition).

Anything more is a waste of money.

ecko

iTrader: (57)

good way to save money.