charcoalgray8

So, i just stopped at the gas station and forgot to let the gas pumper dude to put 93 octane in. He filled up my tank with regular(89) gas... What should i expect from my 8 after feeding it with garbage? should i add an octane booster to the gas? will it be just fine for this time? I bought my 8 two weeks ago. its got 60k miles and just the AEM cold air intake. thanks in advance!

DONX8

i've read some posts about some users using as low as 87. i wouldn't worry about it too much imo

Chad D.

iTrader: (19)

just put 93 in it when you get half way, no big deal. I believe our cars run the best on 91, or at least mine does. I used to run 93 and I actually get better fuel economy running 91 and it's cheaper too.

Old Rotor

Reg gas durring the cooler time of year is usually no problem. Just don't push it to hard til you put in prem.

navyslideby

i put 89 in mine because premium is a 30 cent jump from regular whereas mid grade is only 10, and it has always run fine. i also make like 24mpg city driving aggressively half the time and giving her the daily redline a day too, so there might be something to it......

MazdaManiac

iTrader: (3)

Expect it to perform better.

DocBeech

iTrader: (1)

the ecm will automatically trim your engine and dump more fuel in to adjust for the low compression ratio of the 89. It wont hurt anything just expect less fuel mileage.

as for the guy getting 24mpg I would love to see a fuel log with those numbers. Especially driving city.

MazdaManiac

iTrader: (3)

No, it wont.

DocBeech

iTrader: (1)

The engine reads the exhaust and adjusts the fuel accordingly. Either it will add more fuel, or you will get less horsepower on the fuel it uses. I'm pretty sure the engine is going to try to keep the mixture at 14:1. If its rich or lean its going to make adjustments.

dannobre

iTrader: (3)

The lowest octane fuel the engine will run on correctly will result in the most power...

I ran mine NA on 87 all the time...track included and it ran fine...it is damn difficult to detonate a NA rotary engine

89 will be more than fine


93 isn't "better" gas...you have been drinking oil company Koolaid for too long

dannobre

iTrader: (3)

I'm pretty sure you don't know what you are talking about

The PCM does adjust the AFR based on the WB02 during closed loop operation...

This is based on the Lamba or the residual oxygen in the exhaust

Not on the octane of the fuel......It isn't trying for 14:1 often either

And as far as gas mileage..your mileage will be Higher with lower octane fuel all things equal

Brettus

iTrader: (2)

The only time you need to worry about using low octane is when
your intake temps are very high AND you have tuned it to run leaner than stock AND you mash the throttle .

paulmasoner

iTrader: (1)

you have no idea what you are really saying. 14.7:1 isnt the target AFR, its stoich. big difference. and you made it clear you dont understand what compression or octane ratings are.

as far as the 24mpg comment, i've done 27mpg hwy multiple times.

DocBeech

iTrader: (1)

Like I said I would love to see a 24 or even 27mpg on a regular basis. Some are getting 22. The best I ever saw was 22.5, that was the day I bought the car and I havn't done any 400 mile trips since.

But then again heres your chance to prove 24-27mpg: http://www.fuelly.com/car/mazda/rx-8

The only two people hitting 24 or 25 have two recordings of 72, and one has 103mpg recorded. So those can't be trusted.

paulmasoner

iTrader: (1)

well believe it or not, doesnt matter to me. but i've multiple times over multi-tank trips hit 27. 25/26 isnt uncommon at all for me. this is all at US hwy speeds 70-75mph. fortunately where i live now, i dont generally cruise under ~90mph(145kph)

DocBeech

iTrader: (1)

It says you live in belgium maybe you mean 27 KPG which is 17MPG which is more average.

Brettus

iTrader: (2)

that must suck

paulmasoner

iTrader: (1)

i'm well aware of where i live. lol. and I meant 27MPG. this was primarily over trips up and down the east coast(of the US) area

and FWIW out here they talk about fuel consumption in L/100KM and/or L/tank. I've never heard anyone talk of kilometers per gallon. that mixes imperial and metric measurement...


for gas yeah, at that speed I average ~16mpg at best, and often as low as 13. but its fun. and the occasional exotic/sports/super car caravans that pass are fun as hell to chase/trail at 200-230kph!

ken-x8

Everyone says you're wrong, but nobody has given the right answer....so they share the stool in the corner.

Cars today have a knock sensor. If it detects pinging, the timing is retarded til it stops pinging. The 8, like most cars sold in the US, will run on 87 octane. The owner's manual even says so. Just lower power, because of the retarded timing. Nothing to do with air/fuel ratio, although I suppose AFR could change as a consequence of the timing.

Whether that translates into better or worse gas mileage depends on too many factors to give a blanket answer. The important thing is that the 8 is made to run on octane as low as 87, so no damage will be done.

Ken

paulmasoner

iTrader: (1)

the knock sensor in the 8 is as useless as a 2nd *******. you could almost shoot the thing with a .50 before it'd do anything

nycgps

iTrader: (1)

you won't get lower power with 87. its actually the opposite. but your engine might be more responsive with 87 ---- simply because the gas ignites easier.

Most Rx-8 runs perfectly fine with 87 Octane gas. at 89 it should be 99% ping free. they recommend 91 or higher simply because its "safer" for its stupid high 10:1 ratio.

Higher Octane gas will have higher resistance against pre-ignition. Energy count is about the same.

Don't worry about 87 in your tank. Gas company did a good "scared" tactics ---- it makes most people think higher octane = better/more power. when the fact is it doesn't do **** to power. and its hard to change that.

I told my uncle cuz he keep putting premium into his highlander ---- when all its required is Regular 87. he said "oh Premium is better it burns cleaner" ---- yeah right. But whatever, its his car, his money. I told him what I know. its his choice

oltmann

I've taken calculus, so I know for a fact that 93>87. Also, I love arguments from personal incredulity.

MazdaManiac

iTrader: (3)

Threads like this is one is why I've stopped trying.

Brettus

iTrader: (2)

fixed

MazdaManiac

iTrader: (3)

That too.