New guy here, been searching for an FD for over 2 years now and I purchased xstacy7's (thanks again jack!!!) 93 and I have a question. Searched and couldn't find an answer so here it is.

The 7 requires an octane of 93? or more. In my local area (with 20 minutes that I know of anyway) not a single station that has a premium fuel that is rated at higher than 91. Basically, its 87-89-91 and that's it.

Is this going to be a problem, or cause a future problem? Could a guy mix a higher octance race fuel to even it out or is there another solution if this is even really going to be a concern?

Sorry if this has been covered or is a stupid question.....I couldn't find anything and was a little concerned about it.

 

91 is fine. Just be sure your boost stays where it's supposed to be.

Dave

 

As Dave says, 91 octane is okay, you just have to watch things close. And yes, it is possible to blend in high octane fuel to effectively raise the octane level. This is what is done at filling stations by the pump when you choose 'mid-grade', for instance. If you took 10 gallons of 100 octane and added it to 10 gallons of 91 octane, you'd end up with 95 - 96 octane.

This works fine if your car stays in an area where you have access to this fuel you made, but obviously if you go a distance where you need to refill, then you're back to having only what is available. Storage becomes a BIG issue, not too many people like the idea of having a few 5 gallon cans or 50 gallon drums of gasoline out in the backyard shed, lol! Nor would your home insurance, nor your neighbors, etc.

I've seen a few areas or stations where you can still get 93 octane. I make little notes of where these are at, although fewer and fewer places sell the 93....they just don't move enough of it to warrant having it.

 

The number of locations selling 93 are few in my area, but are well known by local clubs and guys with high performance cars. Check with a local forum, or anyone you happen to see with a car that might need it.
One such location is near my home and at times, it looks like an auto show.

 

91 should be fine, i wouldnt stress especially if your car isnt to built.

 

Hum, whats the highest octane rating fuel you guys have in the USA?

We have a fair amount stations near me that stock 99 oct. but its alot more expensive over here =(

 

man we be lucky if we find a 93 octane place! there arnt really that many at all around in socal.

 

Erf I feel for you all...

 

A stock FD will run fine on 87.

 

wow, i feel bad for you guys...... i was mad when they started taking away our 94 octane pumps.....atleast 90% of the stations here still have 93!

 

I think the European and American octane rating is different. Our 95 is not the same as "American 95 octane. BTW we too have 99+ octane Shell v-power in Finland.

 

Brilliant advice there!


spandy: 91 octane is fine. If you have a close to stock car, you have zero worries. Heavily modified cars just need to be tuned more conservatively for the lower octane.

 

I bought the car from Xstacy7, so here is what is on the car. I don't have the car as it will be shipped from TN to OR, so I just want all my ducks in a row as best as possible for things like this when it arrives. I just copied and pasted from his for sale thread......

Remanufactured Engine with 25xxx miles on it
1999 Spec Turbo's
Koyo Aluminum Radiator
3" Gotham Racing Downpipe
3" Megan Racing Midpipe
3" Greddy SP Catback
All new gaskets with the rebuild
Garfinkle Torque Brace

ELECTRICAL:

Power FC with Commander
Greddy Profec B boost controller
Boost gauge on the A-Pillar
Turbo Simplification
Optima Red Top Battery


91 still okay with this setup?

 

i think you will be fine on the setup, your still boosting the stock 10psi?

 

I believe xstacy7 that built the car has it boosting up to 12psi if I read correctly on one of his threads. I haven't yet taken delivery of the car.

 

93 octane is still the norm here in the the nj/nyc area, thank goodness. I remember being stuck in oklahoma and searching for 93 as I slowly ran out of gas, it was like a bad nightmare.......

 

My car was tuned by Steve Kan on 94, hasn't blown up yet on 93.

 

With your mod list, I don't blame you for worrying.
My stock car seems to runs fine on 91, but here in the midwest, it's strange. 91 is the norm, but when you do find 93, there doesn't seem to be a significant price difference. Since 93 is convenient to me, and about the same price, it usually gets it.

 

Page 3-2 of the owners manual clearly states...

"You may use a regular unleaded gasoline with a rating from 87 to 90; this will slightly reduce performance." The recommended octane is 91.

My personal experience also supports this with a stock car that was bought new and driven hard daily even with cheap gas.

At the time of the post I couldn't tell if this is a modded car but it seems to me that is he worried about hurting the car.

 

I wouldn't go any lower than 91 unless I was about ready to run out. Your still giving bad advice suggesting anything lower is acceptable, even on a stock engine. As vunerable as the rotary is to pre-detonation, your taking unnecessary risks of blowing an engine. And for what, <$1.50 price difference on a fill-up?
Remember that MAZDA was marketing this car all over the world, in places where fuel quality might not be as good...or the higher octane simply not available. Even then, the statement implies that MAZDA does NOT recommend it.

 

Anyone that pumps anything less than 91 octane into a turbo rotary is asking for a blown engine, even if it is bone stock. period.

the owner's manual is not the bible......how many people here follow the oil weight recommendations? i don't see 20sw50 listed. how many people here are still running their 'mazda designed' pre-catalytic converter? plastic ast? etc etc.

 

You keep using 87 then, but those of us who know better aren't going to let you say it's fine.

 

Unfortunately it's technically true but practically all wrong.

While the stock ECU is tuned rich enough that 87 is probably ok, that's assuming that the injectors are flowing at 100% of their rated capacity, plugs are new, the fuel filter is flowing perfectly, the boost is running no more than 10.0psi, the MAP is in perfect calibartion, the car is rarely boosted, etc. Modified or not, you will not find many FDs running like that.

But then again, if cutting your cost at the pump from $45 to $40 is that critical to you, just remember it would take about 1000 tanks of gas to save the money that one rebuild will cost you.

Dave

 

I wasn't even considering running less than 91. Only reason I was concerned is so far, this is the best I have to work with unless I get a tank at home and start having someone bring me 93 or higher to pump myself.

I know running too lean can and will lead to big problems......but what are the major risks of running to rich other than the obvious loss of performance and decrease in fuel mileage? Is it okay to run a little richer than maybe neccessary just to help prevent problems? Or will it cause others in the same sense as running to lean, down the road? The exhaust system has 3" Gotham Racing Downpipe, 3" Megan Racing Midpipe, and a 3" Greddy SP Catback.


The car has a power fc with commander (looks like an apexi), so could I easily recalibrate it to run 91 octane if I needed, or are those units difficult to make changes? I believe they come calibrated at 92 out of the box....that is if this one is even an apexi, but it looks identical.

 

Different octane fuels do not affect your AFRs (practically speaking). When running lower octane, you should run both richer and with more retarded timing. If your PFC has been tuned for 93 octane, you may want to add a slight bit of fuel/retard the timing a degree for a little more cushion.