RatedX8

Any thoughts about using mid-grade gas during the cold weather months?? Here in California premium is fast approaching $4/gallon. Would there be any damage to the 8 engine by using 87 or 89 and revving to redline? I'm new to rotaries, but piston engines usually knock due to high ambient temperature/low octane gas. Is it the same with a rotary? I could trade a few revs/hp, if it is safe, for a long freeway trip where engine speed/load is light and save a few $$ in the process.

Any thoughts, suggestions are welcome.

Jasonawojo

iTrader: (2)

I just put in 89 for the first time, haven't noticed any issues yet. I believe what works varies by car, as some here seem to be able to use even 87, while others have had issues with anything less than 91.

SayNoToPistons

iTrader: (8)

Not worth the risk. Sell the car or get a $1500 beater. $1500 can get you a reliable FWD beater.

2tone

iTrader: (3)

i've run 87 every fill up for 4 years. i think quite a few people do that.

fyi: i was new to rotaries when i got mine, and using 87 came from the sales guy AND the mazda head tech (not that they necessarily know by experience, but they have to at least know what if they are wrong, THEY will be footing the bill on my repairs, so it seems safe to at least assume they really believe that 87 is perfectly fine).

RatedX8

Does the Renesis Rotary have a knock sensor that retards ignition timing? I understand that if so, I will lose hp. My main concern is durability as I love revving the crap out of it.

Uncivilizedracer

I only risk it every now and then when im broke

astrozoom

I recently did a 1400 mile drive putting mostly 87 in it for every fill-up except one with no issues. I do still try to put 89 or 91 in it occasionally, especially since 91 usually has the additives for cleaning your fuel injectors.

Tamas

iTrader: (1)

87 used here (mostly Chevron), with the occasional redlining. No issues.

Earl the Pearl

I have been running 89 since day one with no problems after close to 22k miles.

champi0n

iTrader: (1)

dont worry, we pay pretty much $5/gallon for 87 in canada and thats what i use with no problem.

CarAndDriver

I put in my first tank ever of 87 just to see.

valpac

iTrader: (2)

Predetonation is not good for ANY engine.

Crztrtldck

i wouldnt risk it.
i use 91 and i have no problems. its only about 2-5$ more a tank
so why risk a engine if your only saving a few $$ ?
1000+ $ for a new engine doesnt sound good to me. i'd stick w/ 91

champi0n

iTrader: (1)

87 runs great for me, nice and smooth, no ping, no power loss... but warranty would cover my engine if i ran it with dynamite.

Easy_E1

iTrader: (2)

I have used 89 in the cooler months but not in the summer here.
The way I look at it is,, $0.10-11 cents per gallon saved by going to a lower octane. 13 gallons per fill up. $1.30-$1.43 per tank difference between 89 and 91 octane. If you fill up 10 times a month,, $13.00 - $14.30
Thats about $0.44 per day that you would pay extra for using premium over mid grade.

Is it worth it?

valpac

iTrader: (2)

Dont kid yourself. If you use 87 octane your engine is struggling with predetonation. Thank your anti-knock sensor for retarding your timing to compensate for ping. Thank it again for a loss in power. Just not worth it.

4me2

I never use premium, regular works great.

nycgps

iTrader: (1)

I just use Premium, in NYC 93 is Premium.

Sunoco has 91, but I never tried it.

the diffs between Premium to *Medium* grade is about 10 to 15 cents.

Ahh, big deal. Im ok to pay an extra buck or 2 every fill up.

champi0n

iTrader: (1)

using 87,89,91,93 octane fuel you will always have "predetonation" because it hasnt detonated yet.

low octane fuel (regular) works just fine for me with no ill effects what so ever. No ping, no detonation, the ecu isnt messing with anything and its running happy.

Maybe granted in higher ambient air temps lower octane fuel might (might) cause problems.

I have driven a car that 100% absolutely needed 93 octane! i was stuck at a station with either regular or diesel, put in the lower octane and it drove ok until it started suckin up the new gas.... pdddddddddddddddddddddddddddddddddd, and when the ecu messes with your timing and **** you cant get the sucker over 1500 rpm

Rotary Inspired

iTrader: (1)

Nothing wrong w/ running 87 in your renesis. The old FC motors had 9.4:1 and 9.7:1 compression ratio and ran better on 87 than 91. Mazda once raced rotaries on the 87 until forced to change.

Unless you have a hairdrier under the hood you can fill up w/ 87. Been doing it for 11K, and w/ every n/a rotary I have owned. There is some funny info on 8 club from time to time IMO.

4me2

Isn't knocking a heat issue? So with winter here, why worry about it.

Easy_E1

iTrader: (2)

It is a heat issue. Down here in Phoenix I get detonation on 91 octane. All I know is I can't use 89 or 87 at all if the temp is above 70 degrees. If the temps drop into he 60's. I can use 89. But as I posted earlier why risk it.

4me2

I don't see how some pinging can hurt anything. I'm a machinist, and the metal in the motor is much stronger than the pinging.

4me2

https://www.rx8club.com/rx-8-discussion-3/no-more-detonation-%2Amiac%2A-121249/

don't you do this?

Easy_E1

iTrader: (2)

The problem occurs because the timing of the detonation is not at the rotational point of power, It occurs before the correct engine timing point. Thus causing stress on all the parts. mainly the apex and corner seals.
Picture a piston engine firing way before top dead center on the compression stroke. The piston is moving up from a cycle from another piston. Suddenly the AF mixture lights as it's coming up. Basically combustion wants to stop the piston as its moving upward. Think you would get some stress there? On the piston rod/crankshaft.
Same scenario with the rotary. your trying to push the rotor backwards against it's basic rotation. That is why timing is very critical. Otherwise KABOOM!