mattisax

Is is absolutely neccessary to use premium gas in the 8?

Thanks

bowman

https://www.rx8club.com/attachment.p...chmentid=30427

-=Rowdy=-

Oh the joys of this forum-much like a mini Google. :D

Gambit

or you can use the actual google and put rx8club in there...btw, no it is not necessary, I use midgrade

Mag66

It's also worth noting that as in everything.. there is regular gas.. and there is 'regular gas..'

My own RX8 is fine with Shell or Texaco Regular 87.. but performs badly with other 'cheaper' brands of gas.. I tend to stick with Shell 91 myself because i find I do get a noticable improvement in performance as well as better milage compared to other Premium Octane brands.. but as they say.. "Your mileage may vary"!

Cheers.

Mag

RX8_Ownz

My 8 runs great on 87.

StealthTL

iTrader: (1)

Mr. RX8-OWNZ is right, the '8 runs fine on 87, and Razpewton is taking good care of his ride with the higher-test.

Don't forget that people who have taken the Renesis apart (porting, etc.) are shocked by the amount of crud built up on the rotor on such low-mileage motors.

The 'premium' from the major oil companies (Optimax for instance) has WAY more than the minimum additives to prevent crud buildup - it has to pass stringent long term deposit resistance tests, and it's their main marketing claim.

I am running the Canzoomer with Stage Two maps that include significant timing advance.

Trust me, if you advance your timing, you BETTER be on 'the juice'!

S

therm8

My 8 dislikes 87, or at least it did the 2 times I tried it. I run premium until it gets too expensive, then i'll hedge some of the cost with mid grade.

jtimbck2

A search on "premium gas" on this forum yields these results:

https://www.rx8club.com/rx-8-discussion-3/does-anyone-know-if-rx-8-needs-premium-gas-43406/
https://www.rx8club.com/australia-new-zealand-forum-37/premium-unleaded-fuel-50036/
https://www.rx8club.com/lounge-4/put-mid-grade-my-car-first-time-46778/
https://www.rx8club.com/rx-8-discussion-3/regular-87-octane-fuel-usage-42326/
https://www.rx8club.com/series-i-tech-garage-22/87-octane-vs-91-octane-fact-myth-22681/
https://www.rx8club.com/rx-8-discussion-3/octane-requirements-41170/
https://www.rx8club.com/rx-8-discussion-3/am-i-only-one-running-93-octane-35857/
https://www.rx8club.com/rx-8-discussion-3/fuel-octane-rating-1119/
https://www.rx8club.com/rx-8-discussion-3/octane-milage-34030/
https://www.rx8club.com/rx-8-discussion-3/87-octane-rattling-6000-rpm-32878/

Jackallll

I just got 170 miles with my last tank of 93. I did probably 80% city driving however. In comparison I got 240 miles with 89 octane with 90% highway. Amazing difference.

Zootx8

I tend to get right at about 19 mpg with mostly city driving. Doesn't seem to matter whether it's 89 or 93 (both usually Shell), I will say when I switched back to the 93 this week I surprisingly seem to be getting marginally better mileage than my 89 average - will know more when I refill. Car also seems to start quicker with the 93, no problems at all with idle and either.

LucasET

So, I'm too lazy to look it up and I know it's there, but....what are peoples results with ethanol blend so far? I live in Iowa, and every mid-grade brand is a blend. Ethanol obviously burns cleaner than regular fuel, but it also burns at a lower temp...so would I have less build up but be losing power? And, is ethanol a no-no for the rotary? I've had my 8 for just under a year, and the majority of the time, I use BP premium, mostly because there are no Shell stations to be found where I live. I average about 19mpg give or take.

yamajj

i think there should be a section in the owners manual, if not on the window sticker, concerning the differences in the octane.

here's my input: low octane will burn fast and high octane will burn slowly. i also get to hear my motorcycle friends commenting on the same topic.

yamajj

Fanman

There is a slight burb in the owners manual on this. They recommend using premium fuel. They say you can use lower grade fuel, but it will degrade performance. Essentially the car's normal running pattern is set for 91/93 octane, if you use lower grade gasoline the engine will retard the timing a bit and you will lose some hp. If you do not care then by all means use 87/89, if you want peak performance out of your car than use 91. I linked an article in the previous thread where they test out various vehicle & the differences in performance.

RX8_Ownz

I couldnt find the difference in performance b/w 87 and 91, but I'm pretty sure when I use on 87, I get better mpg.

Sometime I feel my 8 is pulling harder on 87, is it just me?

So...you're saying "higher octane, better performance"?

Fanman

Butt dynos are notoriously inaccurate :D

Yes, the engine/electronics are set for use with 91 octane. In not using 91 octane, gasolines with 87 octane ratings the engine is set s that timing will be retarded further at WOT. In essence you will lose hp because the engine is lowering the timing so as not to get detonation. In the article they tested an M3 (req. 91 octane), Saab Turbo (req. 91 octane), Honda Accord (87) & Ford Mustang (87). The M3 & Saab both suffered between 6%-12% decreases in performance from using lower octane fuel.

RX8_Ownz

So our rotary engine will have the same result?

If it will, Im gonna change from 87 to 91 for a while.

salituro64

I tried 87 once, about three weeks ago. I noticed that when it idled in my garage (while warming up) it made a very faint popping sound in the engine. I am assuming the fuel was igniting due to the compression not the spark. I thought that sound was the pinging on a rotary engine. I need to try it out again, because it also dropped near or below zero for several nights.

Paul_in_DC

I haven't tried lower octane yet, but I've compared different brands of 93 Octane. So far, I've found that Citgo runs rougher and gets slightly lower gas mileage (.5 mpg) than Mobil or Shell. Next I'll try lower octane and see what happens to mileage vs. power.

alnielsen

iTrader: (4)

Has anyone found anything that compares the power supplied by a given measure (BTU?) of gasoline provided by the various refineries?

5Gen_Prelude

BUT! That same article stated the Accord actually lost power with higher octane fuel (but not much).

Fanman

The Accord is set to run on 87 octane. Essentially, the ECU's are set to run at that level of octane. In the RX8 that level is 91/93 octane. The ECU can compensate when you decrease octane by retarding the timing down (lowering hp). In the Accords case, the "highest" performance set by the ECU is with 87 octane. In other words if you put 91 octane you would gain nothing. Much of it is like if you put 100 octane in a regular NA car, no matter how much better the gas is the ECU can't utilize that improvement in octane as it is already functioning at it highest potential. The little bit of difference in the Accord's loss at 91 octane is probably close to standard dyno variation. The loss of 6%-12% performance by the M3 & Saab are not even close.

RX8CaliGirl

Well clearly none of you live in Los Angeles where it doesn't matter what kind of gas you put in; you'll be sitting in traffic so much, you won't be able to gauge what works best.

I've put in all three (87, 89, 91 -- usually I stay on 91 except lately the gas price has gone up so I've been cheap and tried 87 and 89) and haven't noticed anything except that L.A. traffic sucks. :-P

rx8cited

Well then, you can tell us which gas gives you the best idle perfomance . I've seen plenty of opinions on differences in idling with different octanes/brands.

My car is quite happy with Shell 87 octane.

StewC625

I've seen absolutely no difference in running performance between 87 and 93 octane gas. In cold weather, the engine is less likely to knock and detonate, so I switched to 87 for the winter, and I do notice better cold and partly-cold starting on the 87, presumably because of its higher volatilaty.

I'll likely switch to 93 again once warm weather arrives (highs in the 70's and up).

That said, interesting "butt dyno" comment back in the thread a bit. I just got a gTech to fiddle around with. I'll do some "performance testing" with it and see if I can see any difference between 87 and 93 octane. I'd bet that there's none that's consistently measurable.

Stew