AdRoCK3217

I need to go back to English, I suppose. I LITERALLY can't understand your sentence xD. This isn't meant to be one of those "omfg, learn to type!" responses, but, could you elaborate? :-O Use smaller words for me, haha!

Pilgrim

I was skeptical about 87 octane providing anything other than economic benefit, and as one of my posts indicated, cautious about the idea of using it.

And about mixing oil in the gas-I thought it ought to help cut down rotor/housing wear, but probably wouldn't add much to apex seal sealing.

Nevertheless, I did both today, 14 gallons of 87 and 7 ounces of Valvoline two-stroke oil. I got the gas from the same Chevron station where I buy gas for all my vehicles.

And I gotta say, the butt dyno (with all its imprecision) tells me it makes a marked difference in performance. I absolutely did not expect it, and I can't attribute the increase to one or the other or both, so now I'll try a fillup of 91 with oil, then 87 with none, and see what I think about them used that way.

I am, frankly, amazed. It's not like an additional fifty HP or anything, but the zoom factor is noticeably better, especially in midrange, and the engine feels smoother in what before was a hi-freq/low-amp vibration range around 5k RPM.

Has anyone had dyno work done on this subject?

Pilgrim

Raptor75

Your assuming that the engine is automatically pining which may not be the case.

Raptor75

Your still missing the point. A rotary has different combustion characteristics then a piston engine, what is good in one dose not necessarily work well in the other. A quicker burning low octane fuel allows the combustion in the polymorphic chamber to be more efficient in a rotary engine, plain and simple. Your comparing apples and oranges here.

Raptor75

Very simple they want to cover their investment. A few RXs do have pinging issues some even running on 91 octane. So if Mazda can avoid potential warranty claims by telling every one to run 91 octane to help a few sub standard cars it is no skin off their back to tell you to run 91 octane. Of course they are even ambiguous about this because my 05 manual says it is fine to use 87 octane. Just as they say don't use synthetic oil but never state it in the manual.

Do a little searching on this subject and you see that the people who work with these cars and really know the rotary will recommend using 87 octane. While your at it I challenge you to show me one proven test that shows 93 octane gives the RX-8 more hp. I'm going to be a spoiler here....there is none!

Raptor75

You do realise that ethanol is an octane booster.

DrDiaboloco

The only way I'd believe that your butt dyno had found a "marked" difference would be if you rolled the car up to a gas station with a friend, and that friend filled up with one of your four choices of mixtures and you didn't know what that choice was... Then you did it ten or twelve more times with a randomly-chosen mixture, and you were able to see this marked difference with absolutely no knowledge of what was in the tank.

Without doing that, this sounds EXACTLY the same as the K&N commercial where people claim these amazing differences just from changing the air filter (or people claiming 1-2mpg more when they just change their OIL FILTER).

AdRoCK3217

Octane....booster? It takes 3x the ethanol to have the same combustion characteristics are regular unleaded gasoline!

MazdaManiac

iTrader: (3)

3x the ethanol to produce the same power, but ethanol is actually an octane booster.
Ethanolated fuel has a higher AKI than non-ethanolated fuel.
However, it has a lower stoichiometric ratio, so it negates itself.

Pilgrim

From a scientific point of view you're absolutely right (except that human perception wouldn't be involved at all), but I don't claim this to have been a scientific experiment. What I'm talking about here is a perceived result contrary to expectations. And I have enough experience with fictional, imaginary, and wallet horsepower from building Harley motors to know the pitfalls of butt dynos. Only 1/4-mile times or a dyno will say if there was a difference for sure.

What I am saying is that from one experience under uncontrolled conditions I find that the performance was subjectively different enough from previous experience to justify further indulgence of my curiousity about the subject.

Thus, the query about dyno work.

Pilgrim

Fanman

So now you are saying they pinging issues with 87. Yet, it's OK to run it ??? I don't know of any occurence with 91 octane where they had detonation issues.

I never said it wasn't fine to run 87, but in that same manual that you are alluding to it says that it will affect performance. You use the manual to justify your point, but somehow omit the rest of the statement. You believe 1 part of what the manual says, yet, completely disregard the next sentence.

I've seen one person working with 1 outfit (and a very reputable one it is) come out & say they got better results with 87. Not the "people that work with cars" as you have stated.

Show me 1 "proven" test/thread where somebody got more/same hp with 87 than 91 ? I'll play spoiler here "There are none !." There just aren't that many people so interested that they would take dyno time, drain their gas tanks, and run this test. There was a european poster on here that tested the different gasses and did in fact get better results from higher octane gas :

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/dyno-2-types-fuel-97271/

Recently Brettus tested it & got no measurable difference, but then when he switched to 87, got horrible breakup :

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/octane-performance-tests-100573/

Your theory was that the Rotary runs better with lower octane fuels because of engine design, in some cases pointing to Rotary race engines running 80 octane, yet now you say we may get detonation from 87 that is why they tell us 91 ? It's an incomplete story.

Fanman

I didn't say it was. And it also may be the case. You don't have to have your engine groaning before it is detonation. The car is adjusting the timing to prevent detonation/knock faster than your ear inside your insulated car may be hearing it. As I have said before the engine can adjust/retard the timing to a lower grade of gasoline, so it might seem quite normal as you are driving it down the street. If I had you drive a 232 hp RX8, vs say a 220 hp RX8, bet you would not be able to tell which one was which. The difference in hp is minor, but is there.

Paul_in_DC

You will get an amazing increase just by replacing your air filter... if the old one was so filthy air had trouble getting through it.

DrDiaboloco

Of course you will get an increase if you replace a dirty air filter. But "amazing"? It would have to be quite clogged indeed, in which case ANY new air filter would make a difference.

Raptor75

You need to read this whole post, I started out by saying run 87 unless you get pinging, a small portion of RX's do.

There are 1 or 2 people on this board who reported ping with 91 or 93 octane and are fighting with Mazda to resolve it.

My mistake you did not say this, it was another member. As for the seemingly cherry picking of the manual information. I state this because it has been proven by source on this board (see your own link and mine at the bottom of this post) and stated by some very reliable and knowledgeable people here that you don't get the power increase.

https://www.rx8club.com/showthread.php?t=100573

So this person dose not work with cars, specifically RX-8s?????

See my link at the end, you've also already provided two source in your own response. I even remember reading the one.

First I was talking physics and fact, this is no theory this is the way the engine works.
Second, You will find that many things Mazda tells us are incomplete. Should we use 87 or 91? Should we use synthetic or Dino oil? Dose the car make 250hp or 232hp? You have to learn that you can't take everything Mazda or any car maker says as irrefutable. Many times the reason a recommendation is made are for reasons that are not obvious.
-Dose the car really need 91 octane or is it a easy way to address a small portion of defective engines.
-Is the RX-8 better protected using 5w20 motor oil or is it a safety margin to meet EPA standards.

Look it's your money and if you feel better about using 91 octane, knock yourself out. I have been using 87 for almost a year with out any adverse effects. I have recorded a sight increase in mileage using 87 octane over 91. That increase would most likely be attributed to increase efficiency of the combustion process which would logically be an increase in hp. I have no way to test this so it is just speculation. As for myself, I choose to believe those who are very knowledgeable and have raced these cars when they say use 87.

(read the two links that are half way down this page, by the way these are some of the most knowledgeable people on this board.)
https://www.rx8club.com/showthread.p...ht=octane+fuel

Huey52

iTrader: (2)

As we know, one of the innate stengths of the rotary engine's design is its ability to run on low octane fuel. However, as applied to the RX-8, and as manual cited, there may be a loss of performance below 91 octane. Personally I split the difference and use 89.

Silver_Surfer

I tried this.. seemed to be the same as 92

Is'tn it ture that your engine(any) makes the most power just below the ping/detonation?