I'm sure this was discussed several times but I would like to ask a more specific question.

Excluding the cost issues, can the usage of the highest possible octane rating petrol cause any damage to the engine ?
I read somewhere (and cannot find it anymore ) that high octane petrol contains usually higher quantity of carbon hence the usage of it can cause higher carbon deposits.

Is this true ? and if yes, can this be a major issue for the rotary engine or is something that can be accepted ?

 

I've never heard this. In fact, higher octane fuel should burn cleaner and leave less deposits in your engine. Also, [around here] higher octane fuels usually don't contain ethanol [your area may vary] which is also a bonus.

I am running 91 currently and will likely be running 94 this summer.

 

I'm located in Cyprus/EU and per my knowledge we don't use ethanol at all. the ratings we have are different (we use RON):
RON -AKI
-------- ------------
92 - 87
95 - 91
98 - 93
100 - 94

but the principle is the same

I heard a lot about higher octane petrol being 'cleaner' but again this is not proved (or is it ?) as in theory, besides the octane rating, all petrols suppose to have the same amount of detergents hence they are supposed to be equally 'clean' . This is mainly based on the idea that the petrol companies are favoring the higher octane fuel which can be an....urban legend..

My only worry is the amount of carbon which by the way is another 'rumour' which supports the more the carbon the more the power a fuel can produce, therefore in the same line with the 'clean' strory above, the higher octane fuel contains more carbon and this is the reason some people can feel difference of power/consumption when using high octane fuel.

 

the manual says this car should be running at 95 octane as its recommended standard.


higher octane = better for car. nuff said. end thread.

 

Poeple here suggest to drive the car after it is warmed up to the redline a couple of times to burn the carbon. You actually don't have to push the car until you hear the biiiiiiiiippppppp sound. 7500 rpms should raise the temp enough to burn any carbon. Do that often (some say every time you drive the car) and you should not have problems. Never do it if the car is warmed up and the oil level is low!

 

I'd like to see that manual.

When was the last time they made 95 Octang for comercial pumps.

You weren't even born then.

 

That's a RON95 (EU market) which is more or less equivalent to the AKI91 (US market).

The user manual of the RX8 states that RON95 or above should be used.

My question is solely about the carbon contains and carbon residues.

 

wtf? higher amount of Carbon ????

Carbon deposit is a by product of combustion process.

Sure if you run petrol thats way too high (like 100+) it might damage your engine cuz it never burnt completely. but other than that. no.

 

nope.

higher does NOT mean its better for your car.

MSP needs higher octane because it has a ridiculously high Compression (10:1) and if they dont use higher than usual gas, the engine gonna go Kaboom.

Im not sure about FD but FC is happy with 87. and if you use anything higher, say hello to tons of Carbon deposit build up inside your engine.

 

why the higher amount of carbon sounded so weird ?
the octane itself is a carbonhudrate right ? more octane = more carbon (and hydrogen ).

 

*sigh*

you need to study Gasoline(Petrol) a bit more ...

 

It's all hydrocarbons. And they don't actually put octane in gasoline. Octane rating is based on matching the anti-knock properties of gasoline against particular mixes of heptane (which knocks like crazy) and octane (which doesn't). But heptane/octane is a lab test mixture, not a practical fuel.

Higher octane is obtained by refining gas so it has particular mixes of stuff that's naturally anti-knock, or by using additives. Back when tetra ethyl lead was the main additive, high octane gas would cause deposits. I remember that, when buying gas for a camp stove, we'd buy the cheapest low octane stuff we could find so as to minimize lead deposits. Find an old (pre-1970s) shop manual that has pictures of lead fouled plugs.

Gasoline usually has detergent additives, which are good. Don't know how true this really is, but there is a belief that they put better and more stuff like that into the higher priced high octane blends. That's where the idea originated that higher octane gas was better in general. Not the octane, but the additives.

You might take a look at http://www.faqs.org/faqs/autos/gasoline-faq/ for more than you ever wanted to know about gasoline.

Ken

 

I think I am going to get out the BIG WOODEN SPOON and Start SLAPPING!..

What next....

A thread on "Grease Nipples"...did you know the RX-8 ones are CHROME PLATED!

 

Ash8, if you're not helping, just Shuuuuutttttt UPPPpPPPPPPPP !!!!


j/k lol

 

ONE OF THESE DAYS ALICE!...

 

Where im originally from we have 2 types of petrol.

regular 94: 15 cents a litre
premium 97: 17 cents a litre


Prices are fixed and never fluctuate. probably the only good thing about it haaaaa.

 

that would be useful if you had taken the time to put your location in you info..



beers

 

Thanks!

Is really bothering when all those people expressing arrogant comments while they don't use their brains to think that they too hear whatever they think is right from somebody else and as in most of the cases they learn it wrong !

Ken’s reply is really useful in contrast with all the rest 'experts' in here who are just wasting time and space of what was supposed to be a very useful forum.

 

Just curious... Why does fuel quality matter for a rotary? I'm reading John Hege's Rotary Engine history book. He says one of the advantages of rotary over piston engine is its natural resistance to knocking from low quality fuel. Does this only work in theory or the rotary engine prototype?

 

Early Rotaries back in the 70's used Standard Grade (Lower Lead Content) Fuel...it was a requirement then and the engines were lower compression.

The RX-8 is the opposite, a higher 10.1 Compression Ratio and Higher Gas is recomended...by Mazda.

 

Oh im from montreal canada. But my family is from Doha in Qatar. You can fill up the 2 tanks of a toyota land cruiser for 22 bucks.

 

one of places where petrol is cheaper than water

 

Next time, be a man and find the info on your own. These info is for f-'s sake every freaking where.

Dont go online when you fail with Google.

 

whatever....advices coming from a person his engine died on him..

 

Everyone's a comedian - or thinks they are. Just part of the price of free speech. Don't take any of the cracks personally. Most of the folks who said rude things (including nycgps) are good guys, just having some fun.

BTW - if you want to have some fun back with nycgps, ask him if there's a relation between his failed engine and the fact that he used a type of oil Mazda recommends against.

Ken