RustyTumbles

I am new to gas and I was wondering if these gas engines make for power on higher octance fuel? I have read that some people use standard unleaded which is around 85-87 RON depending on where you live and what brand fuel it is. If I was to use a high octane fuel like BP ultimate or shell optimax in my zenoah will I get a good power gain? It seems to work in my car!!! Also is it possible to up the octane by adding octane booster without hurting the engine.

ptgarcia

My Feedback: (36)

Octane alone has no effect on power unless other things are done to take advantage of the higher rating (such as advancing the timing or raising compression ratio). You should run the lowest octane your engine, prop and plane combination will tolerate before detonation occurs. I run all my gasoline engines on 87 octane and Amsoil 100:1 mixed at 80:1 with good results.

tango28charlie

Almost all small engines such as the ones we use on our airplanes will run on rotgut 87 octane car gas with no problem. It is possible to develop more power from a gasoline engine using higher octane fuel, but the engine has to be set up to take advantage of the higher octane rating of the gas, by having a higher compression ratio and/or having the spark timing and fuel mixture optimized to run right at the peak performance on the edge of detonation occuring. Using a higher octane fuel without tuning an engine to take advantage of it will NOT result in increased power. In your car the electronic engine control module keeps the ignition timing and mixture running as close to peak as possible to make the most power while using the least fuel and producing the least emissions. Model engines run rich with less than optimum spark timing because they don't have any fancy electronics to keep the engine performing at peak. It's a compromise when you set up your mixture, and where the manufacturer sets the ignition timing. And only ZDZ brand model airplane engines are designed with a high enough compression ratio to need better fuel.

Additionally, using octane boosters even in your car is simply a waste of money. The best one (104+ brand) raises the octane number of 20 gallons of premium unleaded from 93.0 to a whopping 93.4 octane.
Charlie

WilsonFlyer

My Feedback: (13)

Higher octanes also burn hotter. Heat is an engine's WORST enemy. Regular unleaded (86-87) octane is fine for ANY application in RC no matter whether you're Sunday flyer or a TOC champion.

Homebrewer

My Feedback: (8)

High octane fuel by itself does not in any way increase engine power, not in your rc engine or in your car. However, if your car compression rate is high and your ECU retards engine timing to prevent engine knock then you'll feel a power loss that the grade of fuel that caused these conditions

Schpankme

The octane number of gasoline is NOT a measure of its hotness or coolness in the burning process, and it is NOT a measure of how 'powerful' it is. The octane number is simply a measure of how good the gasoline is at resisting detonation (knocking/pinging).

Octane numbers are measured two ways. The 'research' method of measuring the octane number uses a constant speed (1500 rpm) engine in laboratory conditions. This is the RON - Research Octane Number. The other method is the MON - Motor Octane Number, which uses a harsher test regime more closely related to road conditions. So the MON is usually lower than the RON for the same fuel.

Often you may see the octane rating quoted as (R+M)/2. This means an average of the two methods is used to give the fuel a number. This number method is often called 'pump octane' or AKI (anti-knock index) in the US.

Using a higher octane gasoline in an engine designed for low octane WILL NOT increase it's performance - the octane number is a MINIMUM needed to eliminate detonation, and that's all it is. The octane rating is a measure of the fuel's ability to CONTROL the burning process (to prevent detonation); it is not a function of burning 'hotter' or 'colder'. And the higher the compression ratio (in the same engine), the higher the octane number needed.

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Schpankme

SLINGSHOT-RCU

I run BP 93 oct. All my engines seem to love it. Not saying its better than 87.

GAGAK

So...does this mean that the higher the octane number the better it resist detonation? or is it the other way around? sorry if the answer is so obvious.....[&o]!

tango28charlie

Yes, the higher the octane number, the more resistant the fuel is to detonation. By detonation we are referring to the fuel exploding before it has a chance to be ignited by the spark plug, an obviously unwanted situation. In your car this causes a metallic pinging noise which is the sound of the shock waves from the exploding fuel hammering against the pistons as they are still traveling upward on the compression stroke.
Charlie

Albatross

My Feedback: (7)

What about ZDZ engines, the [link=http://www.rcshowcase.com/html/faq.html#Why%20do%20these%20engines%20require%20pr emium%20gasoline?]FAQ[/link] form the web site RCshowcase, recommends a minimum of 93 octane gasoline should be used.
I am following these recommendations so far ... can anyone else confirm if 93 octane is OK for this type of engines?

Schpankme

Low compression engines 6:6 require 86 octane (RON).

High compression engines 7:8 require 91 octane (RON).

The ZDZ engine uses a 10:1 compression and recommend the use of 93 octane gasoline.

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Schpankme

BBW Walt

My Feedback: (11)

Higher octane fuels "do not" run hotter. They burn slower which is actually cooler. Higher octane runs at a cooler combustion which helps eliminate the dreaded knocking. In some instances the higher octane fuels will add a plus on extremely hot days. I run 100 octane racing gas in all my engines. They love it, it smells better, it has a longer shelf life, it mixes very well and my leaf blower actually pisses my neighbors off on this stuff. At $3.75 a gallon it should..

tkg

My Feedback: (1)

Well maybe the fuel does not run hotter, the engine sure does. I spent the better part of an afternoon running a 3.2 Sachs based engine on different fuels. Regular, Av gas and Coleman fuel
The most power and the coolest temps was with regular gas.
This ain't theory.

Geistware

My Feedback: (16)

I have heard that some engines may develop more power on regular gas compared to HiTest.
I will find this out in a few weeks when I go to burning regular gas in my BME. I have been running 93 Octane and getting around 6000rpm with a 26x10 propeller.

tango28charlie

tkg - I don't know about coleman fuel, I wouldn't run an engine on that stuff, but I think the reason your engine ran hotter on avgas than it did on regular gas is that avgas is less dense than regular gas. Therefore if your engine's mixture was set up for regular gas, you effectively leaned your mixture out by running it on avgas.
Charlie

tkg

My Feedback: (1)

Actually the Coleman fuel ran cooler than AV gas though the power was the same. The carb was adjusted for best performance.
We arn't talking hugh numbers here, the gas ran at 330, Coleman 340 and AV gas at 350.

SLINGSHOT-RCU

A guy at our feild uses Colemans in his heli ,,It runs great .

fiery

My Feedback: (2)

The instructions for my MVVS 1.60 IFS state that it must but run on 95 RON petrol.

I guess it is a "high compression" motor?

I run it on premium unleaded (96 RON) and it seems to run just fine.

ptgarcia

My Feedback: (36)

Here's the thing with manufacturers recommending 96 oct gasoline: You can't get that in the U.S. (unless you buy AV gas or some other racing fuel)! 91 is the highest available in my area. I have seen as high as 93 once on the east coast, don't know what they have now.

tango28charlie

Here on the east coast, all premium unleaded is 93 octane. Sunoco stations have 94 octane, and some Sunoco stations have a special purple pump that dispenses 100 octane unleaded for tunerz drivers.

As far as manufacturers recommending 96 octane fuel, the previous post said that his engine instructions specified 95 RON fuel. In the U.S., the octane numbers posted on the pumps are an average of the Research Octane Number (RON) and the Motor Octane Number (MON). The RON rating is tested under a less severe test than the MON rating, so although you might only be able to get 91 octane fuel, the RON of that fuel could be 96 or better.
Charlie

RustyTumbles

Here in australia we have 98 octane fuel at the pump. There are a few different types or brands but they are all very similar.

Ozmodeller

Bigsport,

Fairly new to petrol (gas) myself. Although I used to run standard unleaded in my Sachs Dolmar 52; I now run BP Ultimate (98 RON) in a DA 100. This was done on the recommendation of the big model flyers up here in sunny Queensland, and I guess if they haven't been having any problems it must be OK.

Just my two cents worth!

Regards

Peter

Schpankme

Coleman fuel is refined white gas (petroleum naphtha) with a rust inhibitor added. It has an octane rating of 50 to 55 and none of the additives found in gasoline.

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Schpankme


ref - Coleman

PJAMESRC

My Feedback: (19)

ADDING MY 2CENTS NOT ALL ZDZ ENGINE REQUIRE 93 OCT GAS. MY 60CC DOES, BUT MY 40CC AND 50CC ARE OKAY ON REG GAS
HAPPY FLYING PJAMESRC

Schpankme

In the US the number shown at the pump is the Pump Octane Number (PON), which is the average of RON and MON: R+M/ 2 = PON.

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Schpankme