95 octane vs 98 octane grade gasoline

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gerre
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95 octane vs 98 octane grade gasoline

Post by gerre » Tue Sep 01, 2015 8:13 pm

Hi all,

Well, I have the following thought last days when using my valved PJ: Is there any difference between 95 octane an 98 octane grade gasoline when using it with pulse jets? I know that 98 grade octane is used for engines with a high compression ratio, but pulse jets have a low compression ratio. Could it be bad to use 98 octane gasoline. Could it give problems for starting and running? I think I made the wrong assumption of thinking that 98 octane gasoline will cause a better combustion... but hey, I'm a newbie ^^

Thanks in advance and greetings from Belgium :)

noclassmac1972
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Re: 95 octane vs 98 octane grade gasoline

Post by noclassmac1972 » Fri Sep 18, 2015 9:06 pm

Use the lowest octane fuel you can buy. THis will give you more power and easier starts. We have a thing called white spirits which is sold in the hardware shop which is a form of very low octane petrol. Personally I stay away from any fuel with petrol as it is to difficult on starts and power. All my jets run on a methanol/nitromethane brew

Robert

gerre
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Re: 95 octane vs 98 octane grade gasoline

Post by gerre » Sun Sep 20, 2015 1:20 am

Thanks for the reply Robert.

I was able to make them run with both 95 and 98 octane gasoline, but it was indeed pretty dificult to get the engine started.
Anyway, I'm just doing some experiments. I'd like to run the engine on methanol too, but I think I will need to modify
my flowjector and perhaps the tailpipe of the PJ for that. Anyways, we'll see how things work out :)

nitro
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Re: 95 octane vs 98 octane grade gasoline

Post by nitro » Thu Nov 03, 2016 1:25 pm

A good rule is Methanol Nitro mix for Control Line and cheep gasoline & perhaps some diesel for RC .Shellite fuel is our low grade octane in Australia & burns super clean but it like Kero is expensive.Thrust of all these mineral based fuels is much the same if combustion goes off good & that depends on pj design more.I liked 90 % Kerosene and 10% Shellite mix most but as the 20% Diesel & 80% Gasoline was so cheep I stick with that now.High octane is just a waste of money

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