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Old 03-11-2008, 07:14 PM
billteg is offline
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Re: Low octane fuel or High octane fuel??

hey guys, I've run 100 octane low lead av gas in a bunch of engines that I've converted. They all run well with it mixed with Klotz Technplate lube. The best thing is that I find the av gas has greater resistance to going stale and sour. That means a lot to me as I don't trust pump gas after having some problems of freshness, albeit some time ago.
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Old 03-11-2008, 07:35 PM
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Re: Low octane fuel or High octane fuel??

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Originally Posted by WOODisGOOD View Post
In the 150 manual it does state to run mid to high octain. This manual was writen back in the late 1990's and will be corrected on the next printing run. 87 to 89 octane gas is what is reccomended for all of are engines however a slightly higher octane may be needed when running tuned pipes. Sorry for any confusion in the manual.
So what your saying is that if you are running greeves or ks pipes you should run like 92ish octane?
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Old 03-11-2008, 07:44 PM
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Re: Low octane fuel or High octane fuel??

I'm sticking with 89 octane in my DA-150 MTW 110s . Not too low, not too high, just right. It's what my engine grew up on.
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Old 03-11-2008, 08:01 PM
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Re: Low octane fuel or High octane fuel??

Funny this thread came up cause I have a zdz60 that I decided to try some of my race gas for my moto cross bike in just this week. I used VP C12 racing fuel in it and although I cant compare it to pump gas I can tell you that it really seems to like it. The guy I bought it from had starting problems and it did not seem to have the power like it does on my plane. Both 50cc wild hares similiar in weight. It starts no problem with me and yanks my extra around no problem. I will try 93 this weekend just to get a comparison. Im sure I wont notice much as most state that more octane is not necessary on these engines.
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Old 03-11-2008, 08:16 PM
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Re: Low octane fuel or High octane fuel??

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Originally Posted by robertp17 View Post
Funny this thread came up cause I have a zdz60 that I decided to try some of my race gas for my moto cross bike in just this week. I used VP C12 racing fuel in it and although I cant compare it to pump gas I can tell you that it really seems to like it. The guy I bought it from had starting problems and it did not seem to have the power like it does on my plane. Both 50cc wild hares similiar in weight. It starts no problem with me and yanks my extra around no problem. I will try 93 this weekend just to get a comparison. Im sure I wont notice much as most state that more octane is not necessary on these engines.
Hi Rob, I used to race motocross too but on Quads! I am fairly certain the reason you might be getting more power out of VP is because it is oxygenated fuel.AKA racegas. You might end up burning up sparkplugs faster but I am not certain.I don't beleve that higher octane alone will add power.
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Old 03-11-2008, 10:24 PM
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Re: Low octane fuel or High octane fuel??

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Originally Posted by Artie Johnston View Post
So what your saying is that if you are running greeves or ks pipes you should run like 92ish octane?
Only if your having detonation problems, otherwise run the 87 to 89 octane.
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Old 03-12-2008, 03:11 PM
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Re: Low octane fuel or High octane fuel??

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Originally Posted by WOODisGOOD View Post
Only if your having detonation problems, otherwise run the 87 to 89 octane.
Thanks for the info Tony, I am actually going to be using Greeves pipes in the 3.0m comp. arf Yak I am putting together.
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Old 03-12-2008, 03:48 PM
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Re: Low octane fuel or High octane fuel??

Quote:
Originally Posted by WOODisGOOD View Post
Only if your having detonation problems, otherwise run the 87 to 89 octane.

So some of the pipes are actually "Super Charging" the motors??... I thought they only attenuated sound and maybe over scavenged a bit.... ????
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Old 03-12-2008, 08:09 PM
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Re: Low octane fuel or High octane fuel??

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Originally Posted by Mithrandir View Post
So some of the pipes are actually "Super Charging" the motors??... I thought they only attenuated sound and maybe over scavenged a bit.... ????
The idea of "tuned" pipes is that, at certain RPM ranges (frequencies) the pressure wave "bouncing" back and forth in the pipe creates a vacuum, pulling more fuel/air through the motor, "supercharging" it. That's how I understand it.
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Old 08-24-2009, 07:59 PM
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Re: Low octane fuel or High octane fuel??

Hi guys, on the field I hear a lot of things about gas octane, so this treath is very helpfulm1 I have a new DLE 55 on the box, so Im very concerned in start it right. The manual says Compression Ratio: 7.6:1, so I think its low compress, right ? is it 86 to 89 octane the best for that ?
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Old 08-24-2009, 08:03 PM
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Re: Low octane fuel or High octane fuel??

yes it is a low compression engine and use 87or89 octane gas. no need for the higher 91+ fuel.
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Old 08-24-2009, 08:37 PM
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Re: Low octane fuel or High octane fuel??

Watch the race gas.If it's not low lead race gas and you try to get every last rpm out of it when it heats up the lead will form into small lead balls and pound the piston and cylinder to death.Been there done that!! LL aviation fuel is better.But to be honest after trying all the fuels the best was 89 pump.The race gas burns way too slow for these engines.I was using it to try and keep the engines cooler during break-in but because it burns so slow with these engines it made them run hotter.Use pump gas and baffle the cowl right and be happy the motor will last longer I KNOW.
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Old 08-25-2009, 06:10 AM
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Re: Low octane fuel or High octane fuel??

Thanks a lot for the advise guys !! Here on the field everybody always says high octane is better, and they use the avigas (leaded) high octane fuel for all class of engine, so now I know that's a myth, and the true is it can also damage the engine
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Old 08-25-2009, 06:46 AM
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Re: Low octane fuel or High octane fuel??

av gas is bad. DA says not to use it.
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Old 08-25-2009, 08:43 AM
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Re: Low octane fuel or High octane fuel??

Well, this is my real world experience with my DA-150 on Stock Mufflers. Here in Puerto Rico (were Gas is stil gas, no Ethanol crap mixed into it) I started with 87 Octane Fuel and then change to 93 Octane (Shell Defenda or Texaco) and I Notice 4 Things.

An increase of 100 RPM's, Better Transition in the Mid range, Better (lower) RPM's in Idle and the engine run Cooler. This was using Ams-oils Saber (100-1 premix), which I have been using on the engine for almost 3 years and this plane flies every weekend, about 8 flights a Day.

My RPM's reading with a 32x10 on Stock Mufflers on the ground:

1. Full power = 5,880 + - 50 RPMS
2. Extreme Idle (with out shutting down) = 890 RPM's (I have it set up for 970 RPM's)
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Last edited by Hector; 08-25-2009 at 10:49 AM.
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