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Difference between car and plane fuel?

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Old 03-26-2007, 05:51 AM
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Captain Ribs
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Default Difference between car and plane fuel?

I have a friend who has a Thunder Tiger MTA4 (two stoke engine) and he was wondering what the difference is between car and plane fuel. Is the nitro content (more, less) different? Given the added expence when buying car fuel as opposed to plane fuel, we figured their must be something different. Any one with an explanation.

Cheers,
CR
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Old 03-26-2007, 06:44 AM
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DaveG55
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Default RE: Difference between car and plane fuel?

All nitro rc fuel is made of the same three ingreadiants. Nitromethane, Methanol and oil. The differences are in the percentage of nitro used and the percentage and kind of oil used. All the planes my father flew used a fairly low percentage of nitro, like zero to 10% and used a natural castor oil. The trucks and cars we run are in a different enviroment and are treated much more harshly than a plane engine and the performance demands are also much greater. So we usually run a higher nitro content, 20% - 30% usually, and the oil is usually a combination of synthetic and natural castors, sometimes with special additives, depending on what the manufacturer wants to accomplish. The amount and kind of oil used will make a big difference in how a fuel burns and how it protects an engine and is usually the biggest difference in fuels designed for different applications.
So, if you want, you can indeed run plane, heli or boat fuel in your car or truck and it will not really hurt anything. But if you want the best performance and protection go with what has been formulated for the kind of engine you are running.
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Old 03-26-2007, 11:10 AM
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Default RE: Difference between car and plane fuel?


ORIGINAL: Captain Ribs

I have a friend who has a Thunder Tiger MTA4 (two stoke engine) and he was wondering what the difference is between car and plane fuel. Is the nitro content (more, less) different? Given the added expence when buying car fuel as opposed to plane fuel, we figured their must be something different. Any one with an explanation.

Cheers,
CR
Airplane engines see a totally different type of rpm load than cars. Airplanes run at a relatively low rpm, and see a consistant, linear engine load. Airplane fuel is usually lower 15% nitro content, and higher 15% oil content. You can run plane fuel in a car, but the engine will run like a terd.
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Old 03-26-2007, 12:30 PM
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Default RE: Difference between car and plane fuel?

Car Fuel Facts
If you read the R/C car magazines, engine instruction manuals or talk to local racers, you'll likely find conflicting information about car fuels. The main controversy seems to focus on how much and what type of oil is needed for a car fuel.

Here the straight scoop based on over 15 years of experience that includes working closely with engine manufactures, industry experts, top-level racers and the results of testing literally hundreds of formulas in all types of car engines and conditions.

Why Not Airplane Fuel

Car engines operate in a totally different environment than do airplane engines. Airplane engines spend a great deal of their running life at full rpm, they have a constant airflow from the prop to aid in cooling and instant throttle response and acceleration is not as critical as with a car engine.

Car engines spend most of their life accelerating from one corner to the next and are seldom at full RPM for more than a few seconds. They rely on an oversize heat sink head to dissipate combustion heat and racers actually tune car engines based on throttle response.

Fuel designed for airplanes typically have from 15 to 20% oil. While the manufactures that truly understand the requirements of car engines typically put 8 to 12% oil in their car fuel.

Why 8% to 12% Oil

Using high oil content fuels (above 15%) in gas car engines won't provide improved engine life, as some would expect. Through extensive testing we've discovered the point of diminishing return as far as oil content to engine life is actually around 8% for most car engines. In other words any more oil than 8% in the fuel does noting to improve the life of a car engine. In fact the secondary effects of high oil content fuels can actually cause engine damage by encouraging over lean runs. Here's how.

Using high oil content fuel causes a car engine to be unresponsive during acceleration acting as if the engine were running rich. Typically when using high oil content fuel, in order to get crisp acceleration and response, an engine will need to be adjusted overly lean. In addition the high oil content prevents lean bog when an engine is over-leaned thus allowing the engine to run at this lean setting without the customary telltale lean bog warning letting you know the engine is overheating.

In summary, high oil content fuels don't give added protection. The point of diminishing return from a protection standpoint in a gas car application is about 8% oil depending on the oil type and engine. Anymore oil than this doesn't offer added protection and has potential secondary effects that reduce performance and can actually cause you to over lean your engine in an attempt to get crisp throttle response and acceleration. Do yourself a favor and follow these two rules:

Rule #1- Always use a high quality fresh fuel designed specifically for gas car use that has between 8% and 12% oil preferably with at least some castor in it. (We recommend Blue Thunder Sport or Race Formula)

Rule #2 - Don't use airplane fuels or any other type of fuels that have over 15% oil in your gas car engine.



http://www.horizonhobby.com/Articles...ArticleID=1318
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Old 03-28-2007, 08:07 PM
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Default RE: Difference between car and plane fuel?

Thanks guys. I have another question or two and will put it up soon. You've explained the fuel situation very well. Thankyou!
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Old 10-20-2017, 05:29 PM
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Bump. I'd like to know who did this testing and what exactly did they use. Way too many variables. Sounds like someone wants to sell fuel with less oil for more money. When my lhs used to sell fuel... The 15% omega was about 17 bucks.... While 20 % car fuel with less oil goes for 30s.
less oil and only 5% more nitro and all these car fuels want 35 bucks a gallon these days.

so a car engine doesn't go wot all the time but it hits 30k plus rpms constantly on and off. This is way harder on an engine than a steady load.

the Aero engines are loaded but not overloaded obviously because they don't overheat. If you go to big on the prop they overheat.

30k plus rpms vs half that in a Aero engine. Fast instant acceleration vs slow build up. I beg to differ and say car engines need alreast as much oil if not more.

Seems most people can't get a car engine to last more than a gallon or 2. While Aero goes on for gallons and gallons.

I think people care about run time more than longevity. If your tune is dead nuts every second on 8% oil you may have decent engine life. One lean run and it's simply done. No arguments. One good overheat and it's a 2 gallon engine at best.

people obviously can't tune because I've ran 20% oil by volume in car engines and they tune just fine. There is so much room for error it's probably overkill but I like breaking in on high oil. Power is only lightly less than at 8 to 10 percent. They actually seem easier to tune with more oil.

you tune the exact same way. Start rich and lean until no more performance and richen from there.

most say more oil runs hotter. I've found it to run about the same. You all must be way lean if you see a significant temp rise. More oil can't make it run noticeably hotter. That doesn't even make sense. By far the biggest factor in cooling is airflow. Put a sock on your head and seem how cool they run. The slight decrease in methanol from more oil wouldn't change the temp. First of all you need to richen the needles in higher oil to get back the same air fuel ratio. So you are running already as much methanol through it because of the richer needles to compensate for more oil.

so someone explain why more oil runs hotter?

I've never seen this with my own testing.

Also castor oil is garbage compared to a good synthetic like Redline which is what I use. Everytime I've run a fuel with lots if castor in a car engine performance becomes sticky for lack of better words. You may not notice it if it's only 1 it 2 percent of the mix or your only running 7% oil. It doesn't have a place anymore. Even using a full Ester synthetic like Redline my 20% could be made for 15 bucks a gallon of I were to use 8% oil. I use more than 8 but for comparison O'Donnell race fuel is more than double the price and I'm not even using super bulk stuff here. I get methanol from a dragstrip for 4.50 a gallon and a gallon of oil is 70 bucks for Redline. Nitro is 210 for a 5 gallon pale in eBay which I have.

we are being gouged and then told to break in our engines cold and rich with low oil and wonder why they don't last.

all ABC airplane engines are broken in full throttle slight rich of peak rpm.

so don't cringe at the idea of full throttle bursts to break in your engine next time. It keeps the pinch lasting if you do this everytime you start the engine. The second it starts I hit full throttle and do a couple laps and it's up to temp within seconds.
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Old 10-21-2017, 04:50 AM
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It seems you don't entirely understand the dynamics between engine types. You should do some more research. It would be of great benefit to you. Look up what Picco and Novarossi recommend for fuel in their engines... They are two of the world leaders in manufacturing race winning world renowned RC engines.
Novarossi's fuel recommendations can be found here: Frequently Asked Questions | Novarossi World - NOVAROSSI WORLD
Picco's fuel recommendations are pictured below.
OS engines are junk and their manuals are written by an idiot, so I won't post that information.
By the way - what brands of engines are you running? What glow plugs (brand and heat range)?

p.s. You will NOT get this kind of performance with airplane fuel (20+% oil and 10-15% nitro) in a car/truck engine once broken in. Not even close.
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Old 03-23-2018, 01:18 PM
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Here's my 2 cents.

I fly planes, helicopters, I'm into pylon racing (planes) and I drive some cars every now and then.

The people saying that a plane engine isn't seeing any abuse because the rpm is constant are wrong. The main reason for the higher oil content in plane fuel is because it is seeing more abuse. Also, lower rpm doesn't necessarily mean less abuse...on the contrary.

You need to run lower oil content because car engines tend to be run a lot richer than plane engines. I can guarantee that a car engine will grenade on you if you run it on 8% oil flat out at max power output. But on cars, if the engine is winding out at top speed, you're not even close to making all the power the engine is capable of. Sure, it's running fast, but it's not making a whole lot of power.
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