SaK610

Hello, i am sorry if this was asked before, but i was wondering what nitro % are acceptable in nitro cars, or more specifically can i run 25% nitro fuel in cars or is the mix for planes/helicopters? Thanks in advance.

-Inverted-

You can, however 20% is prime. Anything lower reduces the power the engine can create, anything higher increases performance in trade that your engine will not last as long.

i8tweety

My Feedback: (11)

25% plane fuel will run just fine in a "buggy" engine. You shouldn't notice any difference in either performance or engine life.

-Inverted-

Really, I was always told that running a higher nitro content reduces the life of the motor?

Dawman

My Feedback: (33)

You will notice a difference in performance and if it is airplane fuel , don`t use it .

J_Bone

My Feedback: (1)

Don't use plane fuel, even if it has the same amount of Nitro. The oil is differnet and in differnet %'s.

FYI..I've ran 30% in all my .21 size and over. I have a RG with over 5 gallons on it and it's still running and all others have at least 8 or more gallons.
But if you are using a small block like a .12, use 20%. 25% will run good in a .18, but keep checking the top of the piston for detonaton. You will see small pits on the top of the piston. If so, you need to shim the head.

ryan_t888

I run boat fuel, 25% Nitro, 20% oil and never had a problem. The plane fuel I use in my plane consists of 15% Nitro and 16% oil. I don't have a problem using that as well.

I would say 25% Nitro is the border line between using a cold plug(or extra shim) and a hot plug. Mostly depends on how your engine is shimmed and engine wear.

I also rarely come across plane fuel with 25% or more Nitro. Typically 0-15% and sometimes 20% Nitro is made specifically for planes.

Ryan

J_Bone

My Feedback: (1)

The oil % is high! For cars, 8-12% is ideal. Anything above and it runs hot and boggish. You won't get much performance out of 20% oil in a land engine.

.. Don't get me wrong. It will run on it and if you don't know how it runs off other fuel you probalby don't know the difference.

ryan_t888

I have used fuel with proper % oil and don't see much of a difference tunning wise and performance. Some car manufactures specifically say "16% or more oil for this engine."

I will do a speed/acceleration test using car/boat/plane fuel tomorrow.

Ryan

digifox

well really that % you see it the oil content

J_Bone

My Feedback: (1)

Does your cars smoke like a 1:1 car that sucked a ring? every heli or plane I see has a bunch of smoke spewing out. That's from the high oil %. Cars don't run at long periods of time like a Heli or Plane does so you don’t need that much oil.
If you tuned them right, you will see a BIG difference!

SublimeJason

Provider Name:
Written By: Horizon Engineering Manager John Adams
Copyright:© 2004 Horizon Hobby, Inc.

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.



More Info Here,

http://www.horizonhobby.com/Search/A...earchTerm=fuel

NitroRage

Thanks for the Great Info on RC Nitro fuel!!!!!!! I'm sure going to check my fuel after reading your post.

Viper_t3

If you use 25%, dont use 20%, I was told never to run lower then what you are running now.

Dawman

My Feedback: (33)

As long as you clean the tank out from the previous fuel , it will be ok .

SublimeJason

Viper-t3's right, if you go Up in nitro % you shouldn't go back down,
The reason for this, is 20% nitro will run hotter and produce less power than 30% or higher nitro, but it changes the expansion of the pinch area of the sleeve.
This means that the pinch area expands more with 20% nitro than with 30%+ nitro. If you switch to 30%, the motor will run cooler, and the pinch area will not expand as much, maintaining your compression.
That's why a lot of racers will up the nitro percentage when they know the motor is losing compression, just to keep it running for a couple of more races (if they're lucky and they don't blow it up).
Going from 30%+ nitro to 20% nitro is not good for the motor. Since it ran and broke in at a cooler internal sleeve temperature, the sleeve and piston have a tighter wear pattern, as the sleeve has not expanded as much as it would have running 20%.
Switching to 20% will run hotter, expand the pinch area more, causing a loss of compression.
Higher nitro content produces more power, and runs cooler. However, more power means, less forgiving on tuning, and a chance of detonation if you're not running the proper head clearances. The higher the nitro, the better your tuning skills have to be, as it is less forgiving, and that could get expensive in a hurry.

ryan_t888

I have an 8 oz tank im my boat and it runs for less than 8 minutes. In my plane I have a 12oz tank and it runs less than 10minutes. In my car I have a 4oz tank and I get 15-20 minutes of runtime.

My boat/plane engines are between 3-6 times bigger than a standard .15 size car engine. This means it does burn more oil and fuel giving off more smoke. Heli's hover spewing a lot of smoke at 16000 RPM in one place. That is also a huge factor of why a dense amount of smoke is seen.

With my boat, I race using 60% nitro and when I run for fun I use 15%. I constantly change from 15-60% in the summer, have used well over 6 gallons of fuel and still have this engine. Sounds a bit steep but I am doing it without a problem.

I conducted a speed/acceleration test with 4 different fuels. A Garmin Geko was used to clock the top speed. Testing was on the same day with a new plug each run. Top speed was averaged between 3 runs. Sequence was Fuel 1, Fuel 2, Fuel 3, Fuel 4 then repeat.

“Proper” Race Fuel:
Exact product http://www2.towerhobbies.com/cgi-bin...&I=LXBBS3&P=ML
Cool Power 20% nitro 10% oil
A maximum of 73.7km/h was achieved with the cleanest/crispest acceleration out of all the fuels. ( max temp = 279F )

Klotz 15%Nitro 20%oil
Top speed of 71.7km/h. Acceleration was clean but careful tuning was needed.
( max temp = 291F )

Klotz 25%Nitro 20%oil
Top speed of 77.2km/h. Acceleration was clean and very strong but careful tuning was needed. ( max temp = 277F )

Wildcat 15% nitro 16% oil
Exact fuel: http://www2.towerhobbies.com/cgi-bin...?&I=LXA299&P=7
Top Speed of 73.2km/h. Acceleration was very good. Wider range for error when tuning compared to the previous 2 fuels. ( max temp = 287F )

Tuning seemed to be dependent on the amount of nitro in the fuel. When more nitro was used a richer needle setting was demanded. This took a whole morning to do and I now have 4 used plugs but it was very interesting to see the end results. Many factors need to be recognized as results vary from fuel brand to car engine ect.

Ryan