percentage fuel?

[RoughRiderBX]

My nitro buggy's recommended 16% fuel and i want to put 30% in, what'll happen?

[kingscott]

Your answer: Nothing really if its set up ok! obviously you will have to Re-tune to the car to run on the new mix.

However.....Just use 20% mate, 30% is rather high.

I used to use 25% but ive moved to 20%. I just get a nicer tune out the car and the extra lube always helps look after the engine.

20% Byron will do you just nice mate

Cheers

[Smoothybb]

What size engine? If big block then 30% should be okay but it's recommended you add an extra head shim to lower the compression slightly or you may have problems. I'd stick to 25% tbh, you won't notice a great deal of difference between that and 30%.

[Nitroholic]

If your 'car list' is anything to go by, your motor is a small block motor in a 1/10 scale. 30% nitro is a waste in that size engine. Won't do any good. You may need to change glowplug to get good running as with higher nitro % you should go fora cooler plug, as well as considering adding a shim to lower compresion a touch. Your engine isn't designed to run on it, so don;t expect it to be faster.

[PRAETORIAN]

My nitro buggy's recommended 16% fuel and i want to put 30% in, what'll happen?

It depends on the size of the engine to be honest.

Personally I would keep to 16% for any engine sizes from .12 .15 engines and possibly RTR grade 20% in a .18 engine. (depending if it tunes ok)

I would use 25% in .21-.28 engines in a buggy/truggy and possibly 30% in .28 engines and above in something like a monster truck. (again depending if it likes it. A friend of mine pointed out the Losi XXL .28 loves 30% - which I now use instead of 25%. Other engines/MT's may not take to it as well)

The basics on fuel/plugs:

The more nitro content, the cooler the plug you will need. (thicker element to cope with the higher combustion temperatures from the higher % nitro). Colder plugs can be a bit ropey and harder to tune though. For fuels with nitro content 20%-25% I would use a medium or medum-hot plug, depending on how the engine is running. For fuels 16% and less I would use a hot plug. Generally higher nitro % means you will need a colder plug to get a consistent tune and the lower the nitro % fuel you will need a medium - hot plug.

Also, check your engine manufacturer as some engines may need an additional head shim to cope with 30%+ fuels.

Now for the technical part.....

Big block engines (.21-.30+) running on 30% fuel can and will run cooler than the same engine running on 20% fuel if tuned properly. It varies by fuel brand and how much oil is in the mixture (and castor : synthetic ratios) but generally a higher % nitro means you can run a bit richer, but still get good power delivery because of the higher nitro content in the fuel by volume. Because you are running slightly richer your engine will run cooler as the oil in the engine (and to some extent the evaporation of the nitro/methanol in the fuel)can transfer heat out of the exhaust. However, running richer can foul up your glow plug if you havent got your tune spot on, so be aware of that. A lot depends on ratios and there are going to be a lot of engine /fuel / air mixture combinations so take what I am saying with a pinch of salt and experiment on your own set up specifically.

However......Smaller engines cant retain heat as efficiently as a bigger engine and so generally need lower nitro/oil % in their fuel along with a hot plug to aid combustion (as the combustion chamber is smaller it cools down a lot quicker so a hot plug aids the fuel to combust as does the lesser cooling effect from less oil / nitro % in the fuel. Also a smaller engine on a lower fuel % will generally need to be tuned a bit leaner. Now if you introduced 30% fuel to a .12 engine you would not be able to run rich as the engine would not be able to retain enough heat for the fuel to keep combusting (I think you would struggle even if you tried using a cooler plug). It would just bog down and stall, but if you did manage to get it going, I doubt it would run very well at all. The other side of the coin is if you lean it out the higher nitro % would mean the combustion generates far too much heat, the result of which is your glow plug melts away (hotter plugs use thinner elements) and/or you cook your engine. If you used a colder plug and run lean, your engine may run, but it would run so hot it would cook itself after a tank of fuel. Either way 30% fuel in a small block engine is never a good idea.

Hope this helps.

Cheers

Edited October 13, 2011 by PRAETORIAN

[CHUNKERLUV]

Yeah....what Matt said lol

[Jumper]

It depends on the size of the engine to be honest.

Personally I would keep to 16% for any engine sizes from .12 .15 engines and possibly RTR grade 20% in a .18 engine. (depending if it tunes ok)

I would use 25% in .21-.28 engines in a buggy/truggy and possibly 30% in .28 engines and above in something like a monster truck. (again depending if it likes it. A friend of mine pointed out the Losi XXL .28 loves 30% - which I now use instead of 25%. Other engines/MT's may not take to it as well)

The basics on fuel/plugs:

The more nitro content, the cooler the plug you will need. (thicker element to cope with the higher combustion temperatures from the higher % nitro). Colder plugs can be a bit ropey and harder to tune though. For fuels with nitro content 20%-25% I would use a medium or medum-hot plug, depending on how the engine is running. For fuels 16% and less I would use a hot plug. Generally higher nitro % means you will need a colder plug to get a consistent tune and the lower the nitro % fuel you will need a medium - hot plug.

Also, check your engine manufacturer as some engines may need an additional head shim to cope with 30%+ fuels.

Now for the technical part.....

Big block engines (.21-.30+) running on 30% fuel can and will run cooler than the same engine running on 20% fuel if tuned properly. It varies by fuel brand and how much oil is in the mixture (and castor : synthetic ratios) but generally a higher % nitro means you can run a bit richer, but still get good power delivery because of the higher nitro content in the fuel by volume. Because you are running slightly richer your engine will run cooler as the oil in the engine (and to some extent the evaporation of the nitro/methanol in the fuel)can transfer heat out of the exhaust. However, running richer can foul up your glow plug if you havent got your tune spot on, so be aware of that. A lot depends on ratios and there are going to be a lot of engine /fuel / air mixture combinations so take what I am saying with a pinch of salt and experiment on your own set up specifically.

However......Smaller engines cant retain heat as efficiently as a bigger engine and so generally need lower nitro/oil % in their fuel along with a hot plug to aid combustion (as the combustion chamber is smaller it cools down a lot quicker so a hot plug aids the fuel to combust as does the lesser cooling effect from less oil / nitro % in the fuel. Also a smaller engine on a lower fuel % will generally need to be tuned a bit leaner. Now if you introduced 30% fuel to a .12 engine you would not be able to run rich as the engine would not be able to retain enough heat for the fuel to keep combusting (I think you would struggle even if you tried using a cooler plug). It would just bog down and stall, but if you did manage to get it going, I doubt it would run very well at all. The other side of the coin is if you lean it out the higher nitro % would mean the combustion generates far too much heat, the result of which is your glow plug melts away (hotter plugs use thinner elements) and/or you cook your engine. If you used a colder plug and run lean, your engine may run, but it would run so hot it would cook itself after a tank of fuel. Either way 30% fuel in a small block engine is never a good idea.

Hope this helps.

Cheers

that is all you ever need to know about fuel percentage!

[Dan13]

Tbh if youre bashing then just use 16%, i use 16% on my hyper 21 engine and it runs lovely. Racing then i agree 25% or maby 30% with a head shim, but dont expect long life. Byrons and optimix fuel good, but i use cheap model technics 16% duraglo and my engines run great, idle fine, mid range a tad to ricj and top end perfect. Its all down to how much time you spend setting your needles up really.

[Smoothybb]

I totally disagree with all but the byrons and optimix comment. You will certainly notice a difference when bashing between 16 and 25% and to a lesser extent 20% Neither 20 nor 25% will harm a big block engine. Tuned correctly the engine will run cleaner and well within it's tolerances and running a lower % won't, on it's own, increase the life of the engine. For a start, consider the mix/quality of oils in the more expensive fuels. Each to their own but duraglo isn't even up to much as a weed killer.

[adolf hamster]

personally, i run 25% byrons on any engine thats .18 or bigger. bigger % tends to make it easier to tune, although when it comes to power, i'm not entirely convinced it makes much real difference [until you start talking full on race engines]

[Smoothybb]

I definitely saw a difference when I jumped from 16 to 25, just a sweeter engine all round. Less so on 20 but it still sounds like the engine is holding back a bit. I don't think you need to be talking race engines to see quite a difference between 16 and 25.

[PRAETORIAN]

I totally disagree with all but the byrons and optimix comment. You will certainly notice a difference when bashing between 16 and 25% and to a lesser extent 20% Neither 20 nor 25% will harm a big block engine. Tuned correctly the engine will run cleaner and well within it's tolerances and running a lower % won't, on it's own, increase the life of the engine. For a start, consider the mix/quality of oils in the more expensive fuels. Each to their own but duraglo isn't even up to much as a weed killer.

Are you saying you disagree with everything in the thread, or just what Dan13 wrote?

Cheers

[Nitroholic]

Just the comment above is what Smoothybb was referring to.

Properly tuned, a big block engine will run happily on 20-25% nitro...and I found my larger motors ran cooler and sweeter on 25% compared to 20% when run with the correct grade plug. There is no loss of engine life as a result. You can run these motors on 16% and they will run, but it's not going to make them run better.

Engine life is as much affected by fuel quality as nitro %. Do a bit of research and it will tell you which fuels use what percentage of oils in their mix, and whether it is synthetic, semi or mineral based. This has a big impact on longevity. Higher percentager oils will run smokier and potentially give less ultimate power....but will help engine life. Lower oil content will burn cleaner. You could have a fuel with 10% oil, 20% nitro and the balance is methanol. You could have a fuel with 10% oil, 30% nitro and the balance Methanol. Both will give the same lubrication, and hte extra nitro will help to reduce temperatures....so the 30% may actually make your engine last longer....But it isn't that simple.

Try putting away the Duraglow stuff and buy a small quantity of 25% Byrons or Optifuel. See how your car runs once you tune it properly to that fuel.

[Smoothybb]

Are you saying you disagree with everything in the thread, or just what Dan13 wrote?

Cheers

Yeah yeah everything!! No, just Dan's comments. Yours was was full of facts that I wouldn't dispute.

[Dan13]

fine, but have tried 25% and bashing it wasnt worth the price difference. My opinion. My hyper engine runs sweet on 16% duraglo and screaams. yes 25% fuel it revved up better and held a slightly better tunes, ran a gallon through it without a re tune but im happy with 2 litres per re tuned tbh. Ypou may dissagree and thats fine, but this is what i find.

[HATZY]

I run byrons in my trx15 that i have in my 4tec atm. Its 25% but the engine is gettin on and needs a pinch. It runs nice on it so its not gospel that high % fuels should only be used with big blocks. In some cases like my trx, the higher % fuel compensates for the lack of compression

[Nitroholic]

I wouldn't advise anyone to do that though Henzy. In your case, you know why you are doing it and the consequences of increased wear don;t really matter as you know your motor is at teh end of it's life and this is squeezing a bit more use out of it

Wouldn't do it to a healthy motor though.

[johnboybelfast]

On 13/10/2011 at 11:06, PRAETORIAN said:

 

It depends on the size of the engine to be honest.

 

Personally I would keep to 16% for any engine sizes from .12 .15 engines and possibly RTR grade 20% in a .18 engine. (depending if it tunes ok)

 

I would use 25% in .21-.28 engines in a buggy/truggy and possibly 30% in .28 engines and above in something like a monster truck. (again depending if it likes it. A friend of mine pointed out the Losi XXL .28 loves 30% - which I now use instead of 25%. Other engines/MT's may not take to it as well)

 

The basics on fuel/plugs:

 

The more nitro content, the cooler the plug you will need. (thicker element to cope with the higher combustion temperatures from the higher % nitro). Colder plugs can be a bit ropey and harder to tune though. For fuels with nitro content 20%-25% I would use a medium or medum-hot plug, depending on how the engine is running. For fuels 16% and less I would use a hot plug. Generally higher nitro % means you will need a colder plug to get a consistent tune and the lower the nitro % fuel you will need a medium - hot plug.

 

Also, check your engine manufacturer as some engines may need an additional head shim to cope with 30%+ fuels.

 

Now for the technical part.....

 

Big block engines (.21-.30+) running on 30% fuel can and will run cooler than the same engine running on 20% fuel if tuned properly. It varies by fuel brand and how much oil is in the mixture (and castor : synthetic ratios) but generally a higher % nitro means you can run a bit richer, but still get good power delivery because of the higher nitro content in the fuel by volume. Because you are running slightly richer your engine will run cooler as the oil in the engine (and to some extent the evaporation of the nitro/methanol in the fuel)can transfer heat out of the exhaust. However, running richer can foul up your glow plug if you havent got your tune spot on, so be aware of that. A lot depends on ratios and there are going to be a lot of engine /fuel / air mixture combinations so take what I am saying with a pinch of salt and experiment on your own set up specifically.

 

However......Smaller engines cant retain heat as efficiently as a bigger engine and so generally need lower nitro/oil % in their fuel along with a hot plug to aid combustion (as the combustion chamber is smaller it cools down a lot quicker so a hot plug aids the fuel to combust as does the lesser cooling effect from less oil / nitro % in the fuel. Also a smaller engine on a lower fuel % will generally need to be tuned a bit leaner. Now if you introduced 30% fuel to a .12 engine you would not be able to run rich as the engine would not be able to retain enough heat for the fuel to keep combusting (I think you would struggle even if you tried using a cooler plug). It would just bog down and stall, but if you did manage to get it going, I doubt it would run very well at all. The other side of the coin is if you lean it out the higher nitro % would mean the combustion generates far too much heat, the result of which is your glow plug melts away (hotter plugs use thinner elements) and/or you cook your engine. If you used a colder plug and run lean, your engine may run, but it would run so hot it would cook itself after a tank of fuel. Either way 30% fuel in a small block engine is never a good idea.

 

Hope this helps.

 

Cheers

Great thanks 👌