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Old 03-22-2008, 07:00 AM   #1
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Default 25% vs 30% nitro

In review of some recent 1/8 results at national level races it appears some are using 25% instead of 30% nitro.

Wondering why and what are pros and cons of 25vs30 and vice versa.

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Old 03-22-2008, 07:12 AM   #2
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Old 03-22-2008, 07:55 AM   #3
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25% gets better fuel milage.
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Old 03-22-2008, 08:16 AM   #4
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Doesnt 25 also run cooler?
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Old 03-22-2008, 09:10 AM   #5
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25% gets better fuel milage.
At the very top level of racing all the cars really have no speed advantage. The only edge you have left is run time. 25% will give you a little bit more run time vs 30% and it should run slightly cool. This really comes into play on a extremely hot day when everyone is trying to make run time.
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Old 03-22-2008, 09:16 AM   #6
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25% in my opinion, with really good fuel (Byrons,Tornado, Maxy's,Werks) has a simular tune like 20%; temps like 20%; but has a snap like 30%.
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Old 03-22-2008, 10:18 AM   #7
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The way it was explained to me...

In all other parts of the world 1/8 scale is limited to 25% nitro (IFMAR rule)

Since all of the engines are made overseas (mostly Italy) they are designed to run on 25%.

So it's just logical to run 25%.

I do know of a couple people who tried 40%, but gave up on it very quickly.
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Old 03-22-2008, 12:02 PM   #8
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I still don't understand
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Old 03-22-2008, 12:59 PM   #9
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Originally Posted by Jamie Corrado View Post
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Whats so secret you do not want to share ?

But 25% is becomming a worldwide (maximum) standard for 8th scale racing as also adapted on world championships.
Over here in europe 20 or 30% which you can get is most used in monstetrucks and mostly they do contain more oil.

25 or 30% nitro will not make a difference in performance for an avarage racer the difference in costs is better shown.

The EFRA already showed plans to lower the Nitro content and maybe next year we will run on 16% nitro.....
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Old 03-22-2008, 04:29 PM   #10
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Why are they thinking of going back to 16% in the 1/8 scale?

Because in the top level of RC racing there is a big difference between 16% or 25% (more power) which you are using nowadays..during tournaments. Going to 16 % nitro has to affect your speed. Resulting in lowering speeds am i right?
More nitro gives you a bigger explosion and more speed, with some rearrangements in gear ratio etc.

The only advantage you will have is that there is more methanol then, so that gives u longer running times. But i don't see why the Efra wants to go back to 16 %..
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Old 03-22-2008, 04:37 PM   #11
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I still don't understand
30 % Nitro or higher vs 25% Nitro or lower

The flame speed of Nitro is much slower than that of Metanol, so by adding Nitro the mixture slows the flame speed. This should not be a problem until you hit very high rpmís. There's a moment where the engine cannot pickup more rpmís because it needs to burn the mixture at much higher speed in the combustion chamber.

30% nitro burns at a lower temp so it will give you advanced timing and therefore more low end power.

With lesser nitro, you may need to lean it a little more and your fuel mileage will be a little better, temps will vary and combustion chamber and carb setup need to be revised, but... more nitro doesn't necessarily mean more power, but yes more fuel consumption and less runtime for the same CCís.

Higher nitro content does not cool the engine, in fact it creates more heat. Basically, more nitro = more oxidizer to the methanol which in turn creates higher combustion pressures which create more heat.

On the other hand, higher oil content will cause cooler running, because the oil tends to help with heat transfer and expulsion, so the more oil the cooler the engine will run (to a point of course), too much oil will cause the mixture to be mandatory leaner to run properly, thus bringing the heat back.

You donít get full RPMís with 30% nitro as you would with lower %.
With 30% you naturally have to richen the engine, it gives you more low end power due to the 30%...but just not all the power at top speed.
With lower % nitro you can lean it out for more top end power.

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Old 03-22-2008, 04:50 PM   #12
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Originally Posted by snowmansion View Post
Why are they thinking of going back to 16% in the 1/8 scale?
And 16% would be the first step to take it down to........ 0%

It is for noise limiting and nature envirement, Nitro is not a very healthy product although I believe one diesel truck is poluting more than rc racing in the hole country.
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Old 03-22-2008, 07:01 PM   #13
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Quote:
Originally Posted by afm View Post
30 % Nitro or higher vs 25% Nitro or lower

The flame speed of Nitro is much slower than that of Metanol, so by adding Nitro the mixture slows the flame speed. This should not be a problem until you hit very high rpmís. There's a moment where the engine cannot pickup more rpmís because it needs to burn the mixture at much higher speed in the combustion chamber.

30% nitro burns at a lower temp so it will give you advanced timing and therefore more low end power.

With lesser nitro, you may need to lean it a little more and your fuel mileage will be a little better, temps will vary and combustion chamber and carb setup need to be revised, but... more nitro doesn't necessarily mean more power, but yes more fuel consumption and less runtime for the same CCís.

Higher nitro content does not cool the engine, in fact it creates more heat. Basically, more nitro = more oxidizer to the methanol which in turn creates higher combustion pressures which create more heat.

On the other hand, higher oil content will cause cooler running, because the oil tends to help with heat transfer and expulsion, so the more oil the cooler the engine will run (to a point of course), too much oil will cause the mixture to be mandatory leaner to run properly, thus bringing the heat back.

You donít get full RPMís with 30% nitro as you would with lower %.
With 30% you naturally have to richen the engine, it gives you more low end power due to the 30%...but just not all the power at top speed.
With lower % nitro you can lean it out for more top end power.

AFM
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