PIT TALK (Bulletin 6) Nitro the facts & thought
Baldwin Racing
For many years I have been asking myself the question of how far can a person really go with adding Nitro before you get no were in power but yet get poor very quickly.
Well, the truth is near. Many people over the years have said to me that 5% makes a difference and then if you want to make any further impact you need to go to at least 20%. I myself have even said that in my time. That is not true.
Tests have been run on a dyno where Nitro was added in increments of 10% right up to 70% Nitro content and the following.
10% Nitro 8% power increase
20% Nitro Another 8% increase in Power
30% Nitro Another 8% increase in Power
40% Nitro Another 8% increase in Power
50% Nitro Another 8% increase in Power
60% Nitro Another 8% increase in Power
70% Nitro Another 8% increase in Power
Very High motor temperatures where experienced at 70% Nitro and prolonged running at that high value of Nitro would most probably damage your motor. What was not expected was that the EGT (Exhaust Gas Temperature) stayed basically the same with all % of Nitro added.
I would like to thank Marty Davis for giving me this information from his extensive experience and knowledge in Dyno testing. Not only that he has published many bits of information that many people would never have been able to know. This I am sure has helped the boaters tremendously. I say thank you to Marty and may you have many more exiting years in this field.
But now with this information we ask ourselves why does my boat then not go faster when I add 10% more Nitro. Well, it does if you set your motor up correctly to accommodate the increased Nitro. Together with that it is important to know that the power required to go faster is not linear. In other words 8% more power will not give you 8% more speed. In fact it may only give you 1% more speed.
For your motor to perform correctly with increased Nitro you need to lower your compression ratio, Richen up your fuel mixture and play with your Tunepipe.Obviously this is over simplified but at least you can understand the concept.
There is one fact that has not been spoken about and that is the Nitro itself. We must all keep in mind that when we speak about Nitro it is a combination of Nitro and Methane (CH3NO2). When the man in the street talks about 98% Nitro it is actually a mixture of Nitro and Methane in a ratio of about 65%/35% mix. That would be a simplified explination. But we need not worry as we are all using more or less the same sort of product. The genuine Nitro product is bottled in brown glass bottles and I have never seen it bottled in bigger quantities than 1 liter bottles. That too is normally mixed with 2% Methane to keep it stable. We are buying 99% Comsol which is that 65/35 mix stated above.Do not worry, you are not being ripped off as if you had to buy the genuine product you would pay round 30 pounds/liter instead of the approximate 10 pounds/liter at present.
That explains why you can go so high and still get effective combustion as 70% Nitro is actually only about 45% and thus you still sit with another 45% combustible and say 10% lubricant.
Why EGT (exhaust Gas Temperature) stays the same yet you get more power with increased Nitro?
Please note that the following is my opinion only and welcome comment : Nitro has NO2 which is very dense as we all know. As we also all know that the more fuel we put into the motor the more it helps cool the motor ( note that this is not the combustion area yet) on its way to the combustion area it cools the motor. Adding Nitro also requires a richer mixture for combustion hence putting more "cooling agent" through the motor.This brings me onto the next point of when it reaches the combustion area.
The added volume of "fuel" and air that enters the chamber and then gets compressed. (Note that the additional dense volume of fuel will have a natural effect of increased compression, thus the required reduction in compression ratio is required) This creates the required heat to start the thermal reaction of converting the Fuel/air combination into the burnt gases namely CO, CO2, NO2, NO3 and H2O.
When NO2 and NO3 (known as NOX) is created as a result of combustion an Endothermic reaction is taking place which is basically a heat absorbing reaction. Then why the extra power. Power is not only heat but is the molecular transformation that is taking place where the dense liquids change into gasses.With more Nitro you have more dense molecules expanding into NOX and other gasses creating a heat absorption and increased pressure hence your power with similar temperature. This is once again over simplified but helps explain what is possibly happening.
Remember that more power however generates heat on its own and your engine is designed to be able to dissipate a certain amount of heat "losses" and once you exceed that capability you will get a thermal runaway and "boom". Take for example when your car starts to overheat. Once it starts overheating it just runs away from you and you end up with a car on the side of the road that needs repair.
It is very possible that at 70% Nitro you are well within that region. Short bursts of power would not make any real affect but to run continuos for 20 minutes you had better look at your cooling.
Hope this has stimulated your thought.
Enjoy your boating and happy experimenting.
Compiled by Gary Baldwin
Last Updated on 03 Apr 2001
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