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50% nitro

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Car God

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I have run a Traxxas pro .15 and bored out the ports on the sleve. A friend of mine makes his own fuel to run in his boats ( and currently holds the record for 10th scale speed at 123mph) gave me a gallon of 50% nitro to try. I use Mccoy #9 and #59 glow plugs, and my truck runs like crap. I've tried to lean it as much as possible and even tried to richen it up. I even went as far as making a home made air intake. Does anyone have any ideas of what to do?



.:bandit:
 
I have never run anything less than 30 and all my vehicles have allways run better with 30 instead of 20.

.:bandit:
 
Arn't you the guy that has the super Pro .15 that would smoke any other .15 ?
 
Small point of fact: Most .15 engines, modified or otherwise, are originally designed to run in the 10-30% range for nitro content. 50% is just a bit over that range, to say the least. To make 50% workable in these engines, you'd have to do some serious modifications...a port job is not going to cut it.
 
I suggest sticking within the parameters that the engine is designed for; unless you can afford you experiment on your engine.

If you want to go for speed within the design parameters of the engine, lean it up for performance on the engine side and then gear the tranny, spur and clutch appropriately for speed. Otherwise, you are looking at some kind of frankenstein job on the .15 engine (bigger carb and stronger internals with increased chamber size).

The higher fuel percentage will require a stronger combustion chamber and a slightly larger volume to handle the extra exhaust gases that the combustion process would generate. This means you will most likely need to bore out the engine to a larger size (which will weaken it...so you need to find a way to make the thing stronger but larger**) and get a larger piston (and stronger con rod and the rest of the internals).

**You might check and see if the .21 engines can handle the fuel...or ask your buddy what he did to his engine to make it handle the 50% nitro. I wouldn't be surprised if he is running a larger displacement engine than a .15.
 
Well he races boats in a .21 class and i've run the 50% in a 1/8th scale buggy with a picco .21 and it hauled ass. I just don't want to have to get a conversion kit to increase speed and power. It allready has beaten the new 2.5 But i want more you know.

:bandit:
 
As I suspected, a .21.

If you want to get more top speed within the .15 engine size, your only other option after doing a quality port job is to regear the drive train for top speed. That means a getting a larger clutch bell (for a more dramatic increase) or a smaller spur gear (for a not so dramatic increase). A combination of a larger clutch and smaller spur can also be very affective. You can go to this link for more information on gear ratios and their impacts:

http://www.maxxskunkworks.com/TechRefGearing.htm

http://www.maxxskunkworks.com/SpeedCalcSheet.htm

These are on Retread's site and are very informative.
 
There is one thing most people over look and thats port matching your header. You can do all the work on the inside of your engine you want but is the spent gasses can't get out all the work you did is for not.
 
Nice catch Hunter...I always forget to mention that little tidbit, yet I do it to all of my headers when I end up replacing them. A couple of minutes with a dremel tool and you get a little extra oomph out of the engine.
 
I'll give it a shot and let you know how it works,
Thanx guys.


.............:bandit:
 

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