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Old 03-01-2006, 06:17 PM   #1
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Default Help! Max modeified .21 fuel high conmumption

Hi,

I have a Max modified .21 on road engine, the problem with the engine has high comsumption.... .each tank only last about 4 mintues and 40 seconds.
Temp is running around 200 degree. The engine is running fine...

Is anything i can do or check to improve the fuel consumption? Because each qualify runs for 5 minutes and i cannot even finish it without refuel.

Thanks.
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Old 03-01-2006, 07:05 PM   #2
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How hot is the weather there? I would suggest to take the temperature up to 220-240. Should give you just about the 5 minutes. Also, before starting the qualify, fuel up and try not to go fast on the lap before starting your time. You could also try a longer fuel line with a fuel filter.
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Old 03-01-2006, 07:09 PM   #3
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First you could lean your engine a bit more. 200 degrees is cool even for a newer .21 motor (my R1 had its last 2 break-in tanks run at 200 degrees at close to full throttle done by one of the top 1/8 racers in the US). Remember temp is a guideline not a rule and every engine is different.

If your running 30%, drop down 20% nitro. Try a longer header (also remember a conical header will make the engine use slightly more fuel). Fuel consumption also depends on what pipe you are running. Also try the INS box (less air means you need less fuel for the same air/fuel ratio). You could also soften the punch on your clutch (slightly earlier engagement).
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Old 03-01-2006, 07:19 PM   #4
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WHAT FUEL ARE YOU USING? make sure use 20-30%nitro and no more than 14%oil. we race with 10-12%oil here.

also throttle control helps alot.
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Old 03-02-2006, 07:53 AM   #5
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Like changing the insbox to reduce the air getting to the engine you could try some smaller venturis. i think 9mm is standard so try using an 8mm to see if you can get the extra few seconds.
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Old 03-02-2006, 06:15 PM   #6
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First I will lean out a bit more and use a 8mm restrictor. In US INS box is not mandatory in most races therefore I will try to avoid using it unless necessary. That will give you 5-10 secs. If not enough then you will need to look into header. If you use max pipes 2017 or 18 you need to be careful. 18 have less fuel consumption but slower, 17 have good accleration but takes in more fuel. also max pipes comes with the shortest header therefore you may need to change to a 6 ring header (NR) for less top end. Also try to slow down your idle a bit and it will also give you run time. Try and see what happens

Quote:
Originally Posted by US_MATRIX
Hi,

I have a Max modified .21 on road engine, the problem with the engine has high comsumption.... .each tank only last about 4 mintues and 40 seconds.
Temp is running around 200 degree. The engine is running fine...

Is anything i can do or check to improve the fuel consumption? Because each qualify runs for 5 minutes and i cannot even finish it without refuel.

Thanks.
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Old 03-02-2006, 07:02 PM   #7
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Do I hear a parrot in here??? ...

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Old 03-04-2006, 03:31 AM   #8
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Thanks for all the suggestion!

I will try to lean out the high end little bit more and adjust the idle as well.
I am using the Max turbo pipe (I guess is the illegal one has longer header)

What does the restrictor do? More top end? What happen if i remove it or change to smaller size like 8mm?

Thanks.
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Old 03-04-2006, 07:20 AM   #9
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Length of the header doesn't make a pipe illegal. I'm not familiar with the MAX pipe.

Changing the restrictor changes how much air goes into the carb (ins box does the same thing in a less controlled way). A smaller restrictor will reduce the amount of air, thus a little less top end but better fuel efficency. A bigger restrictor will increase the amount of air, thus a little more top end but less fuel efficency.

As far as staying away from the INS box because most tracks don't require it. I wouldn't bet on that for much longer. Most of the big races are starting to require them, and it will probably be a rule within two years for 1/8 scale (it already is in Europe). Oh yeah, the newer Novarossi engines (or any European engine manf.) are designed around the INS box and a 3 chamber pipe. So you will actually get the full performance of the engine.
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