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Old 08-04-2010, 09:32 PM
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Default What % of fuel for .21 engine?

I'm new to .21 engine. Which % of fuel should I buy? 20%,25%, or 30%?
I'm going to use Novarossi Plus 21-5K on Losi 8ight-B 2.0.
Let me know, thanks.
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Old 08-04-2010, 09:40 PM
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i would go with 20 % but, get a race bleaded formula 20 % seems to make my engine run cooler and it gives you a wider tuneing window. i have ran 25% before and i cant tell that much of a diffrence.


ge ebmods 20 % race formula if you can.
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Old 08-04-2010, 09:46 PM
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Will Byron or Sidewinder race one nice too?
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Old 08-04-2010, 09:47 PM
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Originally Posted by rcs950racer
Will Byron or Sidewinder race one nice too?


i would go with, byrons fuel i have tried that fuel before and liked it .
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Old 08-04-2010, 10:10 PM
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Originally Posted by rcs950racer
I'm new to .21 engine. Which % of fuel should I buy? 20%,25%, or 30%?
I'm going to use Novarossi Plus 21-5K on Losi 8ight-B 2.0.
Let me know, thanks.
with that motor you need to run either 25% or 30% running any less is going to cause extra stress on the motor, imo i would ask the guy from huston engine service on here what to run, he has his own thread.
20% nitro is not enough to make power with your mill or any mid-high end race mill, they simply are not designed to run that low of percentage of fuel, your going to over stress the rod and your fuel millage will be terrible.
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Old 08-04-2010, 10:24 PM
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30% byrons race gen 2 have always worked great for me never had an issue and isnt as pricey as eb mods...eb mods is a bit more than what a normall club racer would spend on a gollonplus alot of hobby stores carry them theres nothing like goin to a race and expecting to buy fuel because ur low and they dont carry eb mods or torco etc etc.
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Old 08-04-2010, 10:26 PM
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Originally Posted by jsp619666
with that motor you need to run either 25% or 30% running any less is going to cause extra stress on the motor, imo i would ask the guy from huston engine service on here what to run, he has his own thread.
20% nitro is not enough to make power with your mill or any mid-high end race mill, they simply are not designed to run that low of percentage of fuel, your going to over stress the rod and your fuel millage will be terrible.


really i never heard of that one ?

ive ran a nova .21 bf and, now a rb s5 engine thats shimmed for 25% but ive been running 20 % it seems to make enough power.
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Old 08-04-2010, 10:38 PM
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Originally Posted by tc5 man
really i never heard of that one ?

ive ran a nova .21 bf and, now a rb s5 engine thats shimmed for 25% but ive been running 20 % it seems to make enough power.
sluggish bottom tho. and those are sport engines nothing like the engine the guy is running. 30% is needed. i used to not tell the difference but now that ive gotten alot faster and tested the difference, there is a HUGE difference down low but not much up top.... if its shimed for 25 or 30% run that or you will have problems tuning the bottom whether you realize it or not. run byrons 30-9 in that BF and that thing will come alive
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Old 08-04-2010, 10:42 PM
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Originally Posted by jmaxey51
sluggish bottom tho. and those are sport engines nothing like the engine the guy is running. 30% is needed. i used to not tell the difference but now that ive gotten alot faster and tested the difference, there is a HUGE difference down low but not much up top.... if its shimed for 25 or 30% run that or you will have problems tuning the bottom whether you realize it or not. run byrons 30-9 in that BF and that thing will come alive



well ive already got, a gallon of 20% so im not driving a half hour to return it and ebmods doesnt make 25 % anyways.

the s5 might be a, sport engine but it seems to be fast enough for club racing.

i know i can get more bottom end, i just need to lean out the low end more once my first gallon is done.
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Old 08-04-2010, 10:48 PM
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Originally Posted by tc5 man
well ive already got, a gallon of 20% so im not driving a half hour to return it and ebmods doesnt make 25 % anyways.

the s5 might be a, sport engine but it seems to be fast enough for club racing.

i know i can get more bottom end, i just need to lean out the low end once my first gallon is done.
run 30%, its fine, you will still get long engine life. also leaning out the bottom still wont get the bottom the 30% will get, i went with 20% this weekend to get rid of it and i had the bottom so lean that if i leaned it one hour i would get a lean idle, and it still had no snap hardly. i thought my clutch was bad. also running 30% made my engine run about 15 degrees hotter too.
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Old 08-04-2010, 10:54 PM
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Originally Posted by jmaxey51
run 30%, its fine, you will still get long engine life. also leaning out the bottom still wont get the bottom the 30% will get, i went with 20% this weekend to get rid of it and i had the bottom so lean that if i leaned it one hour i would get a lean idle, and it still had no snap hardly. i thought my clutch was bad. also running 30% made my engine run about 15 degrees hotter too.




il try ethier 25 % or 30 % once, i finish my new second gallon i cant waste a whole new gallon.

il just lean out, the low end little by little not any big turns .
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Old 08-04-2010, 10:57 PM
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Originally Posted by tc5 man
il try ethier 25 % or 30 % once, i finish my new second gallon i cant waste a whole new gallon.

il just lean out, the low end little by little not any big turns .
yeah thats why i burned up the rest of my 20%, i didnt want it to just sit there, i used to run 20% in my JPX bc it would snap a rod if you ran 30% bc of the shimming and mad pinch, but it has 9 gallons on it so im runnng 30 on all my engine now, JPX is back up engine.
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Old 08-04-2010, 11:02 PM
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Originally Posted by jmaxey51
yeah thats why i burned up the rest of my 20%, i didnt want it to just sit there, i used to run 20% in my JPX bc it would snap a rod if you ran 30% bc of the shimming and mad pinch, but it has 9 gallons on it so im runnng 30 on all my engine now, JPX is back up engine.




i have brand new, alum clutch shoes so i should get enough punch that i want.

and leaning out the low end little by little more.


also dont run hard, alum clutch shoes they slip too dam much lol.
and heat up.
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Old 08-04-2010, 11:05 PM
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Originally Posted by jsp619666
with that motor you need to run either 25% or 30% running any less is going to cause extra stress on the motor, imo i would ask the guy from huston engine service on here what to run, he has his own thread.
20% nitro is not enough to make power with your mill or any mid-high end race mill, they simply are not designed to run that low of percentage of fuel, your going to over stress the rod and your fuel millage will be terrible.
That's not true. Nitro is like acid in an engine. Less is better. In a buggy, you'll not see a difference in performance with +/- 10% nitro for a avarage driver, unless you drive on bluegroove tracks.
Less nitro = remove a 0,1 or 0,2 mm shim and perhaps use a hotter glowplug.

Run less nitro and use the saved money on good tires. Then you get your laptimes down.
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Old 08-04-2010, 11:11 PM
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Originally Posted by Lille-bror
That's not true. Nitro is like acid in an engine. Less is better. In a buggy, you'll not see a difference in performance with +/- 10% nitro for a avarage driver, unless you drive on bluegroove tracks.
Less nitro = remove a 0,1 or 0,2 mm shim and perhaps use a hotter glowplug.

Run less nitro and use the saved money on good tires. Then you get your laptimes down.


well im running a truggy, with a odonnell #100 plug which is a meduim plug.
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