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Old 04-14-2006, 02:56 PM   #1
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Default nitro fuel qyestion!

I bought a used .15 nitro rustler. The guy said he used trinity 20% but I dont know the exact one. Does it affect/hurt the engine if I change to a different brand? THANKS
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Old 04-14-2006, 06:30 PM   #2
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Quote:
Originally Posted by n3rd420
I bought a used .15 nitro rustler. The guy said he used trinity 20% but I dont know the exact one. Does it affect/hurt the engine if I change to a different brand? THANKS
You can change brands every time you buy fuel because the engine has never learned how to read the label. Some brands have coloring agents, some have more oil, some have less oil and all have marketing hype.

Just adjust the tuning as you normally would for the day's running. You do adjust the tune every time you go out, don't you?
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Old 04-14-2006, 07:23 PM   #3
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Quote:
Originally Posted by AreCee
You can change brands every time you buy fuel because the engine has never learned how to read the label. Some brands have coloring agents, some have more oil, some have less oil and all have marketing hype.

Just adjust the tuning as you normally would for the day's running. You do adjust the tune every time you go out, don't you?
just make sure you keep the same nitro % fuel, and you will be fine.
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Old 04-14-2006, 07:46 PM   #4
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You can switch brands and nitro percentages at any time. You just have to make sure and retune when you do.
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Old 04-14-2006, 11:08 PM   #5
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Switch brands, switch %'s. It doesnt matter Just tune it and you'll be fine


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Old 04-15-2006, 10:53 AM   #6
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I just got the car!!! Havent beens able to pick up fuel yet. Due to my lic suspended. But im going today. Thanks for the tips. Ive been reading alot on tuning but I was wondering what methods do you guys use. Everyone is different. Thanks
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Old 04-15-2006, 11:30 AM   #7
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Default nitro fuel

as everyone has told you here there are right about it doesnt matter what fuel you use except that dont buy airplane fuel as some of those are four strokes and your motor is a two stroke, different oils are used in the airplane that are not good enough for your motor. also boat fule is a bit different but not very much, mostly just different nitro percentages. since your motor could also be used in a boat not much diiferent. as far the % to use stay with 20% for .18 motors and smaller for longer engine life. and will give you more than enough power using 30% is a bit much for a .15 motor.

as far as tuning there are alot of theories out there. but you are basically tuning a two stroke just as in a dirt bike or four wheeler/3 wheeler. if you are versed in jetting your own bikes it will help you out alot. with that the low speed needle affects from idle to 1/8 slide position( the slide in the carb) the high end needle in your motor ,like the main jet in a bike, will affect from 1/8 slide position to full open. low speed needle is like idle jet in a bike. some motors have a three needle carb and the mid range neeedle in those carbs are like change the needle in the carb of a bike with different tapers on the needle at different points on the needle you can affect your mid range tuning with it. but as i said you only have a two needle carb so you will be a little bit rich in the mid to ensure that your high end ,wide open, is proper so you dont hurt the engine. in tuning get your truck started and fully warmed up like 3 to 4 minutes running and set your idle so it will stay running on its own then set your low speed needle to a point that when you pinch the fuel line the truck will increase in idle and die out in about a minute then you have it to point that you can then do some wide open passes to get the high end set. you will always want to see some smoke at high end from the pipe, a temp gun is super helpful if you dont have the ear for a proper sounding two stroke, you will not want to be above 220 degrees between 205 to 215 is best for race performance. then at this point reset the low speed needle just as i explained before. typically you will want the low speed screw 3 and 1/2 to 4 turns out, when you screw it in all the way be careful overtightening will damage the needle in the carb, then back it out. the high end you usually be 2 and 1/2 to 3 truns out sometimes these will be more or less if the motor is coming due for a rebuild and is losing compression if it has been hurt by mistuning or just has been run alot in the period of a year it will be time for a rebuild ,new piston sleeve, piston, and rod.

also something else to consider when choosing your fuel the oils used in the fuels most are synthetic but there are some that are petroleum based oils. over the past 30 years racing motorcycles in the desert requiring dependabilty from my motors and longevity as well as peak performance we have found that petroleum based oils are best for these reasons. one is that syn. oils will build up in your motor because unlike petro. oils they dont burn of fully and overtime it will build up in your crankcase area as well as the connecting rod and in the cyclinder well when your motor is having to sludge through alll this stuff it will cause it to heat up more and then you will start to retune for it and eventually get away from the best tuning zones for your motor thus hurting it. also the oil content in the fuel is crytical as well, you will find fuels from 12% oil to as high 25% oil. the higher the number the samethings will happen as all that oil even petro based oil in the motor as it is running will heat the motor as well by trying to stroke through all the oil. i have been using sidewinder fuels for four years now due to it being petro based oil at a % of 12 in oil. which when properly tuned is more than enough oil. also sidewinder has an afetrun agent in that oil and you wont have to use an afterun oil. when your done running your truck with your finger turn the flywheel so that the piston is in the bottom of the stroke if you store it with the piston at the top of the stroke when the metals cool and constrict down to size it can pinch the piston and you will start to lose compression over time.

also remeber the size of these carbs and motors the are hyper sensitive to ambient air temp changes as well as alltitude changes. so if you go to the track to race for the day and say you start at 4 pm and its 80 degrees outside and as the second round of quailifing comes around now the sun is gone its 72 degrees out now you will need to adjust the high end needle just a bit. with cooler temp you will be leaning out the motor.

i know this is alot of info but i was trying to give all the info you need that a high school dude working at a hobbybench or a hobbytown of that is where your shooping most likely wont have for you. the nitro motors are finky enough as it is with out all the info you need to help yourself out.

good luck with it and have fun. a temp gun is a much neede item though so you dont get it to hot.
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Old 04-15-2006, 03:28 PM   #8
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Two stroke oil for gasoline use doesn't mix well with methanol fuel. It will blob up and float to the top.

You need to be careful to get oil made to mix with methanol be it petroleum, vegatable or synthetic based. Almost all model car fuel uses synthetics and a few still use caster oil.
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Old 04-15-2006, 04:23 PM   #9
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I'm suprised nobody mentioned this.... if you go from 20% to 30% you can run into detonation.. to compensate for this you add a shim to the head to get more head clearance and lower compression.. 30% will give you more power and run cooler. also you should run a colder plug with higher percent fuels... some engines come from the factory shimmed for 30% while others don't.. my advice is to stick with 20% and 12-14% oil....

best fuel I've tried is wildcat eliminator pro..
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Old 04-17-2006, 05:54 PM   #10
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Default fuel

I NEVER SAID TO MIX YOUR OWN FUEL AND OIL, ARE CEE. i was making a comparison on tuning tips for him and the differences betwen the two types of oils used in the fuels for r/c. and yes 30% will run cooler and you do need a colder plug and shim the head however it is still a very vilent combustion for any motor less than .18 the rods and wrist pins in a .15 or .12 motor are not as strong and the 30% will shorten the life of the motor and need rebuilding more often. just cause extra cost that gives a person more power than they are ready for. as it almost all racers put a carb restrictor in anywasy to smooth the power band of a .12 motor so it doesnt hit as hard and makes it more drivable.

well are cee this is one reason why i dont like even posting anywhere, pay attention to what you read so you dont make comments that are incorrect and just confusing the people who are looking for advice and hopong to get the right advice and your comments on this matter were no help at all.
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Old 04-18-2006, 04:23 AM   #11
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Quote:
Originally Posted by AreCee
You can change brands every time you buy fuel because the engine has never learned how to read the label. Some brands have coloring agents, some have more oil, some have less oil and all have marketing hype.

Just adjust the tuning as you normally would for the day's running. You do adjust the tune every time you go out, don't you?


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Old 04-18-2006, 06:51 AM   #12
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Quote:
Originally Posted by octane3117
I NEVER SAID TO MIX YOUR OWN FUEL AND OIL, ARE CEE. i was making a comparison on tuning tips for him and the differences betwen the two types of oils used in the fuels for r/c. and yes 30% will run cooler and you do need a colder plug and shim the head however it is still a very vilent combustion for any motor less than .18 the rods and wrist pins in a .15 or .12 motor are not as strong and the 30% will shorten the life of the motor and need rebuilding more often. just cause extra cost that gives a person more power than they are ready for. as it almost all racers put a carb restrictor in anywasy to smooth the power band of a .12 motor so it doesnt hit as hard and makes it more drivable.

well are cee this is one reason why i dont like even posting anywhere, pay attention to what you read so you dont make comments that are incorrect and just confusing the people who are looking for advice and hopong to get the right advice and your comments on this matter were no help at all.
Chill out.

My comment was only to say that petroleum based oils are not very commonly used in model methanol fuel. Most of the "natural" oil is vegatable based such as Caster oil.

The other thing is that many racers, and I mean people that race more than once a month, who use low oil content 30% nitro fuel like Trinity's premium (9% oil content all synthetic) add a couple fluid ounces of Klotz Techniplate 100% pure synthetic 2-stroke racing oil per gallon.

Your very long and detailed post was informative but you never made the distinction that newbies would understand.
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Old 04-19-2006, 05:58 AM   #13
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i brought an RC over the weekend and i have no clue at all about fuel. the guy sold me a 15% nitro fuel - reading above, it seems this will heat up my engine very quickly. Should i get rid of the fuel and buy new ones instead? thanks for your help
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Old 04-19-2006, 08:10 AM   #14
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I'd use up the %15 and then buy some %20 and re-tune. You'll be fine.
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Old 04-19-2006, 08:17 AM   #15
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Just tune the engine so it runs smoothly, delivers good power at the top end and doesn't bog down at the bottom. You should see wisps of smoke coming from the exhaust.

15% will not hurt the engine, you just have to run it a bit richer than if you used 20%. (The nitromethane functions as an oxygenator not a combustible fuel.)
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