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Old 08-08-2009, 08:56 AM   #31
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Default i'm confused...

hiya folks,

i'm really confused... some peeps here are advocating 0% nitro to increase fuel mileage whilst the RB website says it's 45% (WOW!!!) nitro will increase fuel mileage (as in longer run times).

Exactly which is it? If there are any engine tuners here, It'll be really helpful to hear it from a pro-tuner's point of view.

Also, doesn't a lower clearance (less shims) make the engine run cooler? why dunt engine manufacturers design their engines to run with just 10.1 shim (for sealing)only?

I run a IDM tuned picco P3R on a pretty much stock Kyosho MP9 (stock gearing), i get about 8 mins to a tank, and that's with a crazily long fuel line and a gas cooler on the pressure line.

help?

Shalom and God Bless!

-Alexander
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Old 08-08-2009, 09:59 AM   #32
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IMO Lower nitro does not give you more run time....tried it...and there was no noticeable difference on 4 of the test mules we tried it on.
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Old 08-08-2009, 12:44 PM   #33
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Well. My English comes to a test here

http://en.wikipedia.org/wiki/Nitromethane

Nitro needs ALOT more oxygen to explode compared to methanol. If an engine runs 35000 RPM down the straight, it will suck in a specific volume of oxygen - no matter what fuel you are using. To get the nitro explode, you will have to mix a lot more fuel (nitro) with the specified volume of oxygen. That is why you get shorter mileage with high percent of nitro.

I really hope, someone can explain to me, why it is possible to get better mileage using 45% nitro compared to 25%...

Nitro produce more power but it will detonate at a lower compression ratio.

If you increase the compression ratio and run on FAI fuel (0 nitro), you will get close to the same power, AND your mileage will increase with +20%. (I got +25% with a RB WS7 II).

If you don’t get the ignition and compression ratio right when you run on FAI fuel, the engine – of course – will run like hell, and you will not see any improvements.

I hope to make a lot of tests next year using FAI fuel.
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Old 08-09-2009, 02:04 AM   #34
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Quote:
Originally Posted by foampervert View Post
Also, doesn't a lower clearance (less shims) make the engine run cooler? why dunt engine manufacturers design their engines to run with just 10.1 shim (for sealing)only?
-Alexander
For all I know, an engine doesn't run cooler on higher compression ratio (less shims). You adjust the clearance to get the right ignition (togeter with the glow plug), depending on the nitro persent in your fuel.

Cheers
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Old 08-17-2009, 09:31 AM   #35
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Small update....... Took my old JX (8-gallonsand 2 sets of bearings so far, Put the EBmods V1 button(I had), used ony 1 of the super paper thin shims, P3 plug, 8MM restrictor, OS 2050 and 20% fuel versus 30% b-4. All of this in my MBX6T, Re-tuned it and wow this things runs just as good as 30%, Holy Sheet batman!!! I was really impressed Iwas expecting for it to be somewhat dead and having torun it hot but its not that way at all., I havent had a chance and some quiet time to do a REAL fuel mileage run but I had a little more fuel in the tank after the quals than b-4, I also havent actually measured the deck hieght yet but I will, Did NOT burn any plugs I used the same one all night, 3-quals and a 25 minute main......... so far it seems good....... I am gonna slowly start dropping restrictor size 7-6-5.5 mm one weekend at a time and see where it starts loosing power. Also measure the deck hieght so I actually know and get the V2 button soon.....I wasnt running the tune on kill, I use the spit test right after I walk down to the pit lane after the quals and it was right beteen just sitting there smoking(steaming)/wet after the quals and a tiny bit of sizzle(barely) after the 25 min main.......It was I would say 230-240.............good enough for me. Temp guns are for pussys IMHO .....Thats how I tune them.......
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Old 08-17-2009, 07:02 PM   #36
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Originally Posted by Lille-bror View Post
Well. My English comes to a test here

http://en.wikipedia.org/wiki/Nitromethane

Nitro needs ALOT more oxygen to explode compared to methanol. If an engine runs 35000 RPM down the straight, it will suck in a specific volume of oxygen - no matter what fuel you are using. To get the nitro explode, you will have to mix a lot more fuel (nitro) with the specified volume of oxygen. That is why you get shorter mileage with high percent of nitro.

I really hope, someone can explain to me, why it is possible to get better mileage using 45% nitro compared to 25%...

Nitro produce more power but it will detonate at a lower compression ratio.

If you increase the compression ratio and run on FAI fuel (0 nitro), you will get close to the same power, AND your mileage will increase with +20%. (I got +25% with a RB WS7 II).

If you dont get the ignition and compression ratio right when you run on FAI fuel, the engine of course will run like hell, and you will not see any improvements.

I hope to make a lot of tests next year using FAI fuel.


Lower nitro percentage will slightly give you better mileage if you retune and reshim. The temps get lower with less percentage as Methenol burns cooler than Nitro, therefor tuning temps will be lower and thus you can lean it more. But.... You can only go so far as you can still starve the engine even though your temps are "correct".

The idea behind more nitro (in this case 45%) You can get better mileage again by creating more BTU's (power) requiring less throttle input. (saving fuel) Higher nitro content is hard to make idle and get the tune right. Also engine temps get pretty high even when tuned properly.

FAI fuel would require special glow plugs. There is a science behind why our glow plug wires are platinum coated for Nitro use. Simply tuning your current set up for straight methanol/oil will not work. FAI flyers run their engines wide open. Our cars have to idle.
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Old 08-17-2009, 09:36 PM   #37
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Quote:
Originally Posted by casterdriver View Post
Small update....... Took my old JX (8-gallonsand 2 sets of bearings so far, Put the EBmods V1 button(I had), used ony 1 of the super paper thin shims, P3 plug, 8MM restrictor, OS 2050 and 20% fuel versus 30% b-4. All of this in my MBX6T, Re-tuned it and wow this things runs just as good as 30%, Holy Sheet batman!!! I was really impressed Iwas expecting for it to be somewhat dead and having torun it hot but its not that way at all., I havent had a chance and some quiet time to do a REAL fuel mileage run but I had a little more fuel in the tank after the quals than b-4, I also havent actually measured the deck hieght yet but I will, Did NOT burn any plugs I used the same one all night, 3-quals and a 25 minute main......... so far it seems good....... I am gonna slowly start dropping restrictor size 7-6-5.5 mm one weekend at a time and see where it starts loosing power. Also measure the deck hieght so I actually know and get the V2 button soon.....I wasnt running the tune on kill, I use the spit test right after I walk down to the pit lane after the quals and it was right beteen just sitting there smoking(steaming)/wet after the quals and a tiny bit of sizzle(barely) after the 25 min main.......It was I would say 230-240.............good enough for me. Temp guns are for pussys IMHO .....Thats how I tune them.......
If your running a V1 button it is setup for 30%,,,not 20%.... To run EB Head button correctly with 20% fuel you would need a V2 button.. Then you'll get the power and the run-time.

Quote:
Originally Posted by Racecrafter View Post
Lower nitro percentage will slightly give you better mileage if you retune and reshim. The temps get lower with less percentage as Methenol burns cooler than Nitro, therefor tuning temps will be lower and thus you can lean it more. But.... You can only go so far as you can still starve the engine even though your temps are "correct".

The idea behind more nitro (in this case 45%) You can get better mileage again by creating more BTU's (power) requiring less throttle input. (saving fuel) Higher nitro content is hard to make idle and get the tune right. Also engine temps get pretty high even when tuned properly.

FAI fuel would require special glow plugs. There is a science behind why our glow plug wires are platinum coated for Nitro use. Simply tuning your current set up for straight methanol/oil will not work. FAI flyers run their engines wide open. Our cars have to idle.
+1 except the part about higher nitro % being harder to tune and idle... 30% tunes and idles easier/better then 20%.
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Old 08-17-2009, 10:23 PM   #38
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If your running a V1 button it is setup for 30%,,,not 20%.... To run EB Head button correctly with 20% fuel you would need a V2 button.. Then you'll get the power and the run-time.
Yeah I know. working on the v2 as I type this but I wanted to try it anyways.......I also have a case of 15% fuel that i should have by the weekend
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Old 08-17-2009, 10:48 PM   #39
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Yeah I know. working on the v2 as I type this but I wanted to try it anyways.......I also have a case of 15% fuel that i should have by the weekend
ok just lettin you kno so your aware ... if u need a button lmk i always have a couple extra...
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Old 08-17-2009, 10:54 PM   #40
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I wasnt running the tune on kill, I use the spit test right after I walk down to the pit lane after the quals and it was right beteen just sitting there smoking(steaming)/wet after the quals and a tiny bit of sizzle(barely) after the 25 min main.......It was I would say 230-240.............good enough for me. Temp guns are for pussys IMHO .....Thats how I tune them.......
LOL!

What about on a 95 degree day when your thirsty... try spitting then.. LOL!

Temp guns are for people who worry too much about it... LOL!
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Old 08-17-2009, 11:13 PM   #41
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^exactly if the engine is running good who cares what temp it is. I would rather have an engine run hot and run good for four gallons, than have an engine run cool and slow and last for eight gallons.
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Old 08-17-2009, 11:40 PM   #42
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FAI fuel in planes is not only for WOT flying. Many pilots in eg. Europe and Australia uses FAI, because there are often no benefits and/or need for nitro in an engine to run perfect (idle, transition, midrange, WOT) - I also know it from my own plane engines. It all depends on retune, the right plug and compression ratio. Exactly like if you start using 45% nitro instead of 25% nitro just opposite sign. No hocus-pocus, except you will have an engine that last much longer + increased mileage.
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Old 08-18-2009, 07:00 AM   #43
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The 2 biggest things you can do is put in a smallish carb restrictor (ventury sp?) and run the right pipe. Picking the correct pipe makes a BIG difference in fuel milage. On my RB C6 I used the 2045 pipe & a 6.5mm restrictor & got over 10 minutes everywhere & even more on small tracks. With 10mm restictor & a 2020 pipe, 7 to 8 minutes on the same motor. I also found some fuels are bettter fro run time. Gen3 Byrons gave me a minute + more run time than gen2.
What is Byrons Gen 3 Fuel ?
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Old 08-18-2009, 08:25 AM   #44
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FAI fuel in planes is not only for WOT flying. Many pilots in eg. Europe and Australia uses FAI, because there are often no benefits and/or need for nitro in an engine to run perfect (idle, transition, midrange, WOT) - I also know it from my own plane engines. It all depends on retune, the right plug and compression ratio. Exactly like if you start using 45% nitro instead of 25% nitro just opposite sign. No hocus-pocus, except you will have an engine that last much longer + increased mileage.
I was thinking F1A sorry.

Running straight methanol will not equate to the same power output. You have to burn more methanol to make up for the power loss. Run time in cars is easy to gain (light throttle finger) but at a cost of not putting down enough power to go fast. What everyone wants is maximum throttle with being able to easily run 10 minutes. The top pro's are running 12-13 minutes now using 30%. You have to put the time in to get the right plug, the right pipe and head shims together to accomplish this.


check this video out. Each year we run the Nitro Challenge in AZ there is a International R/C pylon race accross from the track. (this is not AZ though)

These are the planes; http://www.youtube.com/watch?v=MM3nL4KdEqA
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Old 08-18-2009, 11:57 AM   #45
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Haha. No worries mate Cool video.

Well. An engine can't burn more methanol than what is the right mix with the oxygen that goes through the carburator.
Yes, nitro produce more power than pure methanol. If you raise the compression ratio from standard approx. 8,5:1 to 13,5:1, you will have the same (or close to) power AND much better mileage. In a buggy or a truggy the small amount of extra power with nitro, will just produce more wheel spin and perhaps a few hundred extra RPM at topspeed. But still, I’ll make a lot of tests to confirm this.
The needle setting doesn’t become more sensitive than if you use +30% nitro.
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Last edited by Lille-bror; 08-18-2009 at 02:01 PM.
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