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03-10-2010 09:38 PM  8 years agoPost 21
Sean Bosse

rrApprentice

Germantown, MD.

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Justin, as for being able to tell if a motor is experiencing detonation, you can tell by looking either the piston crown or combustion chamber for small pit marks.
Detonation is essentially uncontrolled combustion caused by either unburned end-gases from the previous stroke or too lean a mixture that ignites and expands too quickly before the piston finishes the compression stroke which forces the piston in the opposite direction it is traveling. The result is a pinging noise, similar to what you would hear when you bang a bunch of marbles together.

Sean

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03-10-2010 09:44 PM  8 years agoPost 22
Dr. Fibinotchi

rrKey Veteran

Sioux Falls SD

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spelling
Squish band. You are right I spelled it incorrect, but understand the term and principals.

I can indeed hear a kind of pinging in the motor when I ran coleman after the motor saw an increase in compression. I did not expect it to sound like it did. When I first got into gassers I thought it to be a farse and that the engines never had enough compression to matter. How wrong I was.

We are talking about a very very small fraction of time on the burn time as well and only in a high modded motor. The rest doesnt matter. Coleman is more than fine still for all other apps I agree.

-C

If you want others to be happy, practice compassion. If you want to be happy, practice compassion.

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03-10-2010 09:53 PM  8 years agoPost 23
jones007

rrApprentice

Monterey, CA - USA

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Many currently fielded Unmanned Air Vehicles (UAVs) spec high octane race gas for cooler running. We run VP C10 in ours, which use either an Evo 26GT or 3W-28. Some of the plankers at the local field tried C10 for a while, but didn't see enough benefit for the cost, but then they usually run 10-15 minutes at a shot, as opposed to 2-20 hour flights on the UAVs.

--Kevin

Trex 700N, Trex 600ESP, Trex 500, Trex 450Pro

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03-11-2010 02:53 AM  8 years agoPost 24
Toxic Al

rrApprentice

chuluota, Fl

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I use Redbull, it helps with lift factor, cause Rebull gives you wingslol . Peace, Al

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03-11-2010 02:57 AM  8 years agoPost 25
Justin Stuart (RIP)

rrMaster

Plano, Texas

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I hear pinging in my car when I run the 87 octane gas and lug it in too high a gear going up a hill, but the rest of the time it runs fine. I imagine in a Zenoah you'd hear pinging only when you are trying to bog the engine? Otherwise it would be fine? So do you get a similar sound in the Zenoah? A kind of metal-on-metal tapping?

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03-11-2010 03:34 AM  8 years agoPost 26
jschenck

rrProfessor

La Vista, NE.

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My understanding is that detonation is less likely with smaller engines this is why we can get away with running camper gas in our Zenoah's (at ~ 55 octane) where even a "low performance" car would detonate severely and probably not last long on that fuel. This is even with the consideration that your Chevy likely has a lower static compression ratio than our Zenoah's.

To further add to Raja's post it's my understanding that most gasoline mixtures have to add ingredients to the mixture to raise the detonation resistance (Octane rating). These additive reduce the amount of gasoline in the entire fuel package and therefore reduce the amount of energy available in a given charge of fuel. So as long as your engine does not detonate with the lower octane fuel you should get better performance with lower octane fuel.

The reason BMW's and other high performance engines get a measurable increase on power output with higher octane fuel is the sophisticated engine management systems (computers) can sense detonation and will change the ignition and fuel curves to compensate. These higher compression engines can only operate on the more aggressive fuel and ignition curves with the higher octane rated fuels which prevent detonation in these high compression engines.

This does not apply to our magneto sparked, carbd 26cc engines.

<the preceding was pure bench seat bs'ing >

btw, I sure do wish we could buy an inexpensive EFI with temp, MAF and EGT sensors so I wouldn't have to tune my engine

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03-11-2010 03:57 AM  8 years agoPost 27
Justin Stuart (RIP)

rrMaster

Plano, Texas

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I know clearly the sound of pinging in my car. I'm not sure if I could recognize the same sound in my heli. Sure, we could all go out there and buy 110 octane race gas at $17 a gallon, but I wonder if good old fashioned Coleman fuel wouldn't give the same results or maybe better results?

The difference I see is that a Zenoah engine has a piston which is about 1 inch in diameter where most car pistons are at least 4 inches in diameter. If we're talking about the speed of flame front propagation, then a flame certainly travels 1 inch a lot faster than it does 4 inches. Then there is the RPM difference. I have never seen a car (other than a RX-7) which reved above 6,500 RPM, yet we routinely run our motors at 11,500+ RPM--nearly twice as fast. You need a fuel which will burn faster if you are running a fast RPM. Lastly, we are running 2 stroke engines which don't have any valves. Are you really going to get pre-ignition where the fuel ignites before the piston reaches TDC? Somehow I severely doubt it, especially when the piston is moving so fast.

It just seems to me like a low octane fuel would give better performance.

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03-11-2010 04:10 AM  8 years agoPost 28
jschenck

rrProfessor

La Vista, NE.

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I have never seen a car which reved above 6,500 RPM
side note, a buddy of mine bought an Acura Integra Type-R in 1998 and he regularly hit the rev limiter which was set above 8500 RPM - factory stock. Incrediable little car. He went to local SCCA events and could run lower times than cars with three times the horsepower. Only Acura I've ever seen that didn't have A/C, not even a factory option (dealers would install A/C though)

http://www.itrsport.com/specifications.html

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03-11-2010 04:21 AM  8 years agoPost 29
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Integras are good cars. I have a 1990 Acura Integra with 295,000 miles on it. Talk about getting your money's worth. But I certainly wouldn't run Coleman fuel in it.

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03-11-2010 04:29 AM  8 years agoPost 30
Wayne Parrish

rrVeteran

Apex,NC,USA

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I cannot believe that the "fuel" talks are ongoing . There have been so many posts on this subject ,what again. Go back and check the history ! Plain old regular gas and a quality synthetic oil has served most of us well. As for smell.I of course ran av-gas in my full size bird,but really don't see the problem with regular gas smell. LOL

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03-11-2010 01:08 PM  8 years agoPost 31
Toxic Al

rrApprentice

chuluota, Fl

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Here it is in a nut shell, the only reason I am testing other fuel sorces is the inconsistantcy in pump fuel, the ethanol and additives plus the fact you really don't know how long fuel has been sitting in the pump plays into it. I know most here don't listen or care what I say but there are more reasons then what is posted here for why low octane works for the most part. I have been build race engines for 20 years not just little 2 strokes but full size motorcross engines and jet ski's where the hp to size rating is much larger. Compression is the main factor for octane.Octane is the compressability of the fuel or resistance to burn as it were. unlike 4 stroke engine which are measured using the full stroke to find comp ratio 2 strokes do not, they use effective stroke which is measured from the top of the exhaust port to top dead center which will vary depending on port timing. I have never seen any of these motor suffer from detonaion on 87 and found this to produce more power than 93 on the dyno. some race fuels are oxygenated which can increase power butat the expense I don't see the benefits. I am testing coleman now and like it as an alternative. Wally runs very high compression so his motor might be out of the realm 87 or coleman but most are not.take it or leave it
I don't care do whatever you want.

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03-11-2010 01:27 PM  8 years agoPost 32
Justin Stuart (RIP)

rrMaster

Plano, Texas

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I have a bottle of Coleman fuel, a bottle of 87 octane pump gas, and a bottle of Sunoco 260GTX race fuel. Here is what I have noticed:

Coleman fuel doesn't contain any aromatics which are the cancer causing elements of gasoline. It smells nice and doesn't leave any residual odor on your hands when you spill it. In addition, Coleman fuel seems to be consistent from can to can whereas pump gas has summer/winter blends in addition to whatever crap is present in the storage tanks. I can buy it at Wal-mart for $6.20 a gallon since it is considered a food product and is not taxed.

The Sunoco race fuel is expensive in Texas at about $12 a gallon (when you factor in all of the taxes). It has a hint of gasoline odor, but nothing like the pump gas smell. It is a very thick fuel. Much thicker in consistency than Coleman. It also stores very well, and is manufactured to be very consistent from can to can.

87 octane pump gas is the worst. It is full of benzene and other aromatics. It has a nasty smell which you cannot wash off your hands.

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03-11-2010 01:55 PM  8 years agoPost 33
rbort

rrProfessor

Franklin, MA - USA

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Thank you Toxic Al
I have never seen any of these motor suffer from detonaion on 87 and found this to produce more power than 93 on the dyno.
That agrees with what my tests showed in the motors that I run and they have some increased compression than stock but not as much as the Wally motor.

Justin, since you have the Wally motor you should try all the different fuels that you have and see which works best and produces the most power. I like to try things so I can speak from what I see with my tests. You may very well find that your motor needs high octane to run properly, I remember you were asking about pull starting it and saying it was so hard to pull through you thought you are going to break the chord. Well with all that compression, that can very well be the difference.

-=>Raja.

MA 1005 Hanson 280, 4225 flts
Spectra 27 3DMax, 3325 flts
Whiplash V1-2 Hanson 300, 1650 flts
Whiplash V2 Hanson 300, 504 flts

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03-11-2010 03:34 PM  8 years agoPost 34
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Raja,

I broke that first cord long ago. Fortunately they are cheap and relatively easy to replace. I am bringing spares with me to the field from now on.

I would certainly like to try all 3 fuels and determine which provides the best overall performance with the Wally motor. The problem is, I have no idea what detonation is like in a 2 stroke motor. Sure, I hear detonation in my POS Mazda 626 when I'm going up hills running cheap Texas gas. But we're talking a little Zenoah motor, not a 2L 4 cylinder 4-stroke engine. Will I hear this same detonation sound in the helicopter? If I cannot quickly identify detonation such that I can immediately land and flush my fuel tank, then I have no choice but to run the high octane race fuel all of the time just in case. Running the most expensive fuel does not always give you the best overall performance. When you're running an engine with fixed valve timing and also fixed ignition timing at a governed RPM, then the only variable you can adjust is the speed at which the fuel burns. So therefore testing 98 octane, 93 octane, 87 octane, and Coleman fuel to see which works best is a good idea--unless doing so will cause irreparable damage.

I assume that just like in the full size motors, detonation happens at low RPMs and high load. So this would be when I am trying to pull too much pitch--like in a full collective climb out? There is a lot of speculation about Coleman fuel vs. 87 octane vs. premium vs race gas. But has anyone actually identified detonation with the lower octane fuels?

Has anyone ever heard pinging in their Zenoah engine? And if so, is it the same "metal on metal" sound you hear in your car? Or does the exhaust noise and blade noise totally drown it out?

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03-11-2010 03:49 PM  8 years agoPost 35
rbort

rrProfessor

Franklin, MA - USA

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Justin
I do have a thicker cord from my engine supplier that you can use. You won't be able to put as much cord on, but almost as much (like 1 to 2 inches less) as its thicker and stronger. I'll put it in the mail for you today, and I think this one will work better for you. If you need help figuring out how to do it, call me and I'll walk you through. I did redid mine after many years of usage on my 1005 the chord finally broke.

You need to fly the heli and get some statistic with full power performance. Then you'll be able to tell which fuel is performing the best. I've never heard detonation on any of my motors, at least nothing that I attributed to detonation so I can't really tell you what it might sound like on these little motors.

-=>Raja.

MA 1005 Hanson 280, 4225 flts
Spectra 27 3DMax, 3325 flts
Whiplash V1-2 Hanson 300, 1650 flts
Whiplash V2 Hanson 300, 504 flts

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03-11-2010 05:55 PM  8 years agoPost 36
Dr. Fibinotchi

rrKey Veteran

Sioux Falls SD

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hmm
The discusion was on coleman to reg pump gas not 87-93.

Feel free anyone to fuel up with coleman on Wally's motor. Especially with Jusin's and beyond.

Obvious my reall life experiance of it and the many many conversations with Wally means nothing and that some will just need to pee on the electric fence for themself ...heck maybe we need a video to PROVE it exist...

-C

If you want others to be happy, practice compassion. If you want to be happy, practice compassion.

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03-11-2010 06:47 PM  8 years agoPost 37
C.A.P.

rrApprentice

custer park IL.

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[quote]Power loss

(You will lose power if you go higher octane at the top end and the motor won't run as well. I tested that and can attest to it.

Furthermore, going the other way might mean more power (Coleman at 55 octane) but I have no test experience to back it up.)

This is the statement I was commenting on, it's wrong, toxic's run high rpm engines, and high compression engines like Hanson which the quench is decreased by 0.030 that's not a little increase in compression, that the most seen on a mod production engine, until reasonaly anyways, why he saw more hp with lower octane I do not know. there is a lot of thing that could of did it but I'm sure it's not the lower octane, More it's the compression rate the engine had and the out side air destiny,and gas age,[list],

[read this article from Wikipedia go down to "Effects of octane rating" http://en.wikipedia.org/wiki/Octane_rating

[ Raja: A Dyno is the only way to test for an increase or decrease in hp at any rpm, do you have one? If not please explain how you did your test. If you have found a better way please share,[

[ Every fuel has it's +&- for the type of engine you have, Octane will not increase or decease your hp,(this with at the pump gas) it may maximize it, which may seem to be an increase, but it will not make a 5hp engine into a 9 hp engine, not going to happen, low octane will not decease the hp but may make your hp harder to maintain every day, higher octane is a slower more even burn, or a more controlled burn, which will make your needle more stable day to day, even more so in a engine with high compression, It also helps stop hot spots, which will give your engine more life, We can go around and around on this, Just read up on octane and it causes and stop guessing. [

[ Because of what I do, on Marks forum. I can not go into detail on any test I have done, But if you do a google search on octane you will find everything you need to know, Advice by engineers not ally mechanics, From there, At lease you can have some good advice on what fuel mite be good for you AND WHY,[ Wally

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03-11-2010 07:28 PM  8 years agoPost 38
rbort

rrProfessor

Franklin, MA - USA

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Read Toxic Al's post
Here is a quote:
unlike 4 stroke engine which are measured using the full stroke to find comp ratio 2 strokes do not, they use effective stroke which is measured from the top of the exhaust port to top dead center which will vary depending on port timing. I have never seen any of these motor suffer from detonaion on 87 and found this to produce more power than 93 on the dyno.
The way I read this, Toxic is staying that the 2 stroke motors produced MORE power than 93 on a dyno. Those are his words.

I said the same thing before Toxic agreed with my statement. While I don't have a dyro, I can fly the helicopter and test full power rpms on the motor with repeatability and log data figures that show a difference in top end power between the high octane fuel 93 and the regular gas of 87 octane.

I did this test as I was asked to do it, mixing a gallon of fuel and running it in two seperate motors, the G26 Pro Plus and the G26 3D Max, and they both showed less top end power than when run on regular gas.

Don't shoot the messenger, I did do the tests, the motors speak for themselves, and I report the findings. These tests are done with the motors that I own and run, so I'm speaking for those only. Toxic Al says he found the same results for his motors on a dyno.

-=>Raja.

MA 1005 Hanson 280, 4225 flts
Spectra 27 3DMax, 3325 flts
Whiplash V1-2 Hanson 300, 1650 flts
Whiplash V2 Hanson 300, 504 flts

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03-11-2010 08:27 PM  8 years agoPost 39
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Part of the problem with the cord breaking on the Spectra is that to pull start it, the cord rubs up against the bottom frame of the helicopter. I need to take a file and smooth out the bottom of my frame on the left side more. Not to mention the fact that Wally builds some serious compression into his engine. But it would certainly help if the cord didn't rub against the frame.

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03-11-2010 09:07 PM  8 years agoPost 40
rbort

rrProfessor

Franklin, MA - USA

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You might not be low enough.
Either get down lower or put the heli up higher. Should be pulling parallel to the frame not on an up angle to rub the cord on the frame.

I've seen some folks doing that as I travel around to fun-flys, and try to point that out to them so as to stop that habit.

-=>Raja.

MA 1005 Hanson 280, 4225 flts
Spectra 27 3DMax, 3325 flts
Whiplash V1-2 Hanson 300, 1650 flts
Whiplash V2 Hanson 300, 504 flts

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