consumption difference between saito 100, os91fx and os120ax

consumption difference between saito 100, os91fx and os120ax (Full Version)

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zyklon_chichi -> consumption difference between saito 100, os91fx and os120ax (4/14/2006 6:05:34 PM)
hi, can someone shade some light on how much they drink? Looking for an engine in the 90-100 class, but I thought if the 120ax doesn't drink a lot more than the 91fx, why not pay that little bit of difference for it. Fuel is not cheap over here, which is why it is a big consideration before I purchase an engine.

Ed Cregger -> RE: consumption difference between saito 100, os91fx and os120ax (4/14/2006 8:17:03 PM)
quote: ORIGINAL: zyklon_chichi hi, can someone shade some light on how much they drink? Looking for an engine in the 90-100 class, but I thought if the 120ax doesn't drink a lot more than the 91fx, why not pay that little bit of difference for it. Fuel is not cheap over here, which is why it is a big consideration before I purchase an engine. -------------- Larger displacement two-strokes usually consume less fuel at an equivalent power setting than smaller displacement engines running wide open to maintain that power setting. I hope that makes sense. However, if fuel is such an issue, why move to a larger model? The larger model is not going to do anything significantly better than a .40 to .53 sized model. Social status aside, large glow engines are a waste of money. Go a little larger and begin flying gasoline/petrol fueled models if you really have to have a big'un. As my wife says, "Once they are in the air, they all look the same size". She severely deflated a couple of fellows' egoes with that comment as they were prepping their over 100cc giant twins for flight. She was right. <G>

aussiesteve -> RE: consumption difference between saito 100, os91fx and os120ax (4/14/2006 8:50:49 PM)
I agree 100% with Ed most of the time but especially so on this one. It's not the size that counts but . . . . . We've recently moved into bigger models (bigger than .90 4strokes that is) and it sure does make a difference on the fuel consumption - between the 3 of us (Includes 2 very keen - WOT teenagers) we used to go through 2.5 litres of fuel in a day with our .40 & .60 sized models, we now go through around 4-5 litres in a day with 1.20 - 1.80 sized models. The bigger planes are good for the Ego though!!

zyklon_chichi -> RE: consumption difference between saito 100, os91fx and os120ax (4/15/2006 1:57:50 AM)
Not moving to big planes, wanted to move to gassers, but the smell of petrol in my home really put me off. Transporting of the long fuse will also be a hassle because I only have a camry for transport. Can't afford a truck/van here as ownership of vehicle is really expensive here. I am squeezing a 91fx or saito 100 into a 50 size plane(probably a fliton extra) and I thought if the 120ax doesn't drink much more than a saito, why not go for it and get a 60size plane instead. Might be too much power, but I am still a wot teenager...power is never enough for me. I have a tt pro50(no typo, heli engine) in a under 5 pound plane and performance to me is just ok. AFAIK, so far after some reading, 91fx will drink around 1-1.5oz per minute, while the numbers for the saito has a big range, some are claiming 1oz per minute, while some are going to even 2oz per minute.

STG -> RE: consumption difference between saito 100, os91fx and os120ax (4/15/2006 4:24:05 AM)
quote: ORIGINAL: zyklon_chichi Not moving to big planes, wanted to move to gassers, but the smell of petrol in my home really put me off. Transporting of the long fuse will also be a hassle because I only have a camry for transport. Can't afford a truck/van here as ownership of vehicle is really expensive here. I am squeezing a 91fx or saito 100 into a 50 size plane(probably a fliton extra) and I thought if the 120ax doesn't drink much more than a saito, why not go for it and get a 60size plane instead. Might be too much power, but I am still a wot teenager...power is never enough for me. I have a tt pro50(no typo, heli engine) in a under 5 pound plane and performance to me is just ok. AFAIK, so far after some reading, 91fx will drink around 1-1.5oz per minute, while the numbers for the saito has a big range, some are claiming 1oz per minute, while some are going to even 2oz per minute. I get .5oz min (15%) with my FL330 and SA100. No I am not WOT though. I fly mix of 3D and IMAC and only go to high throttle settings for brief periods. Power is great with a 15x6 or 16x5 or 6 prop. I also get .7oz min on my 10 pound F90 with OS108 and .8oz min with my 11 pound Giles & OS1.6 on pipe -- Worst mileage I have gotten is with a YS110 on an 8.8 pounds EF Yak @ 1.3oz min. On that small/light of a plane I would say the SA100 will have the advantage @21.5oz with muffler. The .91FX is 24oz with light pitts muffler and the 120ax is 27oz with light pitts muffler. The .91FX and 120AX are great motors though. I would expect the 120 to do as well as the .91 on fuel powering a 7 pound plane with throttle management.

Kweasel -> RE: consumption difference between saito 100, os91fx and os120ax (4/15/2006 4:58:27 AM)
The 91 and 120 will be close depending on peak rpm. They have the same sized carburetors, the 91 is typically propped to higher rpm than the 120, so the actual fuel flow is not that different. I know a piped .60 at 14,000 will burn more than a muffled 108 at 10,000.

Harry Lagman -> RE: consumption difference between saito 100, os91fx and os120ax (4/15/2006 5:53:45 AM)
There's some good advice here Zyklon. Another thing I'd add is that the two-strokes will be happy running on 5% nitro, which would be a factor as I'd imagine that nitro is pretty pricey in Singapore.

zyklon_chichi -> RE: consumption difference between saito 100, os91fx and os120ax (4/15/2006 10:53:54 AM)
yeah, been reading around and most of my purchases have been base on the good advice here. Yup, nitro is a bit pricey over here, cp5% only cost US$13 while cp30% heli cost almost US$30. Stg, looks to me you are getting very good mileage. My tt50+ tt46muffler+apc12.25 x3.75 is already doing 0.6oz a minute. That is on a funstar which is flown with less than 1/2 throttle for a big part of the flight. When it was in my low wing trainer, it was doing somewhere around 0.8-0.9oz per minute. Just for comparison, my os 50 hyper in my heli is drinking almost at the same rate of your ys110. Maybe it has something to do with my climate over here. Stilll undecided about which engine, but I am in no rush, waiting for furthur reports on the 120AX.

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