As promised I tried out a different fuel in my Vmax-6 LMH 110+ today. I found the results very interesting. The engine is well broken in and is using 3 shims. Todays weather was about 55 degrees, and very humid with on and off drizzles. I had been using 15% Powermaster, which has worked well. Its a 18% castor/synthetic mix. I bought a quart about a month ago, its always kept sealed and the hobby shop has good turn over. The fuel has worked well. I am almost out and tried some 10% omega airplane fuel, which is a 17% oil castor/synthetic mix. I have heard from some that the Vmax will not run well on anything but 15% or above. I think it actually runs *better* on the 10% than the 15%. The throttle response was a little smoother and there seemed to be more power at certain settings. I did give off a good bit more smoke than the Powermaster, which gives very little. So it IS possible to run on lower nitro percentages, and run well!


Kristopher

Kris , my only concern is will it run good for a long time???? It may cause early life on your motor. Now nothing seems to help my v-7 I had talked to a real believer in norvel motors "airplane" and he said that he has tried it all and found that his norvel's run best and last longest with norvel fuel. Good luck.. Alan

In that case, what have you been running fuel wise? I would think the lower nitro fuels will reduce overall stress on the engine. Norvel agrees. The purpose of higher nitro is to improve the engine's handeling. It seems great with the 10%, so it seems like a win-win. I am a firm believer in a some castor oil for the smaller motors. Its a mess maybe, but hard to beat lubrication wise. Omega is a Norvel reccomended fuel.

Kristopher

That's very interesting news.....the 10% nitro fuel should be cheaper. From my nitro car experience I've learned some good nitro lessons.
#1 The lower the nitro content of the fuel the leaner you have to run the engine to produce good power. But guess what?.....the lower the nitro content of the fuel the cooler the engine runs and it will tolerate the leaner settings required.
#2 The higher the nitro content of the fuel the richer you have to run the engine. If you tune the engine to run well with 10% nitro....... then change to 25% nitro without re-tuning the engine it will be too lean to run or will get so hot it will sieze.
#3 The cooler the weather the lower the nitro (this is a vmax7 thing). In the winter time you can run lower nitro......it's about the same as adding shims to the head in cooler weather. In the warmer months higher nitro seems to produce more power....once again about the same as removing shims from the head.
Anyway these are lessons I have learned.....so I would say that if the vmax lifts the heli and runs reasonably cool then all is well. BTW did you know that you can buy the oil formula for the Omega fuels? We used it alot because the "racing" fuels that the LHS stocked only had 10% lube with 20% nitro. Even O.S. engines require more percentage of lubrication than 10%. We would just add several ounces of the Omega lube to raise it to 18% or so.
Mark

Its difficult to say how much power the little Vmax 6 is putting out, but I would say I was hovering at about 2/3 power. Lots of power for climb out and forward flight. I would like to see a little more oil in the omega, its within the limits, but a little more coule not hurt. The engine seem to run plenty cool, I can refill and restart after a flight and its not too hot to touch the head. I know my TT .46 pro gets a lot warmer.

Kristopher

Mark, you made an important point, we just compensate for nitro by changing the engines comprestion. So really it shouldn't matter which nitro content we use as long as the oil content is good. My first 2 v-6's lost comprestion way to soon so I decided to just use norvel fuel. When I used 15% omega fuel I couldn't lift the heli and I tryed every combination in the book all the way down to 1 washer. I have been watching the temps very closely and I get 198 f at the head and 220 f at the cylinder base with 25% norvel and 5 washers in this weather. The v-6 with 15% omega ran hotter and that was at a setting just enough to lift off the ground. Just my experience so far.. Alan

Alan, thanks for the temperature references. I'm going to check my vmax7 and see what temp. it's running. I do know that Lite Machines recommends 25% nitro content for the vmax7.....which I used in the summer but this winter I'm using 15% Omega (it's cheaper). I do have to run it leaner.....a little less than 2 turns out....but the engine doesn't boil spit. I have a point and shoot thermometer so I'll check the temp the next time I fly.
Mark

I had told lite machines what the temps I was getting and they said I was right on the money as to where they should run. Because I am haveing so much trouble with these v-7's I want to make sure that it's not me thats killing them.. Alan

Alan, it's not you that's killing the vmax7s.....it's some Russian that doesn't give a ****.
Mark

Yes mark i'll bet your right they do not have good quality control....Lite machines told me that they do some machineing on these engines, I knida wonder if in deed they do are they pushing these engines over the top ?? Alan

Alan, what machining do you think they do? The heat sink maybe?
Mark

Mark, I believe that they make the heat sink, the muffler throttle, and Paul told me that they do some machining to the piston so it has better clearence. If this is true then they have to take it all apart. The last engine I had ran GREAT but came up with a crack in the case. I did nothing to it other than fuel and fly. I kinda wonder if Lite had done some resizing in there also cause the case to be a little thinner ?? They also told me that they are "experimenting" with intake sizes to get the most power. NO airplane guys that use these motors have these troubles, they are just confines to us, so I wonder are they just trying to push this little motor to far ??? I di know that norvel does not make a heli engine.. You can go to their web site and look around... Alan

How does the Vmax 7 compare to one of the other Norvels, like the BigMig .061? Just curious if they are really skimping on material. I would think if Lite Machines were making that many change Norvel would be complaining its giving them a bad name.

Kristopher

Kristopher, I'm not familiar wth the other Norvels. As far as flying is concerned I started with the LMH so I have no airplane experience. As Alan said Norvel doesn't mention vmax engines on their web sight.....and I realize that Norvel has a good reputation among small rc plane pilots. Lite Machines does claim that it is Norvel's problem. If you ask me I think the heli was underpowered with the vmax6......I know there are people who disagree. The vmax7 is a much more powerful engine and is a better match to the weight of the heli. Unfortunately we all know about the vmax7's problem. Also I don't know about collective pitch with the vmax7....is it powerful enough? CP upgrades will be available for the Corona..... and maybe the 117 if there is an engine and fuel system that will work.
Mark

I think you are right Mark if they come out with a collective pitch for the 117 the old v-7 motor may not handle it. Hell it can't even handle itself I have talked to airplane pilots who have the norvel .061 and .074. They LOVE them say they are GREAT, but then again these motors are configured differently than the ones we use. I know I am not the only one with v-7 woes remeber when they first came out for the LMH everyone was breaking con rods.. CP mods and aluminum crutchs are GREAT but what good is this stuff with out a good power plant ??? Any one kno w??? As far as nu2rc said he hopes litemachines reads his post, I don't think they will, it takes them forever to answer questions on thier own site if at all.. They are busy with other stuff I guess. Maybe we are just a very small % of people haveing motor trouble. Look at Darth he has had no problem and he loves his v-7 but then again TW never got his to start.. My new motor will be here in 2-3 days and it's back to it again If it blows up then I am done... But I do have my carona.. Alan

Alan, common sense tells me that there are more people having vmax7 problems than are posting here......and I haven't forgotten that it took me several v7s to get a good one.....and Darth too. I think it is a widespread problem.....and I think that Lite Machines is trying to make it right with everybody. It probably is difficult to get an engine manufacturer to build an engine just for your helicopter......and that's the mistake. One of the Quick Helicopters used buggy type engines......and other helis use standard heli engines that are standard to helis in general. I know that the LMH isn't a 30 size heli so the standard heli engines are of no use.....but it has been proven that the buggy engines work ok. What I hate most of all is that folks will get discouraged......the heli will be discontinued........parts will get impossible to get......and we'll all have to buy another type of heli if we wish to continue. That's the shame of it all.....because as far a rc helicopters go.....the LMH is a tough one and can endure the beginner.
Mark