"I have had 2 701s and rotax 100hp is the way to go . Had 85 hp jabiru with the slats removed and vortex gens got the best rate of 600fpm . Rotax is off the ground in 3 seconds with no flaps/ no slats and 1200 fpm"
I have had 2 701s and rotax 100hp is the way to go . Had 85 hp jabiru with the slats removed and vortex gens got the best rate of 600fpm . Rotax is off the ground in 3 seconds with no flaps/ no slats and 1200 fpm
Hi Mike, I am also flying a VW type 701. It is a 2100D Revmaster 75 hp direct drive.
I have about 110 hrs on it, it has not had any real problems to speak of except for the fact that I think it can be better than what it is.
It will rotate at 35 mph. Climb out at 45-50 mph is only 500 fpm, this is Pilot and full fuel, throw in a 150 lb passenger and it climbs at about 200fpm.
It is a good airplane with only the pilot, It does everything I need it to do. Cruise is around 75 mph at 3000 rpm and fuel burn has been about 5 gals per hour.
One thing Wayne touched on is the uneven fuel burn, mine is having the same problem which I hope to remedy soon. I have had a revflow carb on the bottom of the engine with a very long intake, which I am told causes poor atimization of the fuel,(The long intake that is) I am installing Bing 64 CV's like the Rotax uses, they will have very short intakes.
I hope this helps with your decision.
Remember the 701 was built around the Rotax.
Mike, the plane is doing well, I'm up to 71.7 hours now. I feel that I can get in it and go without a great possiblity of something going wrong. Fuel burn with these new heads is 6.1 gph, a little more than a rotax and a little less than a continental so I would say based on specific fuel consumption per hour I'm getting about 75 hp in cruise. The cht is about 350 degrees sensing it over the exaust port. Oil temp runs 195 to 205 depending on ambient temp. In cooler weather it is way to low at 160. I am still disappointed with the climb but I'll just have to live with it since my plane is pretty heavy.
I still have not gotten over what Larry said to me at Oshkosh, I'm sure their engine makes a little more power than mine but in my eyes there is no way they are going to get 120 "reliable" horsepower and keep it cool on a 701. There is just not enough fin area there. With the original fan on a vw the cooling system produced 9 inches of air pressure and FORCED it around the fins for 60 hp. To get 9 inches in a pressure cowling you have to fly 140 mph. Ain't gonna happen in a 701. I have talked toSteve at Great Plains and he said I could move my sensors back to the center head studs and get about a 20 degree drop in readings, it is like move the sensor around until you get the reading you want for piece of mind. No thanks, I want to know what each cylinder is doing at the hot part of the head, the exhaust valve, since that is where trouble is going to start. I've seen to many Vw engines swallow an ex. valve and it is not pretty. This also brings me to my next observation. Since I sense each individual head and exhaust temp I know that I have a slight fuel distribution problem that needs corrected. This should result in a little better performance but more even temps in the heads. If I had just gotten an average by senseing in one spot like Valley and Great Plains and everyone else does I would have been cooking number 2 and 4 valves even though my cht would have shown 330 and the egt about 1200.
I saw the video of the factory 701 with the new prop climbing at 1000 fpm at 65 mph. I would have to see a video of the old prop to believe that it is a wonder prop, after all, they have been advertising 1600 fpm light and 1200 fpm at gross. I have figured out that any performance claims can be cut 30 percent and you are in the ballpark. I have adjusted my prop from course to fine through out it's entire adjustment range and it makes a little but not a lot of difference.
I have to go to work, I'll get back later, but all can say is build it as light as possible and good luck.
Good evening Mike,
Wanted to let you know that I have the new heads on and have flown it several times. The performance is a little better at about 600 fpm at 60 ambient and 1060lbs. I have no oil leaks and the plane seems to be doing fine. I am only up to 63 hours, have not been able to fly much due to work and weather. My new heads do not cool as well as the old ones but this could be due to the little higher compression. I feel a little better about the vw now, this is the first time in a year that I have not had to pull the cowling after every flight and check on something. I still am not happy with the climb rate but it is pretty radical, it just doesn't show it on the vertical speed indicator. I intend to make a video in a few days, my camera has died and we're getting it fixed but as soon as we get things up and running I'll see about getting some video shots for you.
Mike, I ordered a new set of heads from Great Plains and will install them when they arrive later in the week. I have used this down time to repair some other stuff like oil leaks that I have been putting off. I talked to Steve Bennet at GPAS and he has no idea why this happened, I had Never Seize on the plugs and they did not protrude into the combustion chamber. I will repair these heads and have a spare set but right now I want to get back in the air and a new set of heads will provide a little "mental" security. I also will raise my compression with these new heads ( to what Valley Engineering runs) in an effort to improve performance. This is the last straw for me and the vw. Without question I would run the Rotax 912 if I had the money but I don't so my ONLY choice is the vw or nothing. If I have another major prblem thats it, I'll crush the airplane with the dozer and be done with it. I am literally this dis appointed with this setup. When I talked to you right after Oshkosh I was still optimistic but after 57.4 hours since last Nov. 3rd it is apparent that it will never end. I have not had one person running this combo tell me from their own mouth that they are getting the performance claimed by some. I'll let you know how it goes at the end of the week.
Hello Mike, I can't describe how sick I am right now. I went to the hanger this evening to swap plugs and ALL 4 on the bottom stripped out. Actually one twisted off in the head. I had to pull both heads and I have them on the bench back at the shop and I am at a loss as to what to do. I will not be at the open house. Right now I am just about as frustrated as I have ever been. This is probably the end for me and the vw. After repitching the prop it did a little better and I intended to fly it until winter and redo everything under the cowling. I never made it to winter. I'm through with this thing as I can't take anymore disappointment. I just don't know how to say how bitter I am right now. Do not waste your money on the vw. About every 2 hours I have to do something to it and about every 10 it is MAJOR. I have 59 hours on it and the heads have been off 3 times, the engine off the airframe once, belts at 54 hours, oil leaking everywhere, 6gph, on and on and on. It is never going to end and the performance still sucks. I was so excited about this trip but it ain't gonna happen now.
Well I have supper out of the way. First let me say that my 701 is REALLY heavy at 742lbs empty. Bear that in mind. On a cool day I get airborn in under 100 feet, a little over if it is hot. I have taken off on grass with half fuel, about 1014lbs, in 117'. Depending on how hard I run it I get between 70 and 80 mph cruise. Stall is 32mph. Best rate is 45 to 60 mph, thats right, it makes little difference so I rotate at 45 and it leaps, and I mean leaps into the air. I climb out at 55 or so for cooling and after reaching 500agl I pull the power back to about 75 percent. It will climb very steep at 40 mph but it is scary. I have had all sort of trouble but it was all created by myself. If you can get your hands on the the last issue of the Zenair News, and the one coming out I have a lengthy two part story about my ordeal. If you have any questions at all get in touch with me and I'll be glad to help out. Also keep this in mind, I plans built with total cost to 1st flight of under 23 thousand. $1100 was freight. I could have done it much cheaper if I hadn't put all the crap in it. Where ever I land there is always a crowd around it.
Yes I am running a vw with the valley redrive. I bouht parts from Great plains but I bought most of the other stuff locally. I have a Hi Perf. vw shop close by. I like the Vw so far, I'll get back to you later on with numbers, likely tomorrow.
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