Zenith CH-701. What engine to use?

D

docmirror

Touchdown! Greaser!
Joined
Jan 5, 2007
Messages
12,008
Display Name
Display name:
Cowboy - yeehah!
1. NO 2 strokes.

2. Modest price.

3. Decent speed(for the plane of course).

I'm thinking used O-200, but if there are better options I'm hoping to hear. The Rotax 914 turbo seems ideal, but the cost is gak.
 
I don't know squat about it, but for a STOL plane I'd want to keep the weight down.
 
Rotax 912. All other choices pale in comparison. Reliable, proven, 2,000+ hours TBO (many go 3,000+), burns car gas or 100ll @ 3.5-5 GPH, smooth, relatively easy to work on with lots of support, much better resale when the time comes.

0-200 is too heavy IMHO.
 
Last edited:
Geico266 said:
Rotax 912. All other pale in comparison. Reliable, proven, 2,000+ hours TBO (many go 3,000+), burns car gas or 100ll @ 3.5-5 GPH, smooth, relatively easy to work on with lots of support, much better resale when the time comes.

0-200 is too heavy IMHO.
Click to expand...


Agreed... Most successful 701's /750's have the Rotax... They are getting damn pricey though...:eek:
 
Jabiru or Rotax are the way to go.
 
That's what I was thinking. The 914 turbo would be ideal, the 100HP 912 would do fine, but the cost of them is just out of touch.
 
I'm thinking the o-200 too, on a CH 650.

It's a known engine, every GA mechanic in the work can work on it and it will probably still be available decades from now. I'm not sure you'll be able to say that about a rotax or jabiru.

Rather than state their conclusion, does anyone have comparison charts?
 
bflynn said:
I'm thinking the o-200 too, on a CH 650.

It's a known engine, every GA mechanic in the work can work on it and it will probably still be available decades from now. I'm not sure you'll be able to say that about a rotax or jabiru.

Rather than state their conclusion, does anyone have comparison charts?
Click to expand...


The OP asked about the 701.... It is a tiny plane....:redface:
 
N801BH said:
The OP asked about the 701.... It is a tiny plane....:redface:
Click to expand...

The 701 is an earlier version of a Zenith STOL. The Zenith 650 is only a slightly larger plane, 1320 lbs vs 1100lbs, although with higher speeds to 120 kts vs ~95 kts. The wingspan on the 701 is larger, probably associated with the STOL capabilities.

I'm still up in the air about the engine, so I'd like to see comparisons between the Zenith recommended options, there's actually 4 - 0-200, 0-235, Jabiru 3300 and Rotax 912S.

Although interesting - just looking back at their site, I see that the 0-200 is only listed by them as an option for the 750, not the 701.
 
100 hp 912 would be my choice. I have about 500 hours flying behind them. They run like a great big electric motor.
 
bflynn said:
The 701 is an earlier version of a Zenith STOL. The Zenith 650 is only a slightly larger plane, 1320 lbs vs 1100lbs, although with higher speeds to 120 kts vs ~95 kts. The wingspan on the 701 is larger, probably associated with the STOL capabilities.

I'm still up in the air about the engine, so I'd like to see comparisons between the Zenith recommended options, there's actually 4 - 0-200, 0-235, Jabiru 3300 and Rotax 912S.

Although interesting - just looking back at their site, I see that the 0-200 is only listed by them as an option for the 750, not the 701.
Click to expand...

I was not clear on my response.. Sorry.....

Most, if not all 701's that had a O-200 installed was too heavy to deal with.
 
In my experience, the C-90 pulls better than the O-200.

One prop maker in Europe uses 85 hp as the basis for calculating propellers for O-200s.

The C-90 makes its power at 2475 RPM as opposed to the O-200's 2750. Higher RPM is less efficient and suffers more prop drag.

It also makes 95 HP for five minutes at 2625 RPM.

I flew several 150s with the O-200. An anemic airplane when compared to the Ercoupe (Alon Aircoupe) with a C-90, which outperformed the 150 every which way. Same power-to weight ratio, too. I had long suspected the O-200 wasn't everything it was cracked up to be.
 
bflynn said:
The 701 is an earlier version of a Zenith STOL. The Zenith 650 is only a slightly larger plane, 1320 lbs vs 1100lbs, although with higher speeds to 120 kts vs ~95 kts. The wingspan on the 701 is larger, probably associated with the STOL capabilities.

I'm still up in the air about the engine, so I'd like to see comparisons between the Zenith recommended options, there's actually 4 - 0-200, 0-235, Jabiru 3300 and Rotax 912S.

Although interesting - just looking back at their site, I see that the 0-200 is only listed by them as an option for the 750, not the 701.
Click to expand...

I believe 650 is the new version of 601 and both are low wing. 912 would be my choice but a little pricey next would be Jabiru 3300.
 
For the sake of a discussion, buy a used Rotax 912 and put a Zipper Big Bore High Torque engine on it for $42,00. Gets you 105 hp at 6000 rpm and burns 87 octane. (Yes, that's faster than Rotax recommends, but they won't stand behind this engine anyway and besides you can always run it slower.
http://zipperbigbore.com/1484-zipper-high-torque/
Lot's of discussion at TeamKitFox
http://www.teamkitfox.com/Forums/showthread.php?t=5301
and Backcountry
https://www.backcountrypilot.org/forum/big-bore-1484-cc-conversion-for-rotax-912s-15221
 
If you think that 912 is expensive, look at the proce of ULpower 260iS.

One interesting alternative is AeroVee with turbo. Unfortunately, the death of Jeremy Monnett is going to be a major setback for that program.

There are a few crazy Euro engines in this class, such as the D-moto and ICP. But one has to be even crazier than Viking customers to install one of those.

BTW, I'm not sure the 701 really needs a 914. I flew a 950 lbs airplane on the power of 56 hp. That was a torture, but I'm sure 65 hp would be plenty. A 1100 lbs airplane like CH701 is going to do fine on 80..90 hp. If I were building a 701, I'd aim for the 80 hp 912. As a bonus, you could use the ethanol-free gas for boaters, which the 100 hp 912 cannot use. The 80 hp is also much easier to hand-prop.
 
Last edited:
docmirror said:
No offense, but after seeing who's behind the Viking aircraft engines, I"m gonna pass. Hope it works out well.
Click to expand...

Ah, come on doc...

Jan has NEVER conned people in any of his other business ventures..:redface::redface::rolleyes:
 
N801BH said:
Ah, come on doc...

Jan has NEVER conned people in any of his other business ventures..:redface::redface::rolleyes:
Click to expand...

I was getting pretty pumped, then I watched a vid, and I saw something I recognized. I backed up and sure enough -- there he was! In the flesh! Walking and talking like a real guy. I put my wallet back in my pants. :mad::yesnod:
 
zaitcev said:
If you think that 912 is expensive, look at the proce of ULpower 260iS.

One interesting alternative is AeroVee with turbo. Unfortunately, the death of Jeremy Monnett is going to be a major setback for that program.

There are a few crazy Euro engines in this class, such as the D-moto and ICP. But one has to be even crazier than Viking customers to install one of those.

BTW, I'm not sure the 701 really needs a 914. I flew a 950 lbs airplane on the power of 56 hp. That was a torture, but I'm sure 65 hp would be plenty. A 1100 lbs airplane like CH701 is going to do fine on 80..90 hp. If I were building a 701, I'd aim for the 80 hp 912. As a bonus, you could use the ethanol-free gas for boaters, which the 100 hp 912 cannot use. The 80 hp is also much easier to hand-prop.
Click to expand...


UL Power UL 260is is $17500 with the firewall forward package $4450. I'm flying a UL Power 350is in a 750 and it is smooth with lots of power. No gearbox and no radiator to deal with. Don
 
docmirror said:
What about this deal with the Geo engine and the geared PRSU?

thinking of the Geo 13B putting out about 80HP or so. A bit heavier than the rotax. I've had a half dozen Geo cars with this engine, and they were ultra-reliable. The big unknown is the PRSU box.

http://www.airtrikes.net/airtrikes_pricelist_engine_prop.htm
Click to expand...

Most car engines run at higher RPMs than airplane engines. That limits the size of propeller that you can use because at higher RPMs the prop tip is approaching the sound barrier. The PRSU is a reduction drive which lowers the prop RPMs so you can use a larger prop. Switching from a 68" prop to a 84" prop almost doubles the thrust.

That assumes the engine can handle the thrust, which at the LSA end of the scale is probably true.

For a 650, I think I settled on the 0-235 (XO-233) because I like having an engine that everyone knows. But the price plus FWF kit is more than the airframe and the cost is getting over 50k, so now I'm rethinking the entire project.

I'm heading back to something I know, probably a VW engine with reduction drive...some kind of Sonex or an Airdrome replica. Onex might be the choice if I can figure out some cargo space and much better tank range. I don't know why Sonex seems to design all their airplanes with a 2 hour range...
 
N801BH said:
I was not clear on my response.. Sorry.....

Most, if not all 701's that had a O-200 installed was too heavy to deal with.
Click to expand...

After doing some reading on it, I think I've read the same tihing. It looks like a 100hp engine isn't quite enough for a 1100-1320 lb airplane.
 
bflynn said:
After doing some reading on it, I think I've read the same tihing. It looks like a 100hp engine isn't quite enough for a 1100-1320 lb airplane.
Click to expand...
Yeah...

I put a 400 HP engine in a 1190 lb plane to overcome any power to weight ratio issues...:yikes:.....:redface:...

And I know all about PSRU's...:hairraise:
 
N801BH said:
Yeah...

I put a 400 HP engine in a 1190 lb plane to overcome any power to weight ratio issues...:yikes:.....:redface:...

And I know all about PSRU's...:hairraise:
Click to expand...

Isn't your unit a belt? the Airtrikes have a couple closed gear set drives. But, like I said, I don't know anything about their reliability. However, if it's good enough for Conti with their geared drives, I would think it's good enough for me. One thing I do like about them is they use their own lubrication bath, and don't share lube with the internal combustion engine. This has been proven many times over to be a poor substitute, although Conti uses it. I'm guessing in a situation where the oil is changed regularly that helps the pressure rating of the lube in the gears.
 
docmirror said:
Isn't your unit a belt? the Airtrikes have a couple closed gear set drives. But, like I said, I don't know anything about their reliability. However, if it's good enough for Conti with their geared drives, I would think it's good enough for me. One thing I do like about them is they use their own lubrication bath, and don't share lube with the internal combustion engine. This has been proven many times over to be a poor substitute, although Conti uses it. I'm guessing in a situation where the oil is changed regularly that helps the pressure rating of the lube in the gears.
Click to expand...

It is a belt... So is the Geo, that is why I commented..
 
Ok, so I didn't understand the question then...not unusual for me. And I probably don't know the answer either ;)
 
bflynn said:
I don't know why Sonex seems to design all their airplanes with a 2 hour range...
Click to expand...
16 gallons. 4.5 gallon per hour gives you 3 hours plus reserve if you have VW or Jab 2200. you're right about 3300.
 
N801BH said:
It is a belt... So is the Geo, that is why I commented..
Click to expand...

Negative, that Airtrikes link I provided is for an engine with a bellhousing and a gear drive adapter. It uses a reduction gear in it's own lube bath. That's what got me interested in it along with the price.
 
docmirror said:
Negative, that Airtrikes link I provided is for an engine with a bellhousing and a gear drive adapter. It uses a reduction gear in it's own lube bath. That's what got me interested in it along with the price.
Click to expand...

I believe ya.... I didn't click on the link,, I assumed it was the Geo conversion guys out of Colorado...:redface::redface:
 
O-200 is heavier than Zenith recommends. If you're looking for a lower priced engine, the Revmaster R-2300 is a candidate. It produces its power at a lower RPM than do most VW derivatives, and the proprietary cylinder heads should cool better than the VW derived ones most others use.

Being that it's a STOLplane, the time is going to come where you're going to want to get out of something small and static thrust is going to be important. I do believe you'd be happiest with the 100 hp Rotax. I don't see the need for the turbo, and the geared Rotax ought to get you off of the ground faster than the VW derivatives.
 
A couple of weeks ago I looked back at Sonex and found that they were promoting the Aerovee turbo VW engine. I think it take fuel burn to 8 gph, but they were quoting 1100-1300 fpm climb rates in a 1320lb sonex. That would seem to be adequate power for an LSA.

The engine is $11,000, so much less than other choices. I don't know much about it, other than Aerovee had problems with their thrust bearings some years back.

I also spoke with a gentleman at the Zenith booth at Oshkosh and he didn't think much of VW engines, but I'm not sure the turbo has been around enough to make a splash.
 
FormerHangie said:
O-200 is heavier than Zenith recommends. If you're looking for a lower priced engine, the Revmaster R-2300 is a candidate. It produces its power at a lower RPM than do most VW derivatives, and the proprietary cylinder heads should cool better than the VW derived ones most others use.

Being that it's a STOLplane, the time is going to come where you're going to want to get out of something small and static thrust is going to be important. I do believe you'd be happiest with the 100 hp Rotax. I don't see the need for the turbo, and the geared Rotax ought to get you off of the ground faster than the VW derivatives.
Click to expand...

Pricey. Working at altitude, so I was thinking turbo to gain back some sea level pressure. Another reason I could go for that Geo deal, they also offer a turbo normalize kit.
 
bflynn said:
A couple of weeks ago I looked back at Sonex and found that they were promoting the Aerovee turbo VW engine. I think it take fuel burn to 8 gph, but they were quoting 1100-1300 fpm climb rates in a 1320lb sonex. That would seem to be adequate power for an LSA.

The engine is $11,000, so much less than other choices. I don't know much about it, other than Aerovee had problems with their thrust bearings some years back.

I also spoke with a gentleman at the Zenith booth at Oshkosh and he didn't think much of VW engines, but I'm not sure the turbo has been around enough to make a splash.
Click to expand...

Well, here's the deal on the converted VWs. Right now, as I learned there are NO more makers of the stroked crankshaft that are not from China. I just happen to have one of the older 82mm stroker cranks from a short run that Scat made back in the day. I know enough about VW engines to want to stay away from them. In the best days, the VW case was made for about 64HP @ 3600RPM. The girdles in the case just begin to lose their resiliency with higher torque and thrust. It really isn't a heat issue, because the cases have a fair amount of mag in them to keep the air cooled crankcase pretty robust, but the whole thing starts to get dicey when you get up over 80HP. I've built a couple of 2180s, and a 2276 for buggies that were up over 100HP. They were made to last 2-3 seasons of sand buggy running. Of course, the aviation use cycle is much different but that little engine just doesn't last more than ~500 hours when putting out 80 or more HP. The 2300 Revmaster is one of the finest VW conversions out there, but they still use cranks made in China.

The other factor with the VWs that bug me is the thrust issue. It's why Sonex is so in love with their tiny wood or composite props. The prop forces on that crank in the VW is just a mess. It would be better driven off the front(mount flange) end of the case, but that creates huge cooling issues. So, I just can't see winning with any of the VW derivatives that don't need constant care and feeding. Also, when the VW engines let go, they often are catastrophic unlike the Lyc and Conti engines which more often give some warning they aren't happy.
 
docmirror said:
1. NO 2 strokes.

2. Modest price.

3. Decent speed(for the plane of course).

I'm thinking used O-200, but if there are better options I'm hoping to hear. The Rotax 914 turbo seems ideal, but the cost is gak.
Click to expand...

Yeah, the Rotax pricing is getting mighty steep. I would use an O-235 with the 125hp Sparrowhawk conversion if I didn't want to spend the money on a 914.
 
docmirror said:
Well, here's the deal on the converted VWs. Right now, as I learned there are NO more makers of the stroked crankshaft that are not from China. I just happen to have one of the older 82mm stroker cranks from a short run that Scat made back in the day. I know enough about VW engines to want to stay away from them. In the best days, the VW case was made for about 64HP @ 3600RPM. The girdles in the case just begin to lose their resiliency with higher torque and thrust. It really isn't a heat issue, because the cases have a fair amount of mag in them to keep the air cooled crankcase pretty robust, but the whole thing starts to get dicey when you get up over 80HP. I've built a couple of 2180s, and a 2276 for buggies that were up over 100HP. They were made to last 2-3 seasons of sand buggy running. Of course, the aviation use cycle is much different but that little engine just doesn't last more than ~500 hours when putting out 80 or more HP. The 2300 Revmaster is one of the finest VW conversions out there, but they still use cranks made in China.

The other factor with the VWs that bug me is the thrust issue. It's why Sonex is so in love with their tiny wood or composite props. The prop forces on that crank in the VW is just a mess. It would be better driven off the front(mount flange) end of the case, but that creates huge cooling issues. So, I just can't see winning with any of the VW derivatives that don't need constant care and feeding. Also, when the VW engines let go, they often are catastrophic unlike the Lyc and Conti engines which more often give some warning they aren't happy.
Click to expand...

The main issue I have with the VW, Subaru, and Corvair conversions is the drive end crank main journal is not made to take the gyroscopic forces incurred with a prop bolted onto it.
 
You must log in or register to reply here.
Back
Top