The 100HP VW--Reliable? Practical?

[Vigilant1]

Some more on high-power VW Type 1 engines--grist for the mill:
- Wayne Clagg installed a 2276cc engine in his CH 701, complete with a Valley Engineering 1.6:1 redrive and a 74" Powerfin prop. The redrive allowed him to get an estimated 100HP output from the engine (by running at higher RPMs). He had the (anticipated) problems with shedding heat from the engine. He brazed on the "big fin" mods to the head (which he claimed helped quite a bit), but the engine never proved to be reliable. The total firewall forward weight of the engine with "everything" wound up being 223 lbs, which is a lot. He suffered numerous leaky exhaust valves and a cracked head, so he has now installed a Rotaz 912ULS and is happy with the performance. I don't know if he incorporated Bob Hoover's HVX modifications. Overall, it sounds like the redrive allowed him to produce the HP he wanted, but he was unable to beat the problem of removing heat to keep his temperatures sufficiently low to allow reliable performance over time. The CH 701 is a high drag machine and it's possible a cleaner, faster plane would have been easier to cool, but this certainly supports the idea that these higher HPs are hard to obtain in real aircraft use.
April 2011 Kitplanes article
Video [video]http://www.zenith.aero/video/vw-powered-zenith-ch701sp[/video] of the plane taking off, with some comments.

- Another idea for cooling the VW's heads in higher HP applications (turbo, higher RPM normally aspirated, etc): oil spray bars. Circulating a lot more oil through the VW heads provides a means of removing heat (this is done on the BMW R1200 motorcycle engine and many auto engines, including the Porsche 911 engines). Hoover's HVX modifications improve flow of oil to the head (he mentioned 8x more oil flow than the stock arrangement), and the addition of spray bars with their own direct oil supply would permit even more flow. Here's a picture of one installation (from this site):

Doing this also allows use of cooler oil directly from the oil cooler, the other oil in the head has already picked up heat during a trip through the tappets, pushrods, and rocker shaft. So, you'd have the advantages of more oil, cooler oil, and oil put just where it is needed for cooling.

I've not seen this modification in a flying VW, but I'm far from an expert on this. Again, probably not needed (and just extra complexity) on engines producing up to 80 HP, but might be a good modification if trying to push this engine beyond that. The air/oil cooled BMW motorcyle engines are reportedly getting 100HP reliably from an engine roughly 1/2 the displacement of the large VWs. Yes, that's a different engine designed from scratch to do this (albeit with less cylinder and head internal surface area than the VW has), but it does at least indicate it may be possible to get rid of enough heat with a combination of direct air and oil-to-air cooling, if enough oil is circulated through the heads (to cool them and especially the exhaust valves).

Mark

 

[revkev6]

ahhh something I am very familiar with! the autocraft pro series 910 head! not many people use the spray bars even in those full race engines. the spray bars actually point at the rockers not the springs and valves. not meant to cool anything, just supply more oil to the rockers. those heads are like iron! very dependable unfortunately they are setup with huge ports and valves for racing with very little cooling fin area. I've dreamed of making an autocraft VW aircraft engine but can't seem to find a good way to make it efficient. 2.7 liters worth of vw would make a nice little engine if the ports were small enough. my last Autocraft VW engine idled at over 2k rpm!

 

[Vigilant1]

the spray bars actually point at the rockers not the springs and valves. not meant to cool anything, just supply more oil to the rockers.

One of the comments on the site where I found that picture indicated the spray bar shown was actually rotated from the normal position and that the holes were usually pointed to cool the springs and valve stems. Maybe there were differences among various users.
Those AC 910 heads are still available, but sell for $1500--wow. They have 5 (thick) fins. The heads GPAS stocks have 8 fins and sell for $300, FWIW.
Thanks for the info!

 

[Vigilant1]

For as much power as you want I think you are now in the Subaru range with the watercooling. I dont think you can do it economically. You could see if Rotaway Helicopter would sell one of their watercooled fadec engines. They started out with VWs when the Scorpion came out and refined it to their own engine. It still has VW DNA even if not one part interchanges.

TFF, starting with your tip on the Rotaway I dug around a bit and found this interesting tidbit: A few years ago GPAS sold water-cooled heads for Type 1 VWs. Here's the web page (now defunct, along with the company that produced them according to Dunn and Bradstreet).
It looks like 100HP was available from an 1821CC engine at 3600 RPM as a result of running at a compression ratio of 9:1. They claim 92 Octane (RON, the US measure, approx 96 in Europe) was sufficient (hmmm . . .). 88 HP continuous at 3400 RPM. All-up engine weight was 174 lbs, I don't know how much extra for coolant and radiators (probably not much--6 lbs?). Maybe this is old news to VW fans, but I'd not heard of it before. I'm not sure how reliable the setup proved to be, Great Plains reportedly stopped carrying these water-cooled heads due to low demand. There's no doubt the high CR and power output at these RPMs would have placed everything under a lot of stress.
Anyway, another bit of history.

 

[Pops]

Wayne Clagg is a friend of mine, very nice man. He flys his Zenith 701 up to my place when we have our cookouts. You are 100% correct about Wayne's VW engine.
I have the HVX mods on my little 1835 VW engine and it almost runs to cold. If it below 80 degs, I have to block some of the air to the oil cooler. The down side is while pumping the extra oil to the head, the extra volume lowers the oil pressure with a stock small oil pump. Pops

Some more on high-power VW Type 1 engines--grist for the mill:
- Wayne Clagg installed a 2276cc engine in his CH 701, complete with a Valley Engineering 1.6:1 redrive and a 74" Powerfin prop. The redrive allowed him to get an estimated 100HP output from the engine (by running at higher RPMs). He had the (anticipated) problems with shedding heat from the engine. He brazed on the "big fin" mods to the head (which he claimed helped quite a bit), but the engine never proved to be reliable. The total firewall forward weight of the engine with "everything" wound up being 223 lbs, which is a lot. He suffered numerous leaky exhaust valves and a cracked head, so he has now installed a Rotaz 912ULS and is happy with the performance. I don't know if he incorporated Bob Hoover's HVX modifications. Overall, it sounds like the redrive allowed him to produce the HP he wanted, but he was unable to beat the problem of removing heat to keep his temperatures sufficiently low to allow reliable performance over time. The CH 701 is a high drag machine and it's possible a cleaner, faster plane would have been easier to cool, but this certainly supports the idea that these higher HPs are hard to obtain in real aircraft use.
April 2011 Kitplanes article
Video [video]http://www.zenith.aero/video/vw-powered-zenith-ch701sp[/video] of the plane taking off, with some comments.

- Another idea for cooling the VW's heads in higher HP applications (turbo, higher RPM normally aspirated, etc): oil spray bars. Circulating a lot more oil through the VW heads provides a means of removing heat (this is done on the BMW R1200 motorcycle engine and many auto engines, including the Porsche 911 engines). Hoover's HVX modifications improve flow of oil to the head (he mentioned 8x more oil flow than the stock arrangement), and the addition of spray bars with their own direct oil supply would permit even more flow. Here's a picture of one installation (from this site):

Doing this also allows use of cooler oil directly from the oil cooler, the other oil in the head has already picked up heat during a trip through the tappets, pushrods, and rocker shaft. So, you'd have the advantages of more oil, cooler oil, and oil put just where it is needed for cooling.

I've not seen this modification in a flying VW, but I'm far from an expert on this. Again, probably not needed (and just extra complexity) on engines producing up to 80 HP, but might be a good modification if trying to push this engine beyond that. The air/oil cooled BMW motorcyle engines are reportedly getting 100HP reliably from an engine roughly 1/2 the displacement of the large VWs. Yes, that's a different engine designed from scratch to do this (albeit with less cylinder and head internal surface area than the VW has), but it does at least indicate it may be possible to get rid of enough heat with a combination of direct air and oil-to-air cooling, if enough oil is circulated through the heads (to cool them and especially the exhaust valves).

Mark

 

[cavelamb]

I fly behind a VW type 1, 1835, 60 HP, 7.5 CR. Zenith Carb, Slick Mag. No electics. 141 lbs firewall forward weight. Culver 60" X 26" prop, single port heads with stainless valves. Bob Hoover's HVX oil mods with a oil filter, oil cooler, and a hot oil box around the intake at the base of the carb ,( also cools the oil 20 deg). Great engine with lots of power. NO heating problem. Cruise- 80 mph, burning 3 gph at 2700 rpm. ( that's about 35HP). ROC- 1200+ at GW. TO-250'
Aircraft -- Fisher Super Koala Construction, but built to the dimentions of the Koala 202 to look like a Cub. EW- 450 lbs.
Perfect combination of airframe and engine.

This is an ugly question, but asked politely?

Why do you say it's a 60 hp motor?

Do you know how much torque it makes at a giver RPM?

 

[Vigilant1]

This is an ugly question, but asked politely?

Why do you say it's a 60 hp motor?

Do you know how much torque it makes at a giver RPM?

Not asked of me, but two inputs offered:
-- The builders of the bigger VW engines (who have dynos) say their engines put out 75HP continuous reliably.
-- Scores of Sonex builders have fitted Jabiru 2200 engines to their airplanes. These are available in certified form and have been verified to produce 80 HP continuous (85 HP for TO). The large installed base of flying Sonex aircraft allows adequate basis for comparison of these engines with VW-based engines of 2180 CCs and the performance is very similar. This includes many hours on end of cruise flight. There's no way that these VWs are "40 HP engines".

Sorry to butt in, and that your experience with various VW installations did not match this.

 

[cavelamb]

Not asked of me, but two inputs offered:
-- The builders of the bigger VW engines (who have dynos) say their engines put out 75HP continuous reliably.
-- Scores of Sonex builders have fitted Jabiru 2200 engines to their airplanes. These are available in certified form and have been verified to produce 80 HP continuous (85 HP for TO). The large installed base of flying Sonex aircraft allows adequate basis for comparison of these engines with VW-based engines of 2180 CCs and the performance is very similar. This includes many hours on end of cruise flight. There's no way that these VWs are "40 HP engines".

Sorry to butt in, and that your experience with various VW installations did not match this.

Not at all. Welcome to the fray.

I was afraid that would be something like that.
But ok.
That's not my point.

It might be that we are comparing apples and oranges here.

Our aircraft are very draggy low speed things.
My 2180 - with Diehl accessory case, starter, mag, weighed in at 203 pounds.
(Nearly half the aircraft's empty weight!)

THAT hurt - a lot as it replaced a Rotax 503!
In THIS class aircraft, the 503 would outperform an 1835 in all but absolute top speed. (under 100 mph)
The 2180 could keep up in cruise, but the extra weight hurt climb rate - badly.

That engine turned a 60x28 Tennessee Prop - something near 3000 rpm.
(It has been too long to quote exact numbers honestly)

I'm going to guess that the high speed rides will let the engine turn up faster at high speed
thus making more power as the prop unloads?

What kind of props are they using? 56-squared?

Acceleration and takeoff roll will suffer with short high pitched props.
I recall Leeon Davis saying that the prop on his DA-9 didn't "unstall" until it hit 100 knots.
At that point there was a noticeable jump in acceleration.

I have ALWAYS said that the VW can make more that 40 horse.
For a limited time.

75 continuous? I would like to see the raw data.
And the heads.

My only complaint here is stating that this engine make x HP and that one makes Y
without anything more substantial than - it seems to be...

 

[Vigilant1]

Our aircraft are very draggy low speed things.
My 2180 - with Diehl accessory case, starter, mag, weighed in at 203 pounds.
(Nearly half the aircraft's empty weight!)

What else was on that?? A front-drive Great Plains 2180cc engine with a Diehl case, starter, and Slick mags, Force One prop hub, intake manifold, oil cooler, etc weighs 165 lbs .

I'm going to guess that the high speed rides will let the engine turn up faster at high speed
thus making more power as the prop unloads?

What kind of props are they using? 56-squared?

Sonex builders setting up for climb are using 56" x 42" I think, those optimizing for cruise are using 54 x 46 I believe. I don't think an ungeared 2180 would get any kind of performance from a 56" x 56" prop.

My only complaint here is stating that this engine make x HP and that one makes Y
without anything more substantial than - it seems to be...

I'm with you. Stuff like this (no context, just a blanket assertion) probably bugs you, too:

But the bottom line is that the VW is simply too small and turns too fast to be a really useful motor.
40 horse at the prop with more available in bigger engines (1835 and 2180) for 5 minutes or so.

Certified Limbach aero engines, based on the VW engine, with have been cranking out more than 40 HP reliably, on dynos and in airplanes, for many years. Believe it or not.

 

[autoreply]

I have ALWAYS said that the VW can make more that 40 horse.
For a limited time.

75 continuous? I would like to see the raw data.
And the heads.

My only complaint here is stating that this engine make x HP and that one makes Y
without anything more substantial than - it seems to be...

Like Vigilant1 mentioned, a few thousand of those VW's have been flying as certified power plants. Yes, they really make that power (60-75 hp continously) and have reasonable TBO's (1000+ hrs) Anything above that (75 hp) seems to either need drastic measures like water-cooling or drastically drops in reliability.

 

[cavelamb]

Like Vigilant1 mentioned, a few thousand of those VW's have been flying as certified power plants. Yes, they really make that power (60-75 hp continously) and have reasonable TBO's (1000+ hrs) Anything above that (75 hp) seems to either need drastic measures like water-cooling or drastically drops in reliability.

165 lbs .

Did anybody actually understand what they saw in this chart?

3600 rpm? to make those HP numbers!

 

[Vigilant1]

165 lbs .
Did anybody actually understand what they saw in this chart?
3600 rpm? to make those HP numbers!

I can read the chart--what of it? And it takes 3400 RPM for a 2276cc engine to make 76 HP--and do it continuously. There's nothing wrong with that. You said the engines can't produce more than 40 HP for more than five minutes, I'm telling you they can and do put out almost double that rating for hours. How many RPMs is allowable?

Maybe some folks don't like/can't use smaller props, maybe they don't like turning higher RPMs--none of that is germane to the question of the reliable sustained output of these motors.

Edited to add:
Here are the dyno curves for the Sonex/Aerovee 2180 CC engine. If somebody is only comfortable with running any engine like a Lycoming, they can turn the VW engine at 2700 RPM and get 65 HP all day long. It's certainly not the max capability of that engine, and it's a lot more than 40 HP. Right?

 

[cavelamb]

Help me understand, Vig.

What size engine are you using and what size prop ?

Pops gave us his numbers.
I gave you mine.

 

[Vigilant1]

cavelamb,
I'm not running any of them, but I'm in touch with lots of Sonex guys who do. They are running the props we talked about earlier.
If a builder wants to turn a larger prop (for more static/low speed performance) I think they generally use a PSRU. That's what the guys who use VW engines successfully in their WW1 biplane replicas do (and it's hard to get "draggier" than that!). That allows an engine with this torque to twist a larger prop and do it at the higher RPMS where the engine makes its best power.

 

[cavelamb]

No sir.
I've read that in magazines and on the net, but that's not what we see flying.

I know a lot of VW guys. But not a single successful redrive in the bunch.
(Your milage may obviously vary!)

We built a couple of belt drive units but we never comfortable enough to risk YOUR life on one.
Keeping the belt alignment proved more of a problem than expected.

Chuck adapted Rotax gearboxes to a few engines (VW, Subaru, and Geo), but it was never a
really successful endeavor. Higher engine speed of VWs meant heat problems.
And the Geo 3 banger broke it's crank in less than 15 hours.

The Sube worked out best of any of them. But for the weight issue.


The Dawn Patrol guys in Kansas City run VWs on their Nieuports 11s.
That's pretty much the draggiest of the draggy biplanes.
No redrives on any of them

We are using a 1835cc. VW power plant with a Culver prop. (60 x 28)
The engine is all stock with a Weber PIC-30 or Zenith carb and a Vertex
Magneto ignition system. We used baffles to convert the cowl to a pressure
cowl configuration.

The firewall is 34" in Diameter and leaves ample room for a VW to fit in and rattle around.

We are very satisfied with our VWs. I have 495 hours on mine and it's never
missed a lick through rain and really hot weather. Mark and I are the only
ones who have had to make forced landings and that was not the engine's fault.
(Blocked fuel line on Mark's, empty fuel tank on mine.) If we had to do it over,
we'd do it with VWs again. We're not pushing them at all at 2650 rpm cruise
and they run cool in the hottest of weather. A good pressure cowling is the key.

Tom tells me the empty weight of a "bare bones" VW is 117 lbs.

The "bare bones" weight of a VW with manifolds, ignition system, carb
and assorted plumbing is 147-153lbs depending on different configurations.
Glenn Huff is flying his Nieuport 12 with an C-90.

We feel a 1700-1835cc VW is all the engine you would want on these little
planes. Rotax powered Nieuports are flying very well using a 447 or 503.

I'm just trying to say - what get's printed, and what get's flown are not always the same thing...

 

[cavelamb]

What else was on that??

 

[Vigilant1]

The Dawn Patrol guys in Kansas City run VWs on their Nieuports 11s.
That's pretty much the draggiest of the draggy biplanes.
No redrives on any of them

I'm glad to hear the smaller VW engines are working well for them. It might or might not be "optimum", but if they are getting enough output from the direct drive (as it sounds like they are), there's certainly no need to add the complexity, cost, and weight of a PSRU.

 

[cavelamb]

Optimizing any one detail usually makes for poor overall results.

Weight and complexity are the mortal enemy of performance and reliability.
In that regard, the simpler the better.


Richard

 

[Pops]

The only reason I say its a 60 HP is that is what a 1835 should develop at 3400 rpm. (Look at GP's charts) The prop that I am using will not let the engine develop 60 Hp. My WOT rpm is just 3050-3075 RPM with a Culver 60"x26" prop. Since I have not done a WOT fuel flow test, I really don't know how much HP the engine is producing at the WOT rpm,( but guessing at about 50 HP). At cruise RPM of 2650, burning 3 gph it's developing about 35 HP. WOT at takeoff and climb the RPM is 2950. This airframe is overpowered with this engine, (Just what I like for off field flying). I have had the engine at WOT a couple of times (in level flight) to check the RPM , but 95 mph is to fast for the trim of the airframe. Had to hold a lot of down elevator. I am using single port heads and 1 1/4" dia intakes manifolds for max torque at these lower rpm's. If I was propped for 3000 + rpm's at cruise I would use the dual port heads with the larger valves and the larger dia intakes for better breathing at the higher RPM's.
This engine is developing very good torque at the lower RPM's. On the takeoff roll , feeding in full power, it noticeably ? shoves you back in the seat, in a aircraft EW of 450 lbs. and a takeoff roll of 200-250' and a ROC of 1200+. I can climb at 650 FPM at cruise power of 2650 rpm. Thanks for the question.
Not a ugly question, but a good one. Pops

This is an ugly question, but asked politely?

Why do you say it's a 60 hp motor?

Do you know how much torque it makes at a giver RPM?

 

[Pops]

Cavelamb
What size VW engine is that, and what airframe ? Can you give me some details. Pops

Oops, I see that its a 2180 cc.

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