The discussion started at
http://sbeaver.com/cgi-bin/fournier/cutecast.pl?session=Wj6PkQ9gjL95gApmfaFuh1Oc2i&forum=13&thread=701

and developed into my woes at finding my new VW engine is extremely stiff to turn.

The story continues (non-fiction, but not non-friction)...

Hi Jorgen, Ray

Thank you very much for your advice, both of you.
I followed Jorgen's first.

Yersterday I removed the top plugs and had a good look around inside all cylinders with a miniature LED torch.
No corrosion, no obvious roughness in the bores, no clear reason for excess friction.

Of course, with nikasyl cylinders, there should be no rust. It's got chrome piston rings by the way, which is presumably correct for nikasyl cylinders? These are very hard, and would obviously extend the breaking-in period.

So, I put 30cc of oil into each cylinder, and sprayed it all around inside with an air gun.

Result, still the same friction, but more accurately measured now at 12 to 14 pounds force required to move the propeller at 20-inches from the crankshaft center, depending on whether the pistons are at TDC/BDC or in the middle of their travels.
With its plugs still fitted, and no extra oil in its cylinders, the old (42 years, 1,300 hours) Rectimo engine never needs more than 2 pounds of pull.

I can easily turn over the old engine by twisting the prop flange, but absolutely cannot move the new engine's flange.

My concern is that the problem may only be a single, slightly tight main bearing, but it may also be that the crankcase needs to be align-bored.
It is a Brazilian AS41 dual-relief-valve case.
Is there any history of these being poorly made?

It could also be that one of the bearing shells has shifted off its retaining dowel (even if only slightly) or that there is a bit of swarf or a grain of sand or something under one of the bearing shells.

I am told by an expert that it is also possible that the front bearing (on an airplane), which has two holes in it, can be fitted backwards, so that the smaller (oilway) hole is over the retaining dowel, clamping the crankshaft.

Yes, I could just fly it and fly it and hope the engine eases off.
If this engine was in a car, that's what I would do.
And you almost had me convinced Ray, until you said that, after 40 hours, it is only 'nearly' as free as a regular engine.

I have three worries...

1) It's very difficult to start. At a normal starting throttle opening I can only get the engine to fire on one cylinder. It goes 'pop' every time, but won't go pop-pop-pop unless the throttle is half-open or more. I hope you can see my concerns with this.

2) With this stiffness I will never get this engine re-started inflight, either by diving or with the hand-starter.
It is hard to in-flight start a high-compression 1776 engine with normal internal friction. And of course, I often have to do this several times during every aerobatic flight, particularly in competitons, but often also in solo displays, and frequently during practice.
And, while it is a good glider, putting my RF4 down in the Swan River while displaying at Perth city would write off a rare & valuable airframe.
Ditto if I have to put it down in any of the bush anywhere around Western Australia.
The countryside here is not like Europe or America.
Undeveloped land is covered in short (3 metres high), tough trees & bushes, with very little open ground except when grazed by horses (mostly) or cattle. That bush would smash up HDO's wings, although I probably would walk away.

3) If this tightness is caused by a tight bearing or bearings, how do I know it won't start 'picking-up', with bearing material being smeared around and eventually breaking up?

Nasty things could be going on inside my engine, and I would never know from in the cockpit until it seized, or I saw metallic fragments in my drained oil. By then, there would be collateral damage inside.
I really cannot afford another new engine or even a rebuild.

Ray, could you possibly measure your current engine friction weith a spring balance on the prop's leading-edge about 20 inches from the crank's center, then I've got something to compare mine with.

Anybody else out there got a new engine who can do the same thing?

Thanks guys, as usual, I'll keep everybody informed of progress and results.

Today I'm going down there to ease off the crankcase nuts and bolts by half a turn each, to see if I can pin down the friction to a single bearing.

Yours, Bob

[Edit by Bob Grimstead on Monday, January 24, 2011 @ 11:58 PM]

[Edit by Bob Grimstead on Friday, April 8, 2011 @ 10:22 PM]

I thought for sure that would improve things and prove that my problem was in a main bearing.

The propeller seemed to move more easily, but when I measured the friction, it was still pretty similar, 10-12 pounds at 20 inches.

So now I'm gonna have to start dismantling.

It will be cylinders off first, to see whether one big end bearing is noticeably stiff, or the crankshaft's still hard to turn.
If it is of course, that's gonna mean splitting the case, with all that entails.

But none of that will happen for a couple of days, because tomorrow's Australia Day.
That's like Independence Day and Thanksgiving all wrapped into one, big long, outdoor celebration.

In our suburb, this traditionally starts with Australia Day breakfast -- local champagne, fruit, eggs, and a barbecue.

Aus Day breakfast can be a private thing, with a dozen or so neighbours invited around, or a public thing.
There's usually a huge breakfast celebration on the 'reserve' (a big public park) between our house and the Canning River.
Some bloke in a quiet little blue striped airplane with long wings and twin smoke trails usually flies an aerobatic display, but I hear it's not gonna happen this year.

Instead we're going for breakfast on their patio with good friends and neighbours a mile up the road.

Then it's barbecue lunch, with plenty of beer and good Australian wine.
Australian lamb's favourite, or steak & salad, although for us it's usually a salad with local lobster, prawns and mango dressing.

In the afternoon, everybody (half a million folks or more) makes their way to the city parks.
First there's a big aviation thing (nope, I'm not in that this year either) with lotsa planes flying over, a few doing aerobatics, and seaplanes landing on the broad Swan River, while folks play cricket, throw balls, wave flags or just party.

http://www.youtube.com/watch?v=HSXAaIi2ooE

Then a 100-foot high Australian flag's towed past by a big, powerful helicopter at sunset, with another shining a searchlight on it, while we all sing the Nationa Anthem -- very moving, that.

Finally, we have the mother and father of all firework displays -- usually half an hour or so, and costing vast amounts of money, but it's all worth it.

The soundtrack's provided by the most popular local radio station.

So, as you can imagine, I'll be doing no work on the Fournier tomorrow, and probably not much the next day either.

Meanwhile happy Australia Day to you all.

Yours, Bob

[Edit by Bob Grimstead on Tuesday, February 1, 2011 @ 05:49 AM]

[Edit by Bob Grimstead on Tuesday, February 1, 2011 @ 06:40 AM]

Here is an idea: The engine experiences different amounts of friction at different places in its rotation. At TDC and BDC, the pistons are hardly moving, so the cylinder friction is small. Almost all the friction comes from the bearings. At midway between TDC and BDC, the pistons are moving at their greatest rate, so the cylinder friction will be at its highest.

Do you detect a difference in friction measured at about TDC, and the friction measured at 90 degrees later in rotation? If you can detect a difference, then you probably have a lot of cylinder friction, and it may just need a lot of breaking in as others have suggested. Might be worth checking the ring gap though.

If, on the other hand, the friction is about the same, you more likely have a bearing issue and it is time to get the big tool box out.

Steve

You could also try loosening the case halve bolts slightly and then torquing it down again in the suggested pattern, you might relieve some stress in the case, that developed after a bit of running.

I'll see if I can get out this weekend to measure the remaining resistance on my 2000cc VW engine, but its been around 40 hours and feels broken in now so its not nearly what was experienced at the overhaul.

Honestly, I was quite alarmed at the resistance being so high and I was certain that something was not right, just like you.

It took a good 15 hours of running before I could detect any improvement and I drained the oil and took a good hard look to see if I could find any traces of metal....nothing.

I understand in your case especially you need to be extra cautious, but if the resistance varies at some parts of the rotation, then its probably the tightness of your new parts and piston cylinder drag until things can get run in for a couple dozen hours.

I think when I tried that there were some very small zones with only a little bit less friction.

I did have to hand prop the engine last summer. It took two hands and a very forcefull swing to get it through one complete revolution.

Enjoy Australia Day in the mean time.

[Edit by jb92563 on Tuesday, January 25, 2011 @ 05:46 PM]

--------------------

And thank you, Australia Day was great!

Steve, Ray, thank you for you always sage words of wisdom. The engine does indeed exhibit more friction when the pistons are in mid-travel (plugs out), so today I bit the bullet and whipped off the baffles, heads and cylinders.

Now the bottom-end friction is down to 3 pounds at 20 inches. More than on the old engine, but I think acceptable for new bearings in a new engine. That's a relief, so I don't have to get out the big toolbox. Whew!

First good news, there's no sign of corrosion anywhere, despite nearly five years of storage, and no sign of overheating, despite our forgetting to turn on the big cooling fan for our last (full power) dynamometer run. That of course was something I've been quietly fretting about for five years!

So then I measured bore diameters up & down and front-to-back, plus piston clearances and ring gaps.

These are second-hand Limbach 90mm cylinders, so it's not surprising that they are very slightly out-of-round, but they're within the 0.008" limits. Also the piston to cylinder gaps are at the high end of acceptable tolerance, as are all the piston ring gaps. All this suggests it might breathe a little heavily, but I've allowed for that by having two wide-diameter breathers, and they didn't seem to be over-worked.

What still mystifies me is that, with all these big clearances, I'm getting so much ring/cylinder friction.
I'm no good at sums, so please feel free to correct my math, but if it takes 12 pounds at 20 inches to turn the engine, isn't that 20 foot-pounds, or the same as our cylinder head nut torques?
Or maybe it's me who's the nut? But that sure seems a lot.

Anyway, I'm going back down there tomorrow and putting it all back together, then I'll fly ten or twenty more hours (IF I can put in enough muscle effort to get the darned thing started) and see if it's any better.

I would still be grateful for comparative friction figures from anybody else out there, if you get the chance.

Thanks as always to you all.

And Steve, I sincerely hope your son enjoys Australia as much as I always have. I first hit Sydney in 1971, and was instantly smitten, although it took me another 22 years to actually come and live here.

I don't know Townsville, nearest I ever got to it was Cairns, and then only for a couple of days, and that's still a long way away. As you say, you can't get much further from Townsville than Perth and still be on the same continent.

Have a good weekend everybody.

Yours, Bob

If you un-rolled each ring, it would be 2 x pi x 45 mm long, or 280 mm. You have four of those in each cylinder, making 1130 mm, and four cylinders making a total of 4.5 meters (14 feet) of very hard metal pressing very firmly against the cylinder walls. That is a huge amount of rubbing surface, so it doesn't take much extra friction to make a huge difference in the torque required.

Only other thought is that if the dyno says it makes a certain amount of power, but that power is not evident in the aircraft, you have got to suspect the prop. A number of Jungmann owners have gone to the trouble of replacing their 125HP Tigre engines with the 150 HP version, only to find the performance is substantially worse. The 150 HP model has an entirely different power curve than the 125 HP model, and so requires a completely different prop.

Steve

Thank you for confirming my figures.

I should probably not be saying this in public, but here goes.
I am comparing my Aussie engine to an identical British one, using identical (Aussie) propellers in airframes of near-identical weight, drag and configuration. Same pilot of course, and performances checked at 25 degrees C in near-standard pressure.

The British engine (single port heads) produced 54.4 hp on dyno, this Aussie one, with dual-port heads, only 52 hp, and it climbs more than 100 fpm less well. Now I realise this is probably because it has so much more internal friction.

A serial engine builder came and looked at my new engine today (now minus pistons & cylinders). He pointed out that there is no friction in the big end bearings, the con rods flop up and down nicely, but the crankshaft is still quite stiff to turn.
With a prop fitted it goes around OK, but without the prop it is quite hard to turn it over by just the flange.
And this crankshaft is still harder to turn over than the whole, still-assembled 1,300+ hour engine I removed last year. He says a VW crankshaft should turn easily in its case before the pistons & cylinders are added, just as the con-rods flop about on their journals.

I only wish I had a go/no-go torque figure by which to judge this crankshaft friction.

Mike, the guy who built it says very crossly, 'Just go and fly it. It will soon ease off!'
That would certainly be the easiest thing to do, and it would get me back into the air very soon, but my concern is that if there is little clearence between the crank journals and the bearing shells, the oil won't be able to get around through there, and I am risking metal transfer/pick-up and possible seizure.
If this motor was in a car, no question, I would just drive it for 5,000 miles.

Trouble is that Fourniers are irreplacable, and genuine forged VW crankshafts ain't that common nowadays either.

I'm still pondering, but meanwhile I have other things on my mind.

Tropical Cyclone Bianca (Hurricane) is headed this way, so we're busy tying down everything and buying provisions.
It's not likley to be serious, but I'm sure you know that my motto, like the Boy Scouts, is 'Be prepared'.

Speak soon.

Yours, Bob

Scary.

Eugenio

This has been an interesting exercise in phsychology as well as in engineering.

As things currently stand, one VW expert, Mike Munninger, my irascible but lovable 85 year-old friend who built this new engine, says, 'Just go and fly it. It will be fine after a few hours.'

On the other hand, Eugenio and Steve, our Fournier Forum experts, say 'Think of all the friction and heat, and all the damage they can do.'

Bobby Warren, Skyhawks/RedHawks engineer says, 'It's wrong. It should not be like that.'

So does Gordon Johanson, a local aviation expert, who pointed out that there should be no more friction in the main bearings than there is in the big ends.

Matt Hill, RedHawk Leader says, 'What is the best, safest and most efficient solution?'

So, reluctantly, I shall have to open up the case of my expensive new engine and grovel about in its innards to find why there is so much friction.
Worse, I have to go and beg Mike to tell me how his magic front bearing is fitted, and see if he has a hydraulic puller to get the prop flange off.
You'll probably see the mushroom cloud from the States!

Meanwhile, since my BFR is about to expire, first I have to get the Maule flying, and probably re-fit the tired old Rectimo to HDO so I can stay in aerobatic practice.

One final thought.
Can anybody see any clues to my friction problem in these photos, which were taken several years ago during the building of the engine?

Yours, Bob

[Edit by Bob Grimstead on Sunday, January 30, 2011 @ 07:33 PM]

I'm sure the problem will be evident when you split the case, and you'll be glad you did it.

Dann

--------------------

Thanks very much for that info.

I've been using old VW auto manuals (I have four different ones) but none of them mentions this, so I've just ordered Steve's manual, plus another book he stocks.

I'll get to it when the books arrive, and of course I will let you all know how things go.

Yours, Bob

Like you, I also had to take the pistons off if for no other reason than at least some peace of mind
that something stupid had not happened and to separate the two sources of drag.

What I found was that with the pistons detached it was as smooth as silk and the resistance of the remaining bearings etc seemed normal although
a bit stiffer than a well used engine.

Also, you can loosen all the case nuts and tap the case around with a rubber mallet and then torque it up carefully again
using the recommended (Great Plains book) sequence, if the bearings seem too stiff.

In my case I was able to conclude that the new piston/rings where causing most of the drag.

Hopefully you find something similar.

I did not see any abnormal temps as a result of the tightness, as I also kept a close eye on temps, oil pressure and looking for particles in the oil.

Fortunately in my case it was electric start as I could not imagine having to hand prop it being that tight.

--------------------

I put a torque wrench on the prop flange nut.

With all four cylinders removed, and the magneto removed, it still takes 14 foot-pounds to turn the crankshaft (and camshaft).
Plus, I can't seem to discern any play (teeth clearance) between the crankshaft and the camshaft.

Looking back to last year, now I understand better why it took me three days to get this engine started, and then my arm was hanging limp for weeks afterwards!

In the end, I had to stand at the front of the airplane and pull down on the propeller with all my force to get it going, plus having the throttle nearly half-way open to get it to start running.
Not a comfortable situation, as you can imagine.

There was a clue right there, but I assumed it was just the usual tightness of a new engine.

Anyway, the die is now cast.

The old engine's going back in and I'll split the new case when the Great Plains manual arrives.

Another good mechanical friend, Bob Hart (who takes many of the YouTube clips of my aerobatics) has directed me to some useful YouTube clips of dismantling a VW, checking crank end-float etc.
I commend them you you. There are probably many nore.
http://www.youtube.com/watch?v=_LpgsDJ-0z0
TORQUEING AND THEN REFINISHING A VW CYLINDER,
http://www.youtube.com/watch?v=goNVh8Dsspc&feature=related
LINE BORING.
http://www.youtube.com/watch?v=4LVJ0XI-fG4&NR=1
CRANK BIND CHECK
http://www.youtube.com/watch?v=VFPtKoUdoKo&feature=related
ENDPLAY CHECK
http://www.youtube.com/watch?v=XYS2jng1gNc&feature=related
ENDPLAY CHECK
http://www.youtube.com/watch?v=D51T5dU1HtY&NR=1

Yours, Bob

Looks like your son is about to experience one of the more extreme aspects of Australian life.

Our cyclone Bianca lost all its energy over the cold sea, so all we got was a breeze, but on TV we've just been watching the skies darken with Yasi in Townsville.

This country sure does have a harsh and uncompormising climate, but probably partly as a consequence, it breeds strong, resourceful people.

I'm sure he will be alright, but I reckon in a couple of days he'll have some tales to tell.

Our thoughts are with him.

Yours, Bob

--------------------

Its nice of you to be concerned Bob. Thank you!

Steve

I'm glad Ryan won't be there for a while.
Looks like this is going to be a scary one, with Townsville expecting 160-knot easterly, on-coast winds and a big storm surge.
It's built on a flood plain, so it will take a hosing and a hammering.

Amusing to think Ryan & his buddies will have to spend ten days learing about two such very similar cultures.

And now I feel sorry for you with those ice storms!
I think Ryan's going in the right direction, and I sincerely hope he thoroughly enjoys his Aussie (pronounced Ozzie) experience.

Yours, Bob

--------------------

For anyone reading this with a curiosity about Australia, "The Fatal Shore" is absolutely fascinating read, and really gives you an insight
into what makes Australia Australia. Highly recommended.

Steve

We're off wildly topic here again, but only for a couple of days.

Another 'Aussie culture' book Ryan should enjoy is Puberty Blues, by Kathy Lette and Gabrielle Carey.
It deals (amusingly) with teenagers growing up in Sydney's surfing sub-culture, and has become a classic out here.
Unfortunately, it is now a set book in many schools, which tends to put people off (it would have put me off) but it's a great, short read and very funny in parts.
There's also a movie of it, directed by the same guy who directed 'Driving Miss Daisy, among many other (sorry, I can't remember his name).

For a comparison of Australian and American cultures, see Beyond the Black Stump by Nevil Shute.
It's a bit dated now, but still a good read (I recently read it again) and of course Shute was the pen name of skilled aircraft designer NS Norway -- Airspeed, R100 airship (the successful trans-Atlantic one you never hear about because it didn't crash) and de Havilland.

Going back to Townsville; despite this storm being as big and strong as Hurricane Katrina (1,600 dead) it doesn't seem to have killed anybody or done anything like as much damamge, although of course it has made an awful mess along Queensland's northern coast.

I hope you're coping OK with your awful winter weather, and that Ryan did manage to get away to the sun.

Yours, Bob

--------------------

I have at last established the source of my new engine's excessive friction.

Mike M eventually accepted that the crankshaft was too stiff to turn in the crankcase, and admitted that he thought he knew the cause.

For aerobatic aeroplanes, he fits this special two-inch aluminium bearing on the front (dynamo) end of the crankcase.
Inside this goes his chrome-plated prop hub.

He had specifically made the clearances as tight as possible, because he knew I was going to fly full-on aerobatics, but now he admits he overdid it.
He has pulled out the hub and is taking it to the crankshaft grinder to have one thousandth of an inch taken off the outside of it.

Obviously, in an ideal world, that material would be taken off the inside of the aluminium bearing, but that would involve splitting the crankcase, and neither of us wants to do that.

I won't have time to re-assemble the engine before I leave Australia, but I should have a couple of months before the dislay season starts when I return.

It will give me something to do in my 'spare time'.

Thank you all for your advice on this problem and, as always, I will let you know how the new engine performs goes when I do fit it.

Yours, Bob

--------------------

Time is well overdue for an update on my Ausie Aeropower 1750 engine.

I phoned Mike M today on another matter and he gave me his story on my engine.

Remember, this was a new engine with perhaps two hours of dynamometer running plus three hours of flying in just two flights.
He says that, with the prop hub removed, he could still feel excess friction plus 'grittiness' as it rotated, so he split the crankcase.
Inside, he found the centre main bearing 'worn down to the copper backing' plus some metal debris inside the crankcase.

He insists that it was clean when he assembled it and the debris is not from the bearing.

I am certain I have not introduced any swarf or other metal particles, so I guess the metal must have come from either the tight front bearing and prop hub or from the worn main bearings.

Whatever, he has now re-assembled the engine with a new front bearing and prop hub and says it will be ready for me to fit and fly when I get back To Perth next month.

As is so often the case with engines, in the end the long solution was the best solution!

All we have to sort out now is the finances, and that discussion might become quite heated.

Yours, Bob

--------------------

Quote:

All we have to sort out now is the finances, and that discussion might become quite heated.

Yes,
always the problem with Aeroengines; a lot of heat to be dissipated, isn't there? Thanks form the update, Bob.

May the 4's be with you/ Jørgen