Building a VW Aero-Engine

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lakeracer69

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Sorry, I should have said for a flywheel drive engine. I was just over there looking at those

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FWIW, the vendor Pops linked to above, aircooled.net, is one of my go-to sources for VW engine parts. John, the owner, has been at it for years, and knows his stuff. It can take a while to get answers to questions, but his advice is solid. I have never had an issue with anything I have purchased from him, and shipping is prompt. No affiliation, just a satisfied customer.

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lakeracer69

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Pops,

To flesh out using the gland nut and flywheel prop flange some more. The 4130 larger gland nut options seem like a no brainer.
Will either a 42 or 44mm one still work when using a GP prop hub extension? Without having one in hand it is impossible to figure out the height of the nut, or if a larger socket will fit in the counterbore of the flywheel/ dowel pin area, or not protrude and interfere with the prop extension.

Also, with an 8 pin crank it would seem like a bigger nut is better. It also looks like GP has a regular bolt of some kind for theirs. Do you know offhand the thread size for the gland nut? It measures out around 29mm or so. I have attached a picture.

Hub ID is 2.293 with a shoulder depth of .146 Flywheel center counterbore is 2.570 and .648 deep.

Thanks for helping us understand this.

Pops

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I don't know . Good question if you want to use the larger nut.

lakeracer69

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Did my sleuthing yesterday. A 44mm socket will fit in the flywheel counterbore with a little room to spare, so the nut itself will fit fine ( diameter wise) The height of the nut is still unknown for now. I have ordered a 44mm 4130 gland nut to see if it fits under the GP prop flange. If it does, I believe that it is the way to go. Whether you use a 4 dowel crank and flywheel or an 8 dowel, the 44mm nut and washer will provide more contact area than a 36mm one.

Using one of these gland nuts to attach the flywheel flange/ prop flange to the crankshaft, is akin to the Jesus nut on a helicopter rotor hub. You'd better have faith in it. I'm ok with using the biggest/strongest one available. They also say you can torque it up to 400 ft/lbs and red loctite it on some aftermarket crankshafts.

Pops

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I noted the change from 217 to 400 foot pounds. I still would like to come up with a way of locking the nut. On the shrunk fit prop hub for the pulley end of the crankshaft I used loctite on the nut and put a red paint mark on the head of the bolt and checking for movement was a normal preflight item to check. But, the shrunk fit hub is on so tight I don't think it would come off without the bolt.

Pops

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The flywheel prop hub is finally finished by Bob Hoover's plans on his blog. I also cut the center out of a flywheel by his plans.

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Pops

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Forgot to add. The weight of the prop hub is 2 lb and 15 oz's. I would like to not add any weight but with the weight of the flywheel drive hub being a little heavier than the pulley end prop hub and the different engine mount maybe the total firewall forward weight my be a little more. Will be trying to same every ounce.

Dan

karmarepair

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I still would like to come up with a way of locking the nut.
Would this work? Drill and tap for a small socket head cap screw, just inside where a spot face for the nut would land, so that the flat of the bolt will be tangent to the SHCS. I'll try and find a picture of what I mean. I found this trick in this invaluable book https://www.amazon.com/Fasteners-Plumbing-Handbook-Motorbooks-Workshop/dp/0879384069

Another way would be to use a thin jam nut under the main nut. Different fluid, but same principles Propeller Nut Myth Busting. If there is a washer under the hub nut, this might work better than my first suggestion. You might have to mill/grind your own jam nut. But the forces on this application are FAR lower than they would be on a drag racer dropping the clutch, so maybe Red Locknut and Faith In Jesus is enough....

Pops

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The VW bottom oil plate is made from heavy steel. I made a plate from aluminum to save weight and added a small sump so when doing a hard slip It will not un-port the oil pickup tube. I have had good VW street cars where they would corner good enough that the the oil pickup tube would un-port and the oil pressure would fluctuate. I extended the oil pickup tube down in the sump so its about 1/2" off the bottom and cut at a 45 degree angle. The larger threaded hole is for the oil temp sensor.
I remove the pip plug to drain the oil.

Dan

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The VW bottom oil plate is made from heavy steel. I made a plate from aluminum to save weight and added a small sump so when doing a hard slip It will not un-port the oil pickup tube. <snip>
I have made a mental note before that you have done this, but it is nice to see it in pictures. Thanks for posting that!

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Pops

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VW flywheel drive mag mount on the pulley end of the VW engine.

1.-- Cut center our of the VW crankshaft pulley , cut out center of a 4" dia pulley and weld on the center of the VW pulley
2.-- Turn centering jig from 6061 alum
3.-- Machine aluminum mag drive.
4.-- Position and weld 3 mounting spacers for the alum mag drive. After welding the 3 spacers turn surface flat on lathe. Drill an tap for 3-- 3/16 aircraft bolts with drilled head for safety wire.
5.-- Buy slotted mag coupling from Great Plains Co or make you own
6.-- Drill pully mounting bolt for safety wire.
7.-- Maching alum 6061 mag mount ring and drill and tap for 5/16" dia mounting studs with course threads on the aluminum engine.

Next will be the 4130 steel mounting brackets to mount the mag mounting ring to the engine.

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Pops

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Awhile back we had a thread about how to safety wire the large flywheel bolt on a flywheel drive VW engine.
Someone came up with this and I think it was the easiest an simplest way to do it.
Drilled and tapped 2 holes 8-32 on each side of the washer to safety wire to use the safety wire holes in the head of the bolts. Be sure not to drill all the way thru the flywheel, could have a small oil leak. Had to cut the bolts to about 5/16 long. Use a bottom tap to the the thread as close to the bottom of the hole as possible. Also used lock-tight on the treads. I need to drill the corners of the large bolt for the safety wire to the bolt. After the bolt is torqued and safety wired then the prop extension spool can be bolted on the flywheel center.
The large bolt in the picture is a stock VW part. Will be using a hi-strength after market bolt made for high HP engines.

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Pops

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Crankshaft ready to install in the VW case. I'll be installing with the prop extension and flywheel center on the end of the crank after the rear main seal is installed.
All rods has a weight is 600 gr and same measurement from center of holes on each end, and each end of the rods weights the same. All bearings are STD , with a German 69 mm crank.

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Pops

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Have the VW case together. Ordered the drilled headed bolts to mount the prop extension. Picture of where I had to grind 1/8" clearance for the outer edge of the pulley on the outside of the case , no problems with that. Need to design and build the brackets that hold the mag mounting ring. At this time I believe the flywheel drive engine will be about 3 lbs heavier than the engine with the prop on the pulley end. Also I will have a belt drive from the pulley to a 3 lb JD alternator to power the second ignition for the lower plugs on the heads.
The flywheel drive engine with the mag mount on the pulley end will make the engine a little longer. With the other engine I had a 10" long engine mount to put the CG where I wanted it. When the engine is finished, I'll have to weight it and work out the length of the new engine mount to put the CG in the same place as before. I hope I don't have to put a SS metal dish in the firewall wall for clearance of the mag and firewall.

I always install an old dist in the hole to keep the dist drive in place while installing the crankshaft in the case. Also before the final torquing of the case bolts I install the oil pump. The pump housing is a tight fit between the case half's, easier to do it before torquing the case nuts.

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Vigilant1

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Pops,
Thanks for the update, the project is coming along well.
My apologies, I've lost track of your rationale for going with a primary mag ignition (to allow hand propping?). You've put in a lot of work to machine the magneto mount and to weld up the spacer for it, and you are mounting an allternator, too (for a second ignition). Could a less skilled/ ambitious builder avoid the magneto and use two electronic ignitions and still hand-prop the engine (battery power to at least one ignition, zero deg advance timing for start)?
Maybe consider selling plans for the bits you've fabricated. Somebody will want to go down this same path.

Mark

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BJC

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Could a less skilled/ ambitious builder avoid the magneto and use two electronic ignitions and still hand-prop the engine (battery power to at least one ignition, zero deg advance timing for start)?
A Lycoming with PMags can be propped, but needs a small battery to fire the PMag below 1000 RPM. Standard starting set-up is to fire at TDC to 2 after.

Would check EMAG, though, about the opposite rotation.

BJC

Pops

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I want the Slick mag running the top plugs. Can hand prop with the mag. Then I want a cheap second ignition that goes into the dist hole for the second set of bottom plugs. Maybe just use a stock VW distributor and a small light weight auto coil for the bottom plugs for a low cost dual ignition for a VW engine. New 009 distributor is about $50/$60.
Been working on a project where the second ignition will be on line when a switch is ON position , ( takeoff and landing if desired) and center is OFF position and the other position is Stand-by for the second ignition. In the stand-by position the second ignition is on stand-by until .5 seconds with no fire from the mag then it come on before the engine quits. Just be a small burp. Also a large red LED on the panel for warning of the mag failure. With the small JD alternator and a small battery for the second ignition. Engine can be hand propped on either ignition system.
Cheap, light weight and dual ignition system that can be hand propped for VW.
When I get everything working and flying. Infro will be free. Maybe someone would want to make parts.
Yes, someone could use two ignition systems and not use a mag.

Vigilant1

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A Lycoming with PMags can be propped, but needs a small battery to fire the PMag below 1000 RPM. Standard starting set-up is to fire at TDC to 2 after.

Would check EMAG, though, about the opposite rotation.

BJC