Building a VW Aero-Engine

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Bill-Higdon

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Straight weight 30. If its low on zinc, I add STP. But, lately I have been using straight weight diesel for the high zinc content.
A lot of the Gen 1 Toyota Van people use diesel in their engines as the van uses a push rod vale engine from their forklifts
 

fly2kads

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But while doing so, it has occurred to me that i'd really just like to put the heads back on (after inspection, clean and whatever necessary if anything). These have the lapped joint. Can it be done? or do i have to pull the jugs to re-lap them?

Are stainless valves available for VW? are they advisable, or are the standard steel versions better?

Thanks!
smt
I think you could just put the heads back on and follow the proper torque sequence. Plenty of VWs have had heads replaced over the decades without pulling the cylinders.

Stainless valves are available. The cost difference is pretty low, so I think they could be worth it if you are going to be doing a valve job, anyway.
 

Pops

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The lapped joint is between the top of the cylinders and the surface of the head. The 36 and 40 Hp , 1200 cc engines also has a copper gasket between the top of the cylinders and the heads. Can also get copper gaskets for all the larger piston and cylinders sizes to lower the CR. I use the ,060 copper gaskets on my 1835 cc with the 92 mm pistons to reduce the CR to 7.55 to 1. They come in .040. .050. .060 thickness.
The bottom of the cylinder to case uses a paper gasket, and also steel shims to set the CR. My engine has .040 shims in that location.
Be sure to set the CR the same for each cylinder. Sometime they can be different. The tops of each cylinder on each side has to be the same.
I always use SS valves with no problems.


 

Aviacs

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Cleaning the heads before re-assembly, especially considering the lapped joint:
Is glass bead blast OK?
Walnut shell?

considering that my preference is to assemble without pulling the glued-in jugs to re-lap them as described earlier post?

Thanks!
smt
 

Aviacs

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Also, is a hard stop better to find TDC, over say, just a dial indicator?
Is there anything wrong with using a dial indicator?

I get that a hard stop takes all the play out of the system and balances the reading across the top of the piston; However, if all travel is one-way and the indicator indicates on the same location, am i missing any pitfalls to the indicator use?

Thanks!
smt

PS: I did make a jug-puller, but still hope not to have to use it. :)
DSC_0372.JPG DSC_0363.JPG DSC_0364.JPG
 
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When new single port heads were stopped being manufactured the business selling VW engine conversion parts stopped selling single port intake manifolds.
Now new single port heads are being manufactured again but no one is making single port intakes. So if you want to use single ports heads you are going to have to make your own .
Drawing for the part of the intake over the head and down into the head. I use Home Depot bathroom Stainless Steel bathroom handrails . The bends were right. They are .050 wall thickness, wish they were .032 to save weight. Used the same ,but in the 1 1/2" dia for the exhaust.
I have always wondered about the design of most aero-VW intakes. Why does the riser tube come to a dead end then the runner comes off at a 90 degree angle? Why not use a sweep that simply ends where the intake ports begin? My HAPI intakes are made with the dead end. Aeroconversion intakes have the dead end. Revmaster intakes sweep into the head. Is there science behind it? Or is it simply easier to fabricate?
 

Hawk81A

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Also, is a hard stop better to find TDC, over say, just a dial indicator?
Is there anything wrong with using a dial indicator?
Best way to locate TDC is a hard stop BEFORE it reaches TDC. Bring it around until it stops. Make a mark. Roll it backwards and around until it stops. Make a second mark. Halfway between the two marks is true TDC. In using a dial indicator or other method, there are a few degrees around TDC where the piston does not move, but the crank does because of connecting rod swing. Dennis
 

Aviacs

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In using a dial indicator or other method, there are a few degrees around TDC where the piston does not move, but the crank does because of connecting rod swing. Dennis

Understood.
But what is the downside to using a dial, or dial-test indicator at the same position? 20 deg before top? 15 deg before?

I made a reaction plate for other purposes, so can use either a hard stop or DI/DTI.

smt
 

Hawk81A

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The dial indicator is going to have a small amount of "give". You probably could use it. I would say with an indicator you might set it for somewhere BEFORE TDC and then rotate to a reading of maybe .250". This would still give consistent readings for either direction of rotation. I had been thinking of something where you would be going down a sparkplug hole (what I have been used to in helping find TDC - usually inline engines with slipped harmonic balancers and still in the vehicle with the head on). You may be dealing with having the heads off and cylinders installed. Dennis
 

Vigilant1

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I have always wondered about the design of most aero-VW intakes. Why does the riser tube come to a dead end then the runner comes off at a 90 degree angle?
IIRC, there's a good reason for it. As I recall reading about various trial-and-error experiments, in many aero VW installations the induction mix can be a bit sub-optimum due to fuel droplets suspended in the flow. With a normal splitter and sweep, the droplets go to the outside and one cylinder on each side (the downstream one) will be rich and the other will be lean. The dead-end provides a place for any tiny droplets to go and vaporize, eventually being inducted into the cylinders more or less evenly.
Anyway, that's what I've read. If it is right, then with a fuel injection nozzle for each port we could go with something that flows more smoothly rather than the "T".
 

Hawk81A

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I have always wondered about the design of most aero-VW intakes. Why does the riser tube come to a dead end then the runner comes off at a 90 degree angle?
I started to answer this a couple of hours ago and got dragged off. I had a relative (now long passed). Johnny was one of the old time EAAers. Johnny was a long time "Raiders" volunteer in his later years at Sun N Fun. He could sit down with you and a napkin or sheet of paper and scratch off tips or suggestions that were amazing for a home builder. He told me that (with dual port heads) having the intake tube feed straight into the ports would make for an unbalanced mixture going into the "far" (away from the carb) cylinder. Having the stub end caused the mixture to have a more balanced flow.
An induction system for a port injection system is totally different from one for carbureted. PFI only flows air, while carbbed flows mixture. We found this out the hard way doing CNG conversions to our 1992 Ford Crown Victorias. The company that made our conversions induced the gas just before the throttle body. This made the MIXTURE circulate through an intake that was designed to flow AIR. The result was some cylinders got a better delivery, while others burned lean. If anything got just a little out of spec, they backfired through the intake, which blew up the air filter plenums. Dennis
 

Pops

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IIRC, there's a good reason for it. As I recall reading about various trial-and-error experiments, in many aero VW installations the induction mix can be a bit sub-optimum due to fuel droplets suspended in the flow. With a normal splitter and sweep, the droplets go to the outside and one cylinder on each side (the downstream one) will be rich and the other will be lean. The dead-end provides a place for any tiny droplets to go and vaporize, eventually being inducted into the cylinders more or less evenly.
Anyway, that's what I've read. If it is right, then with a fuel injection nozzle for each port we could go with something that flows more smoothly rather than the "T".
Yes, and the resulting turbulence created also helps mix for a more even charge in each intake of the head. When I get time :) , I want test different lengths for the optimum length. Without looking at my intake plans, I think, I have been using 2.5" from the center of the down tube to the inside of the end cap. Its close, but not perfect.
I want to make a threaded end cap so I can very the length and see how close I can get the egt, cht and color of the plugs. Even the airflow from the baffling can change things.
 

Pops

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Been running the throttle, carb heat and choke cables. Also the wires from the instrument panel to through the firewall.
Making SS firewall protection for the cables and wires from some scrap SS of .032 thickness.
I know you can buy these but I like to make things and after all this is homebuilding airplanes.
Use some different size sockets and press the SS by using the large vice. I also use the 2 piece ones for my spark plug wires on the engine baffling.
 

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Hawk81A

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Makes me wonder about the possibility of twisting a close fitting piece of steel and welding it in the tube to give the charge a spiral effect. They used to sell plates for car intake to do this. Not sure how much it helped. I did have an issue years ago with the Kawasaki Mules (V-twin) at work. The earlier ones with the one barrel carb had a tendency to run richer on one cylinder. This was causing plug fouling. I twisted a piece of steel, wedged it in there pretty good and THAT ended the plug fouling. It's really all about flow. I know that with na inline engine, the throttle shaft should be parallel with the crankshaft. With Vees, it's usually perpendicular. On an aviation VW, it probably wouldn't matter because of the tube length. Dennis
 

fly2kads

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I have always wondered about the design of most aero-VW intakes. Why does the riser tube come to a dead end then the runner comes off at a 90 degree angle? Why not use a sweep that simply ends where the intake ports begin?
Good answers above, but they only hint at the "why." The air/fuel mixture has mass, and therefore has momentum as it moves through the intake system. In a curved intake, that momentum tends to carry the atomized fuel past the near cylinder and bunches up at the bend in the intake going into the far cylinder. The "dead end" setup lets that air/fuel mass accumulate at the end of the main tube, essentially creating a mini-plenum that the down tubes draw from. The optimization Pops was talking about would tweak the volume of the plenum and the location of the densest air/fuel charge.
 

Map

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I have made the trip from California to Oshkosh in my VW powered motorglider and can share some real world experiences of operating this engine and working on it to keep going during the trip. Lead in Avgas caused major problems. You can find my trip report at caro-engineering.com on the "News" page.
 
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IIRC, there's a good reason for it. As I recall reading about various trial-and-error experiments, in many aero VW installations the induction mix can be a bit sub-optimum due to fuel droplets suspended in the flow. With a normal splitter and sweep, the droplets go to the outside and one cylinder on each side (the downstream one) will be rich and the other will be lean. The dead-end provides a place for any tiny droplets to go and vaporize, eventually being inducted into the cylinders more or less evenly.
Anyway, that's what I've read. If it is right, then with a fuel injection nozzle for each port we could go with something that flows more smoothly rather than the "T".
That probably explains why the Revmaster intake (dual port heads) splits the flow on the way up; before gravity has any influence on the path of the droplets. This would also make one question the GPASC manifold top casting. That manifold design does not split the flow until just prior to the final curve into the head. I used those castings on my Revmaster 2100-D because the Revmaster top manifold would not fit under the Sonerai cowling. I did not have an issue with the mixture balance but that may have been due to a re-design of the lower manifold as well (see below).

When I designed the lower manifold, Joe Horvath suggested making the first tube after the carb as long as possible. According to Joe, the droplets roll along the tubing and peel off layers of fuel like layers of onion. The longer lower tube would shrink or vaporize droplets before the flow split toward the left and right banks and provide a more balanced mixture. This goes along with Pops' heater box success. I had about 8" of tubing (with a 90 degree sweep) prior to the split. Perhaps that was enough contact to atomize the fuel and provide an even mixture downstream.

No empirical evidence here...just bench banter.
 
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