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#### Vigilant1

##### Well-Known Member
There's a lot of fun to be had in all kinds of vehicles at 60HP and less.

A somewhat related question:
The smaller VWs have a strong reputation for reliability and low maintenance costs. There's no doubt that as we ask more from them (e.g. 2180ccs and up, 75HP and up, higher CHTs, etc) we are starting to bump up against the edge of the envelope. I don't have numbers, but I'd guess most Sonexes, Sonnerei, etc probably get about 200-300 hours before the head needs to be pulled (for a valve job, a crack, etc). Now, that's not terrible (about 4-5 years of flying for most recreational fliers, and the parts to do the work run about $1-2 per flight hour--not bad by airplane standards). But if we built a 2180cc engine and only asked it to give us 50HP except for a minute or so on takeoff, how much would we expect the situation to change? (That's probably how a Beetlemaster would be run by most folks. Even if the RPM would be high at cruise, the MAP would be very low and the engines would be loafing). Would the 2180cc mill be as reliable as a smaller displacement VW giving the same power? If the engine is stroked, then piston speed will be higher at the same RPM, but the RPM >won't< be the same for the big engine, it will be lower. About the only place I can think that the big engines might still have trouble in these low HP scenarios is the cylinder head, specifically the smaller amount of "meat" between the valve seats with these larger engines and valves (with resulting higher potential for cracks). But, if we are running at modest CHTs, cracks and valve trouble are lot less likely. As we've discussed elsewhere, our fairly low RPM airplane engines (approx 3400 max) don't need the bigger valves in these these street-racing heads (5000+ RPM), but the commercially available bigger heads (with large fins) are built for these racers, so they have them anyway. It would be great if we could get a purpose-built "for airplanes especially" VW head at a reasonable price. At lower displacements, they'd be single-port heads (as Pops has pointed out, these can work great). Last edited: #### Pops ##### Well-Known Member Log Member There's a lot of fun to be had in all kinds of vehicles at 60HP and less. A somewhat related question: The smaller VWs have a strong reputation for reliability and low maintenance costs. There's no doubt that as we ask more from them (e.g. 2180ccs and up, 75HP and up, higher CHTs, etc) we are starting to bump up against the edge of the envelope. I don't have numbers, but I'd guess most Sonexes, Sonnerei, etc probably get about 200-300 hours before the head needs to be pulled (for a valve job, a crack, etc). Now, that's not terrible (about 4-5 years of flying for most recreational fliers, and the parts to do the work run about$1-2 per flight hour--not bad by airplane standards). But if we built a 2180cc engine and only asked it to give us 50HP except for a minute or so on takeoff, how much would we expect the situation to change? (That's probably how a Beetlemaster would be run by most folks. Even if the RPM would be high at cruise, the MAP would be very low and the engines would be loafing). Would the 2180cc mill be as reliable as a smaller displacement VW giving the same power? If the engine is stroked, then piston speed will be higher at the same RPM, but the RPM >won't< be the same for the big engine, it will be lower. About the only place I can think that the big engines might still have trouble in these low HP scenarios is the cylinder head, specifically the smaller amount of "meat" between the valve seats with these larger engines and valves (with resulting higher potential for cracks). But, if we are running at modest CHTs, cracks and valve trouble are lot less likely. As we've discussed elsewhere, our fairly low RPM airplane engines (approx 3400 max) don't need the bigger valves in these these street-racing heads (5000+ RPM), but the commercially available bigger heads (with large fins) are built for these racers, so they have them anyway. It would be great if we could get a purpose-built "for airplanes especially" VW head at a reasonable price. At lower displacements, they'd be single-port heads (as Pops has pointed out, these can work great).
I agree 100 %. Build the bigger engine and put it in an airframe that doesn't required but about 1/2 of the HP that the engine can produce. Cool running, at low mp for a long lasting , reliable VW engine. Don't need the dual port heads with the big valve and the cracking problems between the valve seat area and spark plug hole. Below 3K rpm the dual port heads cost you torque. On the SSSC, in cruise of 2650/2700 rpm the 60 hp, 1835 cc engine is just developing about 34 hp at 80 mph.
I need to finish building my 2180 flywheel drive VW engine. Have the flywheel drive and engine mount parts made. Also have a set of single port heads that is drilled for dual ignition. No one sales a mag drive for the pulley end of the engine so will have to make my own. I have about 1/2 of the parts made for the mag drive. Then the lower spark plugs will be fired from the used of the distributor location. Great Plains makes an ignition for this that is 1.5" tall. The engine will be non-electric. How am I going to run the second ignition if it will be non-electric ? Thought you would ask. Been making a circuit that will turn on the second ignition after the mag stops firing for .5 seconds and run off the 12volt 7 amp, jell-cell model airplane starting battery that I use to power the handheld radio and gps. That will get me to an airport with a mag failure.

##### Well-Known Member
HBA Supporter
Pops, are you making a bed mount for that flywheel drive engine? I have seen the drawings and photos on the late Bob Hoover's blog for the bed mount he made. I think the automatic cutover system for the ignition is very clever.

One of the nice things about the VW ecosystem is that it is very open and varied. We have several vendors selling a variety of sizes and styles of engines. The aftermarket parts support is such that you can pursue your own ideas, as well, just as Pops is doing. Tons of choices and options for customization.

I have my own ideas for a high displacement, low-revving VW-based motor, as well. I'd like to experiment with that, too, someday.

#### Pops

##### Well-Known Member
Log Member
Pops, are you making a bed mount for that flywheel drive engine? I have seen the drawings and photos on the late Bob Hoover's blog for the bed mount he made. I think the automatic cutover system for the ignition is very clever.

One of the nice things about the VW ecosystem is that it is very open and varied. We have several vendors selling a variety of sizes and styles of engines. The aftermarket parts support is such that you can pursue your own ideas, as well, just as Pops is doing. Tons of choices and options for customization.

I have my own ideas for a high displacement, low-revving VW-based motor, as well. I'd like to experiment with that, too, someday.
Using Bob Hoover's plans for the bed mount and also the prop hub. I cut the center out of a flywheel for the prop hub to the end of the crank.

#### BBerson

##### Well-Known Member
HBA Supporter
VW exhaust valve seats corrode and only last about 5 years. I am not sure why my Honda car goes 30 years and the VW doesn't.
I was thinking the lack of a long exhaust pipe might let moisture get to the valves.

##### Well-Known Member
HBA Supporter
VW exhaust valve seats corrode and only last about 5 years. I am not sure why my Honda car goes 30 years and the VW doesn't.
I was thinking the lack of a long exhaust pipe might let moisture get to the valves.
I read (on the Sonerai forum, I think) of someone putting desiccant plugs into the ends of their short stacks for this reason. I have not heard if this resolved their problem.

#### BBerson

##### Well-Known Member
HBA Supporter
I think the VW valve seat might be cheaper metal. Lycs and Contintentals last for decades.
When the valves are new it starts easy and has good compression. If it sets for a month the valves rust a bit and gets harder to start. But after a run in it seems to clean the valves.
I don't know any solution other than running it almost every day. Which is difficult.

#### cluttonfred

##### Well-Known Member
HBA Supporter
I have heard of oily rags in the exhaust stubs also intended to keep air and condensation from getting inside the cold engine.

#### BBerson

##### Well-Known Member
HBA Supporter
Spray some fogging oil in the stubs and then plug the rags.
If it has a muffler, a steel tube could be welded in for fogging.

#### Pops

##### Well-Known Member
Log Member
I read (on the Sonerai forum, I think) of someone putting desiccant plugs into the ends of their short stacks for this reason. I have not heard if this resolved their problem.
I have never had a problem with valve seats, but I always make sure my CHT's are down where they should be. Bet the problem is from high heat and not moisture. I have over a million miles driving VW bugs and always check the valve adjustment at 10K and when used on an airplane I check at the 25 hour oil change and record to catch a trend. Had one burnt valve in my life on my first VW bug auto after not checking the valve lash after about 60K.
One thing that I have always done is put MM oil in the fuel. Maybe the reason I never had any valve seat problems. Put it in for valve guide lube. Same for the small cont's, never had a sticky valve.