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A FrankenFour Inline?

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WonderousMountain

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Apr 10, 2010
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Think you'll get better fuel consumption with a 3 valve head.
Driven by a single camshaft. Like the block, the block-head
Is probably going to need modification or substitution. Plate
Based case is a good deal. It could even be bolted, depends
on our luck with Gaskets. Planetary redrive might be best, if
going direct drive, the bellhousing can be swapped, I saw a
few interesting Marine ones lately. Although, I guess you'd
need have to consider Bolt pattern first.
 

BBerson

Light Plane Philosopher
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Port Townsend WA
If this were easily done, we would have already seen it, right? So why do we not see it?
Not sure why it hasn't been done yet. Could be slightly heavier, but I would certainly start with a twin first. And I didn't find any significant excess weight issues with the small single cylinder mower engines I am experimenting with.
All engines are just single cylinder engines working together.
I am not understanding how your crankshaft torsional stiffness comment concurs with this comment from Professor Marks:
"It will be seen that the maximum torque at the propeller end of a 6-cylinder engine is less than the maximum torque exerted by a single cylinder and consequently the crankshaft must be as strong at the free end as at the propeller end".*

* The Airplane Engine, Lionel Simeon Marks 1922
 

Hot Wings

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Could the stock VW heads be cut, as is done for the 1/2 VWs?
<< >>
Someone I know (Hot Wings) was looking at designing single VW heads optimized with porting and cooling fins most appropriate for aircraft use. .
The heads could be cut but it is a bunch of work. They already exist. Just give Casler a call.
I really think that once the tooling* is set up purpose built heads would be quicker and maybe even cheaper than cut heads.

<< >>
Got the last of the old roof removed from the old brick chicken coop that is going to be my work shop this winter, and about half of the concrete forms in place to tie the brick work to the new rafters. It is going to rain tomorrow and snow after that. So I'm now officially 2 weeks behind.

The Briggs 810 is the first project. Space is limited so one project at a time - and my Quickie will take up most of the space once the engine is running. But the VW heads are still on the short list.

*No need for CNC. A few well designed jigs and a mill is all you need.
 

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Sockmonkey

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Apr 24, 2014
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I'm thinking a radial two-stroke with a positive displacement pump to create crankcase pressure would be the ticket because you could use a lot of small cheap cylinders from yard equipment.
 

wsimpso1

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Centrifugal blower will work, too. Even simpler.
How would you start and idle this engine? Centrifugal blowers move virtually zero air at cranking speeds and not much air at low speeds unless hugely oversize.
Centrifugal blowers usually require gearing too. Significant work in this area.
A positive displacement air pump for starting and low power, then turbo for high power and altitude is a solution.
 

pictsidhe

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How would you start and idle this engine? Centrifugal blowers move virtually zero air at cranking speeds and not much air at low speeds unless hugely oversize.
Centrifugal blowers usually require gearing too. Significant work in this area.
A positive displacement air pump for starting and low power, then turbo for high power and altitude is a solution.
It doesn't need much sir or pressure at low speed. Required pressure goes up as the square of speed. That means a centrifugal is actually a good match.
 

TFF

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I always loved the Lee Burger model 7 cyl two stroke. He did get a patent on it. I always think of ways to turn one into a rotary for my RC WW1 models.
 

Sockmonkey

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It doesn't need much sir or pressure at low speed. Required pressure goes up as the square of speed. That means a centrifugal is actually a good match.
Good. Needing belts or gears would defeat the goal of simplicity. Stick 6-8 cheap little cylinders on there and oh sweet lord all that blessed torque.
 

rotax618

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Evans Head Australia
If you were considering a direct drive VW (in-line inverted) perhaps an inverted Suzuki G10 inverted, direct drive would give 40HP and would probably be lighter, the G10 is less than 100lb without radiator, could be driven off the flywheel.
 

cluttonfred

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The Suzuki G10 is well within the horsepower range of the Ace Aviation belt redrives from India sold for the Gaokin GK engines for a very light package. A fuel-injected G10 3-cylinder produced 55 hp at 5700 rpm, so with the Ace 2.33:1 redrive you'd be looking at a prop rpm of just 2450 rpm or so, slow enough to use a fairly big prop. With a decent off-the-shelf muffler it would also be a very quiet installation.

If you were considering a direct drive VW (in-line inverted) perhaps an inverted Suzuki G10 inverted, direct drive would give 40HP and would probably be lighter, the G10 is less than 100lb without radiator, could be driven off the flywheel.
 

rotax618

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I built an adapter to fit a Rotax “E” gearbox to the Suzuki G10, was long ago and can’t find a photo only my drawings, made for a lighter conversion than the SPG gearbox because of the integrated starter, which had no trouble starting the Suzuki, used a lightened flywheel but left the ring gear on, being on the rim it added to the rotating mass without adding too much weight, I used a bing carb and the standard pointless distributor, I think the gear ratio was 2.62:1, you can get other ratios for the E box.
870A5DA1-DD0B-4515-BD98-C7C994358732.jpegD0AC64FA-2357-4C4B-85BC-BD4C95DA5411.jpeg
 
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