DIY Two-Stroke Engine Construction Methods

While it would be too heavy and make too much power for a US UL,
how about converting a VW engine to a two stroke?

You might get something resembling one of the old McCullough
drone engines.

--

FF

Thanks for the responses.

-I planned to have one carburetor (and crankcase) for both cylinders.

-I have access to a lathe and a milling machine but I don't have that
much experience with them so I'll have to learn as I go or get someone
else to do the machining

-I do plan to build the engine in a modular way so I suppose I could
add more cylinders.

-I do have some experience with lost wax casting although not with
much success. The engine casting that I had envisioned may be too
complicated for the simple gravity casting techniques I was planning.
I also worry about hot tears of the cylinder as the aluminium cools
and casting decent heat fins.

-For the cylinder I was planning on just an aluminium wall since I
have heard "cheap" lawn mower engine can get 500h on them. I though
that the bearings in the engine will probably need to be replaced in a
few hundred hours anyways, so the bore could be resized then.

Brock

durabol wrote:
Thanks for the responses.

-I planned to have one carburetor (and crankcase) for both cylinders.

-I have access to a lathe and a milling machine but I don't have that
much experience with them so I'll have to learn as I go or get someone
else to do the machining

-I do plan to build the engine in a modular way so I suppose I could
add more cylinders.

-I do have some experience with lost wax casting although not with
much success. The engine casting that I had envisioned may be too
complicated for the simple gravity casting techniques I was planning.
I also worry about hot tears of the cylinder as the aluminium cools
and casting decent heat fins.

-For the cylinder I was planning on just an aluminium wall since I
have heard "cheap" lawn mower engine can get 500h on them. I though
that the bearings in the engine will probably need to be replaced in a
few hundred hours anyways, so the bore could be resized then.

With some pretty fancy metallurgy you can use an aluminum cylinder wall.
It's how the Chevy Vega was done, and it worked great -- except when
it didn't.

There are other treatments that'll let you run a 'plain' aluminum
cylinder -- but none of them are simple, that I know of.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

"Tim Wescott" wrote in message
...
durabol wrote:
Thanks for the responses.

-I planned to have one carburetor (and crankcase) for both cylinders.

-I have access to a lathe and a milling machine but I don't have that
much experience with them so I'll have to learn as I go or get someone
else to do the machining

-I do plan to build the engine in a modular way so I suppose I could
add more cylinders.

-I do have some experience with lost wax casting although not with
much success. The engine casting that I had envisioned may be too
complicated for the simple gravity casting techniques I was planning.
I also worry about hot tears of the cylinder as the aluminium cools
and casting decent heat fins.

-For the cylinder I was planning on just an aluminium wall since I
have heard "cheap" lawn mower engine can get 500h on them. I though
that the bearings in the engine will probably need to be replaced in a
few hundred hours anyways, so the bore could be resized then.

With some pretty fancy metallurgy you can use an aluminum cylinder wall.
It's how the Chevy Vega was done, and it worked great -- except when it
didn't.

And the Porsche 928 V8, which worked quite well.


There are other treatments that'll let you run a 'plain' aluminum
cylinder -- but none of them are simple, that I know of.

The more interesting ones were Kawasaki's explosive coating of, first, an
iron wire, and then a molybdenum wire, which they used in a few racing
engines. They'd run a wire down the middle of the cylinder and run a pulse
of electrical current through it at some God-awful amperage, which would
vaporize the wire and coat the cylinder walls with iron and then moly.

Porsche and a few others used porous chrome platings; Porsche, in one of the
early versions of their Carrera engine, which I think was the 1350 cc model
used in early Speedsters and maybe the 550 Spyder.

The plain aluminum cylinders used in the Vega and the Porsche 928 used a
hypereutectoid silicon-aluminum alloy that precipitated crystals of silicon
when they cooled after casting. Mercury outboards used that method, too,
IIRC. Some Power Products 2-stroke lawnmowers used a similar alloy, but with
less silicon. Those alloys are similar to the ones used to cast pistons
today.

--
Ed Huntress



--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Ed Huntress wrote:

The plain aluminum cylinders used in the Vega and the Porsche 928 used a
hypereutectoid silicon-aluminum alloy that precipitated crystals of silicon
when they cooled after casting. Mercury outboards used that method, too,
IIRC. Some Power Products 2-stroke lawnmowers used a similar alloy, but with
less silicon. Those alloys are similar to the ones used to cast pistons
today.

Don't most newer Briggs engines use AL
or pot metal block/cylinders?

"Jim Stewart" wrote in message
...
Ed Huntress wrote:

The plain aluminum cylinders used in the Vega and the Porsche 928 used a
hypereutectoid silicon-aluminum alloy that precipitated crystals of
silicon when they cooled after casting. Mercury outboards used that
method, too, IIRC. Some Power Products 2-stroke lawnmowers used a similar
alloy, but with less silicon. Those alloys are similar to the ones used
to cast pistons today.

Don't most newer Briggs engines use AL
or pot metal block/cylinders?

'Don't know. I seriously doubt if it's pot metal.

--
Ed Huntress

On 3/17/2010 10:34 AM, Jim Stewart wrote:
Ed Huntress wrote:

The plain aluminum cylinders used in the Vega and the Porsche 928 used
a hypereutectoid silicon-aluminum alloy that precipitated crystals of
silicon when they cooled after casting. Mercury outboards used that
method, too, IIRC. Some Power Products 2-stroke lawnmowers used a
similar alloy, but with less silicon. Those alloys are similar to the
ones used to cast pistons today.

Don't most newer Briggs engines use AL
or pot metal block/cylinders?

AL but it doesn't last all that long. Tecumseh uses a thin cast in iron
sleeve and that's one of the big reasons their engines last longer. I
also bet the better B&S engines like the Vanguard V twins are sleeved...

Tony

In article , Tim Wescott wrote:
durabol wrote:
Thanks for the responses.

-I planned to have one carburetor (and crankcase) for both cylinders.

-I have access to a lathe and a milling machine but I don't have that
much experience with them so I'll have to learn as I go or get someone
else to do the machining

-I do plan to build the engine in a modular way so I suppose I could
add more cylinders.

-I do have some experience with lost wax casting although not with
much success. The engine casting that I had envisioned may be too
complicated for the simple gravity casting techniques I was planning.
I also worry about hot tears of the cylinder as the aluminium cools
and casting decent heat fins.

-For the cylinder I was planning on just an aluminium wall since I
have heard "cheap" lawn mower engine can get 500h on them. I though
that the bearings in the engine will probably need to be replaced in a
few hundred hours anyways, so the bore could be resized then.

With some pretty fancy metallurgy you can use an aluminum cylinder wall.
It's how the Chevy Vega was done, and it worked great -- except when
it didn't.

There are other treatments that'll let you run a 'plain' aluminum
cylinder -- but none of them are simple, that I know of.

don't forget wet sleeving.

Jim Stewart wrote the following:
Ed Huntress wrote:

The plain aluminum cylinders used in the Vega and the Porsche 928
used a hypereutectoid silicon-aluminum alloy that precipitated
crystals of silicon when they cooled after casting. Mercury outboards
used that method, too, IIRC. Some Power Products 2-stroke lawnmowers
used a similar alloy, but with less silicon. Those alloys are similar
to the ones used to cast pistons today.

Don't most newer Briggs engines use AL
or pot metal block/cylinders?
But they have cast iron cylinder sleeves.

--

Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @

two words:

burt munroe

as an example of home-cast/home machined engines.

--
bigegg