|Howell V-Twin 4-Cycle Gas
is a V-Twin engine that is machined entirely from bar stock. It has no
prototype as it is entirely my own design. Being a single crank pin 90
degree engine, it is extremely smooth and vibration free. V type
engines other than 90 degree can not be balanced except with special
balancer shafts, etc. that you wouldn't want! Witness the vibrating 45
degree motorcycle engines...... The engine is a long stroke, moderate
speed design which provides plenty of torque. A robust cooling system
allows the engine to run indefinitely with a load and never overheat.
Cylinders are of cast iron. Crankshaft is steel. Most of the rest of
the engine is of aluminum alloy. Knife and fork aluminum alloy
connecting rod ends operate on a single hardened crank pin. This
configuration produces an interesting exhaust sound! An internal oil
pump ensures that lots of oil gets to all the internal moving parts.
The crankcase holds two ounces of oil.
The engine is equipped with ball bearings on all rotating shafts. A
sheet metal shroud on each cylinder/head directs cooling air from a
pair of belt driven fans. Dual 2-Jet Throttles have oiled foam air
cleaners. The valve rocker arms have ball bearing rollers on the valve
stem end and clevises with lock nuts on the push rods for valve
clearance adjustment on the other end of the rocker arms. The valve
train is designed so that there is no side thrust on the tappets or the
rocker arms which causes undue wear on other engines.
The engine operates without any oil getting on the outside due to "O"
ring seals at all joints and an efficient crankcase check valve
ventilation system which maintains negative crankcase air pressure.
The ignition system is twin Hall sensor and twin TIM-6 electronic
ignition modules and two model engine coils operating on 6 volts. Each
cylinder is treated as a separate engine and this precludes the need
for a distributor. The spark advance/retard is easily adjusted during
operation. Spark plugs are the low cost 10mm NGK CM-6.
This is NOT a beginners project, but anyone who is particular about his
work, has built a few other successful internal combustion engines and
has a 7 inch or larger lathe and a milling machine with a 6 inch rotary
table should not have any problems building this engine.
Besides just being a nice engine to have and operate, this engine would
be great fun on a bicycle or in a radio controlled boat, car, tank,
etc.! This is a small "real world" industrial quality engine capable of
doing "long hours" of hard work. My engine operates all day long at
shows driving a generator and is stopped only long enough for refueling.
The plans include all engine features in the photos (except the
mounting rails) including the throttles, cooling fans and air shrouds,
plus an ignition system schematic diagram and timing gear cutting
The quality CAD generated and laser printed plans set consists of 41
sheets of drawings and 3 sheets of construction notes.
Flywheel Diameter: 4", Cylinder Bore:
1", Piston Stroke: 1-1/4", Compression Ratio: 5:1, Displacement: 1.96
C.I. (32cc), RPM Range: 800 - 4,500, Height: 6.9", Width: 8.3", Length:
am happy to say I have received my plans that I purchased from you guys
a while back. I must say the late Mr. Howell must have been a very
thorough model engineer as the plans have all the required information
I was looking for. I will cherish the opportunity to have a set of the
V Twin plans in my possession and being located in Australia I have
found it difficult to locate such information locally. Upon completion
of this project I will be sure to send you pictures and maybe a video.
I would like to extend my appreciation for the professional service
that Outpost Enterprises offer." - Barry Thomas.