Belted Air Power

Gale Derosier's Chevy-powered Bushby Mustang II (from July '05 Kit Planes)

I'm flying a Bushby Mustang II which I finished in November 1999 and flew in April 2000.
I have a slightly modified Chevy Vortec 4.3-liter V-6 engine producing about 210 hp.
I modeled my engine on the package produced by Belted Air Power of No.Las Vegas NV,
for the Van's RV series. I used the company's PSRU, which bolts onto the Chevy engine
to slow the prop to normal operating speeds. A friend and I bought and overhauled this engine.
The specs are to purchase an even-fire, non-balance shaft, light truck engine, the change of
cam being the only internal mod. It is a Comp Cam and produces full torque at 3000 rpm.

I have a special Edelbrock intake manifold and a 500 cfm two-barrel Holley carburetor.
I'm using a McNealy mixture block, which is installed between the float bowl and the carb.
The jets and power valve are removed from the carb, using only the cockpit-controlled mixture.
The design stays with the KIS method: keep it simple. A dual-point Mallory distributor is used
with two coils, two sets of points and two condensers. Only one set of plugs is installed;
fouling plugs in an auto engine is highly unlikely.

I run the engine with a Warp Drive ground-adjustable, three-blade propeller. My engine turns
at about 3600 rpm for takeoff-as you level out, the rpm increases to about 3900. I cruise at
3500 rpm, which yields 170 mph with a fuel bum of approximately 7 gph. Full throttle, the
Mustang II trues out at about 190 mph. Of course, if a controllable-pitch propeller were used,
I could get even better performance. Now, I have it set for the best of both worlds regarding
climb and cruise. No modifications were necessary to the airframe, nor was there any ballast
that had to be added. The battery is located aft of the baggage compartment, which is the
same location recommended if you were using a Lycoming IO-360.

The automotive engine is about 45 pounds heavier than a 200-hp Lycoming, but it is mounted
closer to the firewall, bringing the moment arm closer to the c.g. It took me about two years to
produce the firewall-forward installation because of making the engine mount and jig; also,
the cowling had to be built from scratch. A unique arrangement was used for cabin heat and
defrosters. I mounted a small oil cooler on the firewall on top of a distribution box. Fresh air
comes in a SCAT tube and goes through the cooler. I can then vent this fresh air overboard to
help cool the oil in the summer; or I can close the overboard vent and route the 220° air to the
cabin and defrosters. The warm oil heats I much better than a metal heat muff. My temperatures
in the air run about 175-180° on the water due to a 180° thermostat; the oil temperature varies
within the range of 225-240°. I believe my exhaust system contributes to this temperature.
I've thought of putting some NACA ducts in the lower cowl to cool the oil pan, but so far it has
not been a real problem as Chevy specs say you can run the oil temp to 300° in the pan.
NACA ducts may also induce cooling drag. I don't need any more drag! During taxi, my cooling
on the water temperatures seems limited, and it starts to climb during prolonged taxiing.
The only time I really have to watch and take precautionary action is in the long lines at Oshkosh.

I've invested about $7500 for everything firewall forward. Frugal shopping and overhauled items
can save some money. Costs would be higher if everything was purchased new. I cunently have
180 virtually trouble-free hours on this setup and love every minute of it. The tuned headers
exhaust system really sounds throaty and smooth.

Gale Derosier
St. Charles, Missouri
kgderosier@sbcglobal.net