Dynometer Testing
Reprinted with permission from "Secrets"
July 1995
Secrets of Speed Society, Box 957436, Hoffman Estates,
IL 60195-7436
Ron Kelley can be contacted at telephone
(972) 771-1911.
The following excerpt highlights the muffler
results; click
here for the entire article.
wanted to find out how the engines I rebuild compare to
a stock Model "A" engine. I decided that dynamometer
testing would best show the improvements made to the engine.
The tests were done on a Super Flow 901 Dynamometer. It
is a computer machine and is calibrated on a yearly basis.
Testing on the dyno is done
at full throttle. The computer increases the load until
it brings the RPM to a lower preset limit to start the
test cycle. When the test cycle is started the computer
eases the load to allow the RPM to increase. It then takes
measurements at preset intervals until it reaches the
upper preset RPM limit and then returns the engine to
the lower limit. That completes the test cycle.
For these tests I needed an
engine that was as near to stock as I could find in order
to set a reliable base line from which to measure any
improvements. I borrowed an engine from a past customer
who had removed a rebuilt stock engine with only 2000
miles on it. This engine was in good condition and had
been sleeved back to standard bore. The valve train was
rebuilt using reproduction stock parts. The camshaft had
been reground with a stock "A" grind. The crankshaft
and flywheel were stock. This was what I needed for a
base line comparison, a basic stock engine with no modifications.
This engine will be referred to as engine #1.
I rebuilt two more engines
for comparison testing at the same time. Engine #2 was
rebuilt with insert bearings and my preferred parts list.
Engine #3 was also rebuilt with inserts, but was stroked
.360", Which is almost 3/8".
Engine #2 was rebuilt using
parts and services that I have found over time to work
very well together in a Model "A" block. The
engine had insert bearings in the rods and mains and a
counter weighted crankshaft. It was dynamically balanced
and had a lightened flywheel with a harmonic dampener
installed. The pistons were from a Ford 351 ci V-8, which
required a 4" bore. The valves were from a GMC truck
with one piece valve guides from a Buick. The engine had
a mild performance camshaft and the ports were enlarged
and polished.
I also wanted to test some
other bolt on items such as heads, distributors, carburetors,
spark plugs, mufflers, fans and fan belts. I wanted to
see how these things compared to the stock Ford equipment.