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.

Muffler Tests:

Engine #2 was [then] set up for the same test with the 1932 head, stock manifolds, carburetor and a Mallory distributor. I first ran a base line using the house exhaust system. The base line results were 50.3 HP and torque of 117.3 LBS/FT at 2250 RPM. The Aries muffler test results were 52.2 HP and torque of 121.8 LBS at 2250 RPM. The standard repro version produced 48.4 HP and torque of 113.0 LBS/FT at 2250 RPM.

The Aries unit increased power by 1.9 or 3.7% when compared to the base line. The standard muffler caused a loss of 1.9 HP. The Aries muffler, compared to the standard repro, produced 3.8 HP more or a nice 7.8% increase.

The preceding excerpt highlights the results of the muffler tests; for the entire article, click here.
Last Updated: 07/28/2018
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