Jack: All New Performance Majors are Category II hitch units. The Dexta is a Category I. As for the variation in horsepower, previous posts may have been for the Major, Power Major or
Super Major. Engineers were constantly tweaking the engines in the Mark I, II, III and IV Dagenham built Ford 220 cid engines for improved
performance and increased horsepower. I posted horsepower at a specific r.p.m. rating
at the three commonly used ratings of brake, belt and drawbar. One of the reasons for the Nebraska Tractor test was to provide horsepower information in an unbiased 3rd party setting to insure that 'horsepower hype' was minimized and held in context by manufacturers/dealers and the
consuming public. Of course, the FPM will produce more horsepower at a higher rpm; hence why injection pumps may be
'turned up' (to a point) to produce higher rpm and
hence transmit a bit more power to the drawbar. This however is not directly proportional to engine revolutions per minute. A naturally aspirated engine will eventually not be able to provide enough air to the combustion chambers to efficiently burn the increased fuel deposit. The Dagenham built 220 cid diesel engine was improved over the years by engineers resulting in the Mark I, II, III and IV engine series. Sometimes these changes were introduced with a Model change, ie Major to Power Major. Sometimes they were simply introduced within a model series.
(Hence why service manuals, I&T manuals etc may
cite a specific serial number as a reference for
different engine components etc. being used before or after that serial number. The race for horsepower by all manufacturers was a vicious one. Listing the brake, belt and drawbar horsepower looked better because engine brake h.p. is always higher than drawbar performance. A 50 belt horsepower tractor 'looked and advertised' better than a 44 drawbar horsepower tractor. Many times the consuming public and even dealers simply (but not accurately) referred to the
power of a particular model as an average between the two. Even earlier many models were named by their belt and drawbar horsepower.. for example, a McCormick-Deering 15-30 had 30 belt horsepower and 15 drawbar. (I use this only as an example,
although there probably won't be too many M-D collectors reading this post to dispute the fine
details) Hope this helps explain the variation you may see and hear.
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