At least Briggs has all this in writing on their website it you know enough to look for it. Obviously Tecumseh and any other engine manufacturer follows this same rating procedure. Pretty lousy numbers when you think about gross HP as opposed to BHP that we are really concerned with. Still, they don't mention if this rating system takes into account the very lean EPA carburetors, so I'd have to say no, which means its even worse. If you look at the last paragraph that I highlighted in RED, this supposedly 8 hp engine I have that is run in ACTUAL conditions and NOT in optimum laboratory conditions, has a pitiful rating, as do all of our engines.
Horsepower Ratings
The power ratings shown with the individual engine series on the preceding pages are established in accordance with SAE (Society of Automotive Engineers) code J1940 (Small Engine Power & Torque Rating Procedure) (Proposed Revision 2001-09). Power curve and engine performance data are obtained in accordance with SAE J1349 (Net) or J1995 (Gross) Engine Power Test Codes.
In accordance with SAE J1349 (Net) or J1995 (Gross) Engine Power Test Codes, power curves are developed from laboratory test engines and are corrected to standard conditions which are:
| Altitude: 100 meters (328 ft) | Ambient Temperature: 77 F (25 C) |
If the engine will be operated under ambient conditions different from above standard conditions, the following factors should be accounted for in estimating "on site" power output:
| Engine power will decrease 3.5% for each 1000 ft (300 m) above sea level and 1% for each 10 F (5.6 C) above standard temperature of 60 F (15.6 C). |
The actual "on site" power output will also vary depending on other factors including the manner in which the engine is operated, the fuel that is used, and the application in which it is installed.
The "Maximum BHP" curve represents maximum performance output of optimum laboratory test engines of a particular model. A statistical mean of production engines, with 95% confidence, will develop no less than 85% of the Maximum BHP when tested after run-in to reduce friction and after clean-out of combustion chamber, with valves, carburetor and ignition systems adjusted to laboratory standards.
The "Recommended Maximum Operating BHP" is a calculated curve and represents 85% of the maximum BHP curve. For practical operation, BHP load and speed should be within the limits shown in the "Recommended Maximum Operating BHP" curve.
If the maximum speed of the engine specified for a given application is governed to a speed less than the speed at which the Maximum BHP occurs, the engine will not achieve the Maximum BHP in that application. For applications requiring operation at other than the recommended engine speeds, complete details of the proposed engine installation should be referred to the factory for evaluation.
Source: Briggs & Stratton Technical/Warranty
http://www.commercialpower.com/display/router.asp?DOCID=76491
This message was modified Feb 16, 2005 by Richie
Richie
