Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

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:

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:

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

I posted something in the wrong place, but I just fixed it.  I also do recall you mentioning the altitude issue somewhere.  Altitude really makes for some horrible numbers. 

Ben

but you will also notice horsepower numbers are taken at 60 degrees...not much need for a snowblower then.

at realistic temp you will actually be making up for some lost power...when its cold the air is denser and you get a better burn.

the engines are also rated with all there emmisions carbs and if muffler has a calalyst in it then it must be installed.

most engines are tested without a muffler...or with a stack.

any questions.

later chris

Hi Chris,

Well believe me, if the Boss fired everyone for disagreeing with him, I'd be out of a job along, long time ago...

You should see the bench he's designated for you.  It'll take you months just to find it under all the junk - no that's not the right word - crap - no, trash - no...well you get my point.

There's a power saw sitting there from 1950 and a 36 volt generator - so your work is all ready cut out for ya - when shall we expect you to be arriving?

Sherri

If you don't have free speech, what do you have?

Well believe me, if the Boss fired everyone for disagreeing with him, I'd be out of a job along, long time ago...

Hey Sherri,

That's good to know, thanks.  Hey, I love working on the old stuff, I'll get that Saw and Generator working in no time.

BTW...I'm actually buried under all that stuff.  The other day, while kneeling down trying to clean the place up, someone rolled a big heavy snowblower over my back and pinned me there.  I wish someone would come and help me, the tire chains are still digging into the back of my head

the lawnmower is a bit of a different story,your gonna love this.

the engine is capable of its 6.5 horsepower.however the blade is the limiting factor.

there is a certain rpm allowed for the length of blade installed on the mower.

basically it amounts to how many feet per minute the tips of the blade travels.

so in a sense you are CORRECT the numbers are crappy.

they take a high horse motor and slap it on a mower and then wind the throttle speed so far down that it can barley get out of its own way.

remember when we had those little 3.5 or even 2.75 horse 19 inch cut mowers.they would turn up like a racecar and would mow down anything you could push it through.

its all about the blade tip speed  and that even changed,i think it was 21000 feet per minute and now its 19000 .not positive on the actual number but you get the idea.

longer blade ,slower its allowed to go ...or it will break up and thats not pretty especially if you wear sandals.

ps i hope you get your butt out from that pile of junk...i have a bunch of work to get done .

later chris

Mountain,

I have to agree with you on that one  The problem is that over-powered or purchasing more engine than you may need is really expensive.  I suppose the way things are, it's a no win situation for the consumer.