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:

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

MountainMan wrote:

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.

snowshoveler wrote:

Chris,

.     

"I suppose the way things are, it's a no win situation for the consumer."

Well, that might be taking it a tad too far. LOL 

When you get down to the nut cutting, if you bought an engine that will throw your snow how you imagined it to be thrown with the HP you thought you bought, regardless of what the sticker says on the cowling, you're winning.




But, I know what you're saying.

Richie wrote:

Not much different than getting the upgraded larger motor in a truck.  I couldove bought the 9 HP 24", but went to a 1128. Noty like i was doubling the price.

On my 48" mower, price diff between a single cylinder and the Kawasaki twin was negligible, a worthwhile investment. The 15 HP is there when you need it, and if I ever selll it, will hold its value.

MountainMan wrote:

Mountain,

MountainMan wrote:
All the more reason for " OVER-POWERED IS USUALLY ADEQUATE"

Hey Mountain,

I think this qualifies in that area  Here is a really great way to make any OPE engine come to life.  It just goes to show you that no matter what size engine you have, you can always find a company that produces high performance products for it.  Too bad a snowblower would be difficult to modify for this type of thing.  Sure looks real cool and it could make a Briggs 5 HP or larger OPE engine scream

 http://www.hscsupercharger.com/

That would make a Go Cart a screamer!

Marshall wrote:

Marshall,

When I read that, the first thought in my head was as a kid I saw that Munster's episode when Herman decides to take Eddie's go-kart for a ride.  Of course it was filmed in fast forward to make it look like it was going much faster...LOL.  I could imagine that supercharger  on a go-kart, it wouldn't surprise me if that's how fast it would actually appear to go

I'm not sure what the fuss is about. My reading of the original post is that  what they are saying is this:

1. We tested our engines using the following independant standard;
2. Here are the implications of that standard;
3. Here is how production engines relate to the standard; and
4. Here is how we set up production engines, differently from the standard.

It seems very above board and a lot more honest than the so called "9HP" shop vacumns that run on a 115V 15A circuit.

Engines produce different HP under different conditions, that's why there are standard conditions, so you can compare apples to apples. The fact that the company is saying that under normal, non-ideal conditions for an extended period of time the engine produces less shouldn't surprise anyone. They, along with other manufacturers design to meet the standard. If they could come up with a design for an equal or lower price that causes more HP to appear  under "normal" conditions you can bet they would. The physics of the situation make that unlikely.

I'd also argue that "over powered is better" is not true. While it is convenient to have a machine that easily handles the one storm in a hundred it also means that you have too big a machine for the other 99 and have wasted a lot of resources and effort. The smaller machine that fits what you need most of the time will handle the big storm, just not as easily. I see three types of people buying snowblowers:

1. Doesn't research, walks in and gets something too small because its on sale;
2. Has more money than brains, buys biggest baddest  machine around and then wonders why its a pain to clear the 27" walkway; and
3. Everyone in this discussion area who always get exactly what they need .

I hope I've moved from about around 2.5 to 3. I have a 10/28 that I am pleased with and enjoy using. It is actually too big and heavy for my usage patterns and snow patterns. My next machine will be a 9/26 with different options, the 2 big things being an easier way to turn the thing and faster ground speed.

nibbler wrote:

The fuss is about any OPE engine supplier being allowed to place a sticker on an engine, stating a certain HP, yet being allowed to rate the HP and torque at a certain RPM, and actually delivering it to you at a much lower governed speed and never coming close to what it's supposed to be. 

This independent standard the industry is allowed to use is a complete joke.  Because of this, my 8 HP engine only produces somewhere maybe slightly above 6 HP.  A lawn mower generally doesn't require much HP unless the grass is wet or very over grown.  A snowblower or similar equipment usually requires the engine to work much harder.  It would be one thing to say I have an 8 HP engine, and once the power transfers from the crank to the gearbox, pulleys, belts and such, the power available is actually 6 HP.  That would be fine with me if they looked at that as gross Vs. net horse power.  I'd still be able to say I have an 8 HP engine, but that isn't the case here.