I've been buying mowers by horsepower rating for decades.
What gives?
I know that torque is probably more meaningful when cutting grass (especially tall grass) but who decided that this was a good idea?
More government meddling?
Is there any way to correlate torque to HP?
(Automotive experience would seem to say no, but it's not like there's a huge diversity in engine designs for mowers. )

[This message has been edited by Raydar (edited 07-31-2011).]

Okay. I don't want to be like that kid in school who asks the instructor a question and then answers it himself, but I found this.

http://forums2.gardenweb.co...215391823783.html?39

I still don't much like it.

HP is for tuners, TQ gets the grass cut.

A rich and greedy leftist trial lawyer sued all the lawn mower manufactures for not stating the correct HP rating.

Let's say one had one pasted as 5 HP and on the dyno it would be 4.3 HP instead. It would be considered false advertising and defrauding the consumers.

The dude made millions off of this class action lawsuit, and if you had one, there was a claim site where you could have gotten $40 + bucks depending on the lawn mower.

So the manufactures no longer post HP rating on lawn mowers anymore.

That is why.

quote Originally posted by Wichita: A rich and greedy leftist trial lawyer sued all the lawn mower manufactures for not stating the correct HP rating. Let's say one had one pasted as 5 HP and on the dyno it would be 4.3 HP instead. It would be considered false advertising and defrauding the consumers. The dude made millions off of this class action lawsuit, and if you had one, there was a claim site where you could have gotten $40 + bucks depending on the lawn mower. So the manufactures no longer post HP rating on lawn mowers anymore. That is why.

That seemed so silly I had to google it. You aren't kidding....sad.

http://www.lawyersandsettle...ettlement-03250.html

quote Originally posted by WBailey1041: That seemed so silly I had to google it. You aren't kidding....sad. http://www.lawyersandsettle...ettlement-03250.html

Yup. My link kind of alluded to that.
But HP is a function of torque and RPM anyway. One comment stated that the torque is measured at 3060 RPM, so it is at least valid for comparison purposes.

"The new "Torque Ratings" are taken at 3060 RPM, which is more meaningful for typical, homeowner, walk behind mowers, since they operate in that range. At least for that application, you get about as valid of a comparison as one could expect."

Works for me. Of course there are some dissenting opinions, but it is a forum, after all.

[This message has been edited by Raydar (edited 07-31-2011).]

quote Originally posted by WBailey1041: That seemed so silly I had to google it. You aren't kidding....sad. http://www.lawyersandsettle...ettlement-03250.html

You're darn right he's not kidding. I received my paperwork in the mail, and promptly threw it in the trash.

Jim

[This message has been edited by jimbolaya (edited 07-31-2011).]

Horsepower IS torque with a time element.
A gasoline engine requires a minimum RPM to function, therefore Horsepower information becomes useful from an engineering (or performance) standpoint.
Hp = Torque X RPM / 5252
Horsepower is equal to, Torque times RPM, divided by 5252.
6 foot pounds of Torque times 3,000 RPM, divided by 5252 is equal to 3.43 Horsepower.
6 Ft Lbs Torque X 5,252 RPM / 5252 = 6 HP
6 Ft Lbs Torque X 6,000 RPM / 5252 = 6.85 HP
Dynos measure the torque then measure the RPM then calculate the HP.

[This message has been edited by Black Lotus (edited 07-31-2011).]

Horsepower is only going to make sense as a rating when you are 1) using the engine's entire rev range and 2) when you have a transmission. Since a lawnmower fits neither of these, I would prefer to know its torque. Horsepower is an esoteric and meaningless number unless you're trying to measure acceleration.

quote Originally posted by Raydar: More government meddling?

Actually, I'd call it a lack of adequate regulation. It's all about marketing hyperbole and bigger numbers. Either horsepower or torque would be fine to rate, as long as the rating is continuous (power or torque) at the mower's governed rpm. Absent appropriate regulation, marketers will succumb to the temptation to "rate" their mowers outside of the normal operating conditions in order to have bigger numbers to advertise.

Look at shop air compressors. Their "horsepower" ratings are so inflated as to be meaningless. In fact, the "horsepower" claimed for some compressors actually exceeds their rated electrical power input ... implying greater than 100% efficiency. A few seem to base their power claims on electrical input with the motor shaft locked.

quote Originally posted by crazyd: Horsepower is an esoteric and meaningless number unless you're trying to measure acceleration.

No. It's "esoteric and meaningless" only if you don't understand it or if the figures are presented in a way that is misleading. Unscrupulous marketers like to take advantage of ignorance.

Torque, by itself, is equally meaningless. You can use reduction gears to produce almost any desired amount of torque from any engine, no matter how small, but it probably won't be able to do any useful work. You can still have very high torque even at zero rpm.

[This message has been edited by Marvin McInnis (edited 07-31-2011).]

quote Originally posted by Marvin McInnis: No. It's "esoteric and meaningless" only if you don't understand it or if the figures are presented in a way that is misleading. Unscrupulous marketers like to take advantage of ignorance. Torque, by itself, is equally meaningless. You can use reduction gears to produce almost any desired amount of torque from any engine, no matter how small, but it probably won't be able to do any useful work. You can still have very high torque even at zero rpm.

I do understand horsepower Marvin, and I stand by my statement. Why are you lecturing me about gearing when I said it doesn't matter if a transmission isn't involved? You took a small piece of my statement out of context to start an argument; I stated it as simply and accurately as possible and I don't need you to correct me for not being complicated enough.

It takes horsepower to cut grass, not torque. That's why mowers were always rated in horsepower. Because it makes sense to use the unit that is required.

Also, in the first linked article, it mentions the "Horsepower reported to the EPA." Anybody want to bet there was some strange way the EPA wanted horsepower reported, instead of just the peak power the motor could put out?

We all realize our push mowers are goverened to run at a constant RPM, regardless of load. The governor throttles the motor back during less than full load to keep RPM constant. Which is most of the time. We rarely run the mower on the verge of stalling because the grass isn't that high. (Okay, you got me there, I've let mine go a couple of times.) So I'm betting the motor is actually averaging significantly LESS than its max horsepower during most of my cutting. And THAT is what the EPA wanted to know. Like the EPA doesn't report fuel economy at top speed, they don't care about horspower when Zeb is choking his mower through tall grass. Because they realize, most weekends, his lawn is dead, anyway.

Well, some lawyer stumbled across this, and was willing to bet he'd be able to make millions off of this discrepancy. Guess what? Lawyers are smart!

quote Originally posted by crazyd: Why are you lecturing me about gearing when I said it doesn't matter if a transmission isn't involved?

What you said was:

quote Horsepower is only going to make sense as a rating when you are 1) using the engine's entire rev range and 2) when you have a transmission.

That is simply not true.

I hope we can agree that if you know the rpm then either a horsepower value or a torque value will give you exactly the same information. If a mower manufacturer includes a reference rpm value, then I don't care whether they report torque or horsepower at that rpm; I can do the (simple) conversions myself.

[This message has been edited by Marvin McInnis (edited 07-31-2011).]

quote Originally posted by Zeb: It takes horsepower to cut grass, not torque. That's why mowers were always rated in horsepower. Because it makes sense to use the unit that is required. We all realize our push mowers are goverened to run at a constant RPM, regardless of load. The governor throttles the motor back during less than full load to keep RPM constant.

Zeb, I like you and all, but you don't understand horsepower. Most people don't understand it either, and even fewer understand torque, but as a number people understand HP in a relative sense. Your two statements above are contradictory, and I'm going to show you why.

Running an engine at a constant RPM makes horsepower completely irrelevant. All that matters is the torque that engine makes at that governed RPM. Unless you're trying to see how fast you can get the mower to accelerate across your lawn, horsepower doesn't make sense as a measurement because it has a unit of time involved in its calculation - minutes, in this case. For a single engine speed, say 2500rpm, horsepower is calculated from torque as several others have explained above. And when you're cutting the grass you need more torque to chew through it. While that will also mean more horsepower for a given rpm, you can also get the same horsepower with less torque at a higher RPM - but since the engine is governed, that wouldn't cut the grass better, would it?

For a full explanation to anyone who wants it and can stay awake long enough, go here: http://www.vettenet.org/torquehp.html

Comming from 15+ years of kart racing and briggs and stratton race engine building I can tell you for a fact that a 5hp flathead horizontal briggs out of the box is short of 4 horse on a dyno...

Steve go get the new Honda mower. Those things are awsome. Smooth, quiet and have the new speed control. The lawnmower will speed up or slow down acording to how hard you push on the hand bar. Plus it will cut up pretty much any grass in front of it. About $600 for the top of the line push mower. Also Honda is the number 1 manfacturer of internal combustion engines. They have more R&D than most other companies combined.

[This message has been edited by bristowb (edited 08-01-2011).]

I wonder why they didn't just start calling the motors by Numbers minus the HP part.

You know, instead of selling a 5.5 HP Briggs, just sell a Briggs 5.5. Problem solved.

Brad

I just got through reading the actual article cited, about lawsuits etc. The case was thrown out, but the lawsuit did wake up the manufacturers to the fact that John Q. Citizen is becoming aware of their fraudulent marketing schemes. It seems that most lawmower's power ratings as published in sales fliers and marked on the machine itself are woefully inaccurate by large percentages. Most people buying a "5" HP mower were getting 3 or 4 HP. Even the same motor sold in different machines had different power ratings.

The people complaining about the lawyers "taking away their horsepower ratings" are really complaining about their misleading and often times completely fictional labels taken away. LOL. The movie Idiocracy comes to mind...

BTW, basic formula for HP (not mentioned here yet) is (Torque x RPM)5252. As you can see, HP varies with RPM, and is derived from torque. Mowers are typically designed to run at fixed RPMs so maximum torque should be rated at that RPM. Take away torque and/or RPM and you have nothing.

quote Originally posted by jimbolaya: You're darn right he's not kidding. I received my paperwork in the mail, and promptly threw it in the trash. Jim

That's exactly what I do when the "class action" lawyers send me something wanting to get rich off of others' misery.

I picked up one of these, no horsepower questions here.

That is interesting.

I am about due to replace my lawn mower but I'm going to get an electric instead of gas powered mower. I noticed that electric mowers often don't list their torque or horsepower but they all list their voltage.

I just know that I'm going to buy one of the top 3 Consumer Reports picks.


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