cc, gross torque, horsepower-What’s the difference?

I updated the original article November 2014 here: cc to torque to hp Conversion Update!

Well they changed the rules on us again.  Five years ago the power output of every snowblower sold here in the United States was measured in hp or horsepower.

Two years ago they changed the rules and started selling snowthrowers with the power measured in gross torque.  Of course no one understood what this meant and even though companies like Briggs & Stratton tried to explain it, it still didn’t make much sense.

So we just started to get used to measuring an engine’s output in torque and now most of the snow blower manufacturers are dropping the torque measurement and only giving us engine size in cc’s.

I spent a great deal of time researching this and I’m not going to spend time trying to explain why the engine manufactures have changed their terminology.  Instead I’m just going to show you a formula you can use to figure it out yourself.

Here’s the formula I used from the Briggs & Stratton website (rpm x torque / 5,252)   The engine manufacturer’s used 3600 rpm most of the time to rate the engine’s horsepower so I will use that number in the formula.  I also used the torque ratings from the Briggs & Stratton website for their motors to keep this chart simple.  Other manufactures (like Powermore) may have different torque ratings for their motors.  If you are trying to get exact hp measurements you should research the torque ratings for the specific brand.

Here is a simple chart of approximate cc to torque to horsepower conversions.  It’s not exact, but it will give you a better idea of how big the new engines are.  I used 3600 rpm in the formula for this comparison.

179 cc =  5 hp

205 cc = 8 to 9 Gross Torque = 5.5 to 6.5 hp

250 cc = 11 to 11.5 Gross Torque = 7 to 8 hp

305 cc = 13.5 to 14.5 Gross Torque = 9 to 10 hp

342 cc = 15.5 to 16.5 Gross Torque = 11 to 12 hp

389 to 420cc = 18 ft lbs = 13 to 15 hp

To me cc’s is not a good comparison from one motor to another.  It is also not a good comparison from one manufacture to another.  For example, a 190cc Briggs & Stratton side valve motor will not have the same power as a Honda 190cc overhead valve motor.  cc’s won’t give you a good measurement of what the engine is capable of.    True, an overhead valve motor from a specific manufacture should have more power with more cc’s but there are a lot of other factors that go into determining how much power is available for you to use.

The true power of a motor is determined by engine type, (overhead valve/side valve) carburetor, (naturally aspirated/fuel injected/turbo) rpm you use it at, (2750/3100/3650) and many other factors.

I hope this helps.

Got a Question or Comment? Here's Your Chance!

  1. Thanks for this simple explanation. It would have been nice for the manufacturers to just stick to a HP designation, and leave the different engine types right out of the question. Like you said depending on how a motor is doctored up, the Hp outputs can be all over the chart. Why can’t they just tell us the Hp. I wonder if this is just a way to sell a motor that isn’t up to snuff and most people don’t have the capability to figure that out until after the purchase, and they don’t get the performance they expected for the size they bought.
    Charlie Foley

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    • @Charlie, Yes, it would be nice but I’ll give you a quick explanation of why the manufactures no longer use HP.

      1. In the past the horsepower of all small L&G engines was measured on a test stand at 3600 rpm with the muffler and air cleaner removed. This HP rating was listed on the engine. This gave us a reliable horsepower rating.
      2. The actual HP of the engine out in the field though was less. Adding the air cleaner and muffler reduced the horsepower. Then other government requirements also reduced the actual horsepower. Regulations for example that limited the mower blade tip speed (to reduce the velocity of objects that you may hit and throw out of the mower). So instead of the engine running at 3600 rpm it was now operating at 3100 or even 2900 depending on the mower blade size.
      3. The manufactures kept using the tested horsepower for the engine labels even though the actual HP at the blade was less. So few years a go a group of lawyers decided they could make a million bucks or more and created a class action lawsuit stating that the HP listed on the engine had nothing to do with the actual HP available to mow your lawn. Of course the lawyers won and the engine manufactures had to pay everyone who owned a lawn mower between $25 and $75. HP ratings were dropped from most engines.
      4. The manufactures tried the torque rating, but that is a different measurement and it changes for each piece of equipment their engine is mounted on. It’s a measurement of work done. For example, the same motor can be mounted on 3 different mowers, say, a 19 inch, a 21 inch and a 24 inch. The torque at the end of the blade is different so the engine has to be labeled differently for each size of mower. But, it is a fairly consistent measurement and most of the manufactures are still taking the time to rate and label their mowers this way.
      5. Snow Blower, Rototillers, generators, compressors and water pumps are a lot harder to rate the torque. Where do you rate it from? – the front auger? The impeller? at the drive wheels? Because of that the manufactures just decided to quit using HP or torque ratings and stick with cc’s.
      6. Only the U.S. has this mess. In other parts of the world the manufactures can still use HP. If you can find your engine being used, say in Europe then you can get the HP from over there.

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