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

I have a 15 year old Ariens . ST 924. It came with a 8 hp Techumseh. I'm planning to retiring the engine .  Which is better  a Subaru Robin sx30  with 9.5 hp 4000 rpm max , a Honda GX 390. or a 305 Briggs?  The Subaru does not give me as much  HP as the Honda, but I get more rpm. If i put Clarences kit on my unit then is will be even better. The Briggs is the cheapest , but I do not really know its power output They only tell me 305 cc and 13.5 lbs of torque. My Techunseh is a 318 cc so I guess the 305 Briggs is close to 8 HP. I prefer 12 volt electric start. The biggest Briggs is there 342 16.5 I was considering that one too.

Here is an 11 HP Honda GX 340
Peak HP at 3600 RPM, Peak Torque at ~2400 RPM.
Most engines have similar torque curves.

coasteray wrote:
Careful.  HP is a function of RPM and torque at that RPM.  And peak torque and peak HP rarely, if ever occur at the same RPM.  Many times the peak torque occurs well below 3600 RPM.  See the example chart above.  I don't know what constraints manufacturers are under when reporting torque.  Probably, they can report peak torque at whatever RPM it occurs.

So, as you essentially state, it is key that you know at what RPM your torque value occurs.  Then you can calculate the HP at that RPM, but not necessarily peak HP.  If you know that your 14.5 torque is at 3060, then your HP is 8.44 at 3060.  Peak HP may be higher at 3600 RPM.  You appear to come to the same conclusion.

Honda Engines come with sediment cupsfuel shutoff, a throttle (most new machines no longer have a throttle the way your 15 year old machine did, and the B&S engine is probably made in China by coolies.

manjestic wrote:
That just does not seem right. torque with out HP behind it is useless . My 1" 1800 ft lb impact wrench has more torque than my wifes 2.3 engine in her car. If torque was the only factor then i could power my wifes car with my torque wrench. I DON'T THINK SO

bus708 wrote:
Measure your impact wrench's RPM under load.  Then we'll talk. 

I get 20 rpm full load   1800 x 20/ 5252= 6.8 hp    at 1 rpm stall speed i get  .34  hp which is nothing

bus708 wrote: You say your wrench is rated at 1800 ft. lbs. -- but at what RPM? You have to know the rated torque at RPM to determine HP. I suspect that 1800 is stall speed torque.
HP doesn't drive torque, it's the other way around.

BTW, 1/3 HP isn't nothing, look at the rating of the motor in your drill press. Nothing compared to an auto engine, yes.

http://en.wikipedia.org/wiki/Horsepower#Relationship_with_torque

  Referring to cars, Dan Gurney  said :  "   If 200 horsepower was good and 300 horsepower was too much, then 400 horsepower would be about right. "

My   Chrysler  300c  SRT8 is rated at 425  horsepower and it is about right.

The Tecumseh 9 HP was not as powerful as a Honda GX 270 which comes in about 8.5 HP.  IF the friction wheel and drive plate can be made to transfer the power and not slip from 15 years of wear, this would be a wise choice.  The problem is the 15 years will have taken their toll on the friction wheel, and the drive plate making that unlikely at best.   The power is useless if it doesn't transfer to the wheels, that is what you need to concentrate on after 15 years.

New_Yorker wrote:
90% of the horsepower is used to move the snow and only about10% or less to move the machine.  If a human could push the machine into the snow that would be one person power.  The only time the drive system will see a lot of stress is if the operator tries to go to fast into too much snow.  If the operator uses the machine properly and matches the ground speed to the blowers ability to move the amount of snow in front of the blower the friction drive will see very little stress. 

If the operator goes too fast into more snow then the blower section can handle then the blower becomes a snow plow and not a snow blower. 

I put a GX340 on an old 80's Cub Cadet 8/26 that originally came with an 8hp tec flat head and it still has the original friction disk.  If you try to hold it back on dry pavement it will pull you down the driveway or if you can get a good enough grip on it it will spin the tires on dry concrete but the friction disk does not slip.

I would not have any concerns putting a gx270 in place of an 9hp tech flat head.

Carl