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

I know that there had been some previous discussion about B&S engines of the same displacement with different power ratings.  Being an owner of the 305 cc engine also known as the 120000 series, my curiosity has been piqued.  From what I've gathered, the 305 cc displacement is offered in power ratings from 9 to 11 horse power.  It's available as the Intek, Intek I/C, Powerbuilt, Intek Snow and Intek Snow Max.  Correct me if I missed any.  Having some time on my hands, I pulled up a copy of the service manuals for the 9.5 h.p. model (20A414) and the 11 h.p. model (20E414).  I compared parts that I though would have an effect on power output.  Things like crankshafts, pistons, connecting rods, valves, head gaskets, carburetors (including jets, gaskets and spacers.  Other than some variation of crankshafts within the same power groups for both the 9.5 and the 11 h.p. which do not particularly differentiate between power groups, there is no difference in the part numbers.  So, if all parts are interchangeable within all three power groups, what is the secret to the difference in power? 

Someone had mentioned that B&S plan to use carburetor restrictor plates on future engines.  Not sure if that would work.  Restrictor plates are used to restrict flow from the carburetor to the combustion chamber.  This in turn reduces rpm.  If an engine is designed to produce maximum power at 3600 rpm, the restrictor plate would reduce maximum rpm.  So, if an eleven h.p. engine makes max. power at 3600 rpm, the 10 h.p.  would be reduced by approx. 10% and the 9 h.p. by approx. 20%.  That would equate to the 10 h.p. machine achieving max. h.p. at 3200 rpm and the 9 h.p. achieving max. h.p. at 2880 rpm. 

 Maybe I'm wrong here.  If so, I would appreciate any enlightenment that can be provided.  Nonetheless, if anyone can explain the difference in power output from the same engine, I'd like to here what you have to say. 

niper99 wrote:

Yeah I didn't go part for part but I did look at pretty much everything that would have an effect on rpms, breathing and compression.   I cannot fathom why their model line-up is so convoluted.  Particularly when there is so much commonality between the engines.  One would think that a complicated catalog that B&S use would be a burden for them to manage.  There's got to be a simpler system. 

Does anyone know if the governor is set to the same RPM across the lineup?

I believe that all of their utility engines are rated at 3600 rpm as are most other brands. 

Here is some interesting HP  info on Tecumseh 318 CC OHV engines built since 2004!

This is the engine that I have on my 927STE Husky blower.

I bought it as an 9 HP engine, but Spec tells me it is a 11.5 HP engine

It appears, that they are all 11.5 HP, but listed smaller for marketing reasons!

Also, Husky in my case, buys all 11.5 HP engines. Gets big discount on prices for a single order.

Then marks the engines as having less HP!

These are all the same engines, same parts, Etc just different spec number ! !

I compared part numbers on the 8 HP and 11.5 HP. all were the same!!

If your Tec engines Spec on a 318cc OHV engine is:

221200  =    8 HP

221400  =    9 HP

221600 =   10 HP

221700 =  11 HP

221800 = 11.5 HP

Forget it you all have an 11.5  HP engine.          IMHO

                          Fred

Hey Fred:

Do you think that applies to B&S as well?  I suspect that it might.  I know my Simplicity with a 9.5 ohv engine can almost double the distance of my old Craftsman with a  healthy 10 h.p. L head. 

Borat ,

What is the displacement of your Briggs engine?

Yes, I think all of the engine makers rate the HP different on the same displacement engines.

Just like Tecumseh!!!

                                                          Fred

jubol wrote:

It's a B&S 305 ccs (18.6) cu. in. ohv.