small 4 stroke engines-cc's to hp

nwcove

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anyone have a good idea of how to guesstimate hp of a small engine using displacement ? online info suggests 15-18 cc for 1 hp. this works out great for a car engine but not well for a lawnmower etc. i calculate it to be about 35 cc's per hp. if my 35cc number is correct, would it work out for an OHV engine?, or do they make a bit more power than the old style b&s etc motors?
 

MTboatguy

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What brand of motor is it, most motor manufacturers in the last 40 years have websites that you can get that information off of. If they don't have a website, then they have a following of old timers that know the information and often times have blogs or actual websites talking about this stuff.
 

nwcove

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its advertized as a troybilt, no tags anywhere saying b&s or techumseh or anything else. decaled as a 208 cc OHV-S.E.T . cant even find out what gimmick S.E.T stands for. lol
 

MTboatguy

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How old is it, it sounds like the one I have which is a 208cc OHV if so, it is probably an MTD motor How big is the blade on it? does it have power drive wheels on it? Also on the troy built, normally the ID plate is not on the engine, it is usually located on the back of the deck, or on the flap that folds up to you can use the grass catcher.
 

nwcove

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sorry MT, i used lawn mower as a generic example. its a snowblower engine on a new model . have read some stuff that suggests troybilt is having engines built by others and branding as thier own.
 

MTboatguy

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sorry MT, i used lawn mower as a generic example. its a snowblower engine on a new model . have read some stuff that suggests troybilt is having engines built by others and branding as thier own.

If it is a 208cc OHV snow thrower, then it is a 99% chance it is a MTD motor that has been branded by Troybilt, they have been using MTD for years now. Now take into account, for a while, MTD was having Briggs and Stratton building their motors for them. Most of the small motor companies have been bought by other companies over the years, sometimes it is real hard to figure out who built the motor, but normally they parts are all pretty much interchangeable.

You probably have an older model of this one that is sold at Lowes:

http://www.lowes.com/pd_189206-270-31BM63P3711_0__?productId=3052455
 
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nwcove

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its a newer model, probably same engine. was just curious as to why mfg's stopped rating small engines in hp, and went to cc's and torque . and if there was any way to correlate the three dynamics ( two?), and if an ohv engine makes more hp than a same displacement non ohv does? my questions are based soley on water cooler talk! new blower...how many hp?? thing!
 

MTboatguy

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its a newer model, probably same engine. was just curious as to why mfg's stopped rating small engines in hp, and went to cc's and torque . and if there was any way to correlate the three dynamics ( two?), and if an ohv engine makes more hp than a same displacement non ohv does? my questions are based soley on water cooler talk! new blower...how many hp?? thing!

In the future, you will see less and less focus on HP, because of all of the innovations in engines, there is so much more that means so much more to the performance than HP.
 

mla2ofus

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nwcove, several yrs ago the small engine mfgr's got to overrating their HP. This resulted in a few of our upstanding legal profession decideing to file a class action lawsuit over it. When the dust and feathers all settled the lawyers walked away w/ a substantial amount of the settlement, the plaintiffs got a few pennies and the co's agreed to get away from HP. Torque is what gets the work done anyway, but who says torque #'s can't be manipulated??
Mike
 

dolluper

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A standard small engine is 32.5 cc's to 1 hp if you increase compression or other factures hp wil increase so 208 standard non hemi is 6.4 hp
 

cjjjdeck

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I too prefer to see the HP rating just so I have a general idea what to expect out of that size engine. My Dad has a John Deere snowblower with a B&S 305 cc which translates into what I used to know as 9 HP. So the 32.5cc to 35cc per HP estimate is pretty close for us older school types. So many of the engines nowadays are Chinese built or Chinese knock-offs (which personally bugs the crap out of me to buy). Briggs still makes some larger and commercial engines in the US (I usually call them when I'm not sure and they answer truthfully), but most consumer grade engines are built by the Communists, even Honda does it. I actually have been preferring Subaru/Robin engines on any new machine I'm looking at, they still show HP ratings, for what it's worth. It's all US built and many engines have some pretty cool technology (especially the OHC vs. OHV and Fuel injection on some models). I have a pressure washer with a 7 HP OHC and a ultra quiet inverter generator with a 9 HP OHC that have run awesome. I found out that Go Kart racers like use the OHC engines.
 
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