HP to CI & CC

[McCullough]

CI = Cubic Inch
CC = Cubic Centimeter
HP = Horse Power

Ok, I've found the formulas for converting CI to CC and CC to CI, but I am curious about its relationship to HP as pertaining to chainsaws.

From internet research there never can be a exact "conversion forumula" to estimate the HP of a given CC or CI of an engine because each engine is designed differently, how the engine is tuned, as so on - blah, blah, blah.

However, I am curious if there is a general hp rating or range one can use use to determine the hp of a given CC or CI and chainsaws are a lor more similar to each than say cars.

 

[sedanman]

Ever seen a little guy beat the tar out of a big guy? I worked with a wiry Irishman who arm wrestled every person on the job, one after another (a few were giants) with no rest and beat them all. There is NO solid relationship between size and strength.

 

[fishhuntcutwood]

Very true. You'll see saws with more displacement have less power than one of less displacement. The Stihl 390 to the 361 comes to mind. And that's just two of today's saws. Compare a saw of today, and a saw of ten or twenty years ago, and the difference becomes even larger.

 

[sedanman]

double post sorry

 

[PES+]

Horsepower isn't everything

Many times a difference in displacement can create more torque and useable power even though the peak HP is numerically lower. Think about all the claims for added horsepower by aftermarket computer chips for modern cars and trucks. Many times it is stated as a rather large numerical gain but that is only in one narrow RPM range and compared with the stock HP at this same narrow RPM range.

Another consideration is emissions regulations and emissions averaging over an entire product group. Sometimes a manufacturer is forced to build a very bad performing product that runs extrememly cleanly so that the rest of their product range can out-perform the competition

 

[oldsaw]

CI = Cubic Inch
CC = Cubic Centimeter
HP = Horse Power

Ok, I've found the formulas for converting CI to CC and CC to CI, but I am curious about its relationship to HP as pertaining to chainsaws.

From internet research there never can be a exact "conversion forumula" to estimate the HP of a given CC or CI of an engine because each engine is designed differently, how the engine is tuned, as so on - blah, blah, blah.

However, I am curious if there is a general hp rating or range one can use use to determine the hp of a given CC or CI and chainsaws are a lor more similar to each than say cars.

No.

Too many variables. Some good posts on this so far. Engines are tuned differently for different reasons. However, as has been mentioned, more displacement tends to give you more torque, which in terms of doing work, is the more important figure if you are going to bury a saw in big wood. Different design need than for a 35cc saw that is going to trim small branches and not be buried.

Almost 20 years ago, I lived in California, and hung out at a fairly famous motorcycle joint. (I hung out in the the morning with the Euro-bike crowd, the afternoon was the Harley guys) One of the regulars had a 350cc Moto Morini, a two cylinder Italian bike that made maybe 25hp at the rear wheel on a good day. He would regularly race guys with 1000cc plus Japanese sportbikes on this one chunk of curvy road leading up to the place. Very tight turns with very short straights. He never lost to them. He had a fat powerband, meaning that he had most of his modest power anywhere above idle. The Japanese sportbikes of the time had teeny tiny powerbands in comparison, but stupid high horsepower in those power bands. The corners were tight enough that the big sport bikes would continually fall out of the powerband and couldn't get back up until exiting the corner, where they would start to catch up. The 350 was also lighter, could rub it's bar end mirrors in a sharp corner (only a slight exaggeration), and never fell out of it's powerband. The guy was also one of the best riders I'd ever seen.

Variables. There is no formula for HP, only design for purpose and emissions considerations.

Mark

 

[PES+]

You never forget

You never forget trying to dive in to a turn on a KZ anything I HATED it

the only thing worse was trying to leave a turn on a 750 triple 2 stroke

ouch

 

[RaisedByWolves]

Arm strecher, pest?

 

[PES+]

Various shades of road rash

Still have odd colored specks in my legs from those stunts.

Finally gave up and tried to drag the triple......that was a clutch eating waste of money