What is the value of HP/KW ratings?

[cmarti]

Looking at a J-red 630 Great reputation, but only specs at 3 HP for a 61CC saw. I am just a user not a pro, so traditionally used a 290 farmboss (seemed natural to use around a farm) and thought it was the bomb at 3.8 HP. Put together and old Craftsman 3.4 and it cuts with the 290, and they never even listed the HP for it and it don't spin that fast.

I guess where I'm going is if I try to feed CAD do spec sheets have any value, or do opinions matter more. I realize mods and chain are a big part of cutting, but specs, cc's and opinions don't always seem to line up:dunno:

 

[moody]

If both chains are equally sharp in bigger than 16inch wood you'll see the extra half horse . But long story short chainspeed wins. And those ratings are a baseline they saw can be more or less powerful during operation. Don't get to Hung up on power ratings when it comes time to cut wood, go with the gal that brought ya.

 

[deye223]

specs are BS

 

[rburg]

The 630 is rated at 4.3 hp.

 

[SawTroll]

Looking at a J-red 630 Great reputation, but only specs at 3 HP for a 61CC saw. .....

Simply a misprint, it is meant to read 3.0 kW = 4.1 hp.

The exact specs varied a bit with time and version.

 

[cmarti]

Simply a misprint, it is meant to read 3.0 kW = 4.1 hp.

The exact specs varied a bit with time and version.

Thank you ST. The listing had it as 3.1 HP. I was surprised for it's size and positive reviews.

 

[Chris-PA]

Looking at a J-red 630 Great reputation, but only specs at 3 HP for a 61CC saw. I am just a user not a pro, so traditionally used a 290 farmboss (seemed natural to use around a farm) and thought it was the bomb at 3.8 HP. Put together and old Craftsman 3.4 and it cuts with the 290, and they never even listed the HP for it and it don't spin that fast.

I guess where I'm going is if I try to feed CAD do spec sheets have any value, or do opinions matter more. I realize mods and chain are a big part of cutting, but specs, cc's and opinions don't always seem to line up:dunno:

They're really important for armchair sawing. Or maybe sawing wood in the armchair?

 

[SawTroll]

Thank you ST. The listing had it as 3.1 HP. I was surprised for it's size and positive reviews.

3.1 kW usually is 4.2 hp.

 

[Majorpayne]

specs are BS

Oh no! Specs on paper mean everything just ask Sawtroll.

 

[promac850]

Tells you power, but you gotta watch out for how they performed the dyno/mathematics... was it done on the crank or at the wheels/chain/etc.?

For example, 150 hp in a boat motor... was it done at the crank or the prop? Most are done at the crank, with the exception of Mercury in the 80's... they did prop ratings... as a result, those old inline and v6 outboards offered by Mercury really put a whooping on the other brands at the time, even when 'rated' at the same hp. And some of those Mercs still kick some butt to this day. IIRC, they do prop ratings now.

Same thing happens with cars, saws, and anything with an engine. I'd rather have a 200cc engine that puts out 15 hp rather than a 350cc that puts out 10. If I want torque, the 350 would definitely have more, and I would choose that.

Or if you want torque, figure a little less hp the engine will be rated for. Great examples of that are diesels, and some really undersquare (bore smaller than stroke) gas engines. Even a gas engine designed in such a way can put out more torque than horsepower.

In the end, you should really pick what feels right to you and fits your hands well, and send it off to one of the experts here that port and mod the saws... they'll get that saw to wake right up... the EPA has proven many times that they are really choking OPE power output.

Sometimes all that is really needed is the catalyst element to be torn out of the muffler, and the outlet opened up a little bit... and then retuning for proper idle and cutting speeds or sound.

Remember, it's not all about rpm in the cut... some saws bog and slow way down, thus actually taking longer than a heavy torque machine. Factor in the biggest bar you plan to run, and how often is it gonna be buried in the wood? Are you dealing with hard wood or soft wood? White oak will be harder to cut than pine...

 

[SawTroll]

Oh no! Specs on paper mean everything just ask Sawtroll.

No, the power specs only give you a rough idea of what to expect. It is just a snapshot of one point of the power curve. :msp_wink:

 

[Majorpayne]

No, the power specs only give you a rough idea of what to expect. It is just a snapshot of one point of the power curve. :msp_wink:

Echo!Echo!Echo!Echo!

 

[SawTroll]

Echo!Echo!Echo!Echo!

Obvious lack of power never is an asset...:msp_wink:

 

[Majorpayne]

Obvious lack of power never is an asset...:msp_wink:

You contradict yourself because of brand.

 

[H 2 H]

They're really important for armchair sawing. Or maybe sawing wood in the armchair?

:computer2:

 

[rmh3481]

BHP is a calculated potential. None of the manufacturer specs are derived from dyno runs.

 

[one.man.band]

to get tQ/HP measurments = dyno = a TOOL used for tuning

if you knew the saws original TQ/HP numbers, before tuning/mods etc.

one could see where/if/how any improvements were made at what rpm after making changes. which would be of obvious benefit.

what a dyno won't show is how much time it took to spin from one lower rpm point to a higher rpm point. spool up time. this is the greatest reason for a dyno other than tuning.

i for one would hope that pro saws of similar cc made more power stock than thier homeowner version saw of same displacement.

measuring TQ/HP for a saw could be made to measuring a boat motor spinning a prop in the water.

does more TQ/HP accelerate the boat faster...... or does the size/pitch/blade # of the prop make it go faster?

i would guess that a more powerful motor could spin a larger prop with greater pitch faster. same with saws too.

-omb

 

[SawTroll]

BHP is a calculated potential. None of the manufacturer specs are derived from dyno runs.

Wrong - and both hp(i) and hp(m) are bhp, and that designation in itself really is outdated (doesn't tell which it is).

 

[SawTroll]

You contradict yourself because of brand.

No.

 

[discounthunter]

i think hp ratings for chainsaws is a completely useless number.but it does impress the chainsaw lessers if you pull out a sd143 mx with a 36" bar and state it has 11hp!