Another chainsaw dyno...

[NightRogue]

I was bringing up the torque under peak, as a reason some of these saws like a 395, might over preform compared to the “dyno” numbers. Many ported 60cc saws have more hp than a stock 395, and there may be a few 50cc saws that have more as well. Is it solely rotating mass that makes the difference in performance? Could adding flywheel weight alone take a 60cc with 7 hp and turn it into an equal to the 395? It has been brought up the rotational mass has zero effect on dyno numbers, I actually feel the heavier weight would take more hp to turn. Theoretically if an engine didn’t have enough power to turn its own mass, would it run? Or dose it just take a life time to accelerate? So that make me feel there has to be losses for rotating weight. But it may not be that noticeable on the dyno. And if it’s not rotating mass, then it has to be torque under the curve?

I am just curious to some of these crazy details, I also don’t own a 395. Lol

Im completely with you, for me crank weight plays a role on holding rpm in cut and resist load. Something that i cant prove or explain but somehow i can feel in the cut

I remember some discussion about welding weight on mac cranks long time ago, what was that really about?

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[Deets066]

Im completely with you, for me crank weight plays a role on holding rpm in cut and resist load. Something that i cant prove or explain but somehow i can feel in the cut

I remember some discussion about welding weight on mac cranks long time ago, what was that really about?

Sent from my INE-LX2r using Tapatalk

I’m sure that was some sort of a crank stuffer. Adding weight doesn't add power.

 

[Egg Shooter]

To me, nothing compares to the banshee.

A buddy of mine, years back, was at Silver Lake dunes in MI for the weekend. After a day of playing in da sand they were back at his property near the dunes, located on a gravel road. Partying ect. Well one fella had a particularly nasty extended banshee. Big bore, piped ect. Told Joe to take it fir a rip down the road. Joe had never ridden one. He gets oot there grabbed a handful and when that mfer came on the pipe he went over backwards so fast and hard they thought he broke is back. Well a$$. He was full plumb purple from his kidneys to the back of his upper thighs. I'm talking the scariest nasty looking bruising I've ever seen. He came limping into work and I asked, "WTF happened to you"? He dropped trou and said THIS!!! I was like WTF mfer!? Put that sh!t away. He NEVER got on another banshee far as I know.

 

[Definitive Dave]

A buddy of mine, years back, was at Silver Lake dunes in MI for the weekend. After a day of playing in da sand they were back at his property near the dunes, located on a gravel road. Partying ect. Well one fella had a particularly nasty extended banshee. Big bore, piped ect. Told Joe to take it fir a rip down the road. Joe had never ridden one. He gets oot there grabbed a handful and when that mfer came on the pipe he went over backwards so fast and hard they thought he broke is back. Well a$$. He was full plumb purple from his kidneys to the back of his upper thighs. I'm talking the scariest nasty looking bruising I've ever seen. He came limping into work and I asked, "WTF happened to you"? He dropped trou and said THIS!!! I was like WTF mfer!? Put that sh!t away. He NEVER got on another banshee far as I know.

But how heavy was the flywheel in that banshee?

 

[Bigmac]

But how heavy was the flywheel in that banshee?

Like 5 lbs! Lol

 

[Egg Shooter]

But how heavy was the flywheel in that banshee?

Joes smashed a$$ didn't think to ask.

 

[Red97]

I was bringing up the torque under peak, as a reason some of these saws like a 395, might over preform compared to the “dyno” numbers. Many ported 60cc saws have more hp than a stock 395, and there may be a few 50cc saws that have more as well. Is it solely rotating mass that makes the difference in performance? Could adding flywheel weight alone take a 60cc with 7 hp and turn it into an equal to the 395? It has been brought up the rotational mass has zero effect on dyno numbers, I actually feel the heavier weight would take more hp to turn. Theoretically if an engine didn’t have enough power to turn its own mass, would it run? Or dose it just take a life time to accelerate? So that make me feel there has to be losses for rotating weight. But it may not be that noticeable on the dyno. And if it’s not rotating mass, then it has to be torque under the curve?

I am just curious to some of these crazy details, I also don’t own a 395. Lol

Stock 395 has about 5.4 ftlb peak.

Only a couple of the bigger 70cc saws have made more tq than a stock 395. And those were 79cc ish themselves. 5.5 ftlb

Couple of the 60's have more hp, but tq is in the 4ftlb range.

I wonder on these "torque" saws if it's not an abundance of tq we feel, but a lack of hp?

No real hp to wind out the top?

 

[Duane(Pa)]

Where are we at with “it takes fuel to make power”?
What happens to the graph when you add a half turn to the rich side past “properly “ tuned?

 

[Sawrain]

I wonder on these "torque" saws if it's not an abundance of tq we feel, but a lack of hp?

No real hp to wind out the top?

I have wondered something like that myself.

And the opposite also,

That strong never say die torque curves may make some think a saw is stronger (HP wise) than it really is, on the idea that that the strong mid range Torque is presumed to be there at higher rpms when it isn’t.

 

[MustangMike]

Increased flywheel/crank/rod/piston weight will only add a little inertia at the expense of throttle response, they will not change the power (unless we are talking crank stuffers, etc).

In cars, on the street, I always preferred the heavier flywheel as it made it easier to maintain traction with street tires, the lighter flywheel is better for the track when you are running 11" slicks and gears.

I'm sure my ported 462s have very light flywheels, etc, but if you operate it correctly it is easy to keep the saw in it's power range.

 

[huskihl]

Where are we at with “it takes fuel to make power”?
What happens to the graph when you add a half turn to the rich side past “properly “ tuned?

I always thought it took air and fuel at the correct ratio to make power

 

[MustangMike]

I always thought it took air and fuel at the correct ratio to make power

That sounds more accurate to me, heck, just a dirty air filter can kill your power because it makes you too rich!

 

[Duane(Pa)]

I always thought it took air and fuel at the correct ratio to make power

So, that wood fark the ratio and you would go back workerdz as my boy said when he was about 3

 

[Red97]

Where are we at with “it takes fuel to make power”?
What happens to the graph when you add a half turn to the rich side past “properly “ tuned?

Short stubby graph lol

 

[huskyboy]

Perhaps we are all forgetting what puts the power to the wood.... It’s easier to tune a chain for a mid range torque powerband than for a saw that is a screamer at 12000rpm. Maybe that’s why there is differences in real world results?

 

[Cobby08]

Perhaps we are all forgetting what puts the power to the wood.... it’s easier to tune a chain for a mid range torque powerband than for a saw that is a screamer at 12000rpm. Maybe that’s why there is differences in real world results?

Now you dun' it... #chainthread #wtfisjeffy

 

[huskyboy]

Now you dun' it... #chainthread #wtfisjeffy

Nyuck nyuck nyuck

 

[Sawrain]

Perhaps we are all forgetting what puts the power to the wood.... It’s easier to tune a chain for a mid range torque powerband than for a saw that is a screamer at 12000rpm. Maybe that’s why there is differences in real world results?

Maybe, but I can’t help but think of redbulls 9 vs 7 (29% change) tooth sprockets comparison that came up with pretty close results though?

And since plenty of saws already cut at 9500rpm jumping to 12000rpm (26% change) doesn’t seem that huge a task for the chain to deal with, especially when you can run a 7 tooth on the 12K saw, 8 on the 9.5K saw and only have a 10% chain speed difference.

Has the Dyno answered or created more questions at this point?

 

[RI Chevy]

Now you dun' it... #chainthread #wtfisjeffy

I here.

 

[huskyboy]

Has the Dyno answered or created more questions at this point?

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