Chainsaw Porting Theory

[Moparmyway]

Wouldnt they just measure my old piston ?

In most cases yes they could, but there are some cases, like having catastrophic failure when you cant

 

[sawmikaze]

In most cases yes they could, but there are some cases, like having catastrophic failure when you cant

I see....i have 2 saws with popups now that im gonna torture from probably march to november/december this year..i wanna see how they hold up

 

[drf256]

Popups can work better as well. The problem is flame propagation, detonation potential and piston replacement issues (that my little brain sees).

Helpful because you can keep the factory band geometry. Helpful because you don't need to raise the transfers as much, so you don't affect velocity. You also have less chance of ruining the intended entry angle of the transfers cause you're not raising as much.

Depending on the saw, I can see the transfer spray geometry being changed. Maybe for the worse, maybe for the better.

 

[Moparmyway]

I see....i have 2 saws with popups now that im gonna torture from probably march to november/december this year..i wanna see how they hold up

Lets not get carried away ........ if you take care of your saw, any saw, pop-ups included, chances are that you will be just fine

 

[drf256]

I have a question. I've been hogging out my mufflers.

I'm wondering if a small parabolic dish placed in front of the exhaust port inside the muffler could potentially give some benefit to power production.

Weld it, let's say, 1" off the port. Let the toroidal exhaust wave hit it.

Just thinking.

 

[Tor R]

One thing I can see pop up to be best choice is when the cylinder base is thin, wants high compression but doesnt want to weaken the jug to much.

I am putting Huskies 254's together nowadays, love all their jug difference. Normally they end on 165-175 psi stock.
The first two years they had thin ring piston and 2mm gasket, (instead of the later jugs who had bigger combination chamber and 1mm gasket), put an 0.4mm gasket, squish is around 0.020", 215psi. Love to get those changes without doing anything really

 

[jmssaws]

Good thread guys.

 

[drf256]

One thing I can see pop up to be best choice is when the cylinder base is thin, wants high compression but doesnt want to weaken the jug to much.

I am putting Huskies 254's together nowadays, love all their jug difference. Normally they end on 165-175 psi stock.
The first two years they had thin ring piston and 2mm gasket, (instead of the later jugs who had bigger combination chamber and 1mm gasket), put an 0.4mm gasket, squish is around 0.020", 215psi. Love to get those changes without doing anything really

Don't you have to cut the base just as much with a popup vs non?

Am I seeing it wrong?

Still gotta drop the jug over the piston.

 

[drf256]

Popups give me vaginal soreness. Especially on Huskys.

 

[Tor R]

Don't you have to cut the base just as much with a popup vs non?

Am I seeing it wrong?

Still gotta drop the jug over the piston.

not sure if it was my first sentrence or the 254 you mean.
If it's the 254 no pop up

 

[jmssaws]

Yes the cylinder must be lowered with a popup.

 

[Moparmyway]

I have a question. I've been hogging out my mufflers.

I'm wondering if a small parabolic dish placed in front of the exhaust port inside the muffler could potentially give some benefit to power production.

Weld it, let's say, 1" off the port. Let the toroidal exhaust wave hit it.

Just thinking.

@mdavlee suggested something similar to this a few weeks back to a few of us, and I have been playing with some sheetmetal trying to come up with something to do just this.

I am shaping the metal so it can be welded to the front cover, more like a funnel or triangle ........... didnt consider dish shaped

 

[Ironworker]

I believe that as long as you are able to increase the amount of charge getting to the combustion chamber and having an exuast big enough to get the extra spent gas out you have a well powered, heck who am I fooling, I just go in there, hack away and hope for the best. Seriously though I have been having some good results with a less is more approach, sure you can get more torque with a cut base and squish band or pop up, I've done both, but some times all you need is a little grinding to get a little more out of a machine.

 

[CR888]

There is a reason expansion chambers are so long and not confined in a small saw muffler can, its about timing the resonant wave to pull/stuff charge back at just the right millisecond. When buioding a pipe your confined by the laws of physics to some extent, a small dish in front of the exhaust port may be of benefit to reduce noise, but I cannot see it improving horsepower, quite the opposite. Try it I hope I'm wrong.

 

[paragonbuilder]

I have a question. I've been hogging out my mufflers.

I'm wondering if a small parabolic dish placed in front of the exhaust port inside the muffler could potentially give some benefit to power production.

Weld it, let's say, 1" off the port. Let the toroidal exhaust wave hit it.

Just thinking.

What is the theory behind this?
Kind of like tuning a pipe?
Cool thing is it will be easy to try.


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[Four Paws]

100% of the problem with ported saws is 99% of the people don't understand them. This is not me being arrogant and assuming I do understand them, just me offering up my view.

With all things in life balance is critical. I personally feel as we become more specialized, our range of success and impact diminishes, however our magnitude of success and impact in a certain specialized area increases.

Applying this to chainsaws, one could compare a race saw, a work saw and a stock saw.

A race saw can't cut timber or firewood, is costly to produce, burns expensive fuel in custom carburetors and operates on the ragged edge failure. Properly built, it is good at making high horsepower and going fast through a cant.

A stock saw, when cared for and maintained, will reliably fall timber and cut firewood for years at a relatively low cost of ownership. These are the machines that will allow a man to make a good living, heat his house, prune his trees, cut wood for a camp-fire. The jack of all trades, master of none.

A work saw occupies the void between a stock saw and a race saw, and can be on either end of the spectrum. One should look back at the legendary saws of the day and understand what it is that makes them apart from their competition. One must also understand the desired application of the saw, and build accordingly. A 5-cube with an exhaust at 105* is going to have high compression and not bat an eye at a ham-fisted operator dogging in a 36" bar. That same 5-cube isn't going to stand a chance against a like model saw with a 95* exhaust running a good chain and 20" bar through 18" wood. It won't turn the RPM, and the operator will still be sawing the face cut while the second saw is moving to the next tree.

It's my opinion that if you aren't trying new things, and figuring out what works for you, and WHY it works for you, you aren't progressing. You may one day realize all that you have missed while following the herd.

 

[drf256]

Here it is guys. The goal is to make it more "black"




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[Ironworker]

100% of the problem with ported saws is 99% of the people don't understand them. This is not me being arrogant and assuming I do understand them, just me offering up my view.

With all things in life balance is critical. I personally feel as we become more specialized, our range of success and impact diminishes, however our magnitude of success and impact in a certain specialized area increases.

Applying this to chainsaws, one could compare a race saw, a work saw and a stock saw.

A race saw can't cut timber or firewood, is costly to produce, burns expensive fuel in custom carburetors and operates on the ragged edge failure. Properly built, it is good at making high horsepower and going fast through a cant.

A stock saw, when cared for and maintained, will reliably fall timber and cut firewood for years at a relatively low cost of ownership. These are the machines that will allow a man to make a good living, heat his house, prune his trees, cut wood for a camp-fire. The jack of all trades, master of none.

A work saw occupies the void between a stock saw and a race saw, and can be on either end of the spectrum. One should look back at the legendary saws of the day and understand what it is that makes them apart from their competition. One must also understand the desired application of the saw, and build accordingly. A 5-cube with an exhaust at 105* is going to have high compression and not bat an eye at a ham-fisted operator dogging in a 36" bar. That same 5-cube isn't going to stand a chance against a like model saw with a 95* exhaust running a good chain and 20" bar through 18" wood. It won't turn the RPM, and the operator will still be sawing the face cut while the second saw is moving to the next tree.

It's my opinion that if you aren't trying new things, and figuring out what works for you, and WHY it works for you, you aren't progressing. You may one day realize all that you have missed while following the herd.

So what new things are you trying.

 

[Basher]

I feel that way when I see Randy, Jason, Scott, Shaun, Carl, Al, and our other talented builders discuss theories. Hey guys! wait up!

That ole black magic!

 

[drf256]

@mdavlee suggested something similar to this a few weeks back to a few of us, and I have been playing with some sheetmetal trying to come up with something to do just this.

I am shaping the metal so it can be welded to the front cover, more like a funnel or triangle ........... didnt consider dish shaped

I'm thinking stainless sauce cups from restaurants would make a nice cone.

I'll have to palm one tonight from the place I take my lady.

Joking, I despise thieves. I'm gonna buy some on Amazon.