Chainsaw Porting Theory

[Brush Ape]

I want anwsers!!

tl;dr

There is only one answer, Cummins Turbo Diesel or her equivalent. Consider this: while I was away from baby sitting this place, I went to attack a 10-12 cord pile of firewood log that got stacked while a lodge was built two years ago. This stack is/was firewood heaven to one so aquainted with the stuff. American Hickory, Blue Beech, White/Red/ Black Oak and Osage Orange all in crisscross fashion one Dodge length from a compacted 3" limestone drive. Well, it's a 22 mile trip one way with one side drop every other trip. I was making 70 mile passes on exactly 3 gallons fuel. That's with car hauler in tow on the way and 3500 lbs on Dodge and 5000 lbs on hauler on the way back. Do the math.

How can we get this thang up and running again?

 

[Deets066]

Can someone in lamest terms explain to me why saws with pop-ups make no torque ?

It's not necessarily the pop up decreasing torque, but most of the time a long and low intake was affiliated with these pop ups. I've yet to see a low intake increase torque on any saw

 

[Deets066]

I have an 64 piston with pop up in my 046. It runs great

 

[Four Paws]

So what new things are you trying.

I started with mufflers - spent time working them over and making incremental adjustments, measuring gains. Port placement and size. Then moved on to basic woods porting...same incremental testing. I found port shapes to be very important. My most recent experiments are transfer angles. Soon I will be experimenting with crank stroke vs. bore diameter as well as piston design.

I gotta join this class! This is better than english!!

You mean, Engrish?

Nice post Josh.

Thanks. I also liked your interjection on compression, torque and RPM - about sums it up.

 

[Brush Ape]

I've yet to see a low intake increase torque on any saw

It won't because the fuel cannot remain in an atomized state.

 

[Redfin]

Probably the offline version. [emoji41]

The 661 has the exhaust side of the main opening first. I tried it in a 7900.

O I C

 

[Dieselshawn]

Four Paws: yes, engrish, Thanks for the cowwection....

 

[Keith Gandy]

I look at what the factory designers gave us first. Then I take the time to try to figure out why the did things the way they did. After all, they have years of R&D to pull from.

Once I understand the design, I can make a decision on which way I want to go.



1) Raises the max HP point higher.
2) Not sure what you are asking.....higher number, or higher physically?
3) That depends on where the piston skirt is at tdc, and the size of the intake tract.
4) Same as 1)
5) Again, that depends on whether or not more intake is needed. In some cases it does nothing but make the piston wear faster.

2) higher # or lower floor
5) seems the huskies wear the bottom of piston skirt faster than Stihls?

 

[Four Paws]

So, if I am understanding this correctly maybe the work saw is the stock saw with a few EPA regs eliminated, but not a full blown, ported, go fast saw? Properly maintained they will last as long as the stock saw?
I am a REAL amature compared to most on here. I am a wood turner and although have several saws (mild cad) I use my 372 xt exclusively when bucking or noodling bowl blanks. I don't burn wood, and have no other reason to use a chainsaw except for cutting Woodturning blanks. I will never race, and as much as I would like to eventually attend a gtg because I love to see and hear saws, probably never will.
In any case would it be beneficial to me to have the 372xt woods ported? Would it increase cutting power while maintaining fuel efficiency, reliability, and longevity?

Woods ported saws fall into a broad range. They can be built pretty hot, and require more frequent maintenance and repair. They can also be built fairly mild (think cold air intake/free flowing exhaust on your car).

If you want a woods ported 372, by all means, pay to have it upgraded, or learn how to do it yourself. You certainly don't need to have it woods ported.

 

[riverrat2]

Can someone in lamest terms explain to me why saws with pop-ups make no torque ?

Is that a joke???

 

[tree monkey]

i'll take a wide port with shorter dur over a narrow port with higher dur on any saw for any use.
a wider ex port gives a more effective blow down.

 

[Deets066]

i'll take a wide port with shorter dur over a narrow port with higher dur on any saw for any use.
a wider ex port gives a more effective blow down.

I have seen tapered exhaust ports, wider at the top when it first opens and tapered down to almost stock width at the bottom of the port. See any advantage to this?

 

[Mastermind]

Popups do work to raise compression......and some strong running saws can be built that way.

I just rebuilt a hybrid that I built 4 years ago.......it was running a popup, and the owner loves it.

Lots of ways to skin a cat.

 

[Deets066]

Lots of ways to skin a cat.

End result always is bald pu$$y

 

[tree monkey]

I have seen tapered exhaust ports, wider at the top when it first opens and tapered down to almost stock width at the bottom of the port. See any advantage to this?

no

 

[paragonbuilder]

Popups do work to raise compression......and some strong running saws can be built that way.

I just rebuilt a hybrid that I built 4 years ago.......it was running a popup, and the owner loves it.

Lots of ways to skin a cat.

Was???


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[Keith Gandy]

I have seen tapered exhaust ports, wider at the top when it first opens and tapered down to almost stock width at the bottom of the port. See any advantage to this?

I would think most of the exhaust would flow when the port 1st opens?

 

[Mastermind]

Was???


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Still is......I spun a new popup for it rather than redo the jug.

 

[paragonbuilder]

Still is......I spun a new popup for it rather than redo the jug.

[emoji33]
Awesome!!


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[mdavlee]

Remember the picture rattler posted of the exhaust port on a 288 that had a wash pattern in the exhaust floor?