Woods porting

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alderman

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If I were to send a saw to have it ported by somebody in the know, what would I expect to see in return. More power, a bigger power band, which I understand is usable power under more load, or more rpm for a faster cut?
Can somebody put it in very simple terms for those of us who were never around a shop growing up.
 
...More power, a bigger power band, which I understand is usable power under more load, or more rpm for a faster cut?

In a word, yes.


You will likely see both in a woods port. Done incorrectly, a WP will produce a peaky, slow to rev saw. But send it to any of the builders with established reps and you will see increases in power and a broad power curve.
 
They can pretty much do anything. The experienced guys will get it as good as possible for working. Correct me if I'm wrong but the general consensus seems to be you can "jump" 10-15cc with a port job compared to a stock saw.
 
On hard Eucalypt today and it was easy, instant throttle response and spool up, power in the cut that makes cutting almost effortless, slightly rich tune as breaking in but it'll be tuned to 14,600 tomorrow with my new tach and then we'll see! It cuts crazy fast already
 
They can pretty much do anything. The experienced guys will get it as good as possible for working. Correct me if I'm wrong but the general consensus seems to be you can "jump" 10-15cc with a port job compared to a stock saw.

That would be on the mild side.
For example my pop upped and ported 79cc Dolmar 7900 with a 20" bar is around 20% faster in the cut than a stock 93cc Stihl MS660. Once you get to a longer bar like a 32" buried the Dolmar has only a slight edge, maybe 10% faster.
 
Upside as everyone mentioned 20-30% faster and if done correctly better across the board. Bad part louder to extremely loud, more fuel useage and more sensitive to fuel/oil quality. The last 2 are not a big deal to me but a quiet saw is a big plus, fuel is not a concern. Durability? well if you get more HP out of the same parts it would reduce the life of the parts. If there is enough design percentage to handle the extra HP you are good. Most people that I know do not wear out a saw, it either get destroyed or changed out. CJ
 
Upside as everyone mentioned 20-30% faster and if done correctly better across the board. Bad part louder to extremely loud, more fuel useage and more sensitive to fuel/oil quality. The last 2 are not a big deal to me but a quiet saw is a big plus, fuel is not a concern. Durability? well if you get more HP out of the same parts it would reduce the life of the parts. If there is enough design percentage to handle the extra HP you are good. Most people that I know do not wear out a saw, it either get destroyed or changed out. CJ

The other thing to remember though is the amount of wood cut per unit of fuel.
I've ran the numbers in paid falling and I was well ahead with a ported saw compared with a stock saw. The ported saws use more fuel per time unit but they get more wood on the ground in that time.
 
That would be on the mild side.
For example my pop upped and ported 79cc Dolmar 7900 with a 20" bar is around 20% faster in the cut than a stock 93cc Stihl MS660. Once you get to a longer bar like a 32" buried the Dolmar has only a slight edge, maybe 10% faster.

Yeah, I figured it was. So you're 20% faster with 14 less ccs. So that's probably more than 20ccs stock.
 
The other thing to remember though is the amount of wood cut per unit of fuel.
I've ran the numbers in paid falling and I was well ahead with a ported saw compared with a stock saw. The ported saws use more fuel per time unit but they get more wood on the ground in that time.


Using that, another way to look at it is like this:

If you port an engine and modify it for best performance you will lose life on the saw. How much? We don't quite know exactly. But...either way, the saw will still last so long that if you wear out a modified engine, you sure as hell have enough money in your budget for whatever business you're in, to replace the P&C if necessary. Or buy a new saw even. The only downside to porting is cost for someone who is not in the business, for when it's a hobby.
 
My fuel economy doesn't seem to have suffered too much, not that I'd lose any sleep if it did
 
HP makes heat.

Yep, and though a ported saw pulls more fuel and air through it, it also burns more. Now, if it tuned rich, then you are pulling fuel through that doesn't get burn and it will serve to lubricate and cool the engine some.

Muffler mods probably do allow a saw to run cooler bc it is allowing the gasses to escape faster regardless of the state of tune.
 
Yep, and though a ported saw pulls more fuel and air through it, it also burns more. Now, if it tuned rich, then you are pulling fuel through that doesn't get burn and it will serve to lubricate and cool the engine some.

Muffler mods probably do allow a saw to run cooler bc it is allowing the gasses to escape faster regardless of the state of tune.

There was a thread a while back with an 026 where the temperature was taken at different levels of muffler modding. It got cooler.
 
Depending on the builder the saw can either last or fail. Ignition timing is a critical side to the modifications. The one thing to look at is the carb, port the saw and you need to match the carb to the port job.
 
Most saw carbs have enough spare capacity to work well for a woods port. Now for a hot saw, yes, carbs are a very important consideration. And, there are some applications where a carb swap is beneficial in getting that last little bit from a build.
 
What a woods port entails is ever evolving. It used to mean not much more than widening the ports. It's only in the last couple of years that you could expect significant compression increases, ignition advance, etc. Builders pushing builders makes for a buyers market:clap:
 
What a woods port entails is ever evolving. It used to mean not much more than widening the ports. It's only in the last couple of years that you could expect significant compression increases, ignition advance, etc. Builders pushing builders makes for a buyers market:clap:

We've evolved into port mapping really. We did this growing up racing Yamaha/Honda products. Our drag Banshee was my first experience with the term port mapping. Takes time and careful thought process but it's worth the gains.
 

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