Pipe building theory.

[Magic_Man]

So I know this probably belongs in the hot saw section but figured it would get more traffic here. I would love to build a few pipes just to do something different. I have done a good bit of reading and there is little information out there about building expansion chamber style pipes for chainsaws. So what I have gathered so far is this :

1) Saw pipes are tuned to a very narrow rpm power band.
2) Some guys say they use a standard woods port, others say that a pipe will support longer durations.
3) Keep the exhaust port as straight as possible when porting to become an extension of the headpipe and keep velocity up.
4) I recall reading where Scott says he tunes the pipe to the rpm in the cut. If he built a pipe and the rpm went up over 500rpm he built another one.
5) Pipe design software, some say it's great, others say it's garbage when it comes to saws.

That's about all I have, I'm hoping for a meeting of the minds here much like we have had in other topics such as porting, compression, machine work, etc.

 

[Mastermind]

I have a pipe for an 066 that was built by Frank AKA Gink. It's a copy of a Big Dave pipe I think. It works...... it really works. All that stuff is a mile over my head though.

 

[Magic_Man]

I have a pipe for an 066 that was built by Frank AKA Gink. It's a copy of a Big Dave pipe I think. It works...... it really works. All that stuff is a mile over my head though.

There is a lot of science to it, most of which I think comes down to length and pulse frequency.

In simple terms, and someone correct me if I am wrong. You are building a big cave and timing the echo so that it not only pulls the exhaust out but a wave bounces off the back wall and pushes extra unburnt fuel charge back in at the perfect time.

 

[Ozhoo]

The 2-Stroke Tuners Handbook is a nice read on the topic.

 

[jmssaws]

I've built a few pipes for 250cc migit sprints but they were from a pattern and I knew nothing other than how to cut and weld,I'm wanting to learn about pipes for saws and building heads but I can't find much info.

I guess it's like anything else you just start doing it until it works.

Kool thread

 

[Canadian farm boy]

I've always wondered about the science behind building a pipe. I hope this turns into a great discussion.

 

[Al Smith]

You will most likely glean more information about pipes from RC sites than you can ever find from chainsaw sites .Chainsaw guys think it's all top secret or something .

My buddy Louie Baughan who I went through apprenticeship with built the first slide tuned pipe ever used on go karts and he was number two in the AGKA for two or three years .

More times than not a pipe design built saw will allow a tad more height on the exhaust than muffler saws to allow the pipe to back stuff the charge,again port -time-open .Maybe,depending on RPM as high as 92 degrees after .

Big Dave BTW ,if memory serves built a "big bertha" type pipe which had no stinger and was more responsive to a wider power band than a conventional stinger pipe .

The only pipe I ever built for a saw is a trombone slide type for a Mini mac .Odd maybe but for a mini it's fast .Loud too .

 

[Magic_Man]

I've built a few pipes for 250cc migit sprints but they were from a pattern and I knew nothing other than how to cut and weld,I'm wanting to learn about pipes for saws and building heads but I can't find much info.

I guess it's like anything else you just start doing it until it works.

Kool thread

That's where I am too Jason, I used to run pipes back in my motorcross days but never understood what they really did. It was just always the first thing you did to your bike.

It's like saw porting used to be the hidden art, now it's pretty open knowledge thanks to some really good guys. But it seems that head designs and pipe knowledge are still hush hush. I suppose because they are more in the competitive racing area as opposed to work saws.

I am just hoping for some input and knowledge along the way in this thread, but yes most likely I will buy a big sheet of steel, a slip roll, and lots of mig wire. Try and try again until it starts to make sense.

 

[Al Smith]

Now here's the deal on little piped micro saws .Some years ago now at a GTG John Lambert,Gypo and Dave Neiger Aka Big Dave showed up with a couple of piped bumble bees .Then we got into racing tiny saws ,it was fun .Before too long most of use had 020 or 200 T's and those dominated that class .It really was a lot of fun .

 

[Magic_Man]

Now here's the deal on little piped micro saws .Some years ago now at a GTG John Lambert,Gypo and Dave Neiger Aka Big Dave showed up with a couple of piped bumble bees .Then we got into racing tiny saws ,it was fun .Before too long most of use had 020 or 200 T's and those dominated that class .It really was a lot of fun .

That sounds like a blast, I was actually thinking about using something small as my first test dummy. I have a little Stihl ms180 here that the neighbor gave me when he got a new saw. I'm out nothing other than time and steel even if the worst happens.

 

[Magic_Man]

You will most likely glean more information about pipes from RC sites than you can ever find from chainsaw sites .Chainsaw guys think it's all top secret or something .

Big Dave BTW ,if memory serves built a "big bertha" type pipe which had no stinger and was more responsive to a wider power band than a conventional stinger pipe .

See there is a point, all these guys say that chainsaw pipes are nothing like bike pipes. But I remember back when FMF released the "fatty" for mx bikes. It was a shorter, fatter pipe pipe that yep, you guessed it. Had a much wider, rider friendly power band and made useable low end torque. Sounds pretty similar to me....

 

[spencerpaving]

Cutting. ..rolling...and welding is the fun part...designing one that will work well sucks...I have built a lot that worked well...but just recently built a few underbellys that really produced some serious power....the trick is to have torque not just crazy rpm...header and belly dia mean alot

 

[spencerpaving]

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[spencerpaving]

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[spencerpaving]

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[Magic_Man]

@spencerpaving , that last one on the husky is beautiful ! But I'm gonna guess that the two Stihl pipes are better performers with smoother wider power bands.

 

[spencerpaving]

You are correct...but the one on the huski is a strong runner

 

[Magic_Man]

You are correct...but the one on the huski is a strong runner

I'm certain it is, I'm sure they all run. But I see the differences between them.

 

[spencerpaving]

I'm certain it is, I'm sure they all run. But I see the differences between them.

You have a good eye!

 

[spencerpaving]

both of these pipes have the same dementions. ..can anyone tell which one is stronger and why?

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