036 porting

[More horse]

Nice running saw! What would happen if you raised that exhaust? To my understanding it will increase rpm and move your hp curve higher. Bring down your comp too. But too much? What happens then?

 

[Ronie]

Nice running saw! What would happen if you raised that exhaust? To my understanding it will increase rpm and move your hp curve higher. Bring down your comp too. But too much? What happens then?

Thanks, I think you might loose some lower RPM torque but that's best answered by the guys that really know what they are doing.

 

[huskihl]

Nice running saw! What would happen if you raised that exhaust? To my understanding it will increase rpm and move your hp curve higher. Bring down your comp too. But too much? What happens then?

You eventually run out of the power required to keep it in the power band as you start to get into bigger and bigger wood. It’s more noticeable on smaller saws and less noticeable in larger ones. Race saws for example… many have their exhaust open in the 80s and or low 90s. They know they are cutting soft 8 x 8 and you can hear the smaller ones start to run out of power in a 12 x 12

 

[Ketchup]

@More horse

I’m afraid you may have been lured by YouTube pseudoscience. The pipe style muffler you’re talking about isn’t the worst thing, but no one has been able to reliably document power gains greater than an outlet hole of similar size in a stock muffler. For a work saw I would recommend keeping the original muffler and adding an outlet and deflector on the flywheel side of the saw. It keeps the muffler out of the way for daily cutting.

 

[Wonkydonkey]

Send it to @Red97 for experimentation testings unstuffs.
He’s dyno joe

 

[farminkarman]

@More horse

I’m afraid you may have been lured by YouTube pseudoscience. The pipe style muffler you’re talking about isn’t the worst thing, but no one has been able to reliably document power gains greater than an outlet hole of similar size in a stock muffler. For a work saw I would recommend keeping the original muffler and adding an outlet and deflector on the flywheel side of the saw. It keeps the muffler out of the way for daily cutting.

IIRC, Joe tested a couple “pipes” on the dyno. Also, iirc, the dog dong IH pipe didn’t do much more than make noise.

 

[More horse]

I've done a muff mod in the past I'll make a pipe for fun like the iron horse pipe and see what happens I'll keep the outlet 80% size in relation to exhaust port with the pipe same as I did with the muff mod. I'm guessing it'll be same power maybe a little more noise (which I don't care lol) maybe more power? Ill watch the dyno joe vid. Maybe it can keep heat out better? I think that's worth it just to get heat away from cylinder for longevity. I didn't take temp measurement of cylinder temp b4 dissassembaly. But maybe it will make a difference? Idk but anyhow I'm looking to get port numbers either tomorrow or after work on friday.

 

[Ketchup]

I've done a muff mod in the past I'll make a pipe for fun like the iron horse pipe and see what happens I'll keep the outlet 80% size in relation to exhaust port with the pipe same as I did with the muff mod. I'm guessing it'll be same power maybe a little more noise (which I don't care lol) maybe more power? Ill watch the dyno joe vid. Maybe it can keep heat out better? I think that's worth it just to get heat away from cylinder for longevity. I didn't take temp measurement of cylinder temp b4 dissassembaly. But maybe it will make a difference? Idk but anyhow I'm looking to get port numbers either tomorrow or after work on friday.

You’ll see in the video that the T pipe does okay, just not great. There may be something to it if someone wanted to take the time to experiment. Unfortunately the Iron Horse crowd make money off unsubstantiated claims. The high performance world is full of EXTREME HARDCORE ULTRA DOMINATOR SWEDISH PUMP MAGNUM ENLARGMENT!!!

Sounds like you’re going about it the right way. If you want real gains you have to experiment and be honest when something does or doesn’t work. I’m sure many are interested in honest feedback about the T Pipe. Please let us know your experience.

 

[More horse]

Okay got numbers,
Exhaust 106 atdc
Blow down 19
Intake opening 102 abdc
Intake duration 158 degrees
25 thou squish

 

[farminkarman]

Okay got numbers,
Exhaust 106 atdc
Blow down 19
Intake opening 102 abdc
Intake duration 158 degrees
25 thou squish

Most people refer to intake timing in regard to TDC. That would put your intake at 78.

 

[More horse]

Gunna talk to machine shop Monday to see if they can cut 5 thou off base. Not gunna touch exhaust I don't think. Does anyone think I should lower intake? Or raise exhaust? And upper transfers? Looking at piston pins I could bring upper transfers back tword intake a little ways. Don't have the best tools to get in there tho.

 

[farminkarman]

Gunna talk to machine shop Monday to see if they can cut 5 thou off base. Not gunna touch exhaust I don't think. Does anyone think I should lower intake? Or raise exhaust? And upper transfers? Looking at piston pins I could bring upper transfers back tword intake a little ways. Don't have the best tools to get in there tho.

I have never worked on one of these, so I would certainly default to someone like @drf256. I would probably leave your intake at 78 and your transfers at 125. I would try raising the exhaust to 102-103…maybe more. I have yet to widen the uppers on any build I have done. Not to say there aren’t gains to be had in doing so, I just haven’t felt the need on the saws I have done.

 

[Wonkydonkey]

Okay got numbers,
Exhaust 106 atdc
Blow down 19
Intake opening 102 abdc
Intake duration 158 degrees
25 thou squish

Was Your squish @25 thou with or without the base gasket?,
If it was with the gasket your squish will be a bit tight without it.
That’s assuming your squish measurement is correct & you used the thininst solder, (not the thicker stuff, as it doesn’t give accurate readings)

 

[More horse]

Without bg and yes I used thin solder

 

[Ronie]

Gunna talk to machine shop Monday to see if they can cut 5 thou off base

For me it wouldn't be worth it to have a machine shop take .05 off the cylinder to gain a couple of pounds of compression.

 

[Wonkydonkey]

Good evening, and happy new yr .

i was having a reread of this theread, to which made me want to ask. Do you have a link to the popup piston you got for this saw ?.

what yr is your saw and the make is your cylinder ie mahle etc ? A few pics of the cylinder is saw porn to us

i agree with @Ronie . To cut just a little off the base just doesn’t seem worth it especially as you have a popup to put in it.

i think it be good if you were to check the popup against the oem piston side by side (a wrist pin to locate them together as if it were on a con rod) to double check the heights/lengths of skirts & sizes of skirts etc. as some times they differ to oem & pics would be awesome.

now that has been said & if all is good. Then you were to widen the exhaust & intake abit as well as a muff mod and a bump in timing.

i think you will be happily surprised at the gains you will get. You could always easily go back into the cylinder and do a bit more if required

Hey i got an o36 stihl that's a little tired out (bout 120psi) have it apart and am looking at the cylinder it appears to be in really nice shape. So I ordered a pop up piston and did some mild cleaning up on casting imperfections and deburring it. Now I'm looking to move onto cylinder I've been doing lots of reading on porting saws and I get the basics with .020 squish and making the air flow up transfers to top of the intake. But I am no porting expert. Did order a degree wheel that's not in yet but once it comes in I'll get some numbers on the saw. Just curious if anyone has any advice before I start grinding and possibly any numbers these saws like. Any help is appreciated thanks.

 

[More horse]

Okay so I started working on cylinder opening up the transfers and my dremel jumped and took some small plating chips out of cylinder wall. So I'm gunna have to order a different cylinder.... the cylinder appears to have no markings on it so not sure what it is. I ended up ordering a hyway nikasil cylinder. Piston is a hyway pop up as well. Thinking cylinder that was on it is a cheap am not sure tho. Obviously have to redo timing numbers too. Oh well ya live and learn. I did get a pipe made I'll post a pic of it

 

[Ronie]

For practicing porting I would suggest you find a cheap AM cylinder to grind on so you can get a feel for grinding and if you mess it up your not out much money. There is some Farmertec 360 cylinders on Amazon for $15 that don't look to bad. The ports aren't that pretty but you'll be grinding on it so that doesn't matter. www.amazon.com/dp/B07MZD9CH9?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[Wonkydonkey]

Okay so I started working on cylinder opening up the transfers and my dremel jumped and took some small plating chips out of cylinder wall. So I'm gunna have to order a different cylinder.... the cylinder appears to have no markings on it so not sure what it is. I ended up ordering a hyway nikasil cylinder. Piston is a hyway pop up as well. Thinking cylinder that was on it is a cheap am not sure tho. Obviously have to redo timing numbers too. Oh well ya live and learn. I did get a pipe made I'll post a pic of it

thanks for your reply . We’re all (almost all of us )here to share our knowledge & experiences.

if your cylinder was a AM. This would explain the larger squish than what I thought it should be, As oem is pretty consisten and should have been 18\20thou.( Edit ) without bg.

The lowish compression would also point to an AM p&c. But I could be wrong and happy to be wrong .
If it is a Am p&c then you’ve not lost much by your unfortunate dremmel work. And yes we’ve all had mishaps, some worse than others.
Sometimes the odd nick in the plating doesn’t matter, as long as if it’s not in a crucial area.

I’ve been down the AM p&c route, and it got me by for a while. Well until I got Luck on a sh one off eBay. Or just swallowed abit harder as I brought a 200t p&c (the AM 200t was cràp for compression)

also I’ve been looking for a popup for my 36 and there's no one selling them in the UK . I'm also really not interested in the high postal & import costs to get one from just anywhere


Anyhow I’m looking forward to your 036 build..
And if I,m lucky I may get another vid soon of my 036 at work,

 

[More horse]

I know what you mean now about how bit reacts when grinding what makes it skip and what not. Hopefully cylinder comes in soon so we can press on. Gunna try practicing on junk cylinder to get better feel for the grinder.