Sthil 044 transfer height

[tree monkey]

it took me 20 years to learn what i know, it may take 20 years to teach others, and i'm still learning
the only good way to lower the transfers is to lower the cylinder
the intake timearea or dur is a factor in lowering the cylinder, so is comp and freeporting the exhaust
the size of the carb being used is also a factor
case volume as well
port width and skert width, should have at least .50 overlap each side and never excede 70% of bore
the more case presure the better, when the tison closes intake to when the transfers open is all there is to it. so the shorter you keep them the more you will have.
if you don't have enought blowdown, the burnt exhaust gas will backstuff the transfers, this will delay the fresh charge, this is not a big problem with long trasfer tunnels, but not good at all with short tunnels

it all boils down to having enough timearea for a given rpm, the in the cut rpm

yes i raised the transfers on the 390, i think thay were around 108 dur

 

[wigglesworth]

If you look at it, the transfers are angles at the top, not straight across, so in reality, even though the trans peak at 115 there not fully open across the top till around 120.

Just thought I'd reiterate on my last post.

Yes, the initial transfer opening is higher on these particular cylinders. But their not fully opened till around 120. If they were flat on top, and opened all at once at 114, I'm betting they wouldn't run for crap. But they are a progressive opening port, so it's all happening a bit more smoothly.

Again, just my opinion...J

 

[HEAVY FUEL]

MMMmmm. Love those 044's.:cool2:

<iframe width="420" height="315" src="http://www.youtube.com/embed/e1F7RMPdXCM" frameborder="0" allowfullscreen></iframe>

 

[blsnelling]

It's hard to argue with real world experience. Here's a 440 with a 460 topend. This saw only has 14° of blowdown. It has way more than enough torque to man handle a 28" full comp chain in Oak. Talk to Randy and Jeremy about the 460 build-off winners. A shorter blowdown was absolutely key to making the strongest work saw. I've tried both and I know for a fact what works for me. You want a saw that doesn't use more fuel? Stick with a stock saw. You have to burn fuel to make HP.

[video=youtube_share;25Y-ln142vE]http://youtu.be/25Y-ln142vE[/video]

 

[Mastermind]

I don't really know what to say here.......I'm not into arguing. Different strokes for different folks. I like a saw with loads of torque....the numbers I use are the result of quite a lot of testing.

I'm totally transparent when it comes to the work I do and the numbers I use.

My best running MS460s have 200psi and are at 100ex, 118tr, 80in. These numbers are measured from tdc not duration. I also advance the ignition .020 at the key.

No secret recipes or fancy tricks......the piston is untouched for reliability and because I like knowing that a piston replacement somewhere down the road won't change anything.

I have two on the bench right now that are being built this way.......

 

[NPKenny]

It's hard to argue with real world experience. Here's a 440 with a 460 topend. This saw only has 14° of blowdown. It has way more than enough torque to man handle a 28" full comp chain in Oak. Talk to Randy and Jeremy about the 460 build-off winners. A shorter blowdown was absolutely key to making the strongest work saw. I've tried both and I know for a fact what works for me. You want a saw that doesn't use more fuel? Stick with a stock saw. You have to burn fuel to make HP.

On the short blowdown saws, how wide are you going on the intake and exhaust ports? As wide as possible?

I only ask because the strategies listed seem so different, yet they both look to yield excellent results. I followed Wigglesworth's suggestions on numbers and wide ports prior to the recent discussion, but this certainly isn't the last saw getting ported, so all the theory behind results is fantastic discourse in my mind.

Following Wigglesworths thought on the angled transfers and the GBD and TreeMonkey's concept of slightly raised exhaust, would there be any merit is gradually opening the exhaust port to increase blowdown while maintaining compression? I'm sure port opening shape is much more vital than I have given heed to up to now.

Thanks to all parties for the full disclosure.

 

[komatsuvarna]

I vote 044-440 2013 Arboristsite buildoff .

 

[Mastermind]

I vote 044-440 2013 Arboristsite buildoff .

12mm or 10? Are 046 jugs allowed? Race chain or roll? Square or round? Alky???????

:msp_sneaky:

 

[tree monkey]

how about whoes saw cuts the most wood on a tank of gas

 

[wigglesworth]

how about whoes saw cuts the most wood on a tank of gas

Forget that. I don't like all that wood dust and stuff. All I do is start em up a couple times a week for a throttle blipping fest.

Keeps em clean and shiny that way.

Can we have a "Blip off"? I think I can take ya then.



In all seriousness, sign me up for an 044 build off.

 

[GBD]

You should know by now that you "can't bend the laws of physics". All saws need 25°-30° of blowdown.

No sir! I actually often end up with 40* to 50* blowdown, but you sir, wont need more than 12* to obtain 12000 rpm in the cut with 7-pin and high rakers.

 

[GBD]

Newbies. :msp_rolleyes:

Thank you sir, for that insight! Good show!

 

[splitpost]

No sir! I actually often end up with 40* to 50* blowdown, but you sir, wont need more than 12* to obtain 12000 rpm in the cut with 7-pin and high rakers.

are you raising the ex to acheive those numbers?

 

[tree monkey]

are you raising the ex to acheive those numbers?

no and yes
you lower the cylinder to lower the transfers, then you can raise the exhaust to get blowdown

 

[blsnelling]

Are we talking about a 044 or a 7900:msp_confused:

 

[GBD]

Are we talking about a 044 or a 7900:msp_confused:

Reread your own post! "All saws", wasn`t it?

 

[splitpost]

no and yes
you lower the cylinder to lower the transfers, then you can raise the exhaust to get blowdown

yeah so in doing that you keep max revs down but get better cyl charging ,more torq,right?

 

[GBD]

yeah so in doing that you keep max revs down but get better cyl charging ,more torq,right?

Thats right! But you also have to widen the transfers to restore- or even improve transfer timearea depending on what your torque target is.

 

[blsnelling]

Please show us an example of your work, employing said long blowdown in a 044/046.

 

[blsnelling]

The laws of physics applies equal regardless of model and make! Your sucpition regarding blowdown is correct.

You should know by now that you "can't bend the laws of physics". All saws need 25°-30° of blowdown.

Reread your own post! "All saws", wasn`t it?

No, it was you that said that. And you thought I was serious? No saw builder would believe that.