Ported Husqvarna 372xpw

[bwalker]

No, a faster unrestricted flow vs. a lesser flow from restrictions is the issue.

Your not the first nor the last to make this mistake...

 

[tlandrum]

 

[Andyshine77]

Open up the transfers too much and you loose base pressure, the charge will just sit in the case instead of getting pushed into the combustion chamber. The engineers know what they're doing! porting is mostly about exploiting what's already there, and removing the mass production variables. I also proved windowing the piston does nothing, except maybe lowering case pressure.

If you want to learn about high case pressure and transfer volatility have a look at a Dolmar 7900 top end, the transfers are tiny but they flow like mad.

Don't let this stop you from experimenting, however a little research goes a long way.

 

[bwalker]

Transfers duct area and crankcase volume go hand in hand.

 

[Oldsawnut]

Of course the best running open port saw was the original husky 365... Pre special... I would like to think that's what he was thinking since its pretty much the same saw as 371xp

 

[Big_Wood]

Of course the best running open port saw was the original husky 365... Pre special... I would like to think that's what he was thinking since its pretty much the same saw as 371xp

it ain't no 371. same case and appearance yes but the 371 was not open port. it also had the clamp on intake boot same as the 372 and an HD6 walbro instead of the POS zama. best running open port husky to me was the 268 non xp although the 365 wasn't bad at all either.

 

[Chainsaw Jim]

Open up the transfers too much and you loose base pressure, the charge will just sit in the case instead of getting pushed into the combustion chamber. The engineers know what they're doing! porting is mostly about exploiting what's already there, and removing the mass production variables. I also proved windowing the piston does nothing, except maybe lowering case pressure.

If you want to learn about high case pressure and transfer volatility have a look at a Dolmar 7900 top end, the transfers are tiny but they flow like mad.

Don't let this stop you from experimenting, however a little research goes a long way.

That's cool you proved windowing a piston does nothing.
I actually tested this build out with a stock piston before windowing it and recorded time. I recorded a full 3.5 second gain after windowing it. I was cutting 18" diameter doug fir, so three seconds is a notable difference.

 

[Chainsaw Jim]

Transfers duct area and crankcase volume go hand in hand.

Is there any possibility of you starting a thread so you can include all your knowledge on port work in one place so I know where to go for answers when questions arise? I'd rather just get your idea about how a theory will really work instead of wasting time on trying it out.

 

[nenicu]

Look at Echo 600 design:the bottom of the transfers is raised compared with Husky transfers. The piston is non windowed. They seem to run very good. Great torque.

 

[Andyshine77]

That's cool you proved windowing a piston does nothing.
I actually tested this build out with a stock piston before windowing it and recorded time. I recorded a full 3.5 second gain after windowing it. I was cutting 18" diameter doug fir, so three seconds is a notable difference.

I'm trying to give you sound advice. Myself and others went round and round with the topic and quite a bit of testing was done. Windowing the piston does nothing, other than reducing base pressure.

You're really being way too defensive and immature. If you want to learn how to properly port a 372 "which you don't in any way shape or form" myself and others will be glad to help. Or you can dismiss us and stick your head in the sand. The choice is yours.

 

[SawTroll]

Here's a closed port cylinder...View attachment 440118

And here's open port cylinder....View attachment 440119

I obviously didn't close the port. I don't know how you got that out of what I said. The piston is a closed port style piston after modifying it, giving it the closed port function.

No, both are closed port cylinders - the differense is short vs. long transfers or side vs. bottom intake to transfers.

 

[Moparmyway]

That's cool you proved windowing a piston does nothing.
I actually tested this build out with a stock piston before windowing it and recorded time. I recorded a full 3.5 second gain after windowing it. I was cutting 18" diameter doug fir, so three seconds is a notable difference.

Was there anything else done other than windowing the piston between the two test cuts ?
Even just "cleaning up" one of the ports in the corners can yield a significant gain (or loss depending on which port you are working on).

 

[bwalker]

Is there any possibility of you starting a thread so you can include all your knowledge on port work in one place so I know where to go for answers when questions arise? I'd rather just get your idea about how a theory will really work instead of wasting time on trying it out.

Great idea to stop wasting your time. Read Bell and Jennings for starters.

 

[MattG]

Out of interest, when I was a youngster I played with tuning a Yamaha motorcycle (DT175MX). Me and my pal got a copy of this book:

http://www.amazon.co.uk/Two-stroke-Performance-Tuning-Graham-Bell/dp/1859606199

and it gave us a lot of background. Is this relevant to chainsaw tuning, too?

 

[SawTroll]

Great idea to stop wasting your time. Read Bell and Jennings for starters.

...and Gordon Brown!

 

[Chainsaw Jim]

Was there anything else done other than windowing the piston between the two test cuts ?
Even just "cleaning up" one of the ports in the corners can yield a significant gain (or loss depending on which port you are working on).

I pulled the jug and windowed the piston and that was it because my whole point was to see how it ran with that specific mod.

 

[Moparmyway]

Was there anything else done other than windowing the piston between the two test cuts ?
Even just "cleaning up" one of the ports in the corners can yield a significant gain (or loss depending on which port you are working on).

I pulled the jug and windowed the piston and that was it because my whole point was to see how it ran with that specific mod.
I didn't ask for your advise or anyone else's, so stop with the name calling. I never claimed to be an expert on port work, but contrary to your claim, I do know how to properly port a 372. I'm just sharing what I did on this saw with everyone interested in checking it out. I would have shared step by step through the course of the build but I didn't want to be distracted by all the negative comments I knew it would receive.

Someone spit out a head gasket ................
Since I appear to be mentally challenged, would you be so kind as to show me where I called you names or gave you any advise.
Also, please take the time to show me where I claimed that anything you did was wrong or improper

 

[Chainsaw Jim]

No, both are closed port cylinders - the differense is short vs. long transfers or side vs. bottom intake to transfers.

I didn't mean to make it an argument. I'm only going by what one of the better Husqvarna dealers in my area recently told me. I'm double checking with him later today to see what he said that I interpreted as that. That wasn't the subject of the conversation I had with him at the time, so I could have easily heard him wrong.

 

[Chainsaw Jim]

Someone spit out a head gasket ................
Since I appear to be mentally challenged, would you be so kind as to show me where I called you names or gave you any advise.
Also, please take the time to show me where I claimed that anything you did was wrong or improper

Oh wow, I apologize for the mix up. It was Andyshine77's comment that I was trying to refer to. I've been using my phone to reply to these comments because my computer keyboard fried on me yesterday. The pages do not refresh properly and I got all discombobulated.

 

[gunnusmc03]

Here's an "open port" cylinder for reference.