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| Performance Upgrade Article http://www.kawi2strokes.com/forum/viewtopic.php?f=16&t=12390 |
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| Author: | mraxl [ Mon Jan 09, 2017 1:31 pm ] |
| Post subject: | Performance Upgrade Article |
Jørgen Lund has kindly provided an article for posting to the Resource site. Here is the link: http://3cyl.com/mraxl/performance/perftech.htm For future reference it is under How-To> Performance Enhancements A big THANK YOU!!! for sharing the time, effort, and knowledge to our community. 
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| Author: | kawi3cyl [ Mon Jan 09, 2017 5:00 pm ] |
| Post subject: | Re: Performance Upgrade Article |
Thank you Dale and Jørgen for this interesting information. And where do we source the mentioned 2mm thick gaskets in order to lift the cylinders? Edited: Answer to myself  (thanks Looney from an earlier thread) - http://coppergaskets.us/
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| Author: | Hawaii-Mike [ Mon Jan 09, 2017 5:28 pm ] |
| Post subject: | Re: Performance Upgrade Article |
I've seen "blowdown" mentioned a lot lately. Can we get a definition here? I have an idea about it but it's just an idea. |
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| Author: | Jim [ Mon Jan 09, 2017 5:50 pm ] |
| Post subject: | Re: Performance Upgrade Article |
From the web: "Always measure blowdown in degrees of crankshaft rotation from the point where the first exhaust port (highest one) opens to when the first transfer port opens. By definition, that is blowdown." |
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| Author: | Ja-Moo [ Mon Jan 09, 2017 6:47 pm ] |
| Post subject: | Re: Performance Upgrade Article |
Some people get time/area mixed up with blowdown. Blowdown is as Jim described, time/area is taking into account the size of the port and open duration, on order to try and equalize the flow through the motor. |
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| Author: | Hawaii-Mike [ Mon Jan 09, 2017 10:40 pm ] |
| Post subject: | Re: Performance Upgrade Article |
Thanks Jim and Moo for the clarification. |
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| Author: | argo1974 [ Fri Mar 31, 2017 7:59 am ] |
| Post subject: | Re: Performance Upgrade Article |
Blow-down is a process inside the engine between exhaust process start and transfer process start. Blow-down varies depending on engine speed and load. Duration, time-area etc. are just mathematical (inadequate) ways to describe blow-down. |
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| Author: | ALTERED IMAGE [ Fri Apr 21, 2017 4:08 pm ] |
| Post subject: | Re: Performance Upgrade Article |
argo1974 Precisely argo, Geometry is one thing. Actual gas flow is quite different. cliff |
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| Author: | Ja-Moo [ Fri Apr 21, 2017 8:02 pm ] |
| Post subject: | Re: Performance Upgrade Article |
As with anything in engines, there has to be some kind of mathematical baseline, that's blow down numbers. Just like lobe centers on 4 strokes. It takes a super computer to show actual flow figures. Most of us don't have one. But there is decades of measuring blow down with port heights. They are totally valid. |
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