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Post by scooter on Aug 23, 2014 6:08:24 GMT -5
I found this article online. mototuneusa.com/homework.htmTake a look at it and tell us what you think. Is this guy right? Are small, high velocity, ports better than large, low velocity, ports? Is rougher better than smoother?  Before: After: |
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Post by pmatulew on Aug 23, 2014 7:40:16 GMT -5
delete - double post
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Post by pmatulew on Aug 23, 2014 7:44:52 GMT -5
Definitely not that simple. He's not wrong though. And if he can back up his technique with real world before and after perfomance results, well then who am I to judge. There is lots of voodoo involved in the science of fluid dynamics.
His concept is dependent on where the fuel is coming from. With a top mounted carburetor or a single point throttle body assembly the fuel has to travel the length of the intake. Most modern cars have multi-point fuel injection where the fuel is added directly above the valve opening precisely for this reason. Also be aware that what he is doing applies only to the intake side. On the exhaust side you want to flow as much volume as possible.
If you have a spare head to play with and the time to experiment go for it. It appears that his fish scale cuts are just to anchor the epoxy in place. Personally I would never mess with the valve guides. That's just asking for trouble. The overall roughened surface may act as turbulators to help stir the mixture but in a cold motor it is just as likely to cause the fuel to condense along the way as there is more surface area to grab it.
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Freshman Rider
Currently Offline
if God had wanted us to be naked we would have been born that way , Hey wait a minute
Posts: 67 
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Joined: Jun 25, 2014 10:04:47 GMT -5
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Post by nakedguy on Aug 24, 2014 12:43:01 GMT -5
As a old drag racer I can tell you many hours porting and polishing heads , remember a engine is just a air pump , thats why there are better air filters , bigger carbs bigger cc kits , headers and free flow mufflers , you want smooth surfaces , nice easy rounded corners , take a chunk of tape , poke a 1/2 hole over it , put it over you mouth and try running around the block , you will quickly understand the air thingy
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