Jenko_Sport
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Registered: 25th May 06
Location: Stoke-on-Trent
User status: Offline
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Got a c16xe head sat in my bedroom doing nothing and thought why not.
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RCS
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Registered: 26th Jan 05
Location: Lichfield/Dundee
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Its all about comprimise really.
Ideally all you want to do is reduce the friction encountered by the flow to reduce the energy lost. Do this by improving the surface finish of the port wall, reduce the effective angle of the port and blend the area behind the valve seat.
Next stage is to increase cross sectional area without modifying the shape of the port. Cut back valve guides, thinner valve stems and 3 angle valve heads.
Then you get into material removal - most gains in flow from this are at the expense of tumble and swirl. Then you have the effect that cross sectional area has on port velocity - larger area decreases velocity. With this the friction decreases and so does the intensity of the reflective wave.
So you improve your flow but at some engine speeds there are unfavourable pressure differences - so in fact you have just made it easier for flow to escape. This is normally at low engine speeds.
Don't listen to people who quote volumetric air flows, its all about discharge/flow coefficients.
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philip2
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Registered: 1st Oct 06
Location: n.wales/chester
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i was having this convo with gaz'd who runs the purple TOTB corsa...people seem more interested in what it flows cfm a min or whatever it is.
and as you've mentioned, sometimes bigger isnt always better, some people tell you they want a huge amount took out of the ports, but only benefit you 'may; see is top end and thats if you have enough air/fuel getting into the motor.
ive got tons of pics of heads ive done. if want to have a nose to get an idea. ive been asked by several people 'how do you port your heads' and i just tel them that you cant explain, i could show you if face to face, but its very hard to explain over phone, net, email whatever where to cut off, smooth, radius etc etc
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Jenko_Sport
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Registered: 25th May 06
Location: Stoke-on-Trent
User status: Offline
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So in a nutshell dont enlarge the ports size just improve the area's finish?
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philip2
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Registered: 1st Oct 06
Location: n.wales/chester
User status: Offline
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it dpends on the rest of the engine matey whther you enlarge or not.
easiest idea is. you put a full race head on say a 20xe, +2mm valves, mega size ports on a stock engine, you may gain abit of power virtually on the limit, where as if you just kept stock valves, match ported it and worked the valve throats, then you could actually see alot more bhp gained from the lesser spec head so to speak.
ill u2u some pics of an x16xe head i did a few weeks back
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mad_mike252
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Registered: 15th Nov 07
Location: Nottinghamshire
User status: Offline
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http://www.motorsport-developments.co.uk/stus.html
Its all based around the Ford Models, but all of the principles will work on any engine n what not...
some interesting bits to read when your a bit bored
[Edited on 15-06-2009 by mad_mike252]
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Jenko_Sport
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Registered: 25th May 06
Location: Stoke-on-Trent
User status: Offline
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Cheers phil. geat help.
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mattk
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Registered: 27th Feb 06
Location: St. Helens
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quote:
Originally posted by mad_mike252
http://www.motorsport-developments.co.uk/stus.html
Its all based around the Ford Models, but all of the principles will work on any engine n what not...
some interesting bits to read when your a bit bored
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Jenko_Sport
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Registered: 25th May 06
Location: Stoke-on-Trent
User status: Offline
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quote:
Originally posted by mattk
quote:
Originally posted by mad_mike252
http://www.motorsport-developments.co.uk/stus.html
Its all based around the Ford Models, but all of the principles will work on any engine n what not...
some interesting bits to read when your a bit bored
+1
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