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vaxx
P Plater
28 Posts
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 Posted - 25 Aug 2008 : 7:23:39 PM
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OK, started playing with a set of heads today and found out that they are fairly thin near the water jacket around the valve guide :)
Luckily I'm doing it at work (lunchtime) and could weld the back hole up..
I have managed to open the exhaust port up a fair way. Should improve things a bit. I'll take pics in the next couple of days of before and after ports.
No real need to do the inlets that I can see apart from tidying up a few casting marks
Going to change the rocker ratio while I'm at it to. Going to get some ecotech rockers to up the lift a bit.
I need to plug up the existing holes and redrill and tap new holes at the correct position to keep the rocker tip in right place.
Might take me a few weeks of luchtimes, but will be worth the effect.
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vaxx
P Plater
28 Posts
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HOT38R
P Plater
71 Posts
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Posted - 28 Aug 2008 : 3:43:52 PM
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hey VAXX,
hope you got all the dimnsions of the port right, did you get professional advice?
as if they are ported to far it can decrease power and fuel economy dramatically or ported unevenly can also lead to dramatic power loss |
HOT38R |
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vaxx
P Plater
28 Posts
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Posted - 28 Aug 2008 : 9:15:54 PM
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Don't fret, been playing around with heads for the last 2 years :)
Biggest issue in porting is keeping the same cross sectional area. If this varies too much you will get pulsing which causes the burnt gasses to build up in the combustion chamber leading to power loss.
Plus a good feel for the flow too. Hard to explain that bit, needs to be learnt through experience.
The next key part will be the extractors. I've been doing a lot of research on them and have found the buick v6s to respond to a longer primary to drop the peak torque curve down the rev range.
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Benche
Fully Licenced
240 Posts
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Posted - 31 Aug 2008 : 12:30:22 PM
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| i happen to be porting my v6 heads to. big fcuken job. if you dont know what your doing just pay someone to do it. |
VN V6 MANUAL - 14.1sec 1/4MILE, 150rwkw, 350nm |
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trizo
Forum Moderator
3091 Posts
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Posted - 31 Aug 2008 : 2:58:33 PM
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| @vaxx, if you get some spare time do a write up or how to on porting ya heads.. |
3 can keep a secret if 2 are dead |
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vaxx
P Plater
28 Posts
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Posted - 01 Sep 2008 : 8:31:32 PM
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Finished one, need to disassemble the other and do that. Been busy the last few days machining up a couple of pulleys :)
Hmm, how to. Not an easy thing to do. You need to be able to feel how the gas flows.
Main thing is to try and keep the same cross sectional area all the way thru. Also, the port should be around 1 - 1. mm smaller then the exhaust header opening. This stops the sound wave pulsing into the combustion chamber (Had to shorten the answer there. To hard to explain easily. There is a few good web sites about this on the net)
Make sure there are no dips or shallows or casting dags that will induce turbulence. The exhaust port can be polished.
The intake port should be left rough finished to increase atomisation of the fuel droplets.
Basic visualisation of the gas flow helps greatly.
You also need to take into account the exhaust header design.
Apart from that, trial and error and experience :D
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