As above,i have a spare 20vt head which i was thinking about fitting to an na? and was thinking of having a tinker with it port an polish etc? I`m guessing the comp ratio may be different aswell as the cam`s? are the valves bigger/longer? if so could i ditch the turbo cams valves etc and fit the na parts to it? may be a silly idea just a thought that popped in to ma head
Re: differences between 20v na head and 20vt head?????
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#717238 29/11/200812:4729/11/200812:47
Yes, I did wonder if that was the only difference. The manual spec table here doesn't show a tremendous number of differences between the two (pages 12/13/14)
Re: differences between 20v na head and 20vt head?
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#717777 30/11/200815:2130/11/200815:21
are the valves bigger/longer? if so could i ditch the turbo cams valves etc and fit the na parts to it?
i would say that the castings are probably the same, but with differnt exhaust valves as mentioned due to the higher turbo temps. definatly use the n/a cams as they'll probably have a longer duration on the inlet and maybe the exhaust. sometimes its a common mod (never heard of it on a coupe but ive done it on other cars) to use n/a cams on turbos to get a longer duration on the inlet when running higher boost.
def worth giving it a polish but be carefull as it can be detremental if you dont know what your doing. best of luck!
Re: differences between 20v na head and 20vt head?
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#717781 30/11/200815:5230/11/200815:52
Got to be a bit careful though running to much valve overlap on a turbo engine. Its fine for an N/A as it means left over gases are forced out by the new inlet charge. However on a turbo car due to the pressure in the exhaust manifold having a lot of valve overlap can actually force used gases back into the combustion chambers which is a bad thing. For power and for the running of the engine.
Re: differences between 20v na head and 20vt head?
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#718275 01/12/200812:4701/12/200812:47