larger exhaust valve???

stumo

stumo

Active Member
Does anyone know if a 1mm larger diameter exhaust valve is available off the shelf from somewhere?
 
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Odin

Guest
Yes Peter Robinson fitted 1mm over sized valves from one of the other Nissan engines I believe.....


Rob
 
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tro||

Guest
no he didn't cos they didn't work in the end iirc..

he was also most upset when i managed to find some 1mm oversize valves for the gtir on the shelf at a machinists in japland, after his head was put back together.......it is pointless contacting them from the uk though as they dont seem to be able to understand english.lol..but if you know someone in japland they could probably contact them.

i dont have the site anymore is it was on my now deceased laptop but found them using google.jp..tbh it would probably be easier to get a standard valve copied to 1mm oversize than trying to get hold of the place..

standard valves are plenty big enough for most anyways.
 
stumo

stumo

Active Member
standard valves are plenty big enough for most anyways
Click to expand...
agree but they don't flow alot for the size...it's due to the shape of the throat/height of the roof.

With the head completely standard and lifting the valves to HKS 264 specs (in-11.35mm. ex-10.85), the inlet flowed 130cfm, the exhaust was 66% of the inlet (or 86cfm), low lift flow was ok.

flow is now up to 101cfm, that's about the same as a Cossie with virtually no work.

It's just something i want to try on a scrap head before fitting it to my good one.
 
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tro||

Guest
its a known fact that the gtir head is poor on the exhaust.

what about trying a staggered cam pattern ?

if i can find the link to the place that does those valves i'll put it up.
 
stumo

stumo

Active Member
its a known fact that the gtir head is poor on the exhaust.
Click to expand...
this is exactly why i want to try a larger exhaust valve.

With some more grinding the exhaust could be made to flow better but it will take time, fitting a larger valve is a lot easier with the Serdi (and a quick grind to blend it in).
 
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