1zz valve size

[lamcote]

As a matter of interest does anyone know whether it is possible to increase the inlet valve size on our engine?

It seems the head has some pretty trick valve seats which may mean that it isn't possible to increase the valve diameter, does anyone know?

Interested to hear your views.

Cheers

[mrzwei]

There is a link here:

 l viewtopic.php?f=7&t=24404&p=303924&hilit=larger+inlet+valves#p303924 l   (look at the first post)

Also, others may have done it but more seem to have gone the Crower cam route.
Check out spyderchat as well.

I don't think there are massive gains to be had by going the head modification route because it is pretty efficient to start with so lots of bucks for not much bang.
I was seriously looking at this when I first bought mine but decided no. I think Rich Buckingham and Chris GB went along this route for a time. There are a lot of posts in the performance reference section.

[lamcote]

Thanks for that, interesting stuff, I had a look at Wabbitkilla's power curves for before and after crower cams and it looks like it lost a lot of power right through the rev range and just gained a bit past 6000, unless I read the graphs wrong, so I was wondering about any alternatives.

I would love to boost low and mid range power without forced induction but maybe it's just not possible. 82mm pistons may be the best/only way?

[Anonymous]

And he made a good engine. Still yet to have the balls to turn it up to 8k.