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Re: VW & Audi cylinder head port info needed...
> Certainly the 4cyl and 5cyl heads are close enough that you should approach
> them the same in porting. We have had great results by flattening the floor
> around the radius in addition to normal smoothing and enlarging (for wide
> open throttle). I would not enlarge other than the flattening and smoothing
> for the street, but you will still lose some low speed velocity.
Thanks for the input. As a counterpoint, the guy who owns the flowbench
claims the trick with the exhaust port was to widen the roof and leave the
floor pretty much alone since very little flow occurs there ... or so he
says. We'll see what we see this weekend...
> I have used Stainless in racing applications with no problem. In fact I
> currently am racing a VW GTI motor with turbo at 22 lbs. boost using stock
> valves (not sodium) that have been ceramic coated. EGT as high as 1750 F
> short periods and no problems (yet in two years). In other applications we
> use Inconel for the exhaust which is superior to stainless for the heat. An
> ideal situation would be to use stainless intake, Inconel exhaust, ceramic
> coat the chamber, piston top, valve faces and exhaust ports after porting.
> The last stainless 7mm valves I got were custom made, we had to cut to
> length and the keeper groove.
Who made the valves? What coating(s) did you use? Care to share your