what tools are you using for this? just random grinding stones? i did start porting a head but now know ive gone to far with it. as a rule would you all say that only very mild porting is needed on the inlet or just polishing? or none on either? mixed views everywhere about porting inlet sides...from where ive looked anyway. great thread BTW has all the info all in one plae
Polishing is pointless as far as gains are concerned. The starting point is good seat detail & correct shaping below the seat. I'd imagine the mixed views you've seen are by those who's mate's mat'es mate says they dont need porting "cuz they're spot on on std form"!... they're not! A 10-14cfm gain gain be had over standard (subject to the staring point) with fairly minimal, but detail work, and an "extra" 17cfm thereafter, with a lot more hard work, and all on the standard valve.... and no polish. Keep at it and you'll get there.
Ive said this a few times and Ill say it again. I think the vw port is too big in terms of volume. Anyone care to try filling it in to keep velocity up. Flow numbers are nothing without velocity numbers folks.
why dont folks who run tbodies, fill in the injector scoop in the intake port... it will reduce area and for the same massflow increase velocity. side by side to the XE head the vw's one has massive ports, yet the XE kicks the valvers butt in performance terms
The heads can be made to flow pretty well. As you state Brian, size could be a little big. The CC shape in the head is not exactly ideal either. Still, it is what it is...
Exactly, it would be a start. I made what I believe was the first adaptor plate to get around this a while back. It was 6mm thick, an alloy gasket if you like, with cast in 'thumbs' to fill the injector pockets. Fettled slightly to fit snug. I never heard how it performed as It was sent overseas. Edit, I might make some more, I still have pattern someplace.
I would be interested in buying one. As Mr Hillclimber has stated above, and I have found out independently, the cutouts make no difference on the flowbench. However, the bench does not measure port velocity. This could help torque at lower engine speeds through improved fuel mixing.
Yes, that was my thinking too Neal. Youll find they are filled in on the Audi touring head too. Not jumping on the '' it must make a difference tuning crap bandwagon'' but it has to be a good thing. Ill root out pattern and spill some metal the wkend.
So I found the pattern, I thought it would take longer to find, Im gonna cast one up this eve since Im melting anyway. Pictures later.
in terms of mm. How much have you taken from the heads you have done? Were can i find info on valve seat design/cutting calves back etc? Your exactly right about the what ive heard though.....someone i know did a 8v head by taking a grinding stone to it. Then wondred why he had no difference!! By what i have been reading the flow velocity would be pants. I will be binning the head i think. Can always post it up as a 'what not to do' lol
Re: The Higher velocity stuff. You could progressively fill the area up in the port with plasticine to see where you could reduce volume but maintain flow. As you have a flow bench Mr Hillclimber, I suppose this wouldn't be too hard. Gurds
Danster, I know they exist, but they need tigging in, which means pulling head, and a intake face skim, and indeed head skim if the heat gets too much. They are also pretty permanent if you feel like swapping back standard intake at time of sale.
Those blanks get glued in with epoxy / liquid metal. No heat. Or they get welded in the inlet manifold flange as the inlet manifold is tig welded up. They would then come out when that is removed. I know one lad that just fills up the injector voids with the liquid metal by itself. Heads are generally off to get skimmed or ported anyway.
So those things can be put in certain/precise locations to change flow rate? can they change how A/F enters the cylinder. Better swirl? Whats the advantage of putting them in the manifold?
