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1.9 head porting pictures anyone?
by
gldgti
on 09 Aug, 2011 21:21
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I wish I had them to give you guys - but I'm just looking for some! I am midway through rebuilding a 1Y for my wifes '91 cabrio, and I've got the head fully dis-assembled.... while its all apart I'm thinking "what can I do to make it better without too much trouble".
I've totally degreased the head casting I've been looking at the ports.... and basically I reckon they look pretty good.... I mean, we all know the 1.9 head flows much better than the 1.6 head, but could I make it any better with only a small injection of effort?
The car is only going to be running a T2.... albeit with the original 1Y intake manifold, so it should have HEAPS of torque at low rpm, and with the t2 i'm not expecting more than 100hp.
Just wondering if anyone can vouch for porting giving decent increases on the 1.9 head - and if so, where do I start. At the moment all I can think is that if I'm running the T2, porting wont give me anything at all... anyone agree?
Cheers!
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#1
by
regcheeseman
on 10 Aug, 2011 03:27
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I did mine whilst it was stripped, I think it seems much better as a result.
No massive amount of material removed just matched the ports to the manifold.
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#2
by
RabbitJockey
on 10 Aug, 2011 08:39
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damn thats a lot of material there to remove, if u want a quick easy port job that will help a lot, open up the head around the valve seats, thats a really sloppy area, and they say the most important part in porting is an inch before the valve and an inch after. and then gasket/port match for smooth transitions.
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#3
by
burn_your_money
on 10 Aug, 2011 10:54
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#4
by
gldgti
on 10 Aug, 2011 16:22
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thanks guys, i might take a look at the exhaust port near the valves.
cheers!
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#5
by
rallydiesel
on 10 Aug, 2011 16:33
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I would do the intakes too. There is a sharp ridge about 2cm in from the seat on the floor side that could use some shaping.
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#6
by
RabbitJockey
on 10 Aug, 2011 19:55
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#7
by
R.O.R-2.0
on 11 Aug, 2011 09:33
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#8
by
RabbitJockey
on 11 Aug, 2011 10:09
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check out the ports on this freaking that, they are huge!!!
http://www.vwdiesel.net/forum/index.php?topic=11698.0
i would expect nothing less from Dave tho..
yep, he put some amazing r&d into these engines, especially with this head porting, he also had some kind of indent he put into he deck which really helped flow, it was never really discussed very much on here tho, i'll have to dig through some more old threads... like i always do haha
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#9
by
keaton
on 11 Aug, 2011 11:25
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make sure you are not gasket matching the head. you want to port match the intake to the head you also want the cross sectional area to decrease as you approach the valves, not increase. increasing the area slows the air velocity.
my $0.02
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#10
by
RabbitJockey
on 11 Aug, 2011 15:48
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make sure you are not gasket matching the head. you want to port match the intake to the head you also want the cross sectional area to decrease as you approach the valves, not increase. increasing the area slows the air velocity.
my $0.02
or port them both to match the gasket
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#11
by
keaton
on 11 Aug, 2011 16:55
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yeah for a smooth transition but take the velocity of the air particle, you slow it down and then speed it up.
look at race applications, from the plenum to the valve the cross sectional area decreases (increasing velocity), it doesn't increase then decrease....
your effectively doing this:
and when your valves are open for a limited time.... then its kinda important
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#12
by
RabbitJockey
on 11 Aug, 2011 20:39
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i understand that, but if the intake runners are opened up to be equivalent to the gasket size, along with the ports, the only point velocity would change would at the bowl/radius down into the valve seat, the valve seat being the smallest part, it wouldn't be like you picture above, it would be just the right half of your picture.
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#13
by
burn_your_money
on 12 Aug, 2011 04:49
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Isn't the exhaust port suppose to be stepped though (manifold bigger than head opening)? Or is that only gassers?
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#14
by
keaton
on 12 Aug, 2011 09:42
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Isn't the exhaust port suppose to be stepped though (manifold bigger than head opening)? Or is that only gassers?
that's to prevent reversesation of exhaust gases during valve overlap.