GolfGTIforum.co.uk
General => General discussion => Topic started by: Veedubgt18v on 23 September 2004, 15:41
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i been thinking about this and is it 2 valves inlet and 3 exhaust or the other wat round or 2 in 2 out and one that does both? or what im confused ???
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3 inlet 2 outlet
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ok are the outklet bigger than the inlet?
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yep 2 big exhuast valves and 3 small inlet valves, heres a pic of my damaged head which i removed when my cambelt tensioner failed.....
(http://homepage.ntlworld.com/c.hunter101/20v14.JPG)
Gaz 8)
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bit blurred but i understand now! and i suppose a v5 is a vr6 with a cylinder lopped off? must have a balancing device somewhere? sorry just wondering out loud about vw engines!
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yup your assumpton of the v5 is correct, not sure how they balance it though but they are nice and smooth!
Gaz 8)
sorry for quality of pic, i was (as you can imagine, very pi55ed off at the time!!!)
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And i was always it was a five cylinder, with two in, and two out...! ::) :-[
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eh? ???
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eh? ???
Well, two inlet, and two exhaust for each cylinder. Thats four, four times five, is 20.
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though VW are binning the 20v and going back to the 16v with 2.0 turbo unit found in the new GTI
apparently the FSI injection system doesnt like the 5 valve setup
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yup your assumpton of the v5 is correct, not sure how they balance it though but they are nice and smooth!
Gaz 8)
sorry for quality of pic, i was (as you can imagine, very pi55ed off at the time!!!)
So the drinking vast quantitys of beer didnt help the picture taking ;)
Whats the point in a 20v, why not just make a 16v with the same size area in the valve caps ???
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Mix; the whole point of having 5 valves is so that you can fit more valve area in.. you physically couldn't get more area with 4 valves - hence the relationship between 2 and 4 valve per cylinder engines - with 4 you can physically fit in more valve area, and suck in more mixture. More valves also make the engine more tractable at low engine speeds as the two (or three) smaller ports help to keep intake velocity high - giving the air more inertia and filling the cylinders better at low RPM - giving more torque.
Gambit; having seen a 20v head, I think you'd have a problem fitting a spark plug and a fuel injector in there..
In a turbo application you should be able to get away with worse breathing characteristics as the turbo is ramming more air in at higher pressure anyway..
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the spark plug goes down the middle of the valves like teh 16v's. the injector is on the inlet manifold pointing into the cylinder.
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eh? ???
Well, two inlet, and two exhaust for each cylinder. Thats four, four times five, is 20.
i thought the 20v was a four pot engine?
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Dizzie - you still talking about the direct injection / FSi lump, or the 20vT?
Veedubgti8v - The 20vT is based on the same block as the Gti lumps - 1.8 four pot. Each cylinder has 3 inlet and 2 exhaust valves (4x(3+2)=20) - unlike the old Audi 2.2 five pot, which had two inlet and exhaust valves per cylinder; 5x(2+2)=20.
You see ;)
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dont think its dizzie thats got confuesed here, as the injector does sit in the inlet manifold pointing into the inlet port, wether it be an old 16v or the new style 20v engines, the only difference is how many valves they squeeze in and how many lobes on the cams other than that (and maybe a little vvt ) there basically the same engines..........
4 cylinderx4 valves per cylinder =16v
4 cylinderx5 valves per cylinder=20v
5 cylinderx4 valves per cylinder=20v
easy to get confused peeps......
lol
Gaz 8)
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Yamaha were the first to put a 4 cylinder 20v engine out in the 80s.
They claimed that the optimum no of valves were 7! But could only justify 5 due to cost. ::)
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cant beat motorbike engines!!! the bhp they get out of them is unreal!!! id love my 1800cc 16v to whale like a 750 20v yam at 12000 rpm (if it would rev that high and give twice the power out put as my mates race prepped yzf750 r m
Gaz
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Mind you it'd only last for a season before needing a full rebuild :P
It'd be like a blade engined chateram. Fast as F@ck.