Larger valves.

[Baxter]

Thinking future here, not got the time at the moment, more of a parts and info gathering exersize..
So, I have a Caddy.
The 1.6D is fine, it goes, it stops, it starts first time but the 255k on the clock, well it ain't gunna last forever!
So, Diesel tuning is a bit of a speciality, not much information around.
I find this forum very usefull to read, but most of it is trial and error stuff, you know, "Oh I tried this and it worked" type of thing. There doesn't seem to be a Diesel tuning manual outlining the fundamentals anywhere, or if there is I can't find it!
So, I've gathered bit of info from here and there but got a load of gaps missing.
I appreciate from what I have read that the fitment of a uprated cam is more or less a no no for valve to piston clearance problems.
Can't use the ratio rocker trick to squeeze a bit more air into the cylinders so it seems the only other way is to fit, or have fitted larger valves.
So, just wondering around I can't really find a list of what size valves were fitted to what, I should imagine that they are mostly the same anyway..
But, as we are all VW types here we realise that loads of things are interchangeable withing the VAG group and I was wondering if any valves from the petrol engine models could be made to fit?
I was thinking of something fairly mild, probably use a AAZ as a base, seems daft to go to a load of effort on a 1.6 when I can have 300cc's more.
So, AAZ, bigger valves, bit of a porting excersize, pump mods, poss bigger head and rotor, larger nozzles, up boost, bit of balancing, set deck height, 2 1/2" exhaust, intercooler...
I've gotta see 100hp out of that surely?

Anyone got any words of wisdom on bigger valves or am I missing something really basic, when theres a lack of info out there I figured some petrol engine fundamentals would be a good start.

Simon.

[Otis2]

I did a quick search, and didn't see any discussion of experimenting with larger valves than the AAZ already has.  I believe it already has bigger valves the 1.6TD.

But there are some really interesting ideas about camshafts floating around here.  I'm not sure it's correct to say, "the fitment of a uprated cam is more or less a no no for valve to piston clearance problems."  And even if clearance problems did preclude your cam of choice, you're already talking about custom machine work on the head to fit the bigger valves, so you may as well think about machining the piston recesses, too.  

Some useful info was discussed in this thread:  http://www.vwdiesel.net/phpBB/viewtopic.php?t=1318

You might find this one interesting, too - includes a photo of the sprocket that "Caddy" is using to fit a GTI camshaft to the TD head:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=880

And from the old GTD forum:  http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=425

[vwmike]

You're fairly lucky in that diesels are much more common where you live, so it would seem somewhat counterproductive to build a 1.6 when you have 1.9's at your disposal. That said, if you want larger valves then perhaps you should look to the Heron 1.6 that came in the MK1 GTI's (engine code EG I beleive). It had a flat bottom head like the diesel and a small bore...although not quite as small. I beleive it was 79.5mm vs the 76.5mm of the 1.6 diesel.

[Baxter]

AAZ's aren't that cheap though, all the T3 lot want them for their vans, any in scrap yards get snapped up or have knackered cranks.
What does "Heron" mean? seen that a few times.
I was going to ring a petrol engine tuning company and see if they are willing to carry out such work, as I say, from what I have read that some tuning principle apply to both petrol and Diesel.
Ifthey can port a petrol engine im sure they can do the same for a Diesel, same for machining.
I suppose the only thing that may be different is they know how far to go with a Petrol head as they've done thousands, may not be the same for a Diesel and may grind through cooling jackets etc..

[vwmike]

AAZ's aren't that cheap though, all the T3 lot want them for their vans, any in scrap yards get snapped up or have knackered cranks.
What does "Heron" mean? seen that a few times.
I was going to ring a petrol engine tuning company and see if they are willing to carry out such work, as I say, from what I have read that some tuning principle apply to both petrol and Diesel.
Ifthey can port a petrol engine im sure they can do the same for a Diesel, same for machining.
I suppose the only thing that may be different is they know how far to go with a Petrol head as they've done thousands, may not be the same for a Diesel and may grind through cooling jackets etc..

As I have understood it, Heron refers to the type of combustion chamber. The 1.6 in the early MK1 GTI's had no combustion chambers in the head like the diesel, so logically the valves should be the same length. It will take some checking into, that's for sure.

[Baxter]

Im sure ETKA has valve lengths.
I'll go play.

[Baxter]

Why doesn't ETKA give head sizes? (Heh, managed to get "Give head" into a sentence about tuning Diesels, cool)

Anyway, I have managed to gleen the following info.

AAZ - Inlet - 95mm
AAZ - Exhaust - 95.5mm

EG - Inlet - 105.7mm
EG - Exhaust 105.5mm

1Z - Inlet - 96.85mm
1Z - Exhaust - 96.8mm

Could do with knowing head size and stem diameter too.

Wonder if the NA valve head diameter is any bigger?

[Audi80]

Do you have mechanical or hydraulic lifters?  Hydraulic heads has 95mm valves and mechanical has longer. I have Audi 2,0 (or Volvo 2,4D) 36mm intake valves and Fiat Ducato 1,9 TD 34mm exhaust valves in 1,6 mechanical head.
AAZ intake valve is 36mm (stock 1,6 34mm) but the exhaust valve is same. Fiat valves are ~115mm long, they were cut. I have heard that someone has used Nissan 34mm exhaust valves too. I don`t remember EG valve sizes, I`ll have to check from book. I think they are ~38/34mm, not sure.

[golfmk1tdr]

Do you have mechanical or hydraulic lifters?  Hydraulic heads has 95mm valves and mechanical has longer. I have Audi 2,0 (or Volvo 2,4D) 36mm intake valves and Fiat Ducato 1,9 TD 34mm exhaust valves in 1,6 mechanical head.
AAZ intake valve is 36mm (stock 1,6 34mm) but the exhaust valve is same. Fiat valves are ~115mm long, they were cut. I have heard that someone has used Nissan 34mm exhaust valves too. I don`t remember EG valve sizes, I`ll have to check from book. I think they are ~38/34mm, not sure.

Zombie thread jacking 
Can the same valves be used on hydro head?
Also is stem thickness the same? I have fresh rebiuld 1.6 hyd. head, I am wondering if I can just put bigger valves in and overbore valve seats to match or should everything be raplaced again (in which case I would probably be better off tuning another head I guess)
Did you check the book about EG valves? They look like great increase it they fit our heads...

I would really love to decrease EGT's and I think bigger valves should help a lot...

[theman53]

They def. help decreasing EGT. If the head you have is good you can replace the guides to fit a 7mm stem. If you have the 1 grove keeper your machinist should be able to get blanks and cut one grove in them, if it is the 3 grove he can do it too, but it is much harder. Other than that one of the styles is longer than the other, I cannot remember if the mech or hydro was longer. They only work if they are long enough.