Cross flow head conversion

Hi guys new to this forum so excuse me if I'm doing anything wrong.

In need of some real genuine advice here.
I've recently bought a pair of twin 40 weber dcoe's to go on my recently rebuilt 1.8 8v gti engine (PB engine code). After a bit of research and some asking about I know I'm going to experience problems with clearance on the servo.
So one of my ideas was to go to the smaller servo but then I risk loosing braking efficiency so after another bit of hunting about for info I've seen you can fit a mk4 golf 2.0 gti cross flow head to them. Now I know an area on the underside of the head will need filling with weld and machining flat but what I don't know is what else is involved so here's my questions:

First, what happens to the water hoses for the rad that normally go on the front of the head?

Second, will my 4-2-1 exhaust manifold transfer straight over?

Third, will the twin 40 manifold go straight on?

Forth, will my performance cam out of my current mk2 8v head go straight in?

Finally, is there anything else that will need doing that I may be missing here?

Great to hear your answers and suggestions.

 

drop this fella a line

http://www.clubgti.com/showthread.php?132407-My-Mk2-Golf-GTI-Crossflow

 

Hi,

The x-flow heads have a water outlet gearbox end of the head, where the 2nd water outlet is on a counterflow head.

Your exhaust manifold will fit fine with no modification required, the inlet manifold is a different story however and you will need to get a replacement to suit the x-flow inlet ports, you can buy these from a few different places but I would highly recommend Jason @ JMR (Mr Hillclimber on here) He made the one fitted to the x-flow engine in my racecar, if you take a look at his blog CLICK ME you'll see a couple of pics of the manifold and the head.

Cam wise a hydraulic cam will go straight in with hydraulic followers or you can convert to solid followers and use a mechanical cam if you want something a little more lairy, although you'd need to relieve the head to get clearance for the cam lobes

Nope nothing else I can think of you need to do to get things up and running

If you need any advice about heads then drop Jason or I a msg as he has a couple of spare x-flow heads down at his unit that I sent him a while ago

Cheers,

Tim

 

Great thanks for your help guys real useful info there to help me make a decition as to where I'm going to go with it over winter ????

 

If you need any other pics drop me a msg with an email address and I'll fire you some over

 

Thanks mate, this forum is defiantly more helpful than those vw vortex lot lol

 

I thought I'd dig out some pics of the JMR manifold to share with you

 

Awesome manifold...where did you get that Tim! lol

As for the conversion...

I did an 1800 recently...not had chance to post details yet but it's coming soon...used a std 1781cc bottom end with some squish adjustment like the one in our JMR blog, a std valve size MK3 cabrio head with just the seats cut and some basic throat work...2ltr AKL I think...and a 272 degree cam. With throttle bodies and a tubular manifold it makes a bit over 160hp and pulls clean to just over 7k.

40's will work ok as long as ultimately you don't want much over 150hp as the choke size is a bit restrictive for more power than that.

The head also needs some minor welding up on an oil way to align with the 1800 block but that's easy enough to sort. I hear some heads also need some of the head bolt holes opening up...the ones I've done so far haven't needed this. There is also a 1600 version of the head which I would avoid as it needs opening up in the ports to make it work...I've just done one for a customer...so look for the 2ltr head as a base.

What cam have you got that you'd like to use?

 

Cheeky sod....I provided the drawings for the inlet flange based on info I got from another member on here, but re-drew it and the outlet flanges based on what I needed. Jason then worked out inlet length and got the manifold made by his fabricator and then port matched to the head and ITBs.

It is true that some 1600s are to be steered clear of....I am in the process of documenting the head part numbers you need based off of Jason's experience, although I can confirm 'off the bat' that the best head as a starting point is a US spec ABA OBD1 head. These are few and far between this side of the pond however, but 1600 AFT heads are also not bad as proved by Jason's blog which is based on one of those I provided.

 

Digging up an oldie but why are those heads the best to start with?

 

Well the earlier OBD1 head had double valve springs fitted as standard whereas the OBD2 and xflow heads in European cars only had single valve springs and the spring seats are therefore different as are the spring caps. Also the OBD1 'German' heads had slightly larger ports as std and no 'swirl' emission feature in the port

 

Thanks Tim.

Sent from my D5803 using Tapatalk

 

I suspect there was a change in the design around 1995 or thereabouts, which would explain the differences that would have had an impact on the burn rate.
You do know I get nervous IDing components by US emission monitoring compliance! lol

 

Hi Guys, ive been researching doing the crossflow head conversion on my 1.8 GU motor. I have a x flow head from a 2L mk4 gti AQY spare, ive seen alot about welding up the 2nd oil drain hole on the head but no information why it needs to be done or if it does need to be done atall,i believe there is a port to match it on my block already so why is it needed to be blocked??

also how is the cooling system managed as there is 2 water in/out on my U flow head but only one on the xflow?

any help would be greatly appreciated its like a urban legend!! thanks