Head change

[Laner]

Finally decided to chuck the old 1.8 8v spi head on my golf mk3. however does the mk2 8v gti head fit straight on or does it require modification?

Thanks,

andy

[rubjonny]

Yes it will
The only difference is I believe the SPI inlet manifold requires a coolant feed, which the GTI head wont have.  Its very easy to add this though, you simply have to drill a hole of the correct diameter and the right angle, just compare with the old head and drill away!

For more info speak to a dude called 'haribo' off here as he did this to his 1.6 Driver.

[Laner]

if the new head doesn't require it, does it need to be installed? couldn't i just get a new pipe that doesn't have the (split i'm assuming) going to the inlet? head will be arriving soon and it going to be fully serviced (including a skim)before going on anyway including a 2.0 throttle body. Is there any advice on anything that can be done before it goes back on also what oil wud u recommed? Currently running on 0w40 castrol edge sport oil.

thanks,

andy

[rubjonny]

The 1.8 SPI manifold has an extra port on it for coolant to flow through, there is no pipe going to it.  You could try blocking off the outley and see if it will work without any coolant flow, but you may suffer from inlet icing ifd you do that...

..But from what you've said you are converting to injection?  If so you wont need to drill the hole as the injection manifold does not require it.  If I read it correctly, you have mounted a MK3 2.0 throttle body on a 1.8 GTI manifold?

[Laner]

going from a mk3 1.8 8v spi head off a golf cl to a mk2 1.8 8v mpi head off a gti so in theory i can just block or replace the coolent pipe? i'm not sure on the throttle body yet i've seen a few around and heard mixed opions on them. it's off a mk3 2.0 8v gti and has been fitted to a mk2 8v gti before so i wud assume that it's going to fit? damn this is confusing lol y can't all engines just be easy to change.

[rubjonny]

Ok the head will fit, but you'll need to convert to fuel injection if you want to use the GTI manifold, otherwise you wont have any way to get fuel into the engine.
If you want to keep your old SPI system, you need to use your old manifold, and if you do that you'll need that coolant channel. 
As I said its dead easy to drill out, the head is only aluminium after all. Just drill it till you pop thru into the coolant channel, then again with larger drill bits till the size matches the hole on the old head.  Then just flush out any bits of metal in the coolant channel with a hosepipe or something

[Laner]

Wud much rather go down the fuel injection route. what parts would be required for that? assuming this isn't going to take it from DIY level?

[rubjonny]

Right, it certanly isnt an easy job, but it isn't going to be amazingly difficult either.  Since when you have the head & block together you'll essentially have a MK2 1.8 GTI engine, the ideal starting point is getting hold of the complete engine loom & ECU from a post 90 spec MK2 GTI.  Post 90 is easiest, since the plugs on it will be the same as your fusebox.  I think you'll need a MK2 GTI distributor as well, I'm not sure if the 1.8SPI one will work, but it may do.
You'll need to changew the fuel pump as I doubt the SPI unit will be up to the job, and you might have to replace the fuel lines with MK3 GTI items as well!

[Laner]

hmmmm seems quite alot of work, will the gains make it worth the work or am i only joking at a more horses and abit of torque increase or is it worth getting stuck in and sweating it out. On paper it looks a worth while increase?

[rubjonny]

If it was me, I'd just drill the hole and keep the SPI.  You wont gain a massive ammount by fitting the gti injection system as well as the GTI head, you'll gain most of the improvements just by fitting the gti head & cam!
You'll need to leave the old injectors in though, or think of some other way to block the injector holes.

At the end of the day you can always fit the GTI injection system further down the line, all you'll need to do is swap the head with another one without the coolant hole.  There are plentry of MK2 1.6 & 1.8 carb owners out there who will bite your hand off for a pre-modded head suitable for their car, plus 1.8 MK3 SPI owners like yourself!

But tbh, for all the hassle of converting to injection you might as well save the effort for a 2.0 16v conversion or better