Skip navigation

1.8T Conversion Guide


Back to the top

1.8T Conversion Guide

1.8T Conversion into a Mk1 Golf

i get asked all the time so decided to put a thread together for questions and awnsers hope it helps

There 2 different options for engines in this Guide we will be using the engine for a transverse car  to make the conversion as simple as possible .the other option is the longitudal engine but this requires alot of parts to be swapped over so not a good starting point. So engine of choice is an AGU these are found in Audi A3's & Mk4 Golf and possibly other VAG variants
Standard AGU comes with a K03 turbo and 150bhp as standard on the oem ecu. Its always best to try and find a low mileage engine with history for piece of mind but ive know of 50 engines still being good once fitted

To make the conversion simple the 020 gearbox is used this is the standard  Gti gearbox along with the gearbox you will need the complete clutch &  flywheel from any 5 speed 020 derived car just make sure the clutch plate fits the gearbox splines. Remove the standard 1.8T dual mass flywheel clutch ect and fit the 020 hardware . along with this you will be able to use the standard driveshafts 100mm or 90mm most people go for the 100mm but i have seen 90mm shafts used .

So with the engine and gearbox together and an empty bay you need to sort the engine mounts out to get the engine in. On the gearbox side of the engine you can use the standard Gti mounts but it is worth fitting a rear poly mount to give the engine a bit more stability.
The Cambelt end mount will need to be a modified one which are available from places like the caddy forum, gwerks,crazyquiffs ect along with this mount you will need a 16v cambelt tensioner to replace the 1.8T item as it fouls the mount youmay need to get the stud with the tensioner or a longer bolt cam be used before fitting the tensioner you need to space it 8mm away from the head soothe belt runs true !…….. Always worth replacing the waterpump and cambelt whilst your at it as things get a little tight once the engine is in

Fuel System
While theres no engine in the bay its worth gently bending the fuel pipes to the drivers side of the bay then trimming them to the desired lengh be gently when bending them as they can fracture.once in place find a fuel filter that fits i use

Aux items
Power steering pump can be binned leaving just the alternator you will need  to get a smaller fan belt the part number evades me but i sure someone can chime in with this. Standard 020 starter motor is also fine to use and will spin the engine over no problems.

Engine In
So at this point the engine is ready to be fitted youmay find the turbo will catch on the bar bars in the back of the bay a bit of jiggery pokery will get it past, so engine is in and on its mounts at this point get the driveshafts ect fitted ,
Gear Change
You will find the flat bar will foul the turbo actuator don't panic bend the flat bar down so it misses the actuator this may be easier to do on a bench as its quite hard in situ

Water System
Get a mk2 16v radiator and fan as its a bit smaller than a standard Gti one mount this to the left where the original rad would of mounted . for a top hose i found a reanult laguna one fits nicely and a Mk2 Golf lower hose fits snug to then its on to the other hoses it s a case of trial and error i found with the heater matrix pipes cutting them back closer to the bulk head this way the heater matrix supply valve doesn't foul any of the pipework or turbo

Custom intercooler from ebay is fine just make sure it fits between the grill and the rad and the ends sit out ether end of the rad to make getting the pipes on easier decent clamps is a must or the pipes will blow off under boost

So with the engine in you should have an idea of what engine management  you are going to use most come with a pig tail loom and instructions on how to install then its just a case of splicing into the mk1 loom which is easier if you have a multimeter you can use
Different types of ecu's
Its all down to budget

Qpeng do a downpipe whichs fits lovely along with a sleave pipe that reduces the size to fit the mk1 exhaust  

So thats the basics theres loads which ive probally missed but this is the best place to ask questions for all to see ill try and get some pictures together  as we all like pictures don't we lol


Back to the top
With the wiring im sure rubjonny can chime in with all the relevent feeds and wire colours needed to get things like the dash gauges ect working lol


Back to the top
That megasquirt ECU wiring diagram might be useful on here maybe!

I'll be doing my wiring in the spring I think, when my soldering iron will work properly outside!

Whats up with your website Ben? Its been down for a while now.

89 Clipper Cab 20v (97% done!)
97 Peugeot Expert (daily, 510 off of ebay!)
06 Audi A3 (Wifes daily)


Back to the top
fastgolf is now gone i have tried to get in contact with paul to see if he has copies of the guides


Back to the top
piture guides will be great thanks for taking time to this guide

heres my questions now :)

whats throttle cable do i need?

if a engine has covered 112k agu what part should be renewed  waterpump,belts, ?

can i buy of the shelf  pipe work for intercooler and turbo?

if running megasqurit what eles can be binned of engine?


Back to the top
good points

1.3 mk2 cable will be fine

cambelt ,waterpump, oil filter fuel filter usual service stuff to plugs ect

no of the shelf ic piping but you can get kits from ebay which will be universal and fit with some love

with megasquirt the engine only needs the following plugs

temp plug
vr sensor
iat sensor

you can bin the cops, cas sensor wiring knock sensor wiring

its really down to how you make the loom and what coilpackect you want to run


Back to the top


Back to the top
yep if its mk2 1.3 cable then it will fit


Back to the top
ok sorted is it best to change manifold and turbo gaskets

as the engine is out on stand or leave em be as engine has done 112k

also as eddie ant got back to me yet is it easy to fit boost on ecu if it has not got it (megasquirt)


Back to the top
get me a picture of the ecu and i can tell you just looking at it a pic of the end with the big plug

dont worry about the gaskets


Back to the top
jubjonny got my ecu ive asked him to have a look


Back to the top
hi,i have a knackered a3 agu engine could i use a 20v engine out of a passat maybe ie apt etc,what parts would need to be swapped? cheers ben  8)


Back to the top
yep use the AGU parts inlet manifold turbo ect and fit it to the APT lump you may even find the standard drivers side mk1 mount will fit the APT lump without modding it but dont quote me on that lol

also check the inlet on the APT is a big port first as thats what the AGU is so the manifolds may differ on the ports


Back to the top
:mrgreen: cheers ben,its just there a lot cheaper than the agu  :redfaced:


Back to the top
Excellent guide. I just have a couple of questions:
1- Is the 020 box man enough? Some people say you should fit the 02A.

2- Is the engine mount the same one people use for a g60 conversion?



Back to the top
1. not really no, you should fit the 02a. unless you liek swapping gearboxes
2. yes

Hello my name is John and I'm a dub addict.

My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)


Back to the top
Hi Ben, great little guide :D can't believe i'v only jst found it, did you do one in 2007 aswell.??

Right mate i'm doing a aeb conversion i'm jst cleaning my engine up at the min, and i'v built up some question's, i would really appreciate it if you could answer/confirm please:-

1. I'v been lookin at transverse 20vt inlet manifold. How come i'v seen left and right hand intake.? (is it the picture reversed.?)
2. Can I strip my manifold down and put the parts on transverse manifold.?
3. Do I still need to change timing belt tensioner to manual.?
4. What mounts do I need, big block all the way round.?
5. Does my turbo need to be changed to transverse type.?
6. Can i use my exhaust manifold.?
7. Jst to clarify:- a radiator cools water, a intercooler cools the air, do I need an oil cooler.?
8. Do I buy new rubber for the engine mounts.? i'v seen poly for front mount.. is this a good idea.?

I think thats about it at the mo, thats clogging my head up :lol:

Thanx Shaun :D


Back to the top
great write up ben
jus a question i have
i have a 1.5gx with a mk2 16v brake servo and master cylinder installed, willl this be ok in the position it is in as i have been told there is clearance issues when this is done

also are there any links to the mounts required


Back to the top
no master and servo will be fine only clearance issues with the 16v conversion

mounts all depend on which gearbox you use if you use the 020 then you only need the cambelt end mount unless you have a AEB engine then the mk1 mount should bolt straight on if i rememebr correctly


Back to the top
I have been offered an aeb engine but was just unsure what needed changine for this, if i was to use the aeb engine what would i need to change on the engine itself and which cambelt side mount would be best??
Is there much difference between the agu and aeb engine?
0 guests and 0 members have just viewed this: None.