Can those who have carried out an engine conversion on their polo please write a few words regarding the swap and include a few pictures if possible. Please rate the feasibility of the swap, i.e was any welding required, what was plug and play and what wasn't etc. Only reply with conversion info, do not post questions. Please PM the authour of the reply for further info.

MK4 polo gti

I converted my polo 16v to a mk5 gti powerplant when my cam belt tensioner broke and trashed my original engine. The swap is pretty straighforward in all post 98 polos (not impossible on earlier mk4's but require a little more wiring).

Parts required from GTi

Engine
Gearbox
Drivers side engine mount
ECU
Pedal box
Fuel pump
Engine loom
Interior loom
98 onwards headlamp switch
GTi clocks
Mk5 window motors and switches
Mk5 tail lights
98 onwards indicator stalks
I'd also recommend the front brake setup from atleast a 16v

Fitting
The engine lines up onto the original mk4 mounting points (chassis leg and gearbox). There is no welding required at all.
I removed the wiring from the mk4 and replaced it with the entire mk5 loom. You could use the complete dash from the mk5 if you chose to once you have fitted the new looms. This would save on having to splice parts of mk4 and 5 loom together for things such as headlamp switches and heater controls. Essentially you are building a mk5 in a mk4 body shell.

Evaluation

From my point of view this is one of the easiest engine conversions to carry out. Its fairly self explanitory all the way through if you are reasonably able when it comes to car mechanics.

This is only a basic guide, I take no responsibility for problems anyone may encounter trying this swap. I have a zip file of pictures available for anybody wanting to try the conversion. Most of the long standing members will remember the trials and tribulations I encountered. If I was doing it again I would probably not bother. The power gains (25bhp) were not that noticable, a 16v with a few choice breathing mods would be more than capable of similar performance.

Converting a Polo GT to a Polo G40
A pretty common swap, mainly because it offers lots of power and is so damned easy! My conversion was complete within 48 hours thanks to Andy Strange. However, this is something that anyone with a decent set of tools, a garage, an engine hoist and a garage can do, albeit over more time I'd imagine.

What you need from the donor car
- G40 engine
- G40 gearbox - The CL's 8P box can also be used, G40's ATV is better.
- G40 supercharger
- Intercooler
- Wiring loom and ECU
- G40 brake calipers, carriers and discs (if you haven't already!)
- Driveshafts (optional, original ones still work)
- G40 160mph clocks (also optional)

The procedure (in a nutshell)
Begin by ensuring the car is left overnight to get cold, or you'll burn yourself! Switch the heater controls to hot so that the coolant can drain properly and remove the bonnet.

Next strip the GT of its induction system (airbox and associated pipes) and drain the coolant by then, starting at the front driver's side and working back to the ECU, begin unplugging the wiring loom. Then unplug the wiring loom from the ECU and withdraw the whole lot including the fuse box.

Unplug the ignition leads and remove the dizzy cap. Remove the throttle body, fuel rail and inlet manifold. Disconnect the pipes to the heater matrix. Disconnect the wires to the starter motor.

Your engine bay will now look something like this:


Next put the car on axel stands and unbolt the downpipe, pull this free from the rest of the exhaust system. Unhook the gear selector from the back of the gearbox. Now attach the engine hoist to the hooks at the back of the head and jack the hoist up a little so that the ropes are tight.

Unbolt the engine from the chassis at its three engine mounts, remove the nuts that hold the driveshafts onto the gearbox. You are now ready to carefully remove the engine and gearbox from your engine bay. Watch to make sure nothing is still attached to the car as you lift.

And out it comes!


While the engine is out you may want to clean the bay up a bit, this is up to you.

Fitting the G40 engine is a reversal of what you have just been doing. Gently lower the engine and 'box into position, aligning the driveshafts as you do so, then bolt the engine to the car using the three engine mounts. Once the engine is in place, check that the driveshafts spin freely and that all the nuts are tight, then re-attach the gear selector rod and check that the gear change is ok.



Now re-attach the coolant hoses and bolt the G40 downpipe onto the exhaust manifold. Connect the starter motor to the cable, but don't plug it into the battery yet.

If you are fitting a non-standard G40 charger or a smaller pulley, you may now want to transfer the G40 fuel rail and throttle body to the GT inlet manifold. The G40 one is more restrictive, but better suited to stock engines than the GT one I believe.

Bolt the inlet manifold and throttle body with boost return back in place then carefully route the wiring loom back through the engine bay. Connect up the ignition leads.

Remove the front bumper and bolt the intercooler bracket in place, then attach the intercooler to the front crossmember. Remove the fan cover from your old engine, and replace with the G40 one. Now fit the boost pipes from the intercooler to the throttle body ensuring that all are tightened securely.

It will now look something like this:


Next, bolt your G charger in place, attach the oil feed and ensure that the V belts are tight. If you are keeping your boost return pipes, attach these now. If not put your blanking plate onto the vacant inlet on the charger and connect some hose up to the crankcase breather pod on the back of the engine block.



Now fit your air filter/induction kit to the other inlet. Refill the coolant system. Connect the battery.

Check to make sure that you haven't left anything unplugged then cross your fingers and turn the key.

It is worth getting the G40 brakes on before you take it for a spin, these are a straight swap for the existing GT brakes and a simple job to change. Don't forget to bleed the brakes after you swap them though!

Job done!


Worth replacing while you're doing this...
- Both fuel pumps - not cheap, but cheaper than an engine rebuild
- Gaskets - inlet manifold, throttle body, downpipe, exhaust manifold
- Cam belt and water pump
- Get the charger serviced
- Service stuff; air filter element, plugs, leads, dizzy cap, oil and filter etc
- Clutch
- Gearbox oil (if you can take the smell!)
- Engine mounts if the rubber seems tired

Extra stuff for non-GT owners:
- You will need to change at least your inline fuel pump if you have single point injection, your stock one won't be up to the job
- The expansion tank on a GT/G40 has a connection for plug that says when you're running out of coolant, don't forget to get that too. If the conversion doesn't come with it, GSF sell them for £15. (thanks to Jon_S for that)
- It will also be worth you looking at getting a GT/G40 rear beam, as this has a second anti-roll bar

Evaluation
Lots of fun to be had with this engine conversion; damned quick as standard, dead simple to get more power and it sounds awesome too.

But MAKE SURE YOU CAN LIVE WITH THE COSTS!

G40s aren't that light on fuel and require constant attention. PTFE lube in the charger every 1000 miles if you've removed the boost return, new charger timing belt every 10,000 and a full charger rebuild every 30,000 miles is advised. It's worth it though.

To those more in the know than me:
PM me to if you spot anything that I've left out, but I can't remember there being anything else!

QUOTE

Only reply with conversion info, do not post questions.

Just another thing on non GT conversions, I discovered on ETKA that the brake servo is different (in size I think) so this maybe worth changing also if poss, although I'm not sure how much of a difference it will make?

I didn't now that. Just looked and the diesel mk2/3's, as well as the GT/G40 have a different servo.

if you're doing the brakes, get a golf 16v (also passat?) 22.2mm brake master cylinder. bolts straight on, if you buy from GSF you get the blanking plug needed (polo uses 3 brake lines from front) or if you do the whole new pipes, use 4 lines.

What engine could I drop in my 1.0L Polo Mk4. My engine code is AER. Just need a few suggestions to point me in the right direction. Would the engine in the link below fit ? Or does it need to be from another MK4 ?

The rough guide to the 1.6 GT conversion.

Sourcing an engine. (AEE/ABU)

First things first, don’t pay much more then £100 for the engine. If they try and persuade you with the ‘It comes with everything’ tell them you don’t need anything other then the engine itself. Don’t be tempted to buy the whole lot and sell the rest separately as there isn’t much demand for the parts. The only things worth getting are the exhaust manifold and downpipe and oil breather that is bolted to the back of the engine and that’s about it. Everything else will be from a mk3 polo.
So once you have yourself an engine remove the existing parts, engine mounts, inlet ect depending what it comes with.



Engine mount

You can put the mk3 front engine mount on straight away (I used new bolts to be safe) this raises the first issue, no third bolt. You have a few options, cut and weld a piece in, make a bracket that goes to a lower casting hole or leave it. I made a bracket out of 7mm steel, literally goes from the third bolt to a lower cast hole, if I remember rightly it sits flat so a straight piece of steel should do the job. I have also heard of people using higher tension bolts which seems like a good idea if your going to just have the two. Some minor trimming needs to be done on the cam belt cover so that the mount doesn’t push it inwards.


Cam belt change

The next job is to change the cam belt, tensioner & water pump, before you put the engine in otherwise you will regret it later on. So remove the alternator pulley which usually will be a lot wider then the mk3 item this needs to be changed otherwise it wont clear the mk3 chassis leg.



Mk3 Alternator pulley

Once you have had fun changing the cam belt, tensioner & water pump offer the mk3 alternator pulley to the position, you will now find the tensioner bolt rubs on the mk3 pulley, if so you need to grind the head of the tensioner bolt slightly, literally 2-3mm will do so be careful not to go to mad. Once happy fit the pulley (use new bolts if there rusty).



Lower cam cover

Now fit the bottom cam cover, the shape of it means the mk3 pulley rubs on a certain area (the part that bevels in for the tensioner bolt ironically) You just need to trim it so it fits, 5 minute job just make sure nothing catches on the cam belt before putting it all back together.

Flywheel & Clutch

If your going to use the mk3 polo gearbox you want to scrap that huge flywheel! Remove it and replace it with one from a mk3 (there might be an adapter plate in place just remove it and the mk3 flywheel will fit no problem. You also need to use the mk3 clutch and bell housing. (make sure you use new bolts for the flywheel and torque them up properly!) Its well worth using a new clutch, I used a clutch with unknown miles and its just started slipping when booting it! So don’t be tight as the torque of the 1.6 will kill a half knackered clutch.



Gearbox

I used the 8P box from a 1.3 CL mk3 polo, I was tempted to use a GT box but decided against it as I knew the 1.6 would have enough grunt to pull well on the longer box. Make sure you use a healthy box with new oil otherwise you might lose some gears!

Inlet manifold

This is the big one, it doesn’t fit simple as. The bolt holes are so close its annoying. Two sensible options, have the head welded and drilled (exspensive) or have two inlet cut and shut. Niether are particularly good fun. I was quoted £400+ to have the head done which was a big no no seeing as the idea of this project for me was to get standard G40 power for GT conversion money! So the next problem is, all the AEE inlets are plastic, can’t weld with that. However the ABU inlet is aluminum. I found a mk3 Golf and took its inlet. I then spoke to a lot of people about how to cut and shut the inlet. The welding wasn’t much of a problem it was the cutting, it needs to be flat so using a saw and a vice isn’t really ideal.

I managed to persuade a local engineering company to have a go at it and they quoted me a very good price seeing as they didn’t know how long it was going to take. The main problem here is that most places, when you explain what you want doing run a mile! So ABU inlet, cut the flanges off, do the same with the GT inlet and weld the ABU flanges to the GT inlet, easy…
Mine turned out very well, there’s some material that can be ported later on but I haven’t got round to that yet.
You will also need to make some sort of bracket for the inlet to give it some more support, using rubber mountings is a good idea to avoid cracking the welds.




Alternator

When fitting the mk3 alternator and bracket you will find it touches the oil pump cover. Just lightly shave some metal off so it can fit as per the picture.
Starter motor
If using the mk3 flywheel you need to use a starter motor from a 1994 mk3 polo. The AEE one want even turn the engine due to the distance difference in the flywheels.



Coolant system

The GT thermostat housing won’t fit without re-drilling the head. Use the housing & the water pump pipe from the AEE. This also means you need to mount the ISV somewhere else as its bolted to the GT water pump pipe. You can just cable tie it in place where it would normally sit. You will also need the radiator hoses from the AEE as the mk3 ones are too short.
I would recommend using a new thermostat housing and thermostat as they can crack and leak as they get old.

Downpipe

If you use the mk3 exhaust manifold and downpipe you will have problems straight away, because the block is taller it doesn’t clean the ARB and various other things. You can either extend the downpipe or do what I did and use the AEE one.
I used the downpipe from the AEE that had, had the CAT cut off so some extra pipe needs to be welded on.



Oil sensors

The AEE head only has one oil sensor where as the GT runs two, the best way round this is to use a oil feed adapter from a G40.



Injectors

The Polo GT injectors wouldn’t cope too well with this setup so you need to use different ones. I’m currently using Golf Gti injectors which are slightly overkill but seem to work ok, however there are many available from different makes and models. You basically want somewhere between GT and G40 cc.


Cam

You will want to use the GT cam for a bit more power, the timing marks don’t line up so you need to be careful and make sure its setup right. I cant go into detail as I haven’t done it yet.

Parts & tuning
GT parts
Inlet manifold
ECU
Engine wiring loom
Throttle body & piping
Airbox & pipework
Camshaft
Clutch & bell housing
Flywheel
Engine mounts
Gearbox
HT leads / Dizzy + cap

G40 Parts

Backbox
Straight through centre section is worthwhile
AEE/ABU parts
Exhaust manifold & downpipe
Engine
Golf Gti
Injectors (8v)
Air flow meter

Conclusion

I don’t think I have missed anything significant out, there’s possibly a few more things but nothing I can recall of so they can’t be that serious. It’s a worth while conversion as long as your prepared to do some head scratching. In terms of performance it will eat almost all GT’s that are still running GT management, even cam’d and chipped examples. Great fun to drive loads of torque and they do rev nicely with the light flywheel.

You can see my build thread here

Enjoy.

Ash Carver

Hey guys any info about putting a 1.8T into my Polo. Woud it just drop in or would i need to make extra mounts etc ??

Cheers.

you've asked this question, within the FAQ section..... ironic.

no it wont just drop in, unless you have a new polo, that was designed for a 1.8t

subframe, custom driveshafts, custom mounts... blah. use the search function.

I am doing the G40 converswion and this seems very useful but no pictures are showing up on the gt to g40 conversion section. Where have they gone? all i see are little squares with crosses in them. dont telll me they have been deleted .

anyone got a guide for a mk3 1.0 spi to gt?

hey i have a 1993 mk3 vw polo 1.3 cl coupe
and i want to do a 1.8t engine (from a golf) conversion on ma polo
i now its possible cus i have seen it but i just dont now how?
i needs to what i need like a different subframe chasis modifications etc.
any help would be most apprciated
the work will be done by myself.

A guide on the now very popular AFH conversion into mk.2/3 would be great on here, especially if it was as in depth as carver's AEE info. So come on 16v people, give us the lowdown!

Funny you should mention that, a few of us were talking about writing a comprehensive guide the other day, will get on to it.

Please do! Pros and cons of the ABD, AEE and AFH would be useful as they seem to be the top three choices for mk.2 and 3 engine swaps.

iv got a 1.0l 2001 polo and i want to turbo it.. any 1 no were i should look or do lool.

Hey i didnt bother reading the first post and dicided to comment any way...
Nice thread btw

Fuckin lol

very usefull info just what i was looking for ,for my mk2 aee conversion

Has anyone fitted an ABF (2ltr 16v from mk3 golf gti/corrado) into a mk4 6n polo?

I am going to be doing this conversion regardless but would like some pointers if anyone has any?

If not, i will trial and error the bitch into the engine bay and let you all know how it goes.

Cheers

Its a tall block engine and will be a lot if work for very little gain power wise.

Well the work required doesn't really bother me, more of a fun challenge, plus the power gain I think will be worth it as my current engine is a measly 55bhp.
Cheers for the reply anyway, I will have a good think about it.