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Author C20XE Conversion Guide

Registered: 9th Nov 07
Location: portsmouth
User status: Offline
7th Jul 08 at 20:54   View User's Profile U2U Member Reply With Quote

Hey guys,

recently got my hands on this and thought it might be handy for a few of you looking to do the conversion yourself


This will show you all the things you need to consider and tips on how to convert your standard Corsa engine with a 2.0 XE engine from a cavalier or and Astra or even a Calibra.
The Corsa 20XE conversion is outlined below. You need to consider all the points in the list, but the 20XE engine does bolt into the Corsa pretty simply. This conversion is all about preparation and doing homework. It’s made so much easier by reading the following, the Haynes manuals and having and understanding of the components you are using in the new engine. Things will go far smoothly if you do this instead of just jumping in. I have tried my best to keep this as simple as possible but some knowledge of the cars is necessary to completing. There will be problems you will come across in this conversion that may not be mentioned in this guide. AS it says, it’s a guide but if any problems occur they will be easy solved by you. This guide is just to make things easier for you. Hope you enjoy your project.


Axle Stands
Trolley Jack
Engine Hoist
Full socket set and spanners
Various Screwdrivers
Stanley Knife
Hydraulic Car Ramps (makes life so much easier and quicker.)
Allan Sockets
Black Electrical Tape to tidy up wires
Brake Cleaner
Blue Roll or rags for cleaning up
Pry Bars
Angle Grinder
Torque Wrench
Wire Strippers
Bullet Connectors or shrink connectors

Some of these tools you will not need and you can get by and a socket set and whatever else you can find but these tools above will make things go a lot smoother.


Cavalier MK2 1600 Inner CV Joints
SFI Adapter Plate
Ecotec Pipe
Above not needed if purchasing a powercap.
Performance Air filter
Possible trip to exhaust company to mate down pipe
Engine mount (plus rubber – if 16v model)
Anti Roll Bar Tie Bar Mounts (NOT ESSENTIAL)
Possible Fuel Pump Relay – (Notorious for cocking up)
MPI Fuel Pump (if car is a SPI)
Block or bullet connectors – male and female
16v header tank. (if car is a not a C16XE X16XE or X14XE engine.)
Assortment of Nuts bolts in various lengths and threads – In case you round the heads of some.


Before you jump in:

Consider the age of the engine and when it had the timing belt last done. Personally I would get a full service of the engine. New belts, plugs, leads dizzy cap (if you have one) oil filters etc. Ok, it’s an expense but its better than it breaking down in a couple of week’s time, after all the work has gone into it. While the engine is out make use of the free arm space. Change all gaskets as you don’t want them leaking on you. When the engine is out, do the head gasket too, perfect time and it’s also a good time to port and flow the head and get the valve stem seals a change. If you have seen and heard the engine running it’s a good idea to do a compression test. It will give a good indication of what’s going on. Compression test results can vary but the most important thing about them is that the results are even on every cylinder. As a general rule of thumb 1bar between cylinders is acceptable. Any more and there are problems looming.

Yes the new 2.0 16v XE will drop into your engine bay engine bay, but your new insurance premium will be based on the car that the engine came out of. For example an Astra GTE and Cavalier have the same 2L 16v C20XE fitted; however the Astra GTE is a higher Insurance Group (IG) than the Cavalier (because of the 'sporty' GTE name tag). Try and source the engine from a old Cavalier and your Corsa IG will be based on that that car!

V5 or Log Book:
You need to make changes to this as well, change your new engine number and engine capacity, then send it off to the DVLA to get a new V5 form

The fuelling system for the 20XE requires two lines from the petrol tank, one supply, and one return.
As most Corsa’s come with this as standard then it’s very easy. All you do is screw in the feed and return pipes into the XE’s Fuel rail. Job Done. As long as your engines start with the following codes. C16XE, X16XE X14XE
If your car is not one of those codes and is an SPI (Single Point Injection) you will need to get a pump from one of the above cars and fit it in. Fitting is simple, just lift the seat and follow the Haynes manual. Depending on what engine was in your previous car you may also need to either extend or shorten the fuel lines. You can get these from any decent motor factors. If your car was an SPI model, like a 1.2 8v you can use the original fuel line connection nipples from the MPI throttle body. I removed them and fitted one to the fuel rail and the other to the fuel pressure regulator. You will notice that the fuel pressure regulator has an M5 thread on it. You will need to have the nipple lathed down and have a new thread tapped to it to bring it down an M4. This seemed the easiest option for me.

Lots of different theories here. Il give you mine. The engine that is getting installed is 150bhp here or there. You can stitch weld the chassis if you so wish but the Corsa has been strengthened from standard so unlike its older brother the nova is a better put together car. You will be more than ok with just installing your new power plant. But if you’re using it for track days id give it a stitch weld. Weld one in and leave 2 then weld another inch. Still gives you that bit of flexibility.

Engine Mounts:

Picture above is of a 16v mount fitted

Ok, on the Corsa you have 2 different types of mounts. You have the 8v mount and the 16v mount. Depending on what engine you had in the car before this will determine the mount you have to purchase.
The front offside mount must be changed from standard so that the engine sits approx 1-1.5" down from its STD position. This sits the engine straight, and also enables you to shut the bonnet without risk of the engine hitting the bonnet. To do this, you can fabricate your own (to hassle – what’s the point) or you can log onto On here you will find LOADS of guys flogging mounts, 50 quid should cover it. The nearside mount just gets left as it is. Engine bolts directly into that mount. The gearbox is pretty straight forward. People’s opinion will vary on this but it worked well for me. I kept the standard Corsa mount and never bothered with spacing it 10mm – NO NEED!!! I modified the Gearbox rear mount to sit flush against the new F20 Box and used the old bolts to bolt her back up. Simple!!! No need to extend any linkage then. Il explain Later about this.

Running standard up rated shocks + springs is not great, but it seems to work well enough to get you started. Seriously think about getting some proper rated bits for the conversion though, it makes a lot of difference.
The Anti-Roll bar hits the 2ltr tubular exhaust manifold. This can be got around in two ways. You can either remove the anti roll bar all together, and run without one, or you can modify the tie bar brackets to lower them on the front cross member. To do this you need a block about 1incg thick and extended bolts to tighten it back up. With so much more weight at the front of the car with the 20XE engine in, running without the ARB isn't as daft as it sounds. It helps in a way because you tend to get more under steer with the heavier engine anyway. Most people prefer the handling with the ARB removed. It's wise to use a strut brace with the 2ltr conversion IMO.

Drive shafts:
For ages people had to buy expensive custom drive shafts. Whereas it turns out you can just use Corsa 22 spline (that’s a must) drive shafts, and put Cavalier Mk2 (late) 1600cc inner CV joints. These fit in the F16/F20 gearboxes fine

Wiring is easy; the motronic looms are whole looms in their own right. All you need to link between the Corsa and the motronic loom is a permanent live (large red), Switched live (Black) and all the earths, 2 on the fuel rail and 1 from the chassis to the gearbox. This should be enough get her to turn over. You then need to connect up the fuel pump relay wire to get her to start. This wire should be a thick blue and red wire. Connect this to the thick blue and red on ther corsa. And crank her up. Then just connect the dash wires to the relevant places. Most of the dash wires are brought to the ECU part of the loom, where they normally connect across to the dash. If you have the large circular connector in the loom for your 20XE, it contains 90% of the dash signals you need. Its all colour for colour.

these will need to be upgraded no matter what base model of Corsa you have started with. The minimum requirement is to replace the front brakes with the bigger 16v ATE callipers as found on the Astra GTE and Cavalier SRi's (basically any 16v car). The rear brakes don't really need upgrading, but they can if you so wish. Both the SRI and GSi models had bigger brake servos as standard. If your Corsa is not an SRI or GSi, then changing the brake servo to the bigger item will benefit the feel and braking power of the bigger brakes.

2 Choices of gearbox here. 1 is called the F16 which comes from 8v cars and the other is the F20 that comes as standard with the XE engine. Both mate up no problems to the XE block but I’m pretty sure that if you do decide on the F16 you will need an 8V Clutch and plate to fit inside this and possibly the flywheel. I’m not 100% sure on this so before purchasing the F16 please research this. The main difference between the too is acceleration. The F16 has a lower ratio that the F20 so it will get to 60MPH quicker than the F20 but the latter will have a better top speed. You will also need to use the Corsa selector linkage on the new gearbox. Just take the linkage from your old gearbox and place it on the new one. Depending on what type of linkage you have there is a small modification you will need to do to the steel backing plate just in front of where it connects underneath the car. On the backing plate there is a lip on the top facing about 45 degrees forward and on the bottom its facing 45 degrees in the opposite direction. You need to hammer both lips straight to match the rest of the plate making it totally horizontal otherwise it will foul the steering rack and wont let you engage 2nd and 4th gear without a fight. Another handy tip!!!

The existing exhaust system can still be used but the manifold will either have to be modified or a ready made unit can be bought. The C20XE down pipe will not mate with the Corsa system, so the pipes will have to be heated up with a blow torch and bent to shape so they mate. Or you can weld and fabricate the exhaust till it mates correctly. Powerflow exhausts are a good company to build you up a system.

Wire loom/ECU:
There isn't much wiring to be done, but it is easier if your start off with a injection model of Corsa. The whole original Corsa engine, gearbox, wiring and ECU (if fitted) can be removed as a whole from the car but leave the starter wiring loom as this will mate up to the new engine perfectly. Then when you fit the new engine and box in, you need its ECU and wiring loom to finish off the job. Basically there are only a few wires to connect.
The red wire I described above is on the Donor engine loom. You need to connect this to the battery in order to get power through to the engine loom. Here is all the wires you need to connect.

Engine loom > Car loom:

Red (with black cover) constant 12v > battery
Black with 1pin cover > black (ignition live run from inside own car into engine bay)
Green > green (rev counter)
Brown/blue > brown/blue (ECU light)
Blue > blue (water temp gauge)
Thick red/blue > thick red/blue (fuel pump)

All connected inside the car down by the ECU plug, apart from the constant 12v and ignition live which are done under the bonnet
Above it’s not the same for every engine wiring loom. Depends what cars donor engine is coming from but this covers 95%

Oxygen/Lambda sensor:
The lambda sensor reads engine emissions from the exhaust gases and the ECU adjusts the Air/fuel mixture accordingly. Make sure your engine has a functional one of these attached to the exhaust manifold; these are delicate and expensive to replace.

Use a corsa clutch cable
Use an Astra / Cav accelerator cable. Mine needed adjusting on the accelerator pedal to give full throttle.


Engine removal preparation:

Get a Haynes book for the car and read it about the engine, transmission, brakes, suspension....the whole lot. The idea is that you will be become familiar to the terms used, parts and where they are located on your car. It may be useful to have a camera with you and take pictures along the way. That way, when you fit things back, you know how they go and their orientation.
Engine removal:
1) Disconnect the battery and remove.
2) Drain the engine oil and gearbox oil may be an advantage.
3) Drain the coolant system.
4) Follow the Haynes book on engine removal.
5) When removing any electrical wires, connectors or sensors, you MUST label them. This will make life easier when fitting the new engine in.
6) You can leave the following items in the car; brake servo, steering rack and the coolant tank. Everything else can be removed.
7) The engine should be able to be removed from above or below, what ever is easiest for you.
You should have the following items taken out
• engine
• gearbox
• drive shafts
• inner CV joints
• outer CV joints
• radiator
• ECU and cable form/connectors
• gearbox selector/linkage
• coolant pipes
• alternator (on engine)
• starter motor (on engine)
• air box and piping
• anti roll bar (if fitted)
• manifold (on engine)
• ignition coil and HT leads (if applicable)
• Discard the oil cooler and plug up the holes. It’s not really needed unless you’re planning track days.

New engine preparation:
If the new 'big block' engine hasn't been removed yet, it may be wise to label up all the connectors and wires, so you know what to connect it to when fitting it in the Corsa. But again, do the same as above, take notes of what went where and label anything. It’s better to be safe than sorry. Also a HAYNES manual for the engine you’re transplanting isn’t a bad idea either.
With the engine bay empty, inspect the area for rust and bad corrosion etc. Treat the area, sand down and weld up the engine bay. This is the time to put in the new loom ready for your new power plant. Get it all laid out in the empty bay as possible. As you have the engine out and the room to play about with, you might as well do as much as you can here.
You should already have the new engine; make sure you have the following parts/items:
• ECU and all the wiring and sensors that go with it (very important).
• Accelerator cable.
• Air Flow Meter
• Ignition coil and bracket (originally situated behind the headlamp).
• Manifold and down pipe including the oxygen sensor (if fitted).
• All the coolant hoses and clips if possible.
• Starter motor in place
• Corsa linkage from old gearbox now on the f20
• Wiring loom in place in engine bay

It would be ideal if the donor engine has been seen and heard running before fitting it into the corsa


Above picture is without gearbox but its best to fit with gearbox in place.
If the gearbox is attached to the engine, then the engine can be mounted in the Corsa from either underneath or from above. I found up above easy but I had a ramp and the proper tools. Hence you need to decide what method you will use. Above is always the best IMO. I had the engine on the hoist at a 45 degree angle and slid it in gearbox first. I bolted up the gearbox mount first. You may want to get a few mates involved to make sure nothing is getting broken as you are lowering it in. Then bolt up the driver’s side one then the rear, you may need to put a trolley jack underneath the car and raise it a little to do this and. The engine should now sit unaided in the car

Engine Mounts:
Fitting these is apiece of piss, just a matter of bolting them up. The new mount you just purchased from EBAY will be a fabricated one and bolt in directly where the old one was before. If you have power steering in your car the pump will also need a new mount. This also can be purchased from EBAY and it bolts on above the new one. The rear mount needs modified so il explain in detail here. Take the rear mount off; what you need to do is grind lip flat so the mount sits flush against the new F20 box. Not too much as we still need strength in this mount. Once that’s done you just bolt its back up and away you go.

Picture of a 8v mount

Drive shafts:
All you do is take the old shafts, keep the outers from the Corsa and put the new ones from the MK2 cavvy onto the splines on the inner end of the shaft. Hey Presto… Wasn’t so hard was it. Messy job though. Make sure you use plenty of the CV grease. Circlip pliers come in very handy here.
Ignition coil:
Very important to have this, the Corsa one can not be used IF YOU HAVE ONE (well it’s best not too as you will struggle to get anywhere). The 2L coil can be situated anywhere on the passenger side as long the plug can reach. And make sure have a good earth.
This is the bit where everyone panics but really its very simple… you will need to connect 3 wires to make it run as explained earlier…. Live, earth and switched live… The solid red wire with the ring terminal at the end goes to the battery, the black short wire (single pin) that comes off the end of the bigger cord of wires from the ignition coil and the hall sensor gets cut and joined into the black wire inside the car. Then the browns with all the other browns and that’s it, job done. The ancillaries inside the car will need cut and joined also. That’s the wires beside the ECU plug, that’s where the wires need joined inside the car. These wires get fed through the hole in the driver’s side bulkhead.
Here it is again in case you forgot.
The red wire I described above is on the Donor engine loom. You need to connect this to the battery in order to get power through to the engine loom. Here are all the wires you need to connect.

Engine loom > Car loom:

Red (with black cover) constant 12v > battery
Black with 1pin cover > black (ignition live run from inside own car into engine bay)
Green > green (rev counter)
Brown/blue> brown/blue (ECU light)
Blue > blue (water temp gauge)
Thick red/blue > thick red/blue (fuel pump)

All connected inside the car down by the ECU plug, apart from the constant 12v and ignition live which are done under the bonnet. It’s really just a case of colour for colour when connecting up in the car.

Fitting these is very simple as well. They are a direct replacement for your old ones. Read the Haynes manual on your own car on “removing brake callipers” Follow it step by step. You will need a 10mm Allan socket of key to remove the callipers. Once off remove the brake disc and give area a good clean up. Fit new bigger disc then it’s a reversal of the above but with the new calliper. You will also need to bleed the system. A good an easy was of doing this is filling the reservoir, unscrew the bleed nipple 1 turn and let gravity do the rest. Once there is a steady flow on fluid coming through with no drips tighten and do the other side. The ideal way is to get a friend to help and pump the brakes till all air is out and tighten.

This is an area where you can ruin everything if you’re going to be using the car on the twists. The weight of the engine in such a small car is a hindrance already but up rating your suspension will pay off dividends. Get a full Koni set up or the likes. Don’t have your Corsa handle like a boat.

The rest of it:
Once all the wiring has been done connect up all the plugs to the relevant places and all the coolant hoses. You will also need a 16v header tank if your car was not already a 16v. or you can t piece one of the Hoses. The mounting point is in the car already so it’s a case of just sliding it in and connecting up. The fiddly bit is putting the manifold on the car. Once that’s in place, slide the radiator in then the cooling fan. It’s fiddly but it does go in. Here is a picture showing how tight it really is

With the car in the air, its time to mate the exhaust to the down pipe. Lots of ways you can do this but what I did was I bent a piece of pipe slid it over the new engine down pipe and the new nova system then welded it in place. Jobs a good un. Another fiddly bit it the setting up of the linkage. Good way to do it is this. Lift up the gear gaiter in the Corsa, get a screw driver and stick it in the hole on the left hand side of white plastic. That will lock it in place. Then go round the front to the gearbox, there is a plastic plug on the box (you may need the Haynes manual to help you locate this plug) you pull it out and slide in a 4mm drill bit. Once that’s in all you do it tighten up the 13mm bolt on the selector rod underneath the car then tighten up on the box take the drill bit and the screw driver out and your done. You should get every gear now.

Checklist and re-cap:
OK, this is basically a recap from the start to the very but in a brief format.
To remove the current engine:
Disconnect and remove the battery
jack up front end, and put car on axel stands.
Remove wheels.
Remove hub nuts (30mm deep reach socket required)
remove brake disks and callipers
remove hub carriers from the strut, track rod end and tie bars
remove drive shafts from gear box - you will need a bucket underneath to catch the gear box oil.
Remove exhaust manifold.
Loosen and free the gear linkage
disconnect PAS (and AC) pipes (again bucket required)
remove drivers side kick panel and disconnect ECU from loom and unplug engine loom from car loom.
in the engine bay - pull the engine loom through from the car
remove air box and induction tubing
depressurise and disconnect fuel lines from fuel rail.
un plug the grey plug near the gear box (connects aux loom to car loom) - disconnect the car loom from the positive battery terminal
remove water pipes, radiator and header tank
remove vacuum hose from brake servo
- check there is nothing else connected the engine -
support the engine (and gear box) with engine hoist
remove the rear gear box mount and disconnect the gear linkage at the top of the gear box
remove the NS engine mount
finally remove the OS engine mount, the engine should now be "loose" in the engine bay
raise the engine out of the engine bay, looking out for any pipes / wires that may not have been disconnected.

prep -
clean the engine bay and make sure all pipes / wires are out of the way
transfer aux loom from old engine to new
remove exhaust manifold from new engine if it has it fitted
fit new engine loom to engine, (preferably from a cavalier / calibra – very easy to wire up)
transfer water pipes (heater matrix ones etc) to new engine
remove any engine mounts currently on the new engine
mate new gear box and new engine

Fitting -
lower the engine into the engine bay (gearbox end first - so it needs to be at an angle)
line up and bolt up gear box side mount
continue lowering until the drivers side mount lines up - when it does, bolt this up.
bolt rear engine mount to gear box and bottom of car - you may need to jack up the back of the engine to do this
connect water pipes to heater matrix
plug grey plug into car loom
connect fuel lines
re instate exhaust manifold
fit radiator, header tank and other water pipes
fit pas pump and connect hoses (if applicable)
connect gear linkage to the top of the gear box
feed engine loom into car - connect to car loom (colour for colour) and plug in ecu
put 4mm drill bit into alignment hole
loosely connect gear linkage to car linkage
select neutral in the car
tighten gear linkage
remove drill bit
confirm you can get gears
fit vacuum hose for brake servo
connect car loom to battery terminal, along with +ve wire from new engine loom
make up exhaust system from manifold back
fit drive shafts and hubs / hub carriers
fit and bleed brakes
fit wheels
lower onto ground
fit battery
fit induction pipes and air box
fill up water / oil / pas
shut bonnet
turn key
Start the car with it in the air. Check the shafts are secure and in their place, do a once over with all bolts on the suspension and brakes. You can never be too careful.
With a bit of creativity you too can have an engine bay that’s fit for a king. Don’t be frightened to give the covers a lick of paint or the block for that matter. Just make sure you give it a good clean so the paint sticks.
I hope you found this guide informative and helpful and good luck with your project.

[Edited on 07-07-2008 by deex]

Registered: 9th Nov 07
Location: portsmouth
User status: Offline
28th Jul 08 at 16:01   View User's Profile U2U Member Reply With Quote


Registered: 23rd Mar 08
Location: Linconlshire-Horncastle
User status: Offline
28th Jul 08 at 18:18   View User's Profile U2U Member Reply With Quote

Very good guide mate thats got the wiring sorted for me

Registered: 15th Feb 07
Location: Inverness, Highland
User status: Offline
28th Jul 08 at 20:58   View User's Profile U2U Member Reply With Quote

My mate made that guide very helpfull

Registered: 23rd Mar 08
Location: Linconlshire-Horncastle
User status: Offline
29th Jul 08 at 08:52   View User's Profile U2U Member Reply With Quote

Shunt this be in tutorials tho ?

Registered: 15th Nov 07
Location: Nottinghamshire
User status: Offline
14th Aug 08 at 17:00   View User's Profile U2U Member Reply With Quote


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