Lee
19-09-07, 07:39 PM
The nova 20XE conversion is outlined below. You need to consider all the points in the list, but the 20XE and 20SEH engines do bolt into the nova pretty simply. I found this guide on Valvers.com, but they failed to mention stich welding the engine bay (strengthening all welds in the engine bay by welding in 1 -2 inch sections along all joins)
Another thing not mentioned is a brake upgrade which is essential so please see guide to upgrading your brakes.
This is written purely as a guide, not an instruction manual. I take no responsibility for serious injury or death if said conversion is not completed to a safe standard!
Good Luck!
1. Fuel
If you nova is a carb model, you need to install injection fuel lines, or at least think about how you are going to deal with the fueling of the 20XE. The fueling system for the 20XE requires two lines from the petrol tank, one supply, and one return. 1ltr novas do not have a return fuel line, and therefore you either need to braize a fitting into the petrol tank as a return, or you need to install a petrol tank with a return line in it.
The fuel pressure required for an injection engine is much higher than that required for a carb model, and the fuel hose used in the carb models should not be used to carry the high pressure fuel required for the injectors. As a get around, if you don't have time to install the injection fuel lines right down the car, you can mount the fuel pump in the engine bay. Now, as the pump sucks the petrol from the tank, this is not at pressure. Only the section after the pump, and before the regulator is high pressure. Bear in mind, this is NOT the ideal way of doing things as the pump is designed to be as close to the tank as possible. The return line can always be left as the std petrol line.
When using a carb tank, there is no swirl pot in the tank. The swirl pot holds a reserve of fuel if you like, and when you corner hard this reserve of fuel is still able to be put through the pump, even though the petrol in the tank is all being shoved out of the way of the supply line opening because of the cornering G.
So a swirl pot in a fuel injection tank is the best way forward.
The GTE / GSi / SRi fuel pumps are fine for the 20XE, as is of course a 20XE fuel pump. The Spi 1.4i (single injector) pump cannot flow enough fuel at a high enough pressure for the 20XE though, so you will need to replace this pump if it is the model you have.
2. Chassis
The engine conforms to Vauxhalls family 2 layout, and all the Nova mounting brackets will actually fit the 20XE engine and the F16/F20 gearbox. However, there are a few exceptions. The TD engine mounts are different because the lump is an isuzi made diesel, and the 1ltr front offside engine mount is different too.
The front offside mount must be changed from standard so that the engine sits approx 1-1.5" down from it's 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 either use the standard nova mount, but cut the chassis bracket off, and re-weld it onto the chassis leg 1-1.5" further down the leg, OR purchase a 2.0 fitting fit from a specialist, which will also include the spacers for the rear gearbox mount (as follows below).
The other mount that isn't right is the rear gearbox to chassis mount. This holds the gear linkage, etc. You need to use a Nova item, and you can keep the nova gear linkage but flip the plastic universal joint around to give the nova linkage a longer reach.
However, the differential casing of the F20 and F16 are different to the F10/F13, etc small block gearboxes. You need to put spacers between the rear gearbox mount (as mentioned above), and the gearbox differential so that the engine/gearbox is not twisted in the engine bay.
On the 20XE inlet manifold there may be a lug on the part that comes around where the inlet runners meet, this comes into contact with the drivers side heater matrix hose, and needs to be ground off. As well as that, whether you have that lug or not, you still need to cut down the drivers side heater matrix hose by at least 10mm, but take off as much as you can to give that hose more room to bend down under the inlet manifold.
The inlet manifold also gets in the way of the clutch cable exit from the bulkhead. Insert an iron bar into the clutch hole in the bulkhead and make the hole point towards the front passenger side of the engine bay, towards the floor. This will let the clutch cable be free.
Otherwise the clutch cable is pushed about by the inlet manifold, and it ends up snapping the clutch cable.
The alternator pulley hits the chassis leg of the nova right by the drivers side suspension turret. This means you need to alter the chassis leg to avoid the alternator pulley. This mod needs to take the chassis leg in so that it's inline with the suspension turret to miss the alternator. You also need to alter the crank pulley. You must run the single-V alternator pulley, and not the poly-V one that came on later engines. You need to take off the outer V on the crank pulley, which is used for the PAS + Aircon pump belt on cavs, etc. You can machine it off, or grind it down with an angle grinder or similar. Make sure you try and keep it fairly balanced though, as it sits right on the crank.
The engine also moves about quite a bit, especially on standard rubber mounts, so make sure that there is plenty of room for it to move. Alternatively, purchace some solid motorsport mounts.
3. Suspension
Running standard uprated 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. Ideally you want 300lb rated springs on the front to support the extra weight.
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. With the added 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 understeer 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.
4. Driveshafts
Two options here. Either..
Fit 22 spline driveshafts (from Nova Gsi, some GTe and most TD's) mated to MK2 Cavalier 1600 inner CV joints.
OR
Fit custom 2.0 shafts with conversion hubs allowing you to run 2.0 outer CV joints.
5. Wiring
Wiring is easy, the motronic looms are whole looms in their own right. All you need to link between the nova and the motronic loom is a Permanent live ( large red ), Switched live ( Black ),an earth ( Brown ), and a feed to the Fuel Pump (Red/Blue) for the engine to start. The rest of the wires from the Nova's original loom will connect up to the alternator / starter / oil presure / water temp sensors ect.
Notes
Use a nova clutch cable
Use an Astra / Cav accelerator cable. Mine needed adjusting on the accelerator pedal to give full throttle.
Checklist:
Alternator - chassis clearance + bottom pulley to chassis
Front offside engine mount bracket
Gearbox diff spacing
Gearbox linkage
Gearbox bottom lug
Anti-roll bar + tie bar lowering
Driveshafts
Heater matrix driver side needs to be cut down + lug on inlet manifold
Clutch bulkhead exit needs to be bent over towards passenger side
Another thing not mentioned is a brake upgrade which is essential so please see guide to upgrading your brakes.
This is written purely as a guide, not an instruction manual. I take no responsibility for serious injury or death if said conversion is not completed to a safe standard!
Good Luck!
1. Fuel
If you nova is a carb model, you need to install injection fuel lines, or at least think about how you are going to deal with the fueling of the 20XE. The fueling system for the 20XE requires two lines from the petrol tank, one supply, and one return. 1ltr novas do not have a return fuel line, and therefore you either need to braize a fitting into the petrol tank as a return, or you need to install a petrol tank with a return line in it.
The fuel pressure required for an injection engine is much higher than that required for a carb model, and the fuel hose used in the carb models should not be used to carry the high pressure fuel required for the injectors. As a get around, if you don't have time to install the injection fuel lines right down the car, you can mount the fuel pump in the engine bay. Now, as the pump sucks the petrol from the tank, this is not at pressure. Only the section after the pump, and before the regulator is high pressure. Bear in mind, this is NOT the ideal way of doing things as the pump is designed to be as close to the tank as possible. The return line can always be left as the std petrol line.
When using a carb tank, there is no swirl pot in the tank. The swirl pot holds a reserve of fuel if you like, and when you corner hard this reserve of fuel is still able to be put through the pump, even though the petrol in the tank is all being shoved out of the way of the supply line opening because of the cornering G.
So a swirl pot in a fuel injection tank is the best way forward.
The GTE / GSi / SRi fuel pumps are fine for the 20XE, as is of course a 20XE fuel pump. The Spi 1.4i (single injector) pump cannot flow enough fuel at a high enough pressure for the 20XE though, so you will need to replace this pump if it is the model you have.
2. Chassis
The engine conforms to Vauxhalls family 2 layout, and all the Nova mounting brackets will actually fit the 20XE engine and the F16/F20 gearbox. However, there are a few exceptions. The TD engine mounts are different because the lump is an isuzi made diesel, and the 1ltr front offside engine mount is different too.
The front offside mount must be changed from standard so that the engine sits approx 1-1.5" down from it's 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 either use the standard nova mount, but cut the chassis bracket off, and re-weld it onto the chassis leg 1-1.5" further down the leg, OR purchase a 2.0 fitting fit from a specialist, which will also include the spacers for the rear gearbox mount (as follows below).
The other mount that isn't right is the rear gearbox to chassis mount. This holds the gear linkage, etc. You need to use a Nova item, and you can keep the nova gear linkage but flip the plastic universal joint around to give the nova linkage a longer reach.
However, the differential casing of the F20 and F16 are different to the F10/F13, etc small block gearboxes. You need to put spacers between the rear gearbox mount (as mentioned above), and the gearbox differential so that the engine/gearbox is not twisted in the engine bay.
On the 20XE inlet manifold there may be a lug on the part that comes around where the inlet runners meet, this comes into contact with the drivers side heater matrix hose, and needs to be ground off. As well as that, whether you have that lug or not, you still need to cut down the drivers side heater matrix hose by at least 10mm, but take off as much as you can to give that hose more room to bend down under the inlet manifold.
The inlet manifold also gets in the way of the clutch cable exit from the bulkhead. Insert an iron bar into the clutch hole in the bulkhead and make the hole point towards the front passenger side of the engine bay, towards the floor. This will let the clutch cable be free.
Otherwise the clutch cable is pushed about by the inlet manifold, and it ends up snapping the clutch cable.
The alternator pulley hits the chassis leg of the nova right by the drivers side suspension turret. This means you need to alter the chassis leg to avoid the alternator pulley. This mod needs to take the chassis leg in so that it's inline with the suspension turret to miss the alternator. You also need to alter the crank pulley. You must run the single-V alternator pulley, and not the poly-V one that came on later engines. You need to take off the outer V on the crank pulley, which is used for the PAS + Aircon pump belt on cavs, etc. You can machine it off, or grind it down with an angle grinder or similar. Make sure you try and keep it fairly balanced though, as it sits right on the crank.
The engine also moves about quite a bit, especially on standard rubber mounts, so make sure that there is plenty of room for it to move. Alternatively, purchace some solid motorsport mounts.
3. Suspension
Running standard uprated 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. Ideally you want 300lb rated springs on the front to support the extra weight.
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. With the added 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 understeer 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.
4. Driveshafts
Two options here. Either..
Fit 22 spline driveshafts (from Nova Gsi, some GTe and most TD's) mated to MK2 Cavalier 1600 inner CV joints.
OR
Fit custom 2.0 shafts with conversion hubs allowing you to run 2.0 outer CV joints.
5. Wiring
Wiring is easy, the motronic looms are whole looms in their own right. All you need to link between the nova and the motronic loom is a Permanent live ( large red ), Switched live ( Black ),an earth ( Brown ), and a feed to the Fuel Pump (Red/Blue) for the engine to start. The rest of the wires from the Nova's original loom will connect up to the alternator / starter / oil presure / water temp sensors ect.
Notes
Use a nova clutch cable
Use an Astra / Cav accelerator cable. Mine needed adjusting on the accelerator pedal to give full throttle.
Checklist:
Alternator - chassis clearance + bottom pulley to chassis
Front offside engine mount bracket
Gearbox diff spacing
Gearbox linkage
Gearbox bottom lug
Anti-roll bar + tie bar lowering
Driveshafts
Heater matrix driver side needs to be cut down + lug on inlet manifold
Clutch bulkhead exit needs to be bent over towards passenger side