Tuning/adjusting the fuel injection pump for omptimum performance
After fitting the engine I would recommend that it's driven for a while in 'standard' tune, just as it came from the Montego. Run a few tanks of diesel through it, especially if the engine has not been used for a while. Get to learn how the engine performs in range of road & traffic conditions and what the fuel consumption is. This way you will be better able to judge if your adjustments are having any effect! Ultimately to get the most out of the Prima engine you really need to optimise the fuel injection pump settings and fit an intercooler.
However, you can achieve a worthwhile gain in performance from just 'tweaking' the fuel injector pump without the intercooler. This alone, may be more than enough for most people. You will get a very driveable Landy, with good cruising speed, good fuel economy and a little bit of extra for overtaking, climbing hills or towing. This approach may be easier for insurance purposes, although most will treat the engine swap as an 'engine modification' anyway, so an intercooler shouldn't be an issue.
See the link below refering to the Bosch EPVE pump. Making these adjustments is not too hard. Start by turning the smoke adjustment screw 1 turn clockwise. Then remove the top of the diaphragm cover and the diaphragm itself, below you will see a large silver gear wheel - 'star wheel' . Make a reference mark (felt pen) on the pump body at the 3 o'clock position & on the gear tooth next to this. (Your reference point is standing on the LH side of the engine bay with the rad to your left.) Try turning the gear wheel 1/2 turn clockwise to start with. When replacing the diaphram, note the little 'dot' punch mark on the top. This is normally in the 3 or 4 o'clock position. Turn it so that it is in the 9 o'clock position. You will have more movement for the fuel metering rod. Just making these slight changes should give you a dramatic improvement of low down power.The engine will be more tractable around town! It will pull in higher grears. Coupled with this you might want to turn the max fueling screw in (clockwise) 1 to 2 turns max to give a little more fuel at full throttle. This screw adjuster is 'protected' by a steel collar, that is best removed before fitting the engine. Don't over do it, as the engine will over rev, make extra smoke and waste fuel. Again the link below describes very well what you have to do. Any adjustments you make should be done 'one at a time' gradually and road tested before doing more. If the engine makes smoke, back-off the last adjustment you made and try again. You will probably find that the idle speed has crept up a bit and so this might need resetting. Also your static fuel pump timing should be spot on before you start making any of these changes. You should make a note of your starting positions, so that if it doesn't work out, you can reset everything back to standard. You should also consider the condition of the fuel injectors themselves. Various diesel specialists will test and clean them for a modest fee. You need to be sure the engine is running at its best before you start making adjustments to the fueling.
At this point the next step will be fitting the intercooler. This will help keep the incomming pressurized air closer to ambient temperatures. Passing through the turbo will normally heat the air up to 100 C on full turbo boost, the intercooler will reduce this noticeablly, giving a further increase in overall power. The intercooler is just a small radiator, for best results it needs to be mounted in the cold air flow. This will normally be somewhere at the front of the vehicle. In front of the water rad is a good place. You are going to need some long connection pipes in the order of 2" diameter to connect back to the engine. These need to be of good quality with no air leaks and be of rigid tubing - metal tube is best. You can use short lengths of silicone tube for joining up. To much flexiable tube will 'balloon' up during use and add to the turbo lag! (see next section)
Normally the turbo boosts the induction pressure to 0.9 bar before the waste gate valve opens. The waste gate actuating arm has a firmly fixed adjuster. The engine should be able to handle a little more boost pressure - 1.0 to 1.1 bar. You wouldn't want to drive all day at this level, but 'extra' power for an overtaking move is very useful! Doesn't sound much, buts that's about 10% more air going in at the top end of the engine range! This arm needs shortening by about 1/8" of an inch. Access is difficult when the engine is fitted. Remove the arm and loosen the adjuster while the engine is on the bench. You should also consider fitting a proper boost pressure gauge on the dash. The take-off for the gauge should be tapped into the centre part of the inlet manifold to get a representative measure of pressure. Fine adjustments of boost can be done when the engine is running in the car. Once you get 1.1 bar boost, Locktite® the adjuster on the actuating arm.
This link contains all the info you need on tweaking the Bosch EPVE fuel-injection pump.
The nominal engine idle speed is 800rpm. This is a little high for the older non-syncromesh (1st & 2nd) 2/2A gearboxes. If you are having trouble engaging gears, crunching noises etc., then try adjusting the idle speed down towards 600rpm. The idle speed for the petrol Land Rover engines is a very low 450-550 rpm! Make the adjustment after the engine has warmed up. Don't over do it, and check that the engine will idle smoothly when starting from cold. Remember the cold starting idle advance will increase the idle speed by about 150 rpm anyway until the engine is warm which doesn't help when trying to select a gear. You can 'cheat' by selecting 3rd first, (using the synchro to line the box up) then engage 1st, 2nd or reverse gears.
Tuning the engine for more power is a two edged sword. If you take full advantage of the extra performance then overall fuel consumption will increase, but driven sensibley you will have a useful (and more flexiable) gain in performance.
Fitting an Intercooler
This is the last stage in the tweaking process. I used an IC from a 200 TDi (there are plenty of these about on eBay as owners upgrade to on of the Alisport type ICs) But the one from a Renault 5 turbo is similar in size and has easier connections.
I mounted mine alongside the rad to the right. I made a bracket from some dexion angle and fastened it to the bottom 2 rad securing bolts and to the inner RH wing. You need to check & double check clearance over the steering rod. You can cut an M10 thread on the 4 mounting rods on the IC. You bolt the IC to the bracket and make a strap to go over the top mounts and fasten this to the wing. This steadies the top of the IC. I then repositioned the horn. I then cut the RH panel that guides air to the rad, so that this is bent back across the rad a bit to deflect more air into the IC core.
I cut in half in the centre the 'U' tube that connects the turbo output to the manifold. Turned it through 90 degress and tIG welded it back together. This is then mounted such that the free end faces towards the front of the vehicle.
Connecting up. You need a 90 degree silicon rubber hose from the turbo outlet to the IC inlet. You need a length of metal tube ('cos it's going to get hot) to connect this to another tube on the IC inlet itself. I used a selection of silicon bends and some 2" rainwater pipe (the air is now cold) to connect the outlet from the IC to the manifold inlet. Not the most direct route. This can be tidied up later. It would be best to cut off the IC inlet tubes and TIG weld them back at more favourable angles.
The IC does make a difference, perhaps not so noticeable as the initial pump tweaks. The Landy now cruises at 60 mph on half boost pressure and on such runs the fuel consumption has increased a little, maybe by 1 -2 mpg. But the engine feels less strained and there is plenty of power in reserve for overtaking.
This gives an idea of the IC installation. Note the 'redundant' pipe work in the outlet from the IC. You can see that if the outlet were re-welded then the pipe would feed straight into the inlet manifold.
And here it is after the welding has been done - it looks a lot neater now. After a long hot run, the bottom inlet and bottom part of the IC will be warm to the touch, whilst the top of the IC is stone cold! So it's doing its job!
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