4.6 V8 Conversion

This snowballed slightly into some extra tidying up, specifically:

But first, a word on engine conversions - turned into a minor rant, moved to its own section to avoid clogging this page up!

Reasons Why

So, why did we decide to swap the engine in the ambulance?

fuddymuckers.co.uk_gallery_s_300_tech_carbmonkey.jpg Well, first off the original de-tuned 3.5 was not running as well as it might - it felt like a problem of tuning rather than underlying mechanical issue. However, I really hate carbs, don't get on with them at all. My usual approach is to convert to EFI and fit Megasquirt with EDIS distributorless ignition rather than fart about with carbs and suchlike.

Now, we could've done that to the original 3.5 lump using bits from a later engine, but it's a fair bit of faffing about swapping bits, so instead we decided to remove the lump complete & mothball it. P38 Range Rovers are cheap and frequently suffer electrical issues that terrify people, plus they have a more modern version of the Rover V8 at either 4.0 or 4.6 litres, with various useful improvements like cross-bolted mains, polyvee ancillary drive, 100+Amp alternator, and of course fuel injection already present. Not to mention a significant improvement in power & torque over the old 3.5.

The ambulance is a big heavy old hector, so a lump with plenty of low-down torque is just the ticket for relaxed driving.

“But why not a diesel???” I hear multitudes wailing…
Well, there's various reasons, personal preference being a significant factor.

Viable Land Rover diesel engines for a conversion would be the 200 & 300TDi or possibly TD5. The first two are a little underpowered for the ambulance, not to mention being (beloved to some) purely mechanical so somewhat old-school in terms of refinement. Finding a good one is hard these days. The TD5 is easier to find but brings a full ECU & wiring loom with it. Not to mention that when I looked at the fuel consumption of TD5 Discoverys and Defenders it was in the low 20mpg region, perilously close to V8 territory.

We drove a friend's Locomotors ambulance before we bought the 127, and that was fitted with a very sweet MOD-reconditioned Wolf-spec 300TDi which went very nicely. However, there's no escaping the fact that you have to raise your voice to have a conversation and the TDi is having to work to push it along - and he reckons low-to-mid-20's mpg-wise is the average.

Converting to TDi raises other issues too; the majority of available TDi's are not from Defenders and hence adaption of plumbing is required. All of them would require a different gearbox & bellhousing, change or adaption of chassis engine mounts, a new radiator with intercooler, exhaust… basically a fair impact on the vehicle and more work and expense. The gearbox on the 127 was a very clean rebuilt R380 from Ashcrofts so binning it would've been a real waste.

There's also weird issues like being denied entry to certain countries (USA for example) if using an engine that isn't approved.

By comparison, Rover V8's are basically interchangeable - you can bolt one in place of another and only have plumbing to worry about. Doing this we would retain the almost new R380 gearbox that's fitted, and get to leave a lot of other bits untouched or easily put back.

On With The Conversion!

So, decision made we turned to eBay and found a decent looking P38 4.6 down the road in Bournemouth - crucially it had an MOT and was running & driving with no engine issues - by far the best way to buy an engine is in a vehicle you can drive. We won it for £720, a bit spendy by some standards (I've heard of similar P38's being picked up for £250 by the fortunate) but the hassle factor was low, it was local and ticked all the boxes.


We felt a bit bad as the lad who was selling it talked us through the various buttons and things on his pride and joy and I had to admit to really not caring as we were only after the engine!

Anyway, we collected it and I drove it home to Dave's garden with no problems - in fact I was rather surprised to find this:


In fact it was claiming nearly 24mpg by the time we got it back.

There was then a long period of inactivity while builders knocked holes in our house and also built a garage tall enough to actually fit the ambulance in. The P38 ended up in Dave's garden for many months longer than intended, and we owe Dave a debt of many beers. Luckily, no sooner had we removed the P38 than another mate, Mike, “accidentally” acquired about 10 GRP kit-cars and moulds and filled Dave's garden back up, making us look much better by comparison!

Removing the engine

With massively appreciated help from TSD (vehicle storage, trailer rental, workshop space, engine crane, spanner waving, colourful language…) a weekend saw this happen:


Not many cars you can fit an engine, the engine crane, a load of gear in the back and not even have to remove the sofa-bed to make room :rofl:


With the engine home & treated to a coat of looking at, the valley gasket was very crusty so I thought I'd replace it, only to have the last inlet manifold bolt shear off :mad: tried all the tricks but ultimately had to admit defeat so it's having a visit to Banda Engineering in Portsmouth to get it removed.

Engine being looked at: fuddymuckers.co.uk_gallery_s_500_127_img_2688.jpg

Exactly what you don't want: fuddymuckers.co.uk_gallery_s_500_127_img_2694.jpg

But otherwise pretty good inside: fuddymuckers.co.uk_gallery_s_500_127_img_2690.jpg

A weekend visit to Nige at megasquirt-v8 meant I got the crank pulley machined for the trigger wheel, lambda sensor welded in to the exhaust, and collected a big box of bits for the forthcoming megasquirt install - loads of lovely laser-cut brackets, even a full set of shiny new unobtainium connectors for the EDIS-8, I think Nige is the only person on the planet with a supply of these.

Also rather disappointed to find the P38 exhaust manifolds won't fit due to the clutch slave fouling, shame as they seem nicer than the current 4:2 RR EFi ones fitted. Maybe some 4:1 3.9 cast ones should go on the shopping list.

The plan was not to get carried away trying to build it perfect 1st time but to get it up together & usable and then go out & use it to see how it goes, then make changes / improvements as we go. As such, the engine was going to get a quick “freshen up” and be plonked in…

…Well some freshening that turned out to be!

I spent 3 weeks nocturnally occupying the shed, every single little thing fought me all the bleedin' way but at long last it runs and drives again, and by crikey it goes a whole lot better than it used to!

First things first - Banda Engineering did their magic without even having to remove the heads, saved me some grief there and for a very reasonable price.

Before & After:


And while we're doing before & afters - where we started & where this is all heading:


What has turned out to be an series of excellent investments: A £3 lamp from Asda, a £10 set of steps from Home Bargains and a small folding plastic step/stool thingy, excellent when spending hours bent over an engine bay!


Many hours of farting about (not pictured) led to this being in the way of every-effing-thing in the workshop:


And a big space in the front:


Fitting the 4.6

As alluded to earlier in the thread, of course the 4.6 is going to be run by Megasquirt'n'EDIS as is only right and proper. I will be shamelessly plugging Nige's kit (www.megasquirt-v8.co.uk) throughout the next few posts as it really does make life so much easier - and that's despite the fact I already have a shed full of megasquirt bits and wiring gear, I still bought a kit of bits & wiring loom kit from Nige.

While I'm documenting this I'll try and explain what bits do for those unfamiliar with how it all hangs together.

Lambda sensor boss welded into the exhaust - this senses the unburnt fuel in the exhaust to tweak the mixture on the fly:


1st half of the mount for the VR sensor - crank pulley removed for trigger wheel fitting, on P38 lumps there is no timing mark OR pointer so you'll need to work out where TDC is, make a pointer, and then mark the pulley for later use:


For those converting a P38 lump, you need to blank off this hole where the flywheel sensor was (or just leave the sensor in):


You'll also need to either blank off or adapt the heater output on the P38 inlet manifold - it's 1/2“ BSPT (taper thread):


You'll also need to remove the flywheel dowel at 10-o-clock position, sometimes they can be pulled out with pliers, this one fought like a barsteward :mad: :


If you're using Nige's kit with an idle air control valve (also known as PWM valve), you need to drill a hole in the back of the plenum & attach the elbow for it:


I tapped the holes in the plenum to M6, smeared the plate with black silicone (sensor-safe / low acid - Loctite 5910 or 598) and bolted on:


If you are making a loom for the injectors etc. then DO NOT refit the plenum, it is miles easier to get to the n/s injectors with it off.

Again, using Nige's kit, you then mount the joiner for the air intake pipe - this provides somewhere to screw in the inlet air temperature sensor (IAT) and a takeoff pipe for the idle air valve to get its air from:


It's a bit of a faff as you have to remove the throttle mount (black steel frame) make sure you catch all the springs and things when you pull it off! I found later that this bracket needs to be shortened by about 15-30mm for a Defender retro-fit. Also note that all the bolts must face OUT from the bracket or they'll foul the throttle linkage.

Those converting a Defender will want the 50th Anniversary throttle cable, part number SBB104100.

This is (roughly) how most PWM valves fit - an MS sourced from Nige (or one properly modified) will drive any 2-wire valve, Bosch being quite available in most scrapyards:


All the hose fittings are 3/4” / 19mm, for some reason (I think 'cos they're LR parts-bin) Nige supplies narrower pipes and recommends silicone lube, I struggled for ages with this and decided that just 'cos you use lube it doesn't make it consensual :moglite: and reverted to non-standard bits of hose from the bucket of dong.

You'll need to attach the fuel supply hose - 8 or 6mm bore hose is what you want, it MUST be high pressure as EFI pumps can manage 100psi. Again with the P38 conversion, you'll need to cut the original fuel pipe off, carefully to avoid damaging the steel pipe:


Bellhousing before & after:


A couple of bits of bling from Nige / Xcess4x4 - I already had the ali clutch release bearing but the small laser-cut stainless clip for the arm is typical Nige overkill ^_^


Here is my TDC locating effort - I made a (very shoddy) pointer and bolted it to the P38 crank angle sensor (black thing in the front cover behind the pulley):


Then put a feeler thing* down the bore of cylinder 1, rotate back & forth, take mid-point with protractor, repeat with shorter feeler-thing, mark pulley:


Remember that the marks are relative to your pointer, so if you move the pointer your marks are wrong.

Not pictured: original flywheel fitted, new clutch fitted, crank pulley bolted on, Defender engine mounts bolted on:


It fits - although if you're fitting a P38 block in a Defender you'll need to chop the aircon pump bracket down to clear the inner wing:


…and if you're not using the aircon pump, this is the belt you'll need (1870mm, 7-vee, although 1900mm would also work):


Fitting The Megasquirt

Here is the point I made a hell of a lot of extra work for myself - deciding that the Ambulance is quite original and I didn't want to bolt the ECU in the cab with wires trailing to it, or under the seat in the way of batteries/fuel/water tanks etc. I looked around and found an ECU-sized hole - behind the dashboard:


Fishing round in my box of MS detritus I found a case lid I could sacrifice to the experiment, and a 90deg headshell:


Let's see…


Oh yeaaaaaah, loooaaads of room :blink: how hard can it be?

1st step, insert a couple of rivnuts for screwing the ECU into position, this threw up a couple of issues:

Number one: You can't get a drill in there :glare:

Number two: You can't get a rivnut tool in there :mad:

Number one was solved with a drill bit in a tapping handle and patience swearing.

Number two was solved with a makeshift nut-and-bolt rivnut doer-upper which sort of mostly worked after a fashion. :ph34r:

Anyway, moving along, I detoured slightly from Nige's kit as I have some nice but hard to find Bosch sealed injector connectors:


The only snag is you have to remember to assemble them in the right order as the terminals go in from the front:


Happily you can use P-clips and M6-by-short bolts on the inlet manifold (most V8 EFI's are the same) which makes life quite neat:


Other side - yeah, I forgot to leave the plenum off:


Also used 8mm push-fit adapter (shiny thing) onto the existing plenum takeoff, to 6mm push-fit nylon pipe for the MAP (inlet vacuum) to ECU connection.

When wiring, cable ties are your friend - I use cheap brightly coloured ones for temporarily holding stuff as they're easy to spot when tidying up. Also, I didn't follow this advice but you really should NOT wrap the loom until it runs & drives and EVERYTHING is working, there's always one wire you forgot… :unsure:


Those converting to a P38 lump will need to bypass the oil cooler - these ports are metric thread (same as a freelander as it happens), initial trip to Hyphose resulted in an adapter that worked but fouled the steering box (127's have HD 6-bolt boxes, your Defender may vary), this was the 2nd attempt shaved down with a grinder - oil coolers are on the return-to-sump side so low pressure:


Edit from the future: I blanked the ports off, M20 blanking plugs: Deets here.

Let's wire up some coil pack connectors! Everyone gets these confused as you have to ignore ALL the numbers on Ford coil packs, connectors, etc. and ALSO the connectors plug into the coil packs in a way that feels “upside-down”, this is the order you want using the colour codes in Nige's instructions:


This is ALMOST how the crimp should look - don't strip too much off the end of the wire, the 2nd crimp is there to grip the insulation AND the skinny end of the boot, which I realised too late:


This is the 2nd point where I made a load of work for myself by upgrading the fusebox to blade fuses. May as well while you've got the loom in bits!

Before - after:


And mounted a couple of relay holders to the back for good measure - one for the fuel pump, the other spare:


After many hours hunched in the cab, all cables re-crimped to the new holders and new cables for the MS poked through behind the dash:


I deviated from Nige's current MS circuit diagram and powered the coils & injector feed direct from ignition live to put some load on the ignition system and hence avoid needing a diode in the alternator warning light feed to prevent back-feeding & running on as often happens. LR actually did that mod themselves in some vehicles.

Lambda sensor wired up using IP67 connectors supplied by Nige (Ampseal):


ECU with EDIS mounted:


EDIS plug - Nige has gone to a lot of trouble to source brand new plugs & pins so you can make everything all nice with no joints:


The centre earth (black) just grounds the shield wire for the VR sensor, you can see the other end looping back & soldered to the shield - glue-lined heat-shrink out of shot ready to be shrunk over the joint. EDIS switches the ground side of the coils so needs a good ground - 2mmsq wire used here.

The EDIS pins are a bit of a nightmare to get in, it feels as if you're going to bend them trying to push them home so care is needed, I don't know if there's a knack to it. Finished plug:


Time for the ECU plug:


I modded my ECU to control cooling fans as I am ditching the viscous - after a brief search of the scrapyard it turns out Freelander 1.8 fans are an ideal fit for a Defender V8 rad:


One of the nicest things from Nige's kit is the coil pack mounting brackets, makes things lovely and neat:


Another thing that's taken me bleedin' ages is the power steering pipe. The P38 pump is of course in a different place, but I found the Defender pipe will screw in, so a trip to Hyphose later and I've got an adapter:


And a length of high-pressure hose crimped up… only to find the ends are too rigid to bolt up to the pipe in the available space:


Damnit, let's try a 45deg adapter in there (another trip to hyphose):


Nope, now it's too long and fouls the pulley/VR sensor :glare:

OK how about throwing another bend in?


Nope, that fouls even more things :mad:

So thanks to TSD digging round under the bonnet of the donor P38 and hacking the PAS pipe up, I started again with the P38 end:


That looks more promising:


After finding the air intake pipe thingy fouled the washer tank, I had the blessed thing apart and chopped ~20mm out of it:


ECU mods - using a ULN2803 darlington array to give the ECU 4 spare outputs, zener diodes used near the connector to catch spikes coming back from the relays:


As ever, lashings of conformal coating to keep the board nice.

Top tip - bits of old hose make ideal protective sleeves for wiring looms etc. where they touch brackets/edges:


Also you can see how lovely and flush the cable-tie gun cuts the cable ties off, no sharp ends to cut yourself on. It's one of my favourite tools.

Additional fusebox added in engine bay for the main power feed plus fans - as LR don't fuse the main feed (or indeed many other things) I thought I would:


Rad + Fans in:


Another tip - a standard inline filter on the return line (unpressurised return to tank) of the fuel system shows you you have fuel & it's flowing:


More P-clips, alternator feed upgraded to 16mm2 what with it being a 120A alternator and all:


Which means the engine-bay side of things is done… apart from the air filter, which is too big to fit in the hole.


Not pictured: Many, many hours embuggerance with pipes, hoses, clips, clamps, wiring loom, brackets, etc.

Back inside after many, many, many more hours tidying the standard loom up, chasing wires, poking cables through, cable tying, spiral binding, and basically trying to straighten out the rats-nest of wiring that seems to happen behind all Defender dashboards, the ECU and EDIS are tucked away with a serial cable permanently attached (because you're never getting in there to plug one in!):


All tucked away with a bit of slack on the serial cable:


It runs, it drives, the fans come on & off, the PAS works… and it really does go rather well! :wub:

There's a snaglist a mile long of little things to sort out;

  • Need an air box (Defender 200TDi if anyone's got one?)
  • The lambda sensor appears dead, I've got a new one to go in.
  • Need a remote oil filter kit (again, PM me if you have one) as the oil filter is a bit close to the front diff for my liking.
  • Need to check & trim the timing, it looks pretty close but I've not confirmed it is bang on
  • Need to tweak the PWM valve settings, it hunts quite a lot from cold
  • Need to secure the new high-pressure fuel line
  • …well, that's it for the engine anyway!

While I was doing all this farting about, Helen was busy with the power tools creating a kitchen and bed, and we've also bought a pair of Puma front seats to replace the squaddie-spec black vinyl jobs. I still need to chop the rear bulkhead out to make it walk-through from cab to rear and a few other jobs…

No pressure but the ferry is booked for end of the month :blink::rofl:

Update 1

Update: it went fine!

Update 2

Finally got round to fitting a 200TDi air box to it.

There's a bit more detail on LR4x4 here.

alfie/engine_swap.txt · Last modified: 2019/06/08 20:57 by jin
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