You will be pleased to know that I have finally booked the car in for its LPG conversion. LPG is one third the price of petrol here.

I went to see the LPG man yesterday armed with info and pictures from this forum and from Richard (thanks) and we had a meaningful exchange in a mixture of Portuguese and English.

Hopefully he will cut through the Thor inlet manifold to run the pipes ....

Good to hear Spiggy, about the holes in the banana's, if he knows his job (no doubt) he tries to keep the tubes as short as possible. Mine are all about 28-30 cm long.
I was thinking (if you know a machineshop who can do it) about fabricating a aluminium spacer of about 1 cm thick between upper and lower plenum/inlet manifold so you can put the injectorrails on either side of the rockercovers (shorter tubes), use the steel gasket as a template. But that is for later, it was just an idea.

Tony- have you seen my post in the other LPG thread. Mine's got exactly what you are suggesting fitted!
https://rangerovers.pub/topic/288-lpg-what-wears-out?page=2#pid4105

This is just what I mean, apart from the smear. Must be possible to have it fabricated for not too much money, question is will it affect the overall volume of the plenum, I mean fuel mappingwise (I don't think so). Instead of the silicone you could use two steel gaskets. (We did not have a meeting isn't it to come up with the same idea ha ha)

It's pre LPG jets and petrol injectors so will only have a theoretical impact on the air side of things. If on a race engine I'd look at a risk of the longer throat leading to increase in laminar flow hence less turbulent air hence worse fuel air mixing.
On a GEMS it would be the same effect as increasing trumpet length (seen as a good thing in the RV8 tuning fraternity). On the Bosch with the bananas, more of an unknown quantity.
The difference should be so small as to be pretty much irrelevant except perhaps on a dynamometer

I understood that the longer inlet tract on the Thor compared with the GEMS trumpets gave more bottom end grunt. The tuners are usually dealing with engines fitted into TVRs and the like so don't want more grunt, they want more top end so shorten the trumpets. If an extra 1cm does have an effect, it will be to increase bottom end power, just what you want in a P38.

Well, it is done.

I've only driven a few kilometres so far .... and am about to clear up the area around the tank and take it for it first fill of gas.

I'm not clear on one thing.

I understand that a cold engine will start on petrol and change automatically to gas, but what happens when the gas runs out? Does it automatically switch back to petrol?

My Portuguese ran out when the installer tried to explain, but I think he said that the car stops and you have to restart with petrol...

Any help welcome!

Other greater experts than me are on here Spiggy, but when it senses gas pressure is low it'll beep to warn you and then switch automatically to petrol, with the lights flashing to tell you that it's done it.
Unless if it's a single point system (which yours isn't), it'll gradually run out of power and if you continue to force it to run on gas, eventually it will either stop, or blow off the inlet manifold pipe :)
OK, joking aside, there are many people on here who will probably have english translations of the manual if you post exactly what system you have fitted

OB perfectly correct. On a modern multipoint it will be monitoring the gas pressure and if it drops below a certain point, it will assume no gas so will switch back to petrol. Usually with a beep (yes, yet another beep to join all the others a P38 can throw at you) to let you know. You shouldn't have to restart, it'll just carry on running. A very common problem with a system that is inadequate for the engine, or hasn't been set up properly, is switching back to petrol when you floor the throttle as it detects the drop in pressure and assumes you've run out.

The reason for it warming up on petrol is that it is slaved off the petrol system which needs more fuel when the engine is cold (it needs choke in other words). LPG doesn't need the extra fuel so the mixture would be very rich and it would run like a dog until warmed up. There is also a danger of freezing the reducer as the evaporation of the liquid into a vapour requires a lot of heat which may not be there on a cold start.

Thanks so much.

I'm happy to post the details of the system if anyone is interested.

If you want, I'll see if I've got a manual in English for it.

My Zavoli system (based on the generic AEB ECU) will beep at me until I press the button to cancel it when it's run out and switched back to petrol.

If I am under load and it suddenly cuts out (I think my sender is a bit sticky, so it goes from 2 bars to empty!) then I can get a bit of a lurch as it switches back, but there is no stop/restart. If I notice it's getting low and switch back to petrol manually, or if it changes back when it's not under load then it's hardly noticeable.

I've just drilled/tapped my inlet manifold for the LPG hoses, so my next task is to mask/paint the manifold and then also to strip the injector rails off the vehicle and work out the mounting of them... I am tempted to buy pairs of injectors to make the hose runs even shorter, but it's an additional expense which is probably not necessary at the moment, unless I can't get the rails of 4 to sit/mount nicely.

Martyuk wrote:

My Zavoli system (based on the generic AEB ECU) will beep at me until I press the button to cancel it when it's run out and switched back to petrol.

If I am under load and it suddenly cuts out (I think my sender is a bit sticky, so it goes from 2 bars to empty!) then I can get a bit of a lurch as it switches back, but there is no stop/restart. If I notice it's getting low and switch back to petrol manually, or if it changes back when it's not under load then it's hardly
noticeable.

I've just drilled/tapped my inlet manifold for the LPG hoses, so my next task is to mask/paint the manifold and then also to strip the injector rails off the vehicle and work out the mounting of them... I am tempted to buy pairs of injectors to make the hose runs even shorter, but it's an additional expense which is probably not necessary at the moment, unless I can't get the rails of 4 to sit/mount nicely.

Keep us informed, I'm not at mounting injectors yet on my lump, but have been thinking about getting them under the bananas, looking where to get a spacer if required

no10chris wrote:

looking where to get a spacer if required

I have plans to make one myself, looking for a plate of alloy of about 1 cm thick and have it skimmed both sides, then use a gasket as a template for drilling the holes. Must be doable.

The negatives of long pipe lengths are not nearly as pronounced on a group injected engine as on a sequential injected engine (because group injection fires injectors twice as often, and in advance of inlet valves opening), so pipe lengths associates with fitting 2 x rails of 4 injectors on group injection Gems engines are not as critical as on sequential Bosch engines. When I convert a group injected Gems I mount a rail of 4 (down-flow) injectors to the UK driver side middle plenum allen bolt and the other rail to the passenger side front plenum allen bolt (throttle body prevents mounting rail in the middle on this side). Don't worry about keeping all pipes same length, the only 2 pipes that will be a bit on the long side anyway are those that run to the rear 2 cylinders on the passenger side, makes negligible difference on Gems particularly if you use 4mm ID pipe (low internal pipe volume compared to wider diameter pipes). The bosch/sequential is a different story, I mount side outlet injectors atop the bananas on these but remove metal from between the banana runners to allow pipes to fit through to the correct place (for outlets) in the lower part of the manifold beside petrol injectors.

Simon

All of the installations being talked about here are on the later Thor engines so have the bunch of bananas getting in the way. The idea of the spacer is to lift the upper manifold so that there is clearance to either mount the injectors either side, and run the hoses between the rocker cover and inlet, or to mount them under the upper manifold and keep pipe lengths very short. This means that they don't have to be mounted on top where they can eat there way through the sound deadening on the underside of the bonnet. A lot more work and involves making the spacer but on a DIY system where time to do the conversion isn't relevant it'll make for a lot neater install.

GEMS is also fully sequential (according to the Technical Information Bulletin), it was only the Lucas 14CUX system fitted to the Classic and things like TVRs (the ones with a distributor) that weren't.

MJFX singular injectors, perhaps even the larger MJ singular injectors, will fit below the manifold even without a spacer... but in my view there is neat while practical (in terms of future servicing etc) and then there is being slightly OTT neat (dismantling needed to access bits like filters etc, take the top off the engine to get to injectors..). It would take about equal time to fit injectors under the manifold as it does to fit them on top. Some engines might be considered a work of art by some people, other engines probably not... I don't think LPG components installed out of sight in the engine bay of a P38 outweighs positives of easy servicing, I don't think there is a technical advantage in fitting injectors under the manifold on a Rover V8.. If I thought there was a combination of neatness and technical advantage I would do it that way, otherwise the accessibility point wins out.

I believe manifold spacers for these engines are available off the shelf anyway? A sometimes slightly negative point of manifold spacers is that they add volume to the intake manifold, which on some engines (those that use TPS and AFM's rather than a MAP sensor as part of load input to the petrol ECU) will mean acceleration fuelling enrichment will then occur slightly ahead of ECU designer anticipated actual air flow increase past the inlet valves. For sure a negligible effect with a short spacer but one which could offset any negligible benefit from shortening LPG injector to manifold pipe lengths.

Seen a bit of rubbing on sound deadening material with injectors mounted on top, seems to be much worse if sound deadening material sags where it shouldn't.. but while we're talking about neatness we wouldn't want sound deadening material to sag either.

Easy to tell if an engine runs group or sequential injection in LPG software, some systems actually spell out what type of injection the engine runs, or another way to tell is by petrol injector duration - a normally aspirated group engine will idle at around 2ms and full load will be at around 8ms, these are half the usual figures for a sequential engine. Got me thinking now whether I have seen group injection on Gems P38s, I have seen sequential Gems, previous to your post I would have been more certain I'd seen group injection Gems on P38s too, still tend to think I have. As said above it's easy to tell if an individual vehicle runs sequential or group anyway. Most Rover V8's running sequential run with about 4ms pinj duration at idle with warmed engine at just over 0.4bar manifold pressure.

Edit - Last week I had a customer here with a P38, not one of my conversions but one that I repaired a couple of years ago (fitted new injectors on). As usual, the original installer had fitted the injectors atop the manifold without making holes for injector pipes to reach to the correct place in the lower manifold (so injectors fired gas into the upper manifold, several inches from the ideal place). Anyway, on this occasion the car came in because it was running very poorly on gas "It always ran beautiful since you fixed it but recently it went bad all of a sudden while I was driving". Turned out the ECU (AFC, which is really just a rebadged KME Diego) was driving a couple of injectors improperly (all peak current, no hold current). This had caused one of the injector coils to melt - easy to replace the injector coil but would have involved taking the upper manifold off if injectors were fitted under the manifold. Effected a temporary cure while it was here just by fitting another injector coil but warned the owner not to run on gas or at least to keep his eye on the 2 effected coils if he did run on gas (don't want it catching fire) before he returns for the ECU replacement (got a few of the more recent KME Nevo's in stock, Diego are being phased out but I'll get hold of one to make for most cost effective repair). A temporary repair made simple by easy access to components. Should he (unwisely) drive on gas in the meantime, should the coil melt again before I fit another ECU, no big deal changing the coil again (and I won't charge for the coil, got loads of loose ones for these injectors knocking about).

Simon

Part of the reason I'm going with installing the injectors under the manifold is for neatness - and to keep the pipes shorter.
the injectors I'm going to have in there are pretty much brand new Hana 2001+ Gold (rails of 4x each).

The other reason is because on the Thor engines at least, there isn't a LOT of space at the back of the engine and keeping the space free to be able to get hands down to access the coils/HT leads will be a bonus. At the moment, if I want to do anything much I have to take the plenum off anyway - and given it's the air intake duct and a bunch of bolts, it's not that much of a big deal to get under there if needed.

When my injectors/LPG system was first installed, they never made nice mounting brackets for the injectors, so when I swapped out the slowly failing Zavoli injectors the replacements pretty much sit above the coil packs, and at times rattle on the firewall, which is rather annoying to hear the clicking all the time!

My filter is mounted to the side near the reducer (have a new one of them to fit aswell... figured why not, since so much else is being replaced), and then the plan is to have the gas line split at the back of the engine, and then feed each LPG rail of injectors. I've also got 2 other 12mm outlet nozzles to fit to my injector banks, so thinking of doing a balance pipe at the front of the engine, between the 2 banks of injectors too.

Out of interest - what setting in the ECU is best for the Hana injectors? I think I have them set as the same Zavoli injectors that were in the vehicle at the moment - but have option for Matrix aswell.

There's a Bridgeport with 3 axis DRO standing in the corner of my man cave so knocking out a spacer or three should be no problem given dimensions and material. Safe sorta job for me too whilst I'm on light duties after hernia op last week! Must remember that 61 is not the new 21.

Would probably have had a spacer on the go already if the green-machine, needs head job, deal hadn't gone pear shape for reasons I don't understand. Getting tired of the official unofficial kid sister moaning about the 22 mpg fuel consumption of her TD6 L322 and astronomical costs of servicing and new parts (4 sets of front suspension arms in 40,000 miles!) so throwing an LPG converted P38 her way ought to keep her quiet long enough to decide she does like P38's after all! Even if only for fiscal reasons.

Clive

Don't quite follow, Marty. If you want to keep the back of the engine clear of LPG bits in order to allow better access to coil packs, splitting LPG pipe at the back of the engine (presumably to run pipes to Hana rails mounted under the manifold with gas pipes feeding to beneath the manifold from the rear) might not be a great way to go?

Given the limited options for injectors available with a Zavoli ECU would go with the Matrix setting.

No need for the balance pipe and won't make any difference.

Simon