Jaguar 4.2 V8 Supercharged

[Legocar]

I'll try to take some this afternoon and post them tonight.....

[Legocar]

And here they are.....

First the filler. Eventually I'll colour code it but need to find a suitable primer first (heard stories of people paying to have this done as part of the install only for the paint to start peeling off a week or two later)


The tank. It's an 80ltr jobby which will take up to about 63ltrs of gas, so not much different to the petrol tank.


The Changeover Switch / Gauge. Wasn't sure about the location at first but now I'm getting used to it and its actually very practical without doing any visible permanent damage to the dash.


The Engine Bay. Only the vaporiser is visible and even that doesn't look too much out of place.


The Vaporiser. All pipework and wiring is neat and tidy. I haven't lost any covers or cowling and there are no noticeable holes or cutaways.


All in all, a good job and its now running very well indeed......

[zenman63]

Very nice, buy far the best install I have seen on the car.
I know Steve does not come on here now, but nice job Steve.

I can help on the filler if you need it painting.
Just get me a new cap complete with mount and I can colour it without it coming off.

[richard_ha]

Is the single vaporiser enough? Dad's getting another fitted to his becuase the one doesn't provide enough gas at WOT.

[Legocar]

When the tank is nearing empty and I really welly it (foot to the floor, sustained acceleration with the superchargers at full pelt) I can still get it to alarm out due to low pressure, but I'm not sure if that is anything to do with only having a single vaporiser.

I have another week before taking it back for the 1000 mile service. I'm going to speak to Steve about the options, one of which is to go down the route of partial switchover to petrol at full load. I had wanted to avoid this but Steve has explained that he can tune the actual switchover point so that it only happens at the very extremes of the performance envelope (not somewhere that I'll need to visit very often )

On paper this Romano system should be capable of delivering everything the engine will ever need...... maybe just a bit more fine tuning required. Steve's only really had one crack at it so far and that made it 10 times better. What I'm getting now is very occasional and only when pushing the car to extremes.... so perhaps its not such a bad thing afterall. The cost of buying the car and converting it has depleted my cash reserves, so for now I can't afford to break anything.

[zenman63]

My old Mercedes V280 did the same around islands when near empty, it's just the pick up in the cylinder.
I used it as an indicator to re fill with gas.

[rossko]

When the tank is nearing empty and I really welly it ...

If you can verify that it doesn't happen on a half tank, it will be slosh issue. Can't see your tank valving but I guess its at the 'front'.

[Legocar]

Just a quick update.....

Its been about two and a half weeks since I went back for the 1000 mile check-up.
I told Steve about the issues I'd been having and during the test drive he carried out some small adjustments to the ECU parameters. WOW! What a difference! The alarming out issue has all but disappeared (definitely just due to fuel-slosh now) and she goes like stink on lpg

I'd been getting a loss of power at the top end and some waivering during steady acceleration. Steve made an adjustment to something called "Enrichment on Acceleration" in the ECU and all of the issues just disappeared. It seems that the system was actually OVER-FUELLING during peak load! Steve adjusted this and double checked the fuelling via the OBD to make sure it wasn't going lean at all....

What I've now learned is that when it comes to lpg, Rich is good, Lean is bad, Too Rich is worse.

It says a lot about this Romano HD system that it can deliver enough juice to over-fuel a 4.2ltr Supercharged V8 pulling 400bhp!

Anyway, so far so good. I've even noticed a small difference in fuel economy too since the adjustment.

[lpg-jag]

Out of interest what sort of MPG are you getting on gas, assuming you have checked it, I mean real gas MPG not petrol equivilent or what the trip computer shows. My 4.2 supercharged XKR is giving around 15 urban and 21-22 mainly motorway/A road on LPG, running an OMVL system. This is slightly less than I was expecting but still a decent saving over petrol. yet to go abck for 1000mile check up.

[Legocar]

Ok, well being a bit of a saddo I've set up an Excel spreadsheet to monitor my fuel consumption and over the last 4400 miles my overall average mpg has been 16.4 and I have paid on average 75p / ltr.

These numbers include all fuel used (including petrol) and all miles covered, so they truly reflect my motoring costs.

As a comparison, for the approx. 1000 miles I covered before the conversion, my mpg averaged 19.2 but my average cost per litre was £1.33

Based on current usage and compared to the cost of running the car before the conversion, the whole thing will have paid for itself in about 12 - 14 months.......

All in all its a no-brainer

P.S. Apologies for the delayed response, I was on vacation in Lanzarote but obviously couldn't wait to come home to the glorious weather, riots, recession, etc

[lpg-jag]

It would seem the figures I am getting are around the same, I have noticed a slight increase in my gas MPG over the last few tank fulls although it could be simply that the kids are off so less slow traffic! One thing I have noticed though is a greater willingness on my part to put my foot down knowing that it won't cost as much to do so! So far I have only used about £10 petrol in the last few months.

[AndyC]

It's been a while now, can I ask how you are getting on. Did you car get fitted with a flash lube, I ask because I have an STR running a dual BRC set up with no lube. No one seems to know if it needs one or not.

[Gilbertd]

If it's the same engine as fitted in the later L322 Range Rover and Range Rover Sport (and I believe it is), it does need Flashlube or similar.

[Legocar]

If set up correctly, flash lube is not required.

I've done approx 25,000 miles of "spirited" driving since my conversion and so far haven't seen or felt anything that would suggest I'm getting valve seat recession.

The go-lpg website has quite a lot of info on the science behind it but the key seems to be ensuring that the system doesn't run too lean (and therefore hot)

I believe that the 3ltr V6 engine is a different kettle of fish and MUST have flash lube, but once again this could just be a myth.

[AndyC]

Thanks for all the helpfull feedback

[lpg-jag]

I have a similar experience so far to legocar but with a OMVL system instead of Romano. I have done about 16k since conversion with no flashlube on a 4.2 supercharged XKR and so far no problems. As I understand the key is ensuring you don't run lean and hence hot. If anything the set up on mine tends to run richer on gas than on petrol. The petrol map does seen to go quite lean in places. you only notice this when the diagnostics are plugged in as it drives well on both fuels.

[AndyC]

How would I tell if she is running lean on gas or not.

[lpg-jag]

you would need to be able to get the lambda readings out and monitor those, using a diagnostic. As a quick check if when on gas the MPG reported by the trip computer changes compared to on petrol, especially if the reported MPG drops then you need to look into it I think it is this way round. The easiest way I have found to judge this is a short term average on a the flattest road you can find running with cruise on for a few miles on petrol then switch and repeat after resetting the mpg computer. If your car runs lean on gas the petrol ecu will try to adjust by lengthening the injector pulses to richen the mixture. since the mpg computer uses these pulse lengths to calculate the fuel used it is a handy thing to keep an eye on.

[AndyC]

Thanks for the help. I'm flat on my back at the moment but as soon as I'm cleared to drive again ill give it a go.

[LPGC]

Hi,

I say this a lot, but it is true... Most installers fit systems from one or two suppliers. The suppliers put all components into a box and ship it to the installers. The box always contains the same components. The installers fit whatever is in the box onto whatever car they convert and always claim to fit the 'best' system, but they don't really know it is the best because they only fit a couple of systems and don't know any different. When a customer brings a car to them with a different system, they are unfamiliar, and in order to turn this into a profit they often spout hot air and charge for unnecessary parts or simply say 'you need a new system mate'. Much better to get more involved, learn what components go wrong, learn how components perform, do a bit of lateral thinking and design a system based on a list of components you choose that will work well together and compliment each other to suit each LPG conversion you do. That is what we do at LPGC.

Had a scan through this thread and have seen, without mentioning any brand names etc, some bad component advice - Injectors that won't work well on this engine / reducers, etc.

Being a supercharged V8, the engine actually makes more power than is quoted - because the supercharger also uses power from the engine's crankshaft. It is capable of using more than twice the amount of fuel than, say, a 2.1 litre turbo charged engine which doesn't make half the power. It therefore needs a lot of fuelling in total, so will need an even more capable reducer than might be expected. There are several single reducers that will flow enough fuel, some more reliable than others, some more pressure stable than others. The choice of injector can also influence which reducer(s) should be fitted, as some injectors will only flow enough gas for this engine at higher pressures (and some reducers can't be set to higher pressures). One reducer mentioned is probably going to flow enough fuel and will work at higher pressures, but won't fit well in the engine bay and will involve a messy piping arrangement.

Nobody has mentioned any injectors I'd be happy fitting on this engine. Being a supercharged V8, at tickover and low engine loads the petrol injector duration might be just over 2ms, but at full load and maximum torque output the petrol injector duration is at least 16ms. Most LPG injectors would struggle to cope with the short injection times at low loads and the high output needed at high loads - the range of gas the injectors need to supply would effectively be a problem. I could get a wide range of injectors working sufficiently well for the vehicle to be OK on gas, but never great. Only a small range of injectors work great on this engine, and I don't hear them mentioned often on this site. If you are an installer and think this isn't so, look at the fuel trims jumping around when you're running on gas and think again.

The engine is a Ford unit, uses Ford spec metal for the valves, so does need a valve lube system. The valve lube system needs to be an electronic forced type, because the vacuum types don't work when there's no engine vacuum. Being supercharged and high geared, there's no engine vacuum a lot of the time.

If an engine runs lean, the parts that get hot are the valves. The valves get hot because in a leaner mixture the fuel is burning slower and hotter as it exits through the exhaust valves. With petrol, running richer is a great way to keep valves cool whilst gaining more power at the same time (up to a point). On LPG, running richer looses power much earlier as the mixture gets richer, but the faster burn still keeps the valves cooler. This is because petrol goes in as a liquid and LPG as a gas. Gas takes up more space than liquid as it enters the engine. The more space in the ports taken up by gas, the less by air, so the 'volumetric efficiency' of the engine is lowered with too rich an LPG mixture - less power but better for the valves. With petrol it would be more power and better for the valves.

The Jag conversion may need still extra parts (depending on exact model and year) to do a proper job. Petrol bleed offs, injector impedance matching units are the usual sundry items.

If you'd like zero hype about any particular LPG system and a high performing system that will do the job properly (made from components chosen specifically for the vehicle) it would be great to hear from you.

Simon
www.Lpgc.co.uk