The Temptress

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robertXX
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Re: The Temptress

#41 Post by robertXX » Fri Jun 11, 2021 10:42 am

what is the difference in mpg petrol to gas gilbert ?
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

CNG
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Re: The Temptress

#42 Post by CNG » Fri Jun 11, 2021 11:11 am

Gilbertd wrote:
Wed Jun 09, 2021 4:22 pm
About 6 years ago I drilled and tapped my inlet manifold and put plugs in ready to fit nozzles for when I decided to 'upgrade' it to a multipoint but never have. I've even got a complete, working, multipoint system taken off another Range Rover but why would I want to? The Leo connects to an additional stand alone lambda sensor in one downpipe so if the petrol system packs up, it'll still run perfectly on gas. Same the other way round as I've effectively got two separate stand alone fuel systems. The only thing common to both fuel systems is the TPS so I've got a spare one in the boot. I can make it start and run on either fuel and I use about £20 of petrol every 6 months or so. With fuel metering like I'm getting, how can it be improved? I wouldn't fit a Blos though, far too complex and just something else to go wrong and need tweaking. In 11 years and 230,000 miles, I've used 3 stand alone lambda sensors and replaced the original R90E for a new one. I plug the computer in to check the settings probably no more often than once a year.
We're rail-roading Robert's thread here, but agreed, preachin' to the converted. Not sure I always grasp the 'must-have-the-latest' fetish. I'm with you completely, if simple works...
what is the difference in mpg petrol to gas gilbert ?
I'll try to answer this one. Here I'll stick with English over 'American', thus I when I write 'gas' I mean gas, the Yanks sell gas in GGE which is an acronym for 'Gas Gallon Equivalent'. Thus 1 x GGE matches their US "Petrol' gallon for energy.
Hence, whatever Joules of energy there is in a 'liquid petrol US gallon' the same energy sits in a US gas 'GGE'. The US gallon is smaller than our Imperial gallon, but I digress... Whereas here, we sell LPG in litres, only a litre of LPG does not pack the same energy-punch as a litre of petrol. They're not like-for-like. lest we forget, a gallon of deseasel packs a greater energy punch than petrol, and so on. Can't find the arsedness to look up LPG's deficit, but there is one.
Hence, not by much, your litre of liquid petrol takes you further than your litre of LPG. There's also the question of energy density once we're got LPG into its vapour form. In vapour form it takes up more space than petrol, thus there's less room for what we really want to be burning here, O2. Hence LPG likely takes a horsepower hit too. I suspect you know much of this, for the benefit of others....

Stoichiometric Ratios show this best.
Stoichiometric Ratios.png
Stoichiometric Ratios.png (64.76 KiB) Viewed 434 times
AFR Lambda Table 19-02-20 01.png
AFR Lambda Table 19-02-20 01.png (153.06 KiB) Viewed 428 times
Last edited by CNG on Fri Jun 11, 2021 11:29 am, edited 4 times in total.

robertXX
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Re: The Temptress

#43 Post by robertXX » Fri Jun 11, 2021 11:23 am

Thanks CNG ,yup ,i have always tended to assume ,

10% less mpg , and 10% less bhp ,

but since gilbert is so experienced with the leo on his car , and does so many miles i thought he'd have some real world data . :)
Last edited by robertXX on Fri Jun 11, 2021 1:39 pm, edited 1 time in total.
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

CNG
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Re: The Temptress

#44 Post by CNG » Fri Jun 11, 2021 11:35 am

Not Simon, he'll might be along to put things better, or put me right where i err. Reckon, there's decent argument for us selling LPG in PGE or to be more correct, PLE - (Petrol Litre equiv).... but we don't.

I don't bother to think in terms of volume or cost per litre. MPG etc tells me nothing. I do vast miles, I run a 'cost per mile' calculation, eg: in my classic I ask, "I've just put a tenner in, how far does that take me?" On petrol about 22-23 miles, LPG about 35-36, NG 55-60. What that is in mpg is not as useful.

Gilbertd
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Re: The Temptress

#45 Post by Gilbertd » Fri Jun 11, 2021 12:36 pm

I also don't bother with mpg but work on miles per tank. Cost per mile is another way of doing it but when LPG can cost anywhere between 55 and 80ppl it depends entirely on where you fill up. Depending on the type of driving (town versus long run), country I'm in (less hold ups and traffic jams in Europe than the UK) and whether I'm towing and fully loaded at 70 mph or empty and cruising at 80 mph, I get anywhere between 190 and 230 miles to a 65 litre fill. So that works out at between 13 and 15.7 mpg. I've never driven it on petrol far enough to find out what it does but would assume at best 20-22 mpg going on what others get from similar cars.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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robertXX
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Re: The Temptress

#46 Post by robertXX » Fri Jun 11, 2021 1:42 pm

sorry CNG , editted :)

Thank you Gilbert , looking at fuely , which seems to suggest 15 to 18 mpg , that looks like around the 10% lower on gas ....ish ..
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

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Re: The Temptress

#47 Post by Gilbertd » Fri Jun 11, 2021 6:09 pm

Sounds about right I suppose. Thinking about it, in 11 years and 215,000 miles, I've probably driven less than 1,000 miles on petrol. Spent around £42,000 on LPG though......
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


Proud member of the YCHJCYA2PDTHFH club.

LPGC
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Re: The Temptress

#48 Post by LPGC » Fri Jun 11, 2021 6:33 pm

Stochiometric is one aspect, calorific value and density of the fuels are others, engine design is another.

From a chemist's point of view calorific value, call it C, is the amount of heat produced by burning a certain weight of fuel. Burning 1kg of LPG will produce more heat than burning 1kg of petrol... But we buy fuel in litres not KG and since liquid petrol is more dense than liquid LPG, on balance burning 1litre of petrol produces more heat than burning 1litre of LPG.

Could term FC a weight or volume of F fuel multiplied by C it's calorific value. For our purposes we'd normally use volume (litres) for FC. Now if we've got F quantity of fuel at C calorific value we know that by burning that fuel we'll get H heat.

The engine makes it's Power from Heat, there's quite a direct relationship... So could say that the engine makes P power from H heat. To produce that Heat to produce that Power it needs to be consuming FC at a certain rate. Now we could term FCR Fuel (quantity.. weight or volume, we'd use volume) x Calorific weight x Rate of use... So FCR could be litres of fuel at a certain calorific value per minute.

The Rate at which an engine can consume Fuel, and therefore it's Power, are limited by the amount of air it can consume because a certain fuel at a certain rate needs a certain amount of airflow rate to burn it. The amount of air it can consume won't change much regardless of which fuel it runs on but the amount of fuel it can burn (so FCR and H) are limited by the fuel's Stochiometric ratio.

Now let's say we want to cruise down the motorway at 70mph, it takes P power to push the car at 70mph. P is dependent on H. H is dependent on FCR.. For a lower Calorific value Fuel we need to burn more (Rate increase) to get the same Power.

If we had 2 fuels that had identical density and calorific value but 1 fuel had higher stochiometric ratio than the other the driver would have to increase throttle position on the the fuel with highest stoch ratio but the engine wouldn't use any more fuel because of the higher stoch ratio... In fact depending on aspects of the engine design it might use less fuel than the engine running on lower stoch ratio fuel because it wouldn't be suffering as much of a pumping loss (throttling loss with the pistons sucking at a vacuum on intake strokes). But it depends on the engine design because the flip side of less throttling losses is greater compression losses. And then the flip side of compression losses is a greater early pressure rise in the cylinder when the burn begins and perhaps greater peak cylinder pressure.

Already a lot of variables above, some of which will partly explain slight differences in mpg compared to petrol on different engines. And just with those variables we can look at each in more detail... For example regards pumping losses - If we've got a petrol engine injecting liquid petrol and the petrol doesn't fully atomise until it's inside the cylinders that's a different situation to LPG that is already a vapour when it enters the manifold, in that situation the petrol won't much affect pumping losses (because the liquid doesn't take up much volume) but the LPG will take up space in the manifold and since the engine still needs the same amount of air the space that the LPG takes up in the manifold means a slightly higher manifold pressure is necessary.. which would lead to slightly lower pumping losses even if it had same stoch ratio as petro... but it's stoch is higher which further lowers pumping losses. On hotrod forums they talk about standing pressure in cylinders versus useful pressure, something to do with how the molecules move when heated (some molecules in fuel stand still and vibrate, so localised high pressure that doesn't follow the piston on the power stroke, there'll be a slight difference in that respect between petrol and LPG and some of those differences may be due to combustion chamber design.

But we just use rule of thumb and are not often far wrong with our guestimations lol! Even if we knew how to predict which aspects would have what affect and the interactions between different aspects we'd still need a supercomputer to do the calculations for various engine loads etc, and even then the proof would only be in the pudding. I've come to have a bit of insight into which engines do average / more similar / less similar mpg on petrol versus LPG from customer feedback and the insights have made me think of things like bore/stroke ratio and compression but it's only a bit of insight.

Sometimes an engine will do favourably on LPG compared to petrol.. because petrol system components like injectors are worn while LPG system injectors are brand new, and LPG system calibration (and functions in some ECUs) can help compensate for variances in LPG injector flow rates or different engine breathing on different cylinders. A mixer system is good in that respect because the LPG is mixed with air as it enters the manifold and regardless of engine cylinder breathing each cylinder gets the same mixture.
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robertXX
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Re: The Temptress

#49 Post by robertXX » Mon Jun 14, 2021 12:58 pm

Thanks simon , i definitely notice air temp affecting lpg power more than petrol power , which would figure ,since not only is the air thinner, its also being displaced more .


Now here's a good question , i have a solenoid which is 12mm internal bore , which is what i need for my multivalve , but its 8 watts, not 11, which is what i think its supposed to use .....q is , will an 8 watter work ? normal 02 tomasetto 6mm multivalve.
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

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Re: The Temptress

#50 Post by LPGC » Mon Jun 14, 2021 3:33 pm

Difficult to say, don't usually see 8 watt coils. Maybe it will work except if tank pressure is high on a hot day..?

What valve do you have and is that the standard coil for it?

It may have 12mm inlet and outlet but I doubt the plunger inside covers a 12mm hole, may just be a 6mm hole the plunger closes against... Just in case you decide to do the maths to see how much force it will need to have to open against various pressures.

With some valves, e.g. Tomasetto tank valves, there's a version with 6mm outlet (M10 pipe-nut fitting) and a version with 8mm outlet (M12 pipe-but fitting). The internal gas tracts are 4mm / 6mm respectively, the solenoid post internal diameter and solenoid plunger external diameter are the same in both and those parts seem interchangeable... but in both cases the plunger is wider diameter than the 4/6 mm hole it seals against (wider than the rubber at the end), the rubber at the end is a bit wider on the 6mm version (so a 4mm plunger in the 6mm version might allow gas to get past even when closed but a 6mm version on a 4mm valve might seal fine), and the solenoid coils are different between 4/6mm versions (black/blue and I reckon black is 11watts blue 14 watts).
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Re: The Temptress

#51 Post by robertXX » Mon Jun 14, 2021 5:09 pm

valve description is in the question simon ;) stock coil is 11 ,,,8mm coil is 17.
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

CNG
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Re: The Temptress

#52 Post by CNG » Mon Jun 14, 2021 5:47 pm

Not sure either, but if in doubt assuming you've not already done this, source something from Tinley Tech. They seem to have umpteen variants, ask for Mick. The others wil ask daft Qs, Mick has handle on what you'll be wanting. If you go a bit high in wattage, it'll get hotter than need be. I'd think 11W is what you'll want. 17W seems a bit high, it'll get hot but don't fret about it.

You don't have to, but for the pennies they cost, I'd put a flyback diode in there. More so if you've upped the grunt of your coil, liley will but the ECU might not be able to handle the 'overcook', find a 1N4007 or simiar.

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Re: The Temptress

#53 Post by LPGC » Mon Jun 14, 2021 8:19 pm

robertXX wrote:
Mon Jun 14, 2021 5:09 pm
valve description is in the question simon ;) stock coil is 11 ,,,8mm coil is 17.
Sorry I overlooked that, as luck would have it turns out I answered with very relevant info anyway with the Tomasetto valve example. See how it goes and if there are any problems buy a new coil from TinleyTech?

I mentioned in brief a way of working out if it would work when tank pressure is high - The 4mm opening type has 25.12sq mm hole, the 6mm type has 28.26sq mm. There are 645.16sq mm in a square inch so for every 1psi of tank pressure it'll take around 0.0438 pounds (28.26/645.16) to pull the 6mm plunger open (plus a bit more as it also has to pull against the plunger spring), at 10bar around 150psi tank pressure it should take around 6.57 pounds + the bit of spring tension to pull the plunger open. I only used 3.14 as PI and haven't accounted for existing pressure in the line between the tank solenoid and front solenoid which when present (and usually will be present) will greatly decrease the pull needed to open the tank solenoid. I wondered knowing how you test every other aspect of everything you might test how much magnetic pull the coil exerts on the plunger! ;-)

No doubt the tank valve coil you have will work when there is gas in the line between tank and front solenoid decreasing the force necessary to open the plunger, the question is will it work on a hot day when tank pressure is high if you previously ran out of gas and there's little back-pressure in the line between tank and front.
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Re: The Temptress

#54 Post by robertXX » Mon Jun 14, 2021 8:24 pm

i think that hot day concern is a clincher , so i bit the bullet and bought one for 10 quid :)
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

robertXX
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Re: The Temptress

#55 Post by robertXX » Thu Jun 17, 2021 9:03 am

Well i only went and got a bit more done today in the 23c hot sunshine .


firstly i fitted the inlet for the tank ..


Image


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pretty straightforwards , with the flap on its all gone ..

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an interesting thing to note about the flap , it has a very clever over centre spring on it so it stays open , or shut , nice .

oh... something else of interest is , the car was originally elephant grey , and you can see the flap is now gold ,but under it is the grey , so at some point i think my car was gold ....isn't that weeeiiirrddd !?



next ,now i was onto a sweat soaked roll , fitting the reserve tank .


this beam needed straightening ..

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so i gave it some herculean blows with the big long handled sledge hammer ..molnierrree ....and it decided to go straight ,like a newbie from wormwood scrubs.


Image


it may not look it, but it is now straight .



next on the agenda , was the inner boot floor bracing strut ..

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that ^^^^ poxy bit of metal , was a right palava to get off , it was about a foot in under the floor , and i could only cut one side , then try to lever it down and cut the other side ,don't know what its made of but i went through 2.5 s/s cutting thin discs .



anyrdUP , i could now pop in the tank ,and cut the hole for the lid ..


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and fitted ..sort of ...


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snuggy !

the other 90 litre tank , will sit at the back of the boot up against the seat back , and so i will have a 132 litres -20% total fuel capacity.
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

robertXX
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Re: The Temptress

#56 Post by robertXX » Thu Jun 17, 2021 9:05 am

Not a kerlossal amount done today,

i drilled the tank mounting holes ,and big pipe/vent hole, and that all worked out dead in line which was a nice surprise ..


Image


i used a bit of silicone for the vent pipe , this is be sure if any gas should ever leak it will exit outside the car .

i then had a right palava trying to bend 8mm copper pipe into the contortion it needed to screw onto the valve ..

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turned out my used 8mm pipe was swollen to 8.000001mm , and this meant a lot of work to get the olive on and the fitting on ,but in the end ,after standing like a question mark for ages i got er dun..

Image



phewf! ... i definitely don't want to do that again .


i spent a fair while under the car , and , without it jacked up , i was uncomfortably close to the spider web city of dread ,bear in mind i have found 5 seperate false widow spiders under there when doing the brakes , and got bitten 3 times,by one of the little bastards ,and those bites are not at all funny ,so i was not enjoying my little test of courage under there today .

But hey , you shouldn't have joined up if you cant take a joke .:)



tomorrow i crawl under again for the 6mm pipe to the front of the car .



regards
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

robertXX
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Re: The Temptress

#57 Post by robertXX » Thu Jun 17, 2021 9:06 am

SPEAKING OF WHICH ....


i only went and got the other pipe , the one to the engine , fitted ,and yes it took an hour and half just to get the fitting to screw into the multi valve , i even had to use a tiny thin file to rebuild the thread on it ,but hey ho, its in now .

And yes i did get bitten lol , not sure by what, but a 2" white circle with a red dot in the middle came up on my shoulder blade this afternoon , bit of germolene and its now red so i think i am ok .

i went along underneath zipping up the gas pipe , and also i found a bit of 5 core flex , so zipped that in as well , that's my wires for the flow cutoff solenoid , and the fuel level sender .

all that gubbins ended up in the engine bay , so i connected the 2nd cutoff/filter to the pipe , and then that to the reducer ,, so that's all the feed done. And the wires ready to connect to the leonardo gizmo.

noice.
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

robertXX
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Re: The Temptress

#58 Post by robertXX » Thu Jun 17, 2021 9:07 am

i decided to tackle the big job i have been putting off , plumbing the coolant lines , not that this really is a big job , just i knew i probably did not have enough pipe , or clips to do it .

Now normally what you do is , T piece into the feed pipe to the heater ,and run that to the lpg reducer .then T piece in the the heater return , and connect that to the reducer .That way you get a flow of hot water to stop the lpg freezing as it drops in pressure.


with a turbo to cool as well , i decide that instead of another set of T pieces , and even less flow to the heater , i would do it a different way .


i went T piece on the feed to the heater , then that takeoff went to the turbo lower port , then turbo top port went to the lpg reducer , then from there back to a T in the heater return .


this way i get faster warm up of the lpg , which is good for economy and winter .and i get better flow through the car heater .


So to put this into practise , i undid the turbo water connections , cleaned them up and swapped them so they now point towards the back of the car .

then had to 1" movement hand hacksaw the original clip off..

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i don't think that had been off for a while..

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Now i could drag out my big box of hoses to try to make it all work ... the end result of this was failure .

I simply did not have enough water hose of the right size to do the whole thing , so i went lateral , and thought hmm , i wonder if i have any 15mm copper pipe i could bend ...and the answer is yes i did , but right next to it in the rafters , was some 15mm stainless tube .

Now started a fit of cutting and bending the tube in the blazing sunshine like a nutter .

and ended up with this gubbins .

Image

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Luckily i could use just one length with no joins for each run .

Sadly i had to scrimp and search for any clips that would work , so they all need replacing with new when i can .



One more run to do from the reducer to the return hose , and that's the water system done.



regards
robert
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

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Re: The Temptress

#59 Post by LPGC » Thu Jun 17, 2021 10:09 am

All seems to be coming together nicely Rob
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Re: The Temptress

#60 Post by robertXX » Thu Jun 17, 2021 10:42 am

Thank you Simon :)

I am now wondering , will the leo stepper motor work normally when there is boost in the line ?
"The Temptress" thread..... https://forum.retro-rides.org/thread/215234/temptress
'Medusa" thread .....https://www.rodsnsods.co.uk/threads/medusa.206057/

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