SPANK - Smell My Gas!

[ChimpOnGas]

So here I am just starting to wind 'Ol Gasbag' up to scalp yet another local Boxter, as I dump the throttle open on a steep climb and hit 97 MAP I only see a 20 kPa (3psi) increase in gas pressure proving the new Magic 3 Power reducer is the Mutt's Nuts!.....




Fast forward and a few thrilling seconds later and here's the full fat 5,000rpm plus blast past Mr Porky as I peddle 'Ol Gasbag' up that steep dual carriageway hill to properly test my new LPG reducer right to the very edge of it's flow capabilities.....



Jump to 38 mins to watch the last power run of today's mapping session..........

https://www.youtube.com/watch?v=xsOzEyPfP2E

As 'Ol Gasbag' rockets past peak torque the new reducer is only exhibiting a tiny 2kPa drop in my 150kPa idle gas pressure setting when subjected to the very final hard yard up that hill, which believe me in the world of LPG is truly outstanding.



My new Czech engineered Magic 3 Power reducer shown above also delivers outstanding throttle response, more stable AFRs and excellent AFR control during challenging heavy deceleration events. Clearly it's time to fit my new big flow LPG Tech Yeti injectors, but even at 98% duty my Hanas are still hanging in there at 12.4:1 AFR thus nicely keeping the engine in the safe air fuel ratio zone*.

These should bring the very top end high rpm full load duty down to the ideal 85% or less very nicely



As I continue to push on to 5,059rpm in fourth I'm now pulling up that hill smoking the Porsche at a healthy 102 Leptons, and believe me 'Ol Gasbag' is still pulling hard . Boxter Boy is now either back at home shaking and looking at PH classifieds wondering if he's man enough to buy his first TVR.... or on the sofa crying in the arms of his boyfriend



GAS... Not for girls!!! .... Or engine bay polishers



Canems Dual Fuel ECU calibrated to show.... Lambda 1 = 14.7:1 (petrol stoich)*

True LPG stoich = 15.5:1 (depending on % butane content)*

Lambda 1 is lambda 1 whatever fuel you're burning so no clever beggers please

[SILICONEKID 345HP 12.03]

What does the the vessel do ?

[ChimpOnGas]

SILICONEKID 345HP 12.03 said:

What does the the vessel do ?

It's my new LPG reducer Daz, sometimes referred to as a vaporiser....





It's job is two fold:

1. To turn the liquid LPG I store in my tanks over the rear axle and turn it into the LPG vapour my gas injectors deliver to the inlet manifold.

2. To manage the pressure of gaseous LPG supplied to the injectors irrespective of engine demand/load and cylinder pressure/fill level

The Magic 3 reducer is rather unique in it's design, the super small diaphragm improves throttle response and in theory is more resistant to failure, the small cylinder design also gets to operating temperature incredibly quickly during cold starts which means I can start and drive away on gas immediately even in the coldest weather.

Five years on since embarking on my journey and LPG components are improving year on year, injectors become faster and reducers better in every respect, so to continue the development of 'Ol Gasbag' I upgrade accordingly. What remains of course as the foundation of my LPG madness... the excellent Canems Dual Fuel ECU which itself continues to be developed and enhanced by David Hampshire of Canems Engine Management Systems and intelligent minds at Lloyd Specialist Developments.

Hopefully my basic tweaks just enhance what the real brains behind all this are achieving

[Brithunter]

Interesting information. Sadly the funds are just not there for an LPG conversion. By bumping up the purchase budget like we did it left none for any conversions. Shame as there would have been some savings on my across Europe drive. sadly two stations where I refilled in the UK th receipts don't show the amount of litres supplied as was going to add them all up to work out consumption over the journey. We had done 2,372 miles since picking her up at the last fill up and will need to fill up today as our last leg is around 450 miles.

[ChimpOnGas]

The savings are extremely easy to calculate.

Depending on the difference between the petrol and LPG price at the station you're filling up at, you can expect savings in the order of £0.10p per mile.

Here's my fill at Asda in High Wycombe yesterday: 95Ron petrol = £1.187 per litre and LPG = £0.527 per litre

• So that's 1.187 / 0.527 = 2.252 x true LPG fuel economy of 21.5mpg average = 48.42mpg petrol cost equivalent

• A well tuned petrol Chimaera driven sensibly will yield 23mpg average so that's: 118.7p / 23 = 5.16 x 4.546 = 23.46 pence per mile

• If I average 6,000 miles on petrol in every 12 month period, that's £0.2346p x 6,000 = £1,407.60 of fuel

• My LPG Chimaera will yield 21.5mpg average so that's: 52.7p / 21.5 = 2.45 x 4.546 = 11.14 pence per mile

• 23.46 pence per mile - 11.14 pence per mile = 12.32 pence saved for every mile I drive.

• If I average 6,000 miles on LPG in every 12 month period, that's £0.1114p x 6,000 = £668.40 of fuel

• That's £1,407.60 - £668.40 = £739.20 saved

Or just take the pence per mile saving of 12.32p x 6,000 = the same figure of £739.20 saved annually

The simplest way to work out how many miles you need to drive before the LPG conversion has paid for itself in fuel savings is to take the cost of the conversion and divide it by the pence per mile saving, IE:

• Cost of conversion £2,500 / £0.1232 = 20,292 miles after which the conversion has paid for itself, from there on in you simply save £0.1232p for every additional mile you drive

For some people who use their TVR infrequently and as a sunny day toy it will take them years to cover 20k miles, so an LPG conversion isn't going to be especially logical unless they are planning to keep the car for many many years.

Personally my take on owning a TVR is if I'm already paying roughly a £1,000 a year in road fund tax, insurance, and general maintenance before I've even turned a wheel I really should get some decent use out of that £1,000. The way I see it is if I drive one mile or 6,000 miles the annual cost of ownership remains the same £1,000.... so I may as well get my money's worth out of it.

It always amuses me when I'm pressed to financially justify the cost of my LPG conversion, no one challenges other TVR owners for spending £600 - £1,000 a year on tax, insurance and serving then only driving their car 600 - 1,000 miles that year, and no one challenges people who upgrade to an Emerald or MBE engine management system to prove their pay back day in fuel savings which is a good job as you'll be talking close on a lifetime the way most people use their TVR so little.

The truth is I embarked on my LPG project more as an interesting experiment in what's possible rather than a direct exercise in fuel savings, the fact the conversion paid for itself some time ago is largely irrelevant but still pleases all the same.

The big benefit for me came in massively improved drivability with no loss of power, indeed the car now makes more power on LPG than it did in 1996 when it left Bristol Avenue running on petrol. LPG delivered as a gas mixes way better with air which is of course just another gas, if the fuel is managed and burnt correctly this gaseous fuel state and so it's better ability to mix with air delivers huge drivability benefits over a liquid fuel that tends to fall out of suspension in air especially at low engine speeds. LPG is also 110Ron making it massively resistant to knock (detonation), meaning with the right engine management system you can take advantage by running more ignition advance earlier on, further enhancing torque and so further enhancing low speed drivability.

The fact is my TVR is significantly nicer to drive and more flexible on LPG, even when I compare it to my Canems system on petrol which in itself is a huge improvement over a petrol Chimaera running the old 14CUX and distributor setup. So you see LPG is not just about what you save at the pump, it genuinely makes for a better and more pleasing car to drive which combined with cheaper than half price V8 motoring makes it the best thing I've ever done to my TVR, it's also the only thing I've done to my TVR that's completely paid for itself

[ChimpOnGas]

And to conclude my top end mapping with my excellent new Magic 3 Power LPG reducer....

To solve the injector duration issue I'm now running two 12mm LPG delivery hose outputs from the reducer, this not only doubles the supply line volume to my injectors but also opens up a second output port on the supply head of the Magic 3 Power reducer (see arrows below).



With one output the Magic 3 Power reducer is rated at 280hp, but right at the top end and as I rolled over peak torque and headed to peak horsepower 'Ol Gasbag' literally had to run the injectors fully open (100% duty) to achieve the appropriate and safe air fuel ratio.

As we can see in the below screen capture, the Canems software is actually displaying 105% , actually 105% is impossible as you clearly can't open an injector more that 100% because 100% is fully open.



Injector duty is calculated by the ECU so I suspect David Hampshire of Canems Engine Management Systems built a margin of safety into his algorithm so home mappers like me reign it in early, 105% is likely actually 100% so for a true figure we should look to subtract 5% from what the software shows.

Ok so now lets see what happens when I open up that second output port on the Magic 3 Power reducer and double the supply line volume by running the twin 12mm hose strategy.....



As we can see I'm running the engine at full load here (98kPa MAP), at 100% TPS (wide open throttle) at 5,272rpm which means the engine is very much delivering it's peak horsepower. What the data doesn't show you is road speed, which is a good thing as charging up a dual carriageway hill at 5,272rpm in fourth gear in 'Ol Gasbag' would be 105.44 Leptons... which clearly would be a bit naughty on a public road

However, what the data does clearly show us is the new twin output strategy has allowed me to reduce my injector durations sufficiently to bring my duty down to 90% which as we've already established is an overestimation in the order of at least 5%, so lets call it the perfect 85% duty . What it also shows us is I am running the perfect LPG peak load AFR of 13.0:1, if this was petrol I would be running slightly richer at 12.5 to 12.8:1 but as LPG is gas it doesn't cool the richer you go like a liquid fuel so there's absolutely no benefit in going beyond 13.0:1.

Indeed richer LPG AFRs burn hotter not cooler, so because 13.0:1 delivers peak power it would be counterproductive to run the engine any richer, in conclusion the twin hose/output port strategy running an idle LPG pressure of 155kPa and 2.4mm nozzles in my Hana Gold injectors is the ideal setup for 'Ol Gasbag'... once mapped accordingly. The new Magic 3 Power reducer offers outstanding throttle response, more stable AFRs at idle and above, and has further enhanced the car's already superb drivability.... especially compared with a petrol Chimaera running the original 14CUX and distributor setup.

All this in a car that'll take you from zero to 60mph in five seconds and onto a genuine LPG powered 150mph plus, so remember folks.... 'Gas Is Not For Girls'... Oh and did I mention it delivers an average petrol cost equivalent fuel economy of 45-50mpg

'Ol Gasbag' is still every inch a TVR

[spitfire4v8]

What is the duration at over 5200revs though.
The duration percentage may* still increase as you go past peak power because it's a percentage of the available opening time .. as revs rise the available opening time decreases, and if the time decrease is greater than the decrease in power, the injector duty cycle as a percentage of available opening time will increase even though power is falling. (hope that makes sense)

The 105 percent might be a calculation based on injector duty in the map times any corrections added, so if your map duty cycle would be at 100 percent at perfect temps, a change of any corrections for temps and pressures might be the extra 5 percent. Just a thought. But as you say, if the injector calc is correct then 105 percent opening cycle can't really occur except in calculation.

• in fact is more likley to than not unless your bhp graph falls off the edge of a cliff

Edited by spitfire4v8 on Monday 30th April 10:10

[ChimpOnGas]

You're right, but why would I go past peak horsepower

However, the truth is while still running the single output hose strategy I did test what happens if I push past peak horsepower, the results show it would increase injector duty by another 4%, to demonstrate this here is my single reducer output run at 5,217rpm again.



And now lets compare it with a brutal and completely pointless run at 6,559rpm



As engine speed rockets on from 5,217rpm to 6,559rpm injector duty goes from 105% to 109% so a 4% increase, and remember this is all still on the one 12mm output hose and reducer port set up. With the twin output strategy all the evidence suggests the 4% would be less, but even if it was 4% that would show 95% duty on the software which as we now know has been calibrated to over read anyway, so I think it's fair to say the very worst case scenario is I'd be pushing a true injector duty of 89% over 6,500rpm with the twin output strategy in place.

I went through all this in my head and decided there was absolutely no point in doing another brutal 6,500rpm run once the twin output startegy had very much proved itself at peak horsepower, and TBH I'm not in the habit of unnecessarily over revving my engine, clearly that would be pointless . It's also worth pointing out the 85% saturated petrol injector duty rule doesn't really apply with peak & hold LPG injectors anyway, peak & hold injectors flow big volumes which is why we use them with gas, unlike saturated petrol injectors you can easily run them fully open no problem at all.

Of course the other place we find peak & hold injectors is on the drag strip, because if you're running a top fuel race car no traditional saturated injector could ever hope to keep up with the hose pipe flow levels of fuel flow such massive cube missiles demand. Methanol carries oxygen so has a stoichiometric ratio of 6.45:1, if you combine that with the demands of a blown 10 litre V8 making over 2,500hp you've got yourself a serious requirement for fuel flow/volume, only peak & hold injectors can cope and as long as your ECU is up to it.... the system really doesn't mind if you peak and then hold the injectors fully open for ever!

Given the saturated injector duty rules don't really apply with peak & hold injectors I'm really just playing it super safe with all the above, when it comes to injector duty do you really think these boys worry about hitting 100% duty?

https://www.youtube.com/watch?v=2tg6RDUFQJ4

The truth is you can only do stuff like that on peak & hold injectors

[spitfire4v8]

I know that performance isnt your main criteria so of course you can stop revving the engine at any point in the rev range. However to answer your question a very valid reason to rev past peak power is to improve acceleration which is best when you are riding the peak power hump at the end of the rev range .

[ChimpOnGas]

spitfire4v8 said:

The 105 percent might be a calculation based on injector duty in the map times any corrections added, so if your map duty cycle would be at 100 percent at perfect temps, a change of any corrections for temps and pressures might be the extra 5 percent.

Another good point, especially the pressure element as the whole point of switching from my Prins VSI reducer to the new Magic 3 Power reducer was to see if I could deliver the same or better results as I've been enjoying for years, but doing so at far lower reducer output pressures.

The Prins VSI reducer I originally chose is a bit of an oddball in the world of LPG reducers as it outputs the gaseous state LPG to the injectors at a pressure 25% higher than any other reducer on the market. I chose it specifically because of it's reputation for quality and it's ability to support a big V8, at the time the Prins VSI reducer was one of the few that could safely support my power output, but things have moved on so it was time to capitilise on more recent developments and improvements in LPG reducer design.

Enter the brilliant and innovative new Magic 3 Power reducer from those clever engineers in the Czech Republic



Hopefully my data proves to everyone this new and rather unusual reducer design is delivering excellent results, however, it should be noted that we had long since achieved the full load peak horsepower at 90% injector duty results with the old high pressure Prins VSI reducer, that was never in question, however, what always bothered me was I needed to idle at a massive 205kPa (30psi) to achieve it which for a number of reasons it not actually an ideal strategy.

With the Magic 3 running twin outputs I can now deliver the same or better numbers at much much lower pressures and I've not touched my Hana Golds with their 2.4mm nozzles to get there. With the twin output arrangement I've settled on an idle pressure of 155kPa, so that's the same results as the Prins reducer at a whopping 50kPa (7psi) less idle pressure. Things get even more impressive when we look at peak pressures, under acceleration/full load where the Prins reducer would spike at a shocking 275kPa (40psi), which is a 10psi spike above what was already way too much pressure!

Conversely the Magic 3 under the exact same acceleration/load conditions spikes at 180kPa which is just 25kPa over idle pressure so clearly a far better controlled spike of just 3.6psi, take a look at the following full screen shot showing the gas pressure and temp at full load.



For the record and to address the point on temperature, following a cold start and once I've passed through the engine warmup phase the LPG temp remains amazingly constant under all driving scenarios. From idle to highly aggressive full load acceleration events my gas temperature remains a very constant 50 degrees Celsius which ensures my gas temp correction feature remains little used, and 'less correction strategies' the better in my book.

The overwhelming impact of switching to the new Magic 3 Power reducer design has been a marked improvement in throttle response, this makes sense as the Magic 3 has a much smaller and so faster responding diaphragm, it also responds far better to manifold depression especially when there are snap changes in MAP. Finally because ECU to injector latency gets worse as you increase fuel pressure the new Magic 3 reducer and the lower pressure strategy it supports has given me back the lovely crisp throttle response you may only assume is possible on petrol.

All in all it's been an interesting project.... and another victory in the continual development of my stunning and super fast gas powered TVR



Dave.

[ChimpOnGas]

spitfire4v8 said:

I know that performance isnt your main criteria

Are you 100% sure about that?

spitfire4v8 said:

Of course you can stop revving the engine at any point in the rev range. However to answer your question a very valid reason to rev past peak power is to improve acceleration which is best when you are riding the peak power hump at the end of the rev range

Like this then



To be honest my objective has and always be a 'Cake & Eat It' one.

When I set out to convert my Chimaera to LPG it was always my firm belief that all the fuel economy in the world would be completely and utterly pointless if it meant the car I created lost it's wonderful and uniqueTVR sole, and this very much includes it's performance. This was a no-compromise conversion using an innovative twin fuel mapped engine management system that eliminates the normal compromises imposed by traditional LPG piggyback systems.

I set out to prove LPG does not mean a loss of performance, boot space, fuel range or a worsening of drivability... and to that end my work was already done some years back, but I can see why people get hung up on the fuel economy improvement element of my project, after all that's why people convert to gas... right?

I know it's hard, but the thing I really want to encourage people to try and get their heads around is I didn't only do this for fuel cost savings, it was an exercise in what's possible and a chance for me to shoot down all the nonsense and old wives tales that surround LPG.

Why do you think I chose to do it on a TVR?

Because it's a platform that helps me deliver my message in a very visual and impactful way that grabs attention by blatantly flying in the face of convention.... breaking the mold and challenging the ignorant who believe gas is only for taxis, old clapped out 4x4s and forklift trucks was and will always be my objective, and to do it in a TVR means I absolutely must prove I can....

'Still Go Fast On Gas'!

Edited by ChimpOnGas on Saturday 30th June 07:10

[SILICONEKID 345HP 12.03]

Are those coins your change after buying the gizmo

[Sardonicus]

SILICONEKID 345HP 12.03 said:

Are those coins your change after buying the gizmo

No thats what change is left of the lottery win that paid for this LPG conversion ........................... ........................................................... Sorry Dave just digging ya in the ribs

[ChimpOnGas]

Sardonicus said:

SILICONEKID 345HP 12.03 said:

Are those coins your change after buying the gizmo

No thats what change is left of the lottery win that paid for this LPG conversion ........................... ........................................................... Sorry Dave just digging ya in the ribs

Brilliant, I luv you boys

For the record, the conversion paid for itself a long while back and my new Magic 3 Power reducer was less than £90.00

https://www.ebay.co.uk/itm/LPG-GPL-Autogas-Magic-3...

Oh, and my old Prins reducer will be sold on eBay for £125.00, so the whole reducer change project will actually pay me a £35 profit, in a world where we see people paying thousands on these cars to gain just a few horsepower this seems like good business to me

That's the thing about LPG, you can buy really good quality components for very realistic money because people in the LPG world would never allow themselves to get ripped off like many TVR owners often do

Gas is good folks