Another MPG willy waving thread.
Discussion
By best you know what I mean! 
d was driving 
db484bhpv8 said:
Just done 280 miles from Somerset to Cumbria in under 4.5 hours on 1 tank and still have this much left...
Cant be bad for a modified 4.6 with 329 bhp
Very impressive Derek.
Cant be bad for a modified 4.6 with 329 bhp
Lets say you've got another 10 miles left in there, meaning you can cover 290 miles on the 12.5 gallon tank.
It also means you're seeing 23.2mpg, and covering 280 miles in 4.5 hours is a very respectable average speed of 62.22mph.
In a modified 4.6 making 329bhp the only way you'll improve on that is by going dual fuel & running it on LPG.
My dual fuel 4.0 litre Chimaera makes 261hp on LPG & currently delivers the cost equivalent of 35mpg no matter how I drive it.
It turns in the cost equivalent of 35mpg cruising at 80mph, & the cost equivalent of 35mpg cruising at well over the ton, I'm also pretty sure its also not far off the cost equivalent of 35mpg in town too.
This seems to indicate there's a world of economy at an 80mph cruise just waiting to be untapped with some more attention to the mapping at this light load 3,000rpm area.
At this point I should point out my cost equivalent of 35mpg would be even better if I wasn't being forced to pay the rip-off LPG prices in and around London, cheaper LPG from the Countrywide Stores for instance could easily see that figure hit the cost equivalent of 40mpg.
Lately I've just been too busy driving & enjoying the car to get it on the rollers for the minor cruise economy tweaks, although it will happen in a few weeks when I fit slightly smaller injectors & increase the LPG capacity by 2.5 gallons.
This extra capacity combined with a touch more economy should definitely see me achieve my target 300 mile LPG range.
This means no touring range compromise over a standard petrol only car, with an added benefit of an additional 150 miles available from the auxiliary petrol tank giving an impressive dual fuel range of 450 miles.
In cost terms at it's current pre-tweaked economy levels I'm already saving £0.08p a mile running LPG against petrol, every time the odometer clicks over another 10 miles it's like someone putting £0.80p in your pocket
And it doesn't take long for all those pennies to add up into something that you can feel in your pocket.
All this with no downsides in performance, drivability or luggage capacity; actually I'd say it drives smoother at that difficult 1800rpm window on LPG than it does on petrol.
Other than that and a smoother idle too on LPG, it's impossible to tell what fuel I'm running on without checking the changer switch position.
On the basis of 6,000 miles per annum, running LPG is currently delivering a worthwhile yearly fuel saving of £480.00.
Granted, recovering the cost of the conversion will take some time so it's definitely a long term investment.
I guess I could always make it my daily driver, doubling the mileage doubles the savings and also cuts the time to the "Break Even Point" on the cost of the conversion in half too.
I'd say we've proved (if done correctly) that LPG is definitely a compromise free real world fuel saving option for the higher mileage Chimaera driver.
And from what I can see it's the only genuine way to make a meaningful difference to the cost of fuelling a TVR.
Edited by ChimpOnGas on Wednesday 26th June 16:41
db484bhpv8 said:
23.2!
I have already proved 28 mpg + before.
From experience i guess it would take 45 litres to refill which would equal if not better the 28.
If i ran the tank dry i reckon i could do over 350 miles!
Truth is it all boils down to what's genuinely left in there Derek.I have already proved 28 mpg + before.
From experience i guess it would take 45 litres to refill which would equal if not better the 28.
If i ran the tank dry i reckon i could do over 350 miles!
I'm sure you know the only real way to tell is to brim it, drive it, record the mileage & to brim it again.
Do the simple maths and that's your figure.
I know TVR gauges are unreliable but that gauge doesn't look like there's much left to me.
A Chimaera tank holds 12.5 imperial gallons which is 56.75 litres, if your saying it'll take 45 litres to brim it with the gauge that low your also saying there's 11.75 litres (2.59 gallons) left in there.
That just seemed a bit optimistic to me looking at your gauge but only you know your car.
I got to 23.2mpg by assuming there's not much more than half a gallon (2.27 litres) left in there with the gauge needle where it is in your photo.
Only the brim to brim technique will prove or disprove your genuine mpg figure.
I dont doubt 28mpg is possible, mine will regularly do that & better on a petrol run.
At 28mpg you would indeed empty your 12.5 gallon tank in 350 miles, but can you hand on heart say you've ever driven 350 miles between fills?
The truth is even though it's theoretically possible I never did a 350 mile run on petrol, because the average economy over that fill always got knocked from the perfect 28mpg down to something more realistic.
I find you inevitably always end up in town or worse still a traffic jam at some point over that tank fill, & obviously it's just the same on LPG.
But what helps the average is for some reason my LPG seems way more efficient in town and at high speed than on cruise right now.
The best I ever did on petrol before bottling out & pulling in for a fill was 321 miles, and believe me she was running on fumes.
I'm not doubting you Derek but you've got to brim back up & do the maths to get that genuine figure.
Better still repeat the exercise 10 times, that will be your real average fuel economy.
And it's the average fuel economy over a significant period and many tank fills that's the important figure.
That's what I've tried to do when reporting my LPG economy, and it would be all too easy for me to over egg the LPG pudding.
But my promise to the forum is to report absolutely honest uninflated figures & real world feedback on how the conversion performs.
My LPG average over 3,000 miles of mixed driving is the cost equivalent of 34.8mpg.
My average petrol fuel economy since the Canems installation measured over 3,000 miles of similar mixed driving was 25.54mpg.
Only LPG can give you the cost equivalent of a 9.26 mpg improvement measured carefully over 3,000 miles of similar mixed driving.
That's a massive 36% economy leap & ultimately cost improvement, just by switching fuels.
At 110Ron LPG works well on the strip too Derek
Roush Performance/Industries are delivering the same power & torque on liquid propane as the do on race gasoline.
http://www.youtube.com/watch?v=uLuR_3PgfAU
Even the vapour systems still work great on the strip, especially in forced induction applications.
http://www.youtube.com/watch?v=NrZm_eKfOKk
LPG, it's the way forward
Edited by ChimpOnGas on Wednesday 26th June 18:48
Monday morning I did 400 miles to lands end in my 400 at a steady 70-75 and worked out at 31mpg I generally get 30 when driving carefully some distance obviously normal running about is 23-25.
I think chimp on gas's LPG conversion is great as an engineering project and for somebody doing the work themselves as a project I fully understand but I don't think many general tvr drivers would see any cost saving once they'd had to pay somebody else to do all the work.
I generally bottle it and fill up at just short of a quarter myself!
I think chimp on gas's LPG conversion is great as an engineering project and for somebody doing the work themselves as a project I fully understand but I don't think many general tvr drivers would see any cost saving once they'd had to pay somebody else to do all the work.
I generally bottle it and fill up at just short of a quarter myself!
Bloody hell you do go on sometimes 
I do know how to measure mpg properly. Like i said ive proved 28+ before.
I brimmed the tank, drove 200 miles in 3 hours upto 90+ on the motorway then brimmed again.
The 200 miles was confirmed on the route and tomtom as was the speed.
Result was 28+
Today i drove a little easier on the motorway but also had a 20 minute crawl through traffic in Bath.
Just to settle i will go brim it tomorrow just to prove.
I do know how to measure mpg properly. Like i said ive proved 28+ before.
I brimmed the tank, drove 200 miles in 3 hours upto 90+ on the motorway then brimmed again.
The 200 miles was confirmed on the route and tomtom as was the speed.
Result was 28+
Today i drove a little easier on the motorway but also had a 20 minute crawl through traffic in Bath.
Just to settle i will go brim it tomorrow just to prove.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff