Economy and how it can be improved

The D1 Hot-wire EFI use a Wheatstone bridge circuit, these circuits are frequently used in sensing circuits, gas detection for example.
There's also engine and fuel temp sensors to add to the mix for the ECU to deal with with it's basic logic curcuitry, therefore the fuel mixture will be the same for a warm engine what ever the outside temps are.

You can't make it economical, at all

You can make it better

Pump up your tyres nice and hard.

Fitting Megasquirt which tunes itself to the engine as best as can be expected makes basically no difference. Not done an accurate test but not noticed an special mpg improvements.

Does give you LOTS more power though!!!

Which brings me onto the final point:

For economy, DO NOT floor it!!!!!

I can spend £40 on a nights laning if I go easy, or £100 if I nail t everywhere.

It is that simple!

And Megasquirt makes flooring it so much more worthwhile it makes you do it more which can get expensive SO you have to have exceptional self control.

I know from my fueling tables that after a certain point it is basically balls out pouring fuel in for maximum power.

Stay out of this zone and its not too bad.

The loud pedal makes the biggest difference to a RV8.

Cheers

discool said:

The D1 Hot-wire EFI use a Wheatstone bridge circuit, these circuits are frequently used in sensing circuits, gas detection for example.
There's also engine and fuel temp sensors to add to the mix for the ECU to deal with with it's basic logic curcuitry, therefore the fuel mixture will be the same for a warm engine what ever the outside temps are.

Click to expand...

Could just be a poorer mix of fuel in winter then, was thinking it was the case with the maf given that my economy is far better in the warm than the cold even when the engines at full temp as I reset the trip log once warm

Righty, after a 300 mile round trip to Bristol, I have a base line

Petrel 12.7 MPG

LPG 14.3 MPG

That's at a steady 70 MPH with the tyres a pinch over recommended pressures

sidewaysste said:

Righty, after a 300 mile round trip to Bristol, I have a base line

Petrel 12.7 MPG

LPG 14.3 MPG

That's at a steady 70 MPH with the tyres a pinch over recommended pressures

Click to expand...

that doesn't sound right as LPG is less calorific than petrol ? :s

I know, but they're the figures I got.

I presume that suggests it's running particularly inefficiently on petrol for some reason.

People forget that LPG has the equivalent of about 120RON so properly optimised it can have benefits...

I know the lambda sensors are not working so the ECU is running open loop

I wish I could do a 300 mile trip at "steady 70 MPH" in the UK anyway

Ah, 70mph... this might be a significant factor. Lighter right foot might help

You seem to be doing most of the right stuff already: high quality parts in the ignition circuit as essential, especially with LPG which is harder to ignite than petrol.

I used to have a 3.5 v8i and running on petrol at a steady 55 I used to get around 24 mpg. I had it converted to LPG but can't remember what I got out of it then. This was back when LPG was cheap so I wasn't particularly bothered.

For comparison I get 30-35 mpg from my 300tdi. For short runs I find giving it a few minutes to properly warm up before starting off helps.

sidewaysste said:

I know the lambda sensors are not working so the ECU is running open loop

Click to expand...

Seriously? And you're considering modifications costing £££s? I'd certainly consider fixing the bloody thing first. You may even get more mpg :hysterically_laughi
I used to manage 21mpg on a run with my 4.6, but that was trying really, really hard.
You could have a look on the Hypermiler forum. All I can really suggest is making sure the tyres are well inflated.

Yes seriously. You've clearly Missed my point completely, but go ahead, make fun! Do you know how much 2 oxygen sensors cost? I could replace them or put the money toward a standalone ecu, I'd be over 1/3 the way there! And that's before considering the fact that a previous owner welded the sensors in place and it would require purchasing a new y pipe...

I don't mean to make fun of you.. but honestly, if you get it running properly you'll probably (definitely) fix the problems you're having! I bought two NTK sensors for mine, they were around £50 each and are of fine quality. Get another Y/downpipe, second hand will be fine. No point messing about with megasquirt etc at present when you can just optimise what is there anyway for not much cash.

I can sell you a y pipe

You're still missing the point though bud, this isn't purely a cost saving exercise, it's an experiment. Titania sensors are very expensive, usually £100 or more. I'm not having any problems and whilst I appreciate suggestions of help, I am a professional mechanic and ecu tuner/ installer and have checked and rechecked the basics. I'm more concerned with conducting a fair test than immediate cost savings, I'm after a longer term real world gain. The 4.6 will be more economical as it has more sophisticated engine management.

Good luck with it mate.

Thanks you do raise a valid point though - how much difference do bad lambda sensors make? If someone cares to donate a brand new pair of Titania sensors for the cause, I'll gladly accept....

Running in open loop on a car map uses a LOT of fuel!!

You would be better disconnecting the lambdas and fitting a non cat tune resistor!!

Righty I've mad a little modification. I had a rear silencer but no mid silencer. It was very loud, very coarse and not particularly pleasant. I've now welded in an absorption type center silencer and cut out the rear silencer. I cut just before and just after the rear silencer and welded the original tip on to the end of the cut pipe. It's now nice and light and well out of the way for offroading (got the idea from Mr Noisy) I've got a nice burble and hopefully a bit freer flowing exhaust. Time and another run will tell. The next step will be to fit a pair of electric fans that are sat on my bench in place of the massively inefficient viscous fan

Swap your 285's for my 205's for less friction and better economy ;0)

I found that twin electrics did not cool my motor enough in the warmer months, even with hd 4 row rad fitted.

I also had numerous problems with reliability of bearings etc AND just once forgot to turn them back on which resulted in a boil over at tickover.

As such I am back on viscous, and I do not find it innefficient because it is completely disconnected from the engine when at normal temp, I can stop it with my hand with no trouble!!

viscous isnt massively inefficient