TopicToaster
Can you give us a little info on how to read these plots. Where is accelerator position shown? What are the contours showing? and what are the coloured lines showing? Where is fuel consumption shown?Originally Posted by Dougal
Dead right, the "big lazy engine" theory is complete bollocks. Smaller engines have less internal friction and less pumping loss. This is why car makers are turning towards smaller boosted engines to reduce fuel economy.
Here's the BSFC plot for a VW 1.9tdi. One of the most efficient engines you'll find on the road regardless of size.
Thanks
ForumSage
Nope, check out the BSFC charts I posted above.
Flooring it in a higher gear uses less fuel than revving it in a lower gear. I've covered the reasons why.
Driving a car with a real-time fuel consumption readout will make this very clear.
OldBushie
Hey Dougal, are you an Engineer in your day job, by chance?
ForumSage
Possibly.
OldBushie
Hehe, thought so, now whats that joke? pigs, mud, engineers, enjoys.....Possibly.
Wizard
I have a diesel,however when i had a 69 v8 monaro i achieved the best fuel economy after i fitted a vacuum gauge to the inlet manifold,the more vacuum in the manifold the more fuel being sucked into the engine this helped with the lead foot approach i had at the time.As already mentioned the fitting of a better exhaust system will help as well.
ForumSage
Just to keep rovercare amused a little longer.
The more vacuum you've got in your intake, the less air and fuel you've got going in with each stroke.
Full throttle = minimum vacuum (maximum intake pressure) and maximum flow.
Idle = maximum vacuum (minimum intake pressure) and minimum flow.
ChatterBox
SubscriberFuel is not 'sucked into the engine' by manifold vacuum, in a carburettor engine fuel is drawn from the carby jets by venturi effect, this is a product of air flow. Less vacuum means more airflow which means more fuel drawn through the metering jets in the carby. On those old vac guages, the 'economy' end of the scale is where the lowest pressure is; low pressure = high vacuum.
Back to the topic, I think it's unrealistic to hope for decent fuel economy from a 2 tonne V8 with constant 4wd. I'm planning on fitting the closed-loop mod to my EFI system, haven't got around to it yet but that is one of the few mods that may help economy.
Pete
OldBushie
If you want to save a few bucks a week in fuel buy a pushbike,ride to the shops to get bread and milk,good exercise and you will save more money than any economy measures you do to your vehicle. Pat
Swaggie
SubscriberI have done LOTS to my 3.9 RRC, but the fuel economy gain is not great. I got 15.5-16 L per 100Ks towing my 600-650 KG camper trailer at 100KMh on cruise control on flat ground, which is better than many/most .
I have closed loop, free flow muffler, Thor inlet, Unichip, snorkel ,modded heads with higher CR ( about 8.7:1) , and modern 4 hole Bosch injectors.
IMHO The drivetrain on a 92 RRC causes a lot of drag/inefficiency.
For example, I suffered a blocked inlet on my fuel pump on my long trip. The engine would take very little throttle and struggled to get to 85KMh without going into a massive lean miss. If I could coax it to TC lockup, I would gain 10Kmh plus with the same fuel flow.
So by inference if the lockup were lower , then at say 90Kmh it would use far less fuel.
The driving of both axles must cause drag, and the shape of the car is very poor aerodynamically.
If you look at modern AWD's they have a teardrop shape, only connect the front or rear axle when there is a speed difference etc, as well as the latest engine control tech such as variable valve timing, direct injection etc etc.
Modern 4WDs like a Range Rover V8 get much the same economy as an RRC/Disco at cruise.
So my conclusion is that you and I are never going to get much better economy.
Regards Philip A
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