B14 fuel consumption

[Clan]

Well I'm now averaging 42 -45 mpg on a weekly basis , same journey every day sometimes slow moving traffic for about 20% of the journey . 2 long hills and a short steep hill to get up on the way .

How? i asked myself , I was expecting just over 30 mpg like the rest .
well:

The later 340 has a one piece rear wheel bearing , same as front wheel drive cars , lower friction than the older two ball bearing races each side .

The car has the idle valve fuel cut off as described above .

There are aerodynamic plastic pieces around the front panel and behind the bumper.
The car runs very freely and will coast for a long way , however this will not save fuel as the idle jet will not close off .


I fitted the 1.7 5 gear transaxle to replace the 4 speed M45R . the lower 4 gears are the same , 5th is higher , same rear axle ratio. I use it as often as possible .
( Perfect low mileage 4 speed M47R transaxle available )

Low friction Castrol Syntrax Synthetic Final drive oil

ATF in the gearbox not engine oil

5w/30 Synthetic engine oil .

new Vriedstein snowtrac 3 tyres @ 35 psi .

The instrument panel has the vacuum gauge .

have a 92 degree thermostat

I'm not particularly driving for economy but not exceeding 60 mph except down hill ,

Idle speed is 1000 rpm , haven’t had chance to turn it down yet .

fuel tank is filled to the brim each time ,


So there it is , still room for improvement , might fit an Oil to water heat exchanger under the oil filter to warm up the oil quicker . then drive for economy … stop/start anyone ? Fuel injection would help , must be a later Renault using this engine with injection ?

Nice to have modern car fuel economy from my 28 year old Volvo  And it goes better than any 340 1.4 i have driven before when you get the revs up .

Like the recent Driv e models there are about a dozen modifications they have done to help economy , each one on it’s own would make no noticeable difference , but the sum of them certainly does ….

[classicswede]

That is good consumption.

Fuel injection is not likely to improve Consumption unless it was running off a wide band. A well setup carb will give better consumption than older fuel injection.

I remember years ago someone was looking at how air flows around a 340 and one of the worst areas was the mirrors!

[macplaxton]

I've got a set of Snowtrac 3's and the normal pressure is 31 F , 35 R.

They are grippy buggers in the cold and like every other winter tyre, aren't exactly low rolling resistance.

The vast majority of your gains is down to your right foot.

On a run without hanging around in my 1982 vario, doing 70mph where permitted I can get 34 mpg. I've had as little as 15mpg in a late 5sp B14.4E, but that was towing a weighty car trailer at 60mph and going up Shap on the M6.

A couple of times in the past, I took a 2002 Ford Transit MWB 90hp up to Scotland. Driving like WVM resulted in the tank empty after 350 miles and doing 22mpg. Driving the complete opposite was 500 miles and 34mpg. (That's about a 55% gain.)

[340man]

In the owners handbook it gives typical fuel consumption for various models.

Years ago I was surprised that on a long run, my over 100,000 mile 1.7 gave more than 50 MPG. Indeed, at first I thought that the fuel gauge needle had stuck.

Only done short trips in my 1989 1.4, not sure what it's consumption is, but it's not disastrous.

Just added a scan of the stated fuel consumptions.

So it looks like over 50 MPG for a 1.7 is not unusual.

[340man]

Here is the late Tiddles checking over the 1.7's engine, photo about 7 years old.

DSCF7249 by A60man, on Flickr

[Clan]

Originally Posted by 340man

Here is the late Tiddles checking over the 1.7's engine, photo about 7 years old.

my cat was always interested in the engine bay too :-)
The 1.7 was the ideal engine for the 300 series , in standard form it was detuned from the renault version , It would do 105 mph instead of the 93 of the B14 and had a lot more torque with no penalty increase in fuel consumption .
You could get more power than a 360 engine using Renault parts ,In the formula Renault racing cars they were about 170 bhp .

[340man]

Originally Posted by Clan

my cat was always interested in the engine bay too :-)
The 1.7 was the ideal engine for the 300 series , in standard form it was detuned from the renault version , It would do 105 mph instead of the 93 of the B14 and had a lot more torque with no penalty increase in fuel consumption .
You could get more power than a 360 engine using Renault parts ,In the formula Renault racing cars they were about 170 bhp .

That is if one changes the cam belt before it breaks! I had a lot of things going wrong in my life, neglected the cam belt. The obvious happened, fortunately, a second hand cylinder head and a few hours work fixed it!

Tiddles loved the Volvo, would often sleep inside.

[340man]

A bit off topic, apologies, but the extra weight of Tiddles may not have helped fuel consumption.

[340man]

More photos of Tiddles / 340GLE

[Clan]

Originally Posted by 340man

A bit off topic, apologies, but the extra weight of Tiddles may not have helped fuel consumption.

we had one like that next door called Murphy he had a keen interest in cars too !