Fuel economy

[popcorn balls]

What do you get?

Just calculated mine after a 105 mile round trip...... and it's f@@***g terrible :shock: even allowing for the inaccuracy of the fuel guage (which magically started working last week!!! but still seems to run for miles on empty!) and that most of the trip was motorway at 3500-4000revs which won't have helped either....

What should/could i expect on a single carb set up?

71 1600tp
009 (would a change to SVDA improve economy?)
Carb is an brand new repro thing that T2D fitted as the original was leaking.

 

[chrisby]

Vac dissy,electronic ignition modual both I think help to improve mpg.
My fully loaded Westy poptop at 55-60 mph does 24 mpg on petrol and 21 mpg on LPG ,but the gas is half the price.

 

[easy]

I did a trip of around 350 miles last year with a fully loaded van, it cost £35 in fuel at about £1 per gallon, so i think thats about 45ish MPG :mrgreen: happy with that 8)

 

[popcorn balls]

£1 per gallon

:shock: you wish :lol:

 

[easy]

per litre i mean :roll: :lol:

 

[popcorn balls]

I reckon i got less than 20mpg at the weekend!!! probably about 17

 

[stagger lee]

vacuum distributors and electronic ignitions may/will give negligable potentially unoticable improvements only. first thing is to check it's not running too rich, though it'd have to be bloody rich to return late teens. check you are not losing fuel anywhere, the smallest of leaks could evaporate as it leaves, so can go unoticed and cripple economy. check the fuel pump isn't leaking fuel into the case etc (inspect oil).

also the fuel isn't the best indicator of fuel consumption anyway, i don't thik they're linear? fill it up, drive a lot of miles, then fill it up again. work out your mpg then from the litres added.

other than fuel injection; from a t3 for a 16. best way to improve economy is with a pair of sensible carburettors. they'll pay for themselves in a year on a well used van.
make sure generally descent engine; compression and valve clearences.

45mpg from a fully loaded van is a miscalculation or dellusional, sorry.

 

[oneday!]

meet freedy flint stone :lol:

 

[easy]

vacuum distributors and electronic ignitions may/will give negligable potentially unoticable improvements only. first thing is to check it's not running too rich, though it'd have to be bloody rich to return late teens. check you are not losing fuel anywhere, the smallest of leaks could evaporate as it leaves, so can go unoticed and cripple economy. check the fuel pump isn't leaking fuel into the case etc (inspect oil).

also the fuel isn't the best indicator of fuel consumption anyway, i don't thik they're linear? fill it up, drive a lot of miles, then fill it up again. work out your mpg then from the litres added.

other than fuel injection; from a t3 for a 16. best way to improve economy is with a pair of sensible carburettors. they'll pay for themselves in a year on a well used van.
make sure generally descent engine; compression and valve clearences.

45mpg from a fully loaded van is a miscalculation or dellusional, sorry.

I am being dellusional you are right! it must be my early starts that are plaing havok with my brain it was 250 miles I drove! :lol: went to falmouth to Newquay and then partly back to Bristol on £35 8)

 

[oneday!]

stiil not bad dude i be happy with that 8)

 

[Tofufi]

vacuum distributors and electronic ignitions may/will give negligable potentially unoticable improvements only.

Not quite true, the vacuum distributors provide more advance at low throttle than 009s, meaning they can/should give better MPG at slower motorway cruising speeds - about 2-3mpg more depending on your driving style.

I get about 28-30mpg from my totally stock engined van.

Things like stock air filter, distributor and having it all set up and tuned correctly all help.

 

[stagger lee]

tofufi, i believe were saying the same hting; 'can/should' give better mpg' and 'may/will give negligable' etc etc. on the blackboard or blueprints, i'm sure they do. 2-3mpg, possibly/potentially on optimal conditions. come on, if that ain't negligable what is? average that out over avergage driving; m-way/town etc you will not notice it, belive me.

volumetric efficiency is key here. lots of a little add up to somehting, but bits of a little, ain't much at all.

i get easy 30, slightly more maybe from a fairly empty minimally interiored panel driven sensibly on a good run. that goes down to about mid 20s round town.
stock 16
t25 distributor
t3 twin solexes
monza

 

[Anonymous]

come on, if that ain't negligable what is?

A 3mpg improvement on 17mpg is about a 17% improvement, I would say that was a bit more than negligible

 

[Trikky2]

come on, if that ain't negligable what is?

A 3mpg improvement on 17mpg is about a 17% improvement, I would say that was a bit more than negligible

Exactly. 3 MPG improvement means 30 more miles per tankful - over say a years usage that adds up.

Thats the whole reason engines were fitted with the more expensive dissy with a vac unit rather than the cheaper 009, which was originally meant for use on industrial engines often governed to run at a constant rpm.

This subject has been done to death for such a long time that there must be the equvalent of an entire encyclopedia of articles and posts about it.

 

[stagger lee]

hot tomally, there's alot of theoretical talk here. granted 3/17 as a percentage is 17, slightly more infact. but these are figures plucked out of the air, hypothetical values, guesses. well maybe someones gut feeling, subconcious self-wellbeing they're running much better oh yes, superb now that filter is fitted. thats one spicy meatball eh?

minor changes be it low rev vacuum advance control as opposed to centrifugal, or that extra fraction of a thou' toward optimal valve clearence, those few more milliamperes of coil current due to semiconductor switching (forget the worn gears, backlash, cam wear, low comp etc). maybe they would show a few mpg's over a thousand miles at constant revs in top gear. but where does that happen apart from a manufacturers test track, on a computer simulation model or the regurgitations from some armchair mechanic. in the real world they just get swallowed up in modern day driving conditions. and pass unoticed. i'm talking from experience, not what i read somewhere or hypothesised based on the laws of physics and dynamics.

all i'm saying is that, unless the engine runs like a bag of pooh. then a few tweeks here and there will not make significant improvements to the overall running of the vehicle. the biggest economy inhibitor on a aircooled vw is the inlet manifold, it's rubbish. simply too much meandering tubework to get optimal atomised fuel into the bores. most of it ends up on the inner walls. get rid of that get the carbs as close to the inlet ports and you're onto a winner, even if you have a 009 fitted.

another way to improve economy is to ditch the roofrack and those old suitcases, cooler boxes and petrol cans.

if your margins of economy is that you need to gain an extra few tens of miles out of a tankfull. you can't afford to run a van.

 

[Air Cooled Rookie]

Popcorn,

I can only relate my experiences with my ’72 cross over running completely standard.

When I bought it, I was getting 18 mpg round town and 22 mpg on a long run. Over the years the mpg has gradually improved as I have sorted out each small problem.

In summary I changed the 009 dissy for a brand new vac advance unit, fitted electronic ignition, had the carb re-built, changed the inlet manifold (the original had coked up heat risers), replaced the missing tinware/thermostat/cooling flaps and got the vacuum operated hot air inlet flap working properly.

All these small things added up to improve both mpg and the way the van drives (no more flat spots, juddering, etc). It wasn’t cheap and took a long time but was definitely worth it as I enjoy driving the van so much more now. I get an average of 25/26 mpg and have got as much as 29 mpg on a motorway run.

I have found that taking your time setting the engine up pays dividends. Although it’s possible to whip round and set the tappets near enough in 20 minutes or so, it can and has taken me an hour & a half to set the tappets and get them so they are spot on. It’s the same with the ignition timing and carb settings.

Are you due an MoT soon? If so ask the tester to carry out an emmisions test on your van. No matter how high the reading he can’t fail you and it will give you a good indication of how well your carb is set up.

Other things to check are tyre pressures (they affect mpg significantly), brakes, (are they dragging), cleanliness of the air filter, the choke mechanism (how long does it stay on), and as others have said, the amount of needless junk that you’re carrying around in the van.

Just a thought: Are you running on standard diameter wheels & tyres? If not, that’ll affect your mpg calculations.

 

[noddy]

I was getting about 26mpg on a fully loaded westy, crusing on motorway at about 55 to 65mph (tucking in behind lorries), and about 22 around town using normal day to day stuff.

1600SP vac dissy and 30 pict 3 carb.

 

[currylager]

1641 twin icts on a 800 mile round trip, combined town centre with 65 mph motorway cruising (thrapin) at 27 mpg, foot rammed to the floor in most cases 8) . 25 MPg has got to be the average surely.

 

[JLT]

What should/could i expect on a single carb set up?

71 1600tp
009 (would a change to SVDA improve economy?)

On my '71 1600tp, I was getting 16.31 mpg with a Brosol H30/31 carburetor and a 009 distributor. When I converted to an aircooled.net SVGA distributor, I got 18.88 mpg. (Note that this is US gallons, a bit smaller than imperial gallons.)

I haven't mucked with the jetting on the carb.

FWIW, I used to get 20 mpg in town and 23 on the freeway in my old 1971 bus with the stock 34PICT-3 carb and a 009, but I think I was probably running way lean, and that bus wasn't as heavy as my current one (no poptop, lighter camping outfit).

 

[KateLovesPurple]

All this just goes to show that a well sorted engine, that opens up its breathing capabilities, i.e. better induction and better exhaust will make all the difference. I have a mildly worked over 1641 with a better cam running with twin 36 DRLA's and a very free flowing exhaust. Most of the rest is pretty stock-ish. I have done the old fill it, drive it and refill it a couple of times over the summer on motorway journeys doing about 3200 rpm, about 58 mph and both times it has returned 32mpg! More than happy.

The VW engine is very capable of producing loads more power and consequently economy if the original strangling induction and exhaust systems are replaced.