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Garage => Test Drive => Topic started by: Maat1985 on 31 August 2009, 06:52 AM

Title: petrol usage
Post by: Maat1985 on 31 August 2009, 06:52 AM
i was just wondering everyones experience on driving how much petrol they use.....
atm my odo doesnt work sop dunno how many km's i can get from my petrol but so i will just refer to engine revs....

at 50 - 60kms is what i find the best in my 280se as this is bottom of 4th gear and it is 1500 - 2000rpm
accelerating when in drive at any point never goes above 3000rpm which is great.....
70 - 80kms is around 2000 - 2500 rpm.... and accelerating is never many more revs than cruising unless i give it a bootful and kickdown gears....

however the prob i find is because of the gearbox and the diff i assume..... at 120km/h it is sitting on 3500 rpm because it has been in 4th for the last 60km/h and the ratio in the diff is quite high i think..... and this really chews the petrol i nthink i used somewhere between 1/3 and 1/2 a tankl on a 45min freeway drive.....

and i know there is nothing i can do about this without losing acceleration just wanted to know everyone elses experiences and at first i thought i could never afford to drive a v8 but now i really think i can cus this thing does guzzle the gas.... not so much round the city at 50 - 70km/h but on the freeway jeez it is bad......
Title: Re: petrol usage
Post by: Big_Richard on 31 August 2009, 07:09 AM
my 6.9 has allways done between 400 - 500 k's per tank, and I'm certainly not gentle on the throttle. All w116 fuel tanks are the same size.

I'm lead to believe 280 - 6.9 is irrelevant in terms of fuel consumption, because they are all simply atrocious. They are incredibly inefficient transport devices with all that metal - have you ever tried picking up just one bumper ?? ;)

Title: Re: petrol usage
Post by: another sad 280s on 31 August 2009, 07:22 AM
don't forget that the petrol guages on these aren't linear. secondly if you honestly used that much then something is seriously wrong
Title: Re: petrol usage
Post by: Maat1985 on 31 August 2009, 07:33 AM
i know my car is running slighlty rich but jeez cant make that much of a difference..... i need a new manifold pressure sensor..... and that drive was sitting on 120km/h steady for almost the whole way.....
Title: Re: petrol usage
Post by: another sad 280s on 31 August 2009, 07:37 AM
get them done and then judge it properly. with my poorly tuned 280s i was getting between 17-20L per hundred. 500-600km per tank
Title: Re: petrol usage
Post by: oscar on 31 August 2009, 07:49 AM
A new MPS Maat?  Was it yours that might have been tampered with? ie adjustment screw possibly adjusted previously?  PM 13B and see if he has any left, he had a couple of spares a while back.

IMO just about all w116's could've benefited from an overdrive in the driveline for those long cruises on a fwy or hwy.  My 350 is no different, doing 120km/h the revs are up there at 3500 or so and you just wish it could change one more time. 

The only way you could economically introduce some economy for the hwy Maat would be to throw on a used shorter diff from a 350 or better still a 450.  Of course your speedo and odo will read wrong but in real terms your revs will be lower at cruising speeds and fuel consumption would drop.  Your take off speed would be lower round town and whether that would lead to too much labouring and worse economy for city driving I don't know.
Title: Re: petrol usage
Post by: s class on 31 August 2009, 08:29 AM
My daily mix is a combination of traffic and freeway driving at 4000rpm-plus in my 280SE K-jet.  I usually drive pretty hard, and get about 600km on a tank.  If I do more traffic driving, and if I drive hard it can get as poor as 580km per tank.  If I'm on the open road only at 4000rpm plus, it can get as good as 625km on a tank. 
Some 280SE owners have reported over 700km on a tank with sensible driving (100km/h crusing).

The 6.9 gives me 450km on a tank if used in anger, and 530km on a tank of fast highway driving.

Be aware that out-of-tune D-jet 280's can really chew fuel.  I know of a few that can only get 250 to 300km on a tank.  But on the other hand, when sorted, the D-jet should be more efficient than the K-jet. 
Title: Re: petrol usage
Post by: Papalangi on 31 August 2009, 11:26 AM
I can't figure how to convert MPG to metric but my 1976 450SEL (M117) gets 13 MPG, the 1971 250C (M130) got 15 MPG and the 1976 280C (M110) got 14 MPG.

My 1974 Ford F250 may get as much as 9 or 10 MPG.

Michael
Title: Re: petrol usage
Post by: OzBenzHead on 31 August 2009, 09:52 PM
My 1979 Euro K-Jet 280SE M110 gives me, on open-road work (cruising up to 120 km/h) and drinking 98 RON, 11-12 litres per 100 km (approx. 23.5 - 25.5 mpg). If I extrapolate that to distance per tank full it comes to 800 km / 500 miles or better.  This car has 300,000 km on the clock and is serviced properly every 8,000 km / 5,000 miles. It has a dry-element air cleaner.  Although not a hoon, I am not a slow driver and tend to fang it up hills, passing all those who can't / won't maintain at least the posted speed limit. The handbook suggests about 11-12 litres / 100 km.

Around town it is quite thirsty, but as I live in a smallish rural city and walk to most of the shops (a block away from home), that's not really an issue.

OTOH, a poorly maintained 1978 280SE M110 (Oz spec), with oil-bath air cleaner, that I bought for parts returned, on the only two trips I made in it before taking it off the road, about 15 litres per 100 km (17.75 mpg).

From my 1970 W108 280SE M130 (oil bath air cleaner) I also get 11-12 litres per 100 km (approx. 23.5 - 25.5 mpg) -- though this car is less thirsty around town, probably because it has the fluid coupling rather than a slushy torque convertor. This car has almost 837,000 km on the clock.

My 1965 W111 220Sb M180 (oil bath air cleaner) is a very thirsty beastie: 15-16 litres per 100 km (17.75 - 18.8 mpg), but it does have two dual-throat Zeniths. (Approx. 233,000 km on clock.)

My 1965 W112 300SE M189 coupe (oil bath air cleaner) is also thirsty: 14-15 litres per 100 km (18.8 - 20 mpg) -- but is well within the factory-claimed range for the six-plunger-injected M189 engine of 11-18 km per 100 km. (Approx. 250,000 km on clock.)

Wherever I go, I always carry a large toolbox, gallons of spare vital fluids, and sometimes a 2.5 tonne capacity trolley jack, so a reasonable load in the boot. (Of course, I only ever need those tools and supplies when they aren't on board! Carrying them seems to prevent problems.  8) )

I have no complaints about fuel consumption. I wonder if there is usually a big difference in thirst between Euro, US, and Oz-specced versions.
Title: Re: petrol usage
Post by: Maat1985 on 01 September 2009, 12:36 AM
QuoteA new MPS Maat?  Was it yours that might have been tampered with? ie adjustment screw possibly adjusted previously?  PM 13B and see if he has any left, he had a couple of spares a while back.
yes that is exactly what has happened to mine.......
QuoteBe aware that out-of-tune D-jet 280's can really chew fuel.  I know of a few that can only get 250 to 300km on a tank.  But on the other hand, when sorted, the D-jet should be more efficient than the K-jet. 
what needs to be done to tune properly???? i have changed the spark plugs recently.... it has good ignition leads and the dizzy appears to be quite new as well..... i imagine i need new air filter...... i recently have put in a few loads of injector cleaner..... so other than the MPS what should i look at????? adjustments to be made???? filters to replace???? should i take it to a mechanic to get it done properly or should i attempt it myself?????
Title: Re: petrol usage
Post by: Maat1985 on 01 September 2009, 12:42 AM
will it be performing better if its out of tune and using more petrol or is it just being wasted????? i know it is probv performing better cus it is running rich......
Title: Re: petrol usage
Post by: s class on 01 September 2009, 03:14 AM
Running the car grossly rich will just waste fuel, foul the plugs, dilute the oil and lead to excessive cylinder wear.  Slightly rich will benefit performance slightly compared to slightly lean.  Getting the MPS sorted out is a big part of sorting D-jet out.  Other issues that will negatively impact your consumption (and performance) are valve clearances (significant effect) and ignition timing.  Both valve clearances and ignition timing are pretty simple to sort out.  I would check those, then get to a workshop that has an exhaust gas analyser so you know just how rich you are running.  It really would be beneficial to sort out the odo as well, so you are not working in the dark. 
Title: Re: petrol usage
Post by: 13B on 01 September 2009, 03:37 AM
Ignition timing is very critical with D-jet, because as you move the distributor you also change the timing of the trigger points, making them fire slightly earlier or later as you move the dist. back and forth.

We experimented on my 450SE V8 D-jet race car and found that it always ran the best with ignition timing set to 0 degrees TDC, wheras with other non-MB V8 race cars we found somewhere between 10 and 15 degrees advance was a sweet spot.

I.
Title: Re: petrol usage
Post by: Maat1985 on 01 September 2009, 03:45 AM
how do you check and adjust the ignition timing????

and valve clearence??????
Title: Re: petrol usage
Post by: 13B on 01 September 2009, 06:09 AM
To answer your 2nd question first - if the cams quiet and not "clattery" then no adjustment is needed.  On a D-jet with manual adjust lifters, they can be slightly audible and thats OK.  If they are annoyingly loud - ticking - they probably need adjusting.

To adjust valves its job # 753:

And to check ignition timing its job# 782: Link (http://handbook.w116.org/Maintenance/MY72/782.pdf)

I.
Title: Re: petrol usage
Post by: s class on 01 September 2009, 07:19 AM
Ian, its true that the valve clearances are probably OK, but my thinking was that since he's trying to get the car in a proper state of tune, one needs to start by checking the basics before moving on to the fuel system.  I have noticed on my 280SE, since the banning of leaded fuel here in South Africa (only about 4 years ago) that I do need to adjust the valves from time to time, due to what I can only assume is some seat recession. 
Title: Re: petrol usage
Post by: Maat1985 on 01 September 2009, 07:38 AM
QuoteTo answer your 2nd question first - if the cams quiet and not "clattery" then no adjustment is needed.  On a D-jet with manual adjust lifters, they can be slightly audible and thats OK.  If they are annoyingly loud - ticking - they probably need adjusting.
well i hear no noise from the motor at all that is abnormal so i would say is all good......
Title: Re: petrol usage
Post by: s class on 01 September 2009, 07:41 AM
If the valve clearances are too tight, they will be very quiet, an you will notice loss of power and increase in consumption.  Valve seat recession leads to a progressive loss of valve clearance, hence the need for periodic checking. 
Title: Re: petrol usage
Post by: Maat1985 on 01 September 2009, 07:51 AM
also too once i replace the MPS i would think mayb it is best to get it serviced and tuned properly.... where in sydney would be a good place to do this... i imagine places like ultratune while specialising in tuning of cars prob dont have much of an idea and is prob better left for a merc specialist.... what is others opinion on this and who do you reccomend i hear merc talk in botany are really good however that is a fair way from where i am......
Title: Re: petrol usage
Post by: s class on 01 September 2009, 08:03 AM
Good plan.  Don't let this talk of valve clearances detract you from MPS replacement, as that is probably where your biggest problem lies.  You are correct - you need a specialist, as the average workshop servicing recent model cars will have no idea about D-jet, or probably even with solid tappets. 
Title: Re: petrol usage
Post by: oscar on 01 September 2009, 06:40 PM
Maat, if you're going to seek help from workshops I can't think of anyone off the top of my head in Syd, but check the NSWMBC forum for recommended workshops or one close to you.  I'm sure there was a Sydney thread in the link below but start another if you can't find it.  You should get plenty of pointers for where to go.

http://www.mbcnsw.org.au/forum/index.php?board=9.0
Title: Re: petrol usage
Post by: 13B on 01 September 2009, 07:47 PM
Can't find the picture at the moment but on my engine you can see on the cam lobes its shiny where they touch the rocker arms, and varnish on 'backs' of the cams indicating the valves are closing properly.  This applies to manual-adjust tappets.  Hydraulic lifters as fitted to 1976-onwards V8s give cams which are shiny the whole way around.  Do any of the 6cyl cars have hydraulic lifters?

I.
Title: Re: petrol usage
Post by: s class on 02 September 2009, 10:24 AM
No - all the M110's have old fashioned manual tappets. 
Title: Re: petrol usage
Post by: 13B on 02 September 2009, 05:54 PM
In this picture of my D-jet 450SE engine with the cam cover off you can see the shiny lobes and varnished backs of the cams.  Its not very scientific, but if you top end doesn't make much noise and the cams all look like this (shiny lobes/varnished backs) then I'd say they are adjusted pretty much right.

(http://ianmav.customer.netspace.net.au/mercedes_b/Copy%20of%20Picture%20or%20Video%20850%20Large%20Web%20view.jpg)

On this engine you can hear the cams clatter a little when cold but they quieten down once the engine has warmed up.

This is a warm start:

Link (http://www.youtube.com/watch?v=XJC1OIY6iOM)

I.
Title: Re: petrol usage
Post by: Maat1985 on 05 September 2009, 06:56 AM
i'll see how it goes once i get my MPS sorted....
i ran a heap of top quality injector cleaner through at the same time i filled up ith 98 octane and now i have noticed an improvement as i have just driven 200kms this week in a mix of city and freeway driving and have used just under 1/2 a tank.... between 1/3 to 1/2 a tank but it is hard to tell exactly so i'd say atm i'm looking at between 450-550km per tank.... is hard to estimate with no odometer...
i just went onto google maps and put everywhere i have driven this week and added it up....
BTW does anyone know how much it'll cost to get my odo fixed as i'm not that confident to do the job myself...... is it the same job to fix the trip counter or is that seperate cogs etc.....
Title: Re: petrol usage
Post by: OzBenzHead on 05 September 2009, 07:20 AM
A few years ago I consumption- and performance-tested 95 RON and 98 RON over a 6-month period on both my M130 280SE and M110 280SE.

Both cars usually gave similar consumption figures on identical fuel. The extra cost per litre of 98 over 95 was bettered by a percent or five (I can't locate the record just now) lower consumption in km per tankful; i.e. 98 proved more economical over the tankful, performance was notably better, and the cars seemed to maintain better tune between services (especially notable being my twin-Zenith Finny with rebuilt carbs). Win-win-win (the first winner being, of course, the oil companies and government coffers).

In just about any Benz, I reckon 98 is best for car and pocket.

I'm not into additives in the dailies, but my 'ancient' Sunday drivers get Shell's version of Flashlube with each fill -- just for the extra feelgood vibes.

Once every couple of months I add 0.5% (half litre per full tank) synthetic two-stroke oil (Stihl, made, I think, by Shell). Seems to keep things really clean, makes no smoke or ash.
Title: Re: petrol usage
Post by: Maat1985 on 05 September 2009, 07:31 AM
i find that few so often i am adding an injector cleaner.....
i think that if 98 is gunna give me better economy..... (less L per KM = more KM per tank = less money spent in fortnight of driving)
and a cleaner motor (better performance and a longer lasting motor)

that there is no way you can possibly lose....
i just worked out that at 220km per 1/2 tank which is roughly what i am doing atm is 21.8888888L per 100km/s which is shocking.....
i am hoping for 600km per tank which is 16L per 100km/s after changing my MPS then even more after a service and tune which will prob have to wait a while (NO $$$$$$$$$ ATM)

I just wonder how much performance i may lose after changing my MPS cus running richer to some extent will increase performance......

if i lose a decent amount i will keep the old MPS for when i wanna have fun and not worry bout petrol consumption ie. track day....

mayb i should get it dyno tested with both and see if there is a difference....

never know mayb it'll be a great performance upgrade...... if it is i'll easisly be able to switch between economy driving and performance driving... just pull over for 5 mins and change it.... lol.....
Title: Re: petrol usage
Post by: TJ 450 on 05 September 2009, 08:43 AM
There wouldn't be much, if any difference between fixing the odometer or the trip meter, it is probably just slipping or jammed cogs.

I would say 600km per tank is overly optimistic for around town... what you are estimating now is actually what I would imagine to be about the maximum achievable.

After replacing the MPS, you can always adjust the mixture accordingly. At least you know everything is functioning properly then.

I seem to recall getting about 300km to half a tank in my 450 driving out to the WA German Car Day recently. The mixture was obviously lean at the time.

Tim
Title: Re: petrol usage
Post by: Maat1985 on 05 September 2009, 08:51 AM
when adjusting the MPS how do you tell the optimum setting????? without being able to measure the exhaust gas... ie without tools and exuipment?????
Title: Re: petrol usage
Post by: TJ 450 on 05 September 2009, 09:16 AM
Yes, you need to have an exhaust gas analyzer to adjust it to spec. Any decent workshop will have one though and it would only take a few minutes to adjust if they know where the ECU is located.

You may be able to ballpark it, but you run a few risks there if it goes wrong. I'm not sure how sensitive the adjustment is either.

Tim
Title: Re: petrol usage
Post by: Papalangi on 05 September 2009, 12:43 PM
For a very detailed odo repair method, check this (http://www.pelicanparts.com/techarticles/Mult_gauge_repair/mult_gauge_repair.htm) out.

See the gear in figure 15?  Instead of taking the whole thing apart, I put a drop of green Loctite on the shaft and twisted the gear back and forth a bit to spread it.  Green Loctite is a wicking type that does not need the joint to be disassembled prior to applying it.  It's been working over three years now and the '76 280C I fixed the same way lasted until it was stolen by the City of Seattle.

In the states, a cheap GPS can be had for under $100.  Might be a reasonable odo substitute.  It's how I can up with my original milage estimates when we drove the car home from Dallas Texas to Seattle Washington.  Did about 17MPG at 85MPH.

Michael
Title: Re: petrol usage
Post by: flutes on 10 September 2009, 06:12 PM
I need to have a chat with my mechanic ... with a well-serviced '77 450SEL I'm lucky to get 350 - 400km per tank.  I do drive, um, enthusiastically but this seems pretty poor compared to what others are getting...

Can anyone else with a 450 add their thoughts?
Title: Re: petrol usage
Post by: TJ 450 on 10 September 2009, 08:51 PM
Over 20L/100km is certainly on the high side. Enthusiastic driving around town might result in this sort of thirst, as will frequent cold starts though. If you are doing mainly country driving, then I would say a checkup is needed.
Maybe you just need a new air filter element...? I would check that first.

Tim
Title: Re: petrol usage
Post by: 13B on 10 September 2009, 10:32 PM
There's a chart in the glovebox handbook for the W116 (non-6.9 and non diesel models) that shows the fuel consumption of the three engines (280, 350, 450) for moderate driving over a normal speed range and they are all within 2mpg of each other.

As young man interested in buying one of these cars I rationalised that the 450 makes the most sense as it has a lot more power and torque than the 280 and only uses a little bit more fuel.

Road & Track mag in the 1970s found the 450 returned 13mpg, and the 280S returned 15mpg.  A few years later when the 6.9 was released they found it also returned 13mpg, so thats why I drive one now... I get more or less the same economy as 450 drivers, but loads more power and torque on tap.  By 1978 R&T has pretty much said if you want better economy in the W116, go for the 300SE - 24-25 mpg and quicker than a 280S.

I.
Title: Re: petrol usage
Post by: TJ 450 on 10 September 2009, 11:07 PM
I would have to agree totally. It's funny how people automatically assume that the 6.9 should use much more fuel than it's smaller engined counterparts.

In my case, I'm pretty sure that the 6.9 uses less fuel than my 450. The condition of the drivetrain is better.

In a couple of weeks, I'll hopefully be taking the 6.9 on an 550km economy run out to Bencubbin... it should be a good test. This is weather depending of course and yes, I'm afraid it is going to be driven on unsealed roads. ;)

Tim
Title: Re: petrol usage
Post by: 13B on 11 September 2009, 12:14 AM
Tim, if you can keep the car in the 100-120 range you should be able to do it in 1 tank.

A few weekends ago I had a return run to Winton (450km) which I sat on 120 with the occasional burst to 130 which used about 3/4 tank petrol.  I reckon 550km would be about its range in this situation, if you can resist overtaking everyone in sight (my vice).

I.
Title: Re: petrol usage
Post by: TJ 450 on 12 September 2009, 07:02 AM
Excellent, that actually sounds quite reasonable.

Tim
Title: Re: petrol usage
Post by: flutes on 13 September 2009, 06:22 PM
Thanks Tim.  Most of my driving is around town, and had certainly been from cold starts as well.

I've been using regular unleaded - based on comments here I'll try premium and see how that fares.

Regards,
Matt.
Title: Re: petrol usage
Post by: Maat1985 on 14 September 2009, 12:27 AM
i have a new 2nd hand MPS ready to install to my car the only reason i have not done this yet is cus then it needs tuning.... however given the fact that i have just noticed under high revs my car blows grey smoke and smells like a 2 stroke lawnmower and therefore realised just how rich it is running.... so i am going to put the other MPS cus i figure it has to be better tuned than my broken one surely....

what i do need to know is when i do tune it is it as simple as measuring the exhaust gas under different revs and adjusting the screw on the MPS accordingly....
Title: Re: petrol usage
Post by: 13B on 14 September 2009, 03:51 AM
Hi maat, the mixture isn't adjusted from the MPS, thats set at the factory.  The mixture is adjusted at the ECU (inside the kick panel in the front passenger side footwell).  Not many people remember thats where the ECU lives and try to get the car running right by adjusting the MPS - bad move.

I.
Title: Re: petrol usage
Post by: Maat1985 on 14 September 2009, 04:02 AM
thanks.....
Title: Re: petrol usage
Post by: Maat1985 on 14 September 2009, 04:08 AM
moved this here Link (http://forum.w116.org/mechanicals/engine-smoke-and-smell/) as i thought the smoke and smell might actually be another issue and requires a new topic....
Title: Re: petrol usage
Post by: Zagato on 03 October 2009, 12:18 AM
I get 7 - 8 MPG in the city, and I'm talking dense traffic, and 13 - 14 mpg on the highway.
Title: Re: petrol usage
Post by: OzBenzHead on 03 October 2009, 10:29 AM
Quote from: Zagato on 03 October 2009, 12:18 AM
I get 7 - 8 MPG in the city, and I'm talking dense traffic, and 13 - 14 mpg on the highway.

Zagato -- do you use "real" gallons in Canada or US gallons?   That sounds like terrible consumption, but if it's US gallons (3.7+ litres) it's not so bad as if it were Imperial gallons (4.5+ litres).

Also, is your engine high- (Euro) or low-compression (NA), and what grade of fuel are you using?
Title: Re: petrol usage
Post by: Zagato on 03 October 2009, 12:03 PM
QuoteZagato -- do you use "real" gallons in Canada or US gallons?   That sounds like terrible consumption, but if it's US gallons (3.7+ litres) it's not so bad as if it were Imperial gallons (4.5+ litres).

Also, is your engine high- (Euro) or low-compression (NA), and what grade of fuel are you using?

I believe I used US gallons to calculate it. Normally we do ?L/100km in Canada, but my car is American spec with American dials. So miles used for trip computer.

Don't know about compression, it's a 1974 model in US-spec. So I'd assume low compression.
I use 91 Octane fuel, as the owners manual recommends. In my country, the only octane ratings higher than that are 92 and 94.
Title: Re: petrol usage
Post by: OzBenzHead on 04 October 2009, 02:56 AM
Quote from: Zagato on 03 October 2009, 12:03 PM[...] Normally we do ?L/100km in Canada, but my car is American spec with American dials. So miles used for trip computer.

Same in Oz: litres per 100 km -- though all but one (W201) of my Benzes have mile speedos / odos, so a degree of conversion is necessary.

Quote from: Zagato on 03 October 2009, 12:03 PMDon't know about compression, it's a 1974 model in US-spec. So I'd assume low compression.
I use 91 Octane fuel, as the owners manual recommends. In my country, the only octane ratings higher than that are 92 and 94.

Yep, I expect it's low-comp. And I believe the US (possibly all of NA?) octane ratings also don't match ours. Perhaps 91 is recommended, but in Oz ratings I'd go for the better fuel. My cars return better distance per volume on our 98 RON than on lower-octane fuel -- enough to more than cancel the price difference. And the additives in the higher-rated fuel also (allegedly, and my experience tends to support it) keep the entire fuel system cleaner and happier.

I'm also fortunate that none of my Benzes (except the W201) have catalytic converters of other allegedly anti-pollution equipment -- they are a mix of Oz- and Euro-spec, all high-comp.

We have 91, 95, and 98 RON grades. The 91 is bats' pee.  :P
Title: Re: petrol usage
Post by: flutes on 21 October 2009, 03:23 AM
After a completely non-scientific test of AU "premium" (98RON) the fuel gague is at about half and I've done about 300kms.  This is about 100kms higher than it usually is at this point.

I'm shocked (SHOCKED!) at the difference in fuel efficiency with regular vs premium.

Australian petrol = US beer.
Title: Re: petrol usage
Post by: Big_Richard on 21 October 2009, 04:08 AM
US fuels are FAR lower quality than what we have become accustomed to in Australia, and Western Australia has the highest quality fuel in the country - most notably BP. It costs more, but as with everything its worth paying more for something decent.


Title: Re: petrol usage
Post by: TJ 450 on 21 October 2009, 04:29 AM
I might add that using anything less than 98 RON in a 116 is a false economy. Yes, it will run, but performance and mileage will be poor. It is therefore more expensive, IMHO. ;)

Tim
Title: Re: petrol usage
Post by: oscar on 21 October 2009, 05:13 AM
Quote from: Patrick Bateman on 21 October 2009, 04:08 AM
Western Australia has the highest quality fuel in the country

I've heard this before - why is it so?  Where does the stuff come from?
Title: Re: petrol usage
Post by: flutes on 01 November 2009, 03:56 PM
OK so some numbers are in, and are they surprising.

In the weeks since I've changed to 98 RON I've consistently achieved around 30% more Kms from the same amount of fuel. This has been across a mix of driving conditions (70% city, however) and with all other factors being more or less equal.

Next step - blow the cobwebs out see post (http://forum.w116.org/test-drive/drive-your-116/msg66700/#msg66700) - and see what difference that makes.
Title: Re: petrol usage
Post by: arman on 02 November 2009, 03:12 AM
I always use RON98 for my '74 450SEL. But I'm beginning to understand that that is not a guarantee for good gasoline.
I was on a long trip with my wife and kids from Sweden to Germany via Danmark. Somewhere on the way back I had to fill up with gas. Now today it is not so easy anymore to find RON98 at gas stations in Northern Europe.
I got a tip from a pedestrian to find a SHELL station some kilometers off the highway.
There I found they had SHELL V power which is RON99 and especially developed for (modern) high performance cars. It is said that this is the only gasoline which is transported to gas stations 'as is'. I mean they don't mix  the stuff with additives at the station which is probably normal then for the other types of gas.
I know they mixture with additives like ethanol and white spirit in normal gasoline depending on winter or summer weather.

Now I'm generally not impressed by -in this case Shell's- marketing drive for SHELL V-power. That means that I tend to be suspicious to marketing tricks.
Normally I get 600km out of a tank and then I fill it up with 80-83 litres when I drive steady highway speeds of 110-120km/h. Now with SHELL V-power I'm already over 600km's and I have not been driving on the highway alone! The reserve light is still not on! (and it isn't broke, because it worked when I drove down the steep slope into the garage :)).

Of course Vpower is even more expensive as RON98 but when I fill up the tank next time I will report the economical calculations and get back to this thread.

An other thought came up to me and that is that when I park the car for the winter, the best thing is to fill it up with gasoline. Gasoline deteriorates a little bit has been said over here. Well, even if SHELL V power is not economically justified it is probably a very 'clean' gasoline and it would maybe be a good idea to empty your tank of average RON98 and fill it up with 20 litres of Vpower that can sit there 'till next spring?

(this is not a disguised commercial, I just wanted to let you people know about my experiences... )
Title: Re: petrol usage
Post by: OzBenzHead on 02 November 2009, 08:35 AM
Arman and other interested parties:

A salutary lesson in false economy (cheap fuels)

You've probably read my rants before on the sense of using Oz 98 RON in my Benzes, so I'll not repeat my own words -- rather I quote from the latest Super Star (MBCQ magazine, p 26; the article is unattributed):

A Benz factory-trained technician's tale of warning about low-octane fuel.

QuoteComplaint

A 2001 C180 coupe was towed to the service centre with the complaint that it would crank over but would not fire.

This was a car that had travelled only 100,000 km and had been meticulously cared for by its one owner from new. It had had all of the scheduled and required services throughout its life and is a well presented motor car.

Cause:

The car was found to have very low compression on three cylinders, caused by low octane fuel which caused carbon to build up between the rings and the ring land.

Correction:

The following work was required: the engine was removed from the car and the cylinder head, lower sump and pistons were all removed.

The pistons were cleaned, new rings and bearings fitted, valve stem seals renewed and the head was pressure tested.

The engine was reassembled.

Cost of repair: Approximately $5,800.00.
[...]

Over the vehicle's life [...] the owner may have saved around $1300.00 by buying low octane fuel.

So the fuel cheapskate was at least $4500 worse off that he should have been had he used 98 RON. (This is an Oz story.)
Title: Re: petrol usage
Post by: OzBenzHead on 02 November 2009, 08:38 AM
Oh and BTW: Wherever possible I fill up with Shell V-Power -- 98 RON in Oz.

There are only two trusted 98 outlets in my town, and the Shell is far closer to home.
Title: Re: petrol usage
Post by: koan on 02 November 2009, 03:37 PM
Quote from: OzBenzHead on 02 November 2009, 08:35 AM
A salutary lesson in false economy (cheap fuels)

Not so sure about this story OBH.

Why would a low octane fuel cause more carbon build up than higher octane fuel? This implies any vehicle designed to run on low octane fuel is going to suffer the same fate. That an injection problem putting in too much fuel or cheap fuel shandied with some unknown hydrocarbon might cause carbon build up I can understand but not just low octane fuel.

As far has higher octane fuels developing more power in 116 engines it depends on how the engine is adjusted.

The amount of energy (BTUs/lb or whatever the metric measure is) in low and high octane fuels is much the same, the difference is the anti-knock value allowing engines to have higher compression ratios and run with more ignition advance.

Put any octane fuel in a modern engine and the management system will adjust the ignition to prevent knocking/pinging. Higher octane fuels will let the engine develop more power because the computer can wind more in ignition advance to just before pinging starts than it can with a lower octane fuel.

But our old technology, pre-computer, low compression engines have fixed mechanical advance. If the engine is designed for a particular fuel grade and set set up to run on that fuel just filling up with a higher octane fuel is not going produce more power because there is no difference in the energy in the fuel.

Only if the static ignition timing is advanced to take advantage of a higher octane fuel's resistance to pinging will it develop more power.

Now having said all that the last couple of fills have been 98 fuel. Not done any economy calculations but kms covered and fuel gauge readings do suggest I might be getting better economy with this fuel. I'll you know.

koan

Title: Re: petrol usage
Post by: Mforcer on 02 November 2009, 05:30 PM
I agree with Koan.

Generally, higher octane fuels are better quality. It is just easier to market a higher (octane) number.