Author Topic: Fuel economy  (Read 2724 times)

Bill

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Fuel economy
« on: July 01, 2022, 20:22:05 »
I recently put a new(rebuilt) 280SE engine in my 230SL. It runs fantastic but uses a lot of gas. I doubt that I’m getting more than 10-12 miles per/gal. Is this mileage normal for a 280SE? Bill

teahead

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Re: Fuel economy
« Reply #1 on: July 01, 2022, 20:29:14 »
Any black smoke?

How are your spark plugs?

WOnder if you're running rich.
1970 280SL auto, AC - aka "Edelweiss"

Cees Klumper

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Re: Fuel economy
« Reply #2 on: July 01, 2022, 22:49:53 »
My 280SL averages around 19 MPG.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

Benz Dr.

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Re: Fuel economy
« Reply #3 on: July 01, 2022, 23:04:23 »
I get 10km per liter with my car. It is a 250 but a 280 shouldn't be that much less.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

roymil

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Re: Fuel economy
« Reply #4 on: July 02, 2022, 01:55:35 »
Milage of course depends a lot on how it's being driven.   I too have a 280SE factory rebuilt engine, with about 4K miles on it.   It has been getting 18-19 MPG driving up to ~60MPH around town, but that dropped to 15-16 MPG on a recent 500 mile jaunt at mostly 80MPH++ one day when I really was driving hard.   The only time I had milage around 10MPG was early on when I was messing around with FIP adjustments and idling it a lot.   Like they say, "Your milage may vary", but it does sound like your 280SE block is rich.    As suggested, confirm with the plugs.

This site has all kinds of help on many things that can make it run rich but I'd recommend first going back through the linkage and tune up tours and check all the easy stuff first.   My linkage was badly misadjusted after the SE block went in some 30yrs ago.  I also found the timing was way off and vacuum was leaking several places.  Then when I eliminated everything else I figured out the distributor was just a mess. I spent a day or two messing with the points and then I punted and bought a 123 ignition and that was a great decision.  It just works.  Good luck.
Mark Miller
1968 280SL
Rode in his pagoda's first mile.

roymil

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Re: Fuel economy
« Reply #5 on: July 02, 2022, 02:12:17 »
Dr Benz  ,  I just converted 10 km/liter and get 23.5 MPG!   Wow.  Thats awesome as long as its not too lean.  I don't question you at all, I've been reading and learning a lot from your posts and other vets on this site for the last 2-3 years as I bring my covid-pagoda back to life.   It's just that I can see now I have a lot more work to do to figure out how to improve my milage from where I'm at.  My plugs look great, exhaust gasses measure good so I thought I was done.  I guess I need to learn more along side Bill.  Appreciate any tips.  thanks
Mark Miller
1968 280SL
Rode in his pagoda's first mile.

lreppond

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Re: Fuel economy
« Reply #6 on: July 02, 2022, 02:25:44 »
I recently had a long block overhaul (Metric) and I’ve also had the FI system rebuilt/calibrated as well.  This past week I drove from my place in the East Bay up to Sonoma to show my dad his car.  I didn’t drive it hard at all, it was all flat driving and I don’t have A/C and the car has a manual transmission  My mileage was 25.4 mpg.  I can’t imagine ever getting better than that considering all the factors influencing mileage were in my favor.  I would think that if combined with a little city driving, it would be around what Cees’ car is averaging.

Mileage at the 10-12 mpg range seems suspiciously low…unless you’re driving it really hard and doing full throttle takeoffs or you’re in stop and go traffic. 
« Last Edit: July 02, 2022, 02:35:38 by lreppond »
~Len

1971 280 SL
576G red/251 Beige
4 speed manual
Family owned since new (father —> son)

H. Keith Henry

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Re: Fuel economy
« Reply #7 on: July 02, 2022, 16:42:15 »
Recently completed a 3,000+ mile trip and averaged 18.84 mpg going roughly the speed limit on mostly interstate roads. The middle third of the trip was handicapped by burned points (as reported in another thread today).
1970 280 SL, auto, US spec, 050 white with burgundy interior and soft top. Originally special order, white on white on white tex. Manufacturing date May 1970
2002 Mercedes C320 wagon
1989 Honda Civic wagon
1979 MG Midget, original owner

rmunson

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Re: Fuel economy
« Reply #8 on: July 13, 2022, 21:49:17 »
After recent color spark plug tune up this spring, getting about 18 mpg driving mostly backroads around CT; some highway short distances.  Running great.  Using 93 octane high test.
1969 280 SL  77K miles.
R.Munson
1969 280SL

UJJ

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Re: Fuel economy
« Reply #9 on: July 14, 2022, 14:40:54 »
I get 20-22 mpg with my car.
4 speed manual with 3.27 Diff. Highway speed mostly 75 mph.
Urban Janssen
Grass Valley, CA
1968 280 SL - 4speed manual
173 anthracite grey

Peter h

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Re: Fuel economy
« Reply #10 on: July 15, 2022, 13:42:23 »
Today 300 km from moselle ,france alsac to blackwood forrest Freudenstadt.
3.46 Differential
Nice sunny weekend to All.
Peter
08.68 280sl automatic white 717 G  blue MB Tex
09.68 280sl  4-speed, now 5-speed Getrag 180 G dark green MB Tex

Desertpagoda

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Re: Fuel economy
« Reply #11 on: July 26, 2022, 00:15:49 »
16-18mpg is the best Ive EVER gotten over on 15 M130 cars in 35 yrs
kb

Revelstoke

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Re: Fuel economy
« Reply #12 on: October 04, 2022, 12:22:34 »
Have recently installed a new electronic ignition, air filter, plugs and wires. Using Chevron 94. Just back from a 1453km weekend of mixed spirited driving, and frustrating traffic,...the 230 didn't miss a beat and averaged 14.63 l/100km or 19.02 miles/imperial gallon. Definitely a little thirsty!
« Last Edit: October 05, 2022, 19:19:43 by Revelstoke »
Rich Hamilton
Revelstoke, BC

1965 MB 230SL
2017 Porsche Macan GTS
2018 Husqvarna 701