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MG MGB Technical - More miles per gallon?

I HAVE SEEN THERE IS MANY DIFFERENT WAYS OF GETTING A BIT MORE POWER OUT OF THE OLD B BUT WHAT ABOUT IMPROVING FUEL ECONOMY DOES ANY ONE HAVE ANY IDEAS ABOUT HOW TO DO THAT. I am curently getting about 25 out my b gt le on the open road is there a way to get it up to near 30??
sam

try putting deisl in it it may help get a slight increase
toss

try pumping up the tires untill they wont take any more air
tit

Sam, Make sure your car is in excellent tune and follow Paul Hunt, he seems to get better fuel economy than most of us. Seriously, to get better fuel economy you have to be patient and it's a good idea to drive as if you had an egg between your foot and the gas pedal. No fast starts, start slowing down far enough away from stops so you need to use little or no brakes to stop. Avoid floorboading the gas pedal as much as possible. You get the idea, do everything gently. Would that be fun to you? If so go for it. Clifton
Clifton Gordon

Sam,

try to get rid of any useless weigth: i.e.
- spare wheel (get a spray can of 'tyre repair')
- wheel jack
- passenger seats (and passengers)
- weight watch yourself ;-)

By a rule of thumb every 100 kilogram you get rid of gives you another 3 or 4 mpg.

good luck

Mark


Mark Leitiger

.. i forgot one: aerodynamics!

Lower your car, especially at the front.
This looks good and helps with high speed fuel economy.
So does removing unnecessary add ons to your cars body like fender or passenger rearview mirrors.

And always remember: Do not use the brake pedal ;-)

Mark
Mark Leitiger

Go to the Google search site and enter your query. You are more likely to find the answers you are looking for. Clifton has given you good advice, and Mark has the right idea, if not quite the most practical methods. :-)
Bob Muenchausen

If your car is not equipped with overdrive then your mileage is about right.
My GT has a 5-speed and a wber dg carb. I get 29 travleing to the mountains in the summer with the air on.
Overdrive is the best thing for economy.
steve

Aren't US gallons and UK gallons different? Which one is this measured in?
Simon Jansen

You don't need to change anything, you just need to make sure everything's within spec. Tune your SUs properly, get your timing right (electronic ignition helps here) and they can be pretty efficient when driven right. If I cruise down the motorway at ~75-80mph I get 40mpg (UK gallons) easy. When I have fun on country roads I doubt that I even get 10.

Best check is the colour of your spark plugs... if they're black, you're over-fuelling.

hth,
--
Olly

P.S. please don't SHOUT - we can hear you just fine :o)
Oliver Stephenson

Sam, Some friends of mine are working on a vapour carb. To all else we,ll keep you posted.
Victor Gardino

By the way, Des Hamill states in his famous book on tuning SU-carburettors that they are quite the most fuel efficient ones of their times, i.e. 60s/70s . Webers do need more fuel but they are also able to produce more top-end-power with highly modified engines. This is just race-relevant....

Mark
Mark Leitiger

On my last marathon L.A.-to-San Francisco round trip I was averaging 30-32 mpg, highway, on
101 (north), and twisty Highway 1 (south). My B/GT has Special Tuning exhaust manifold, 2" exhaust
pipes w/ deleted center muffler, Isky cam, DCOE Weber w/ K&N filter, flat top pistons, ported head,
lowered ride height, single 12V battery (it's lighter than dual 6V's) and I pumped the tires to 30 psi.
I also tuned the engine and checked the valve lash two days before leaving. Also, a GT is arguably
more aerodynamic than a roadster.

In addition to suggestions posted by others, try:

Keep the top up (roadsters), and windows closed (or partially closed).

Dump all non-essential junk out of the trunk (leave your barbells at home). Drive solo.

Check the rear brakes to make sure they aren't dragging (adjusted too tightly, or parking brake not
fully releasing).

Install a vacuum guage in the cockpit (...at least temporarily). It'll help train your "go" foot to be more
mileage conscious.
Daniel Wong

What about fitting a higher geared rear diff crusing at 60 the revs are aproaching 2750
dhead

Buy a taller tire. It's the poor mans overdrive. Dick [Da Killer Beez]
MG LTD

In my 68 GT, with my lead foot, I get about 17-18 mpg around town and on a trip, I average about 31-33 mpg depending on tailwinds and downhill grades available. I once got an honest 36 mpg, but it has never been replicated, so it must have been just the right set of circumstances or a fluke. FWIW.
Bob Muenchausen

You can add a Le Mans type front end for better aerodynamics.

Following large trucks very closely will also save you some gas, but after ramming a few trucks the accident bills will defer the savings in gas.
Luigi

" but after ramming a few trucks the accident bills will defer the savings in gas. "

I meant to say "override the savings", I think.
Luigi

I have looked at the gas mileage for a long time & what I have found is elect. ing. helps & set the timming to 40 deg. TOTAL adv. at 3 to 3500 r.p.m., with the vac. adv. hooked up & make sure the vac. unit is working. I love my S.U.s but I can get 5 m.p.g. more with the down draft webber with the hot water on the bottom of the manifold & I run the auto choke. Make up a cap to go over the carb. then a fresh air hose to go from the carb to infront of the raid support, to get cool fresh air. If you build a motor use the early 8.8 - 1 comp. pistons & then cut .060 off the head to rais the comp. even more. I have done this & can still run 89 oct. Run at least a 180 thermostat, I run a 195. I use the Datsun 5sp in my 4 cyl. & there is 4 to 5 m.p.g. more & it is 40lbs. lighter. I just got back from fla. with my 74 G.T V-8 with a 4.2efi, at 80 to 90mph. I did 25 m.p.g. & at 65mph I did 28. There are other things you can do but this is a good start.
Glenn Towery

My mga has a newly built 3 main 1800 in it. It's got 500 miles on it. I'm getting 16.8 mpg. It's got mga h4 carbs with std needles, a head that's been opened-up and polished with 3 angle grind, pertronix ign and the plugs, which I just replaced with bosch platinum, were dry and light brown when removed. I don't go over 4000rpms and I don't push the engine hard or lug it but I do drive rather spirited.

I have just retorqued the head, reset valves and changed plugs so maybe it'll improve, but I'm also planning to go to mgb #5 needles.

Any comments?

Thanks

Fred Horstmeyer

It's all down to the state of tune and how you drive them, but you can still get decent mileage with 'spirited' driving. My best-ever was 34mpg over 320 miles returning from Le Mans last year - in the V8.
Paul Hunt

In Road and Track magazine a few months back, there was a technical article on how to drive for the best fuel economy. The author maintained that pumping losses were the greatest impediment to economy, and part throttle operation leads to more restriction of the airway and worse fuel economy. The consensus was that full throttle acceleration and shifting at very low revs was the most efficient way to accelerate. I have tried this on my 1.8 turbo VW Passat, which has instantaneous and average MPG readouts (and a manual transmission of course) and it seems to work. But why do we care? One of the marvelous things about the B is that you can thrash the stink out of it, and still not use much gas.

My engine in my '66 B is built about like Fred's and I usually drive it wide open all the way to redline. about 3 years ago I drove it through the Blue Ridge Parkway, which was all very slow, conservative driving (pregnant wife) and I was amazed at how little fuel I used, even climbing the mountains. The economy meters in my VW have taught me that driving style has a huge effect on economy, and typically, the less you change your speed the better off you are. And MPG starts to fall off at about 60 mph.
Chris

Try shifting to neutral going down hill or better still if you don't have power steering shut down the engine completely or hitch to a semi. Just for laughs
:-)

Cec
Cec

Full-throttle acceleration through the gears up to top speed then coasting back down before accelerating away again in top is said to be the most economical way to drive - but hardly practical. What is practical when cruising is to try backing off the throttle pedal just a fraction, it makes a difference to consumption but hardly any to road speed.
Paul Hunt

This thread was discussed between 16/04/2003 and 25/04/2003

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