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MG MGB GT V8 Factory Originals Technical - Build a mileage monster?

I'm surprized that there's not more talk about the high fuel prices we're seeing at the moment. Every time they go up, it gets me to thinking about building a 'B to get great gas mileage.

Here's my thinking. Aerodynamics could be enhanced with a front airdam and headlight covers. Rear spoiler? Not sure if that would reduce drag.Strip the chrome moldings off the side. Do away with the 3rd wiper on North American cars. Remove outsde mirrors. Eliminate the door handles and install a remote. Still all pretty tame. Now we can get a bit more radical. Rear fender skirts (ugh!), full undertray. Reduce the radiator inlet size. Maybe graft in an early midget grill? Or a droop-snoot front end like the '60s Le Mans car. I haven't mentioned any hardtops or the GTs, as I don't know if I'm willing to give up wind in the hair for a few MPG. But the potential's there.

Running gear could be changed a bit, too. Narrow, low rolling resistance tires with flush hubcaps. Lowered suspension to keep air from under the car.

Now the tie-in with the engine conversion forum! A VW 1.9 TDI-PD mated to a 5-speed gearbox! Although only 100hp, there's of torque! And in the Beetle, it's rated at 46mpg. Not enough power? Then there's the B5 Passat with 134hp/247ft.lbs. Still not enough? Chip it!

That's 168hp/265ft.lbs.

How about a 6-speed box and of course there's alway biodiesel to consider. If you don't mind smelling like a chip truck!

Derek Nicholson

Some of those aero ideas would yield such tiny gains... Third wiper?

IMHO, one of the smartest first steps for a roadster would be removing the windshield - and wear a motorcycle helmet or goggles - for a big reduction in frontal-area.

Don't forget to snap-in your tonneau cover (assuming you don't have a passenger). Back in the late sixties / early seventies, my dad used to drive his MGB convertible from under a modified tonneau - modified sort-of like a kayak so his head and shoulders stuck out above it. In good weather, he still kept the passenger-side cover in place. When us kids rode with him in bad weather, we'd ride under the tonneau cover. Fun!

I bet a full belly pan would work better than any of the aftermarket air dams.

Modern tractor-trailers loaded to 80,000 pounds gross are routinely getting 9 mpg (highway / on diesel) with HUGE frontal-area and with engines that produce over 400hp... (so it's pretty clear that all SUVs and pickup trucks are really LOUSY from an efficient-design point of view, isn't it!) You could glean some other good ideas from big trucks and trucking companies.

The first tip: hire yourself a professional driver and pay him a fuel-economy bonus for keeping his foot light on the throttle. Plan all driving/routes to minimize starting and stopping.

Pay a lot of attention to gear/axle ratio and the programming of the fuel injection system.

Give tire and wheel selection a LOT of thought. There are really good reasons why big trucks run 100 psi tires! Get rid of tire sidewall deflection and instead absorb ALL shock in the suspension. Also, most wheels and tires are way, way too heavy. Once you're at speed it's no problem, but every time you accelerate heavy wheels/tires waste fuel.


There is one further exceptional European engine that is worth considering, that is the 2.7L 'Lion' V6 as fitted to Jaguar and Land Rover vehicles, which is good for 205PS in standard trim and in the order of 480Nm. This is the class leading engine for refinement.

Regards, James
J E G Eastwood 1


take away a quarter of the wight and you will safe a quarter of the gas or go slow.
Headlight cowls are fine, I am searching for an insallation frame for mine since I bought them 10 years ago.
BTW we went to The Neatherlands last year. There is a seed limit of 100 to 120 Kilometres/h (62 -75 Mph) and made nearly 33 mpg on constantly 100 Kph (62 Mph).
Jetting in the Holly is 49 primaries, 51 secondasies.


A couple of things come to mind, Diesel Rabbit from the 70's, if you can find one it will get about 45 to 50 miles per gallon, it aint a B but at that economy who cares? Moss has EFI conversion for the B, Im wondering what kind of milage that will get? Any ideas?
CW Strong

Remove bumpers & strip chrome mouldings - reduces weight, improves aerodynamics & also removes a potential corrosion problem.

Remove wing or door mirrors.

Fit adhesive number plates front & rear.

Cowl headlights... etc..

Remove windscreen wipers and rely on Rain-X (probably illegal but works !).

Polish car.

Every little helps - remember what Colin Chapman said "Simplificate & add lightness".

Nigel Steward

Or, say the heck with it and let the four barrel make music!
Kelly Combes

There are a lot of good ideas there but I can't help thnking that starting with 'B is really putting yourself behind the 8 ball unnecessarily.

Since the Rabbit and other diesels are such fuel misers then start there if you are willing to forgo the brand / marque loyalty aspect to go chasing better eceonomy numbers.

Just as an aside I drive a Holden Commodore (think Pontiac GTO with 4 doors) with 3.8 litre spark ignition engine and my average fuel economy is about 7.0 litres / 100 kms (US 33.6 MPG)...pretty good for a 4 door family hack with auto , air con and an all up weight of about 1500 KG.

Best I ever managed was 4.8 (US 49 MPG) but to be fair I have never managed to repeat the effort.

Cheers , Pete
Peter Thomas

There are lots of other things you can do.

grinding off the rain gutters will make a big difference, as will replacing the quarterlights with solid glass.

Fit a bonnet which is higher at the back, which will fair in the wipers and angle the air better over the windscreen.

replace the rear quarter lights with perspex panels that are flush with the bodywork.


Here's a snapshot that shows a couple of Dave's aerodynamic tweaks implemented... sortof:

I didn't grind off the GT's rain cutters, but I did remove their trim to streamline them a bit. They still function as rain gutters and they didn't require special bodywork to look finished.

GT rear quarterlights are surprisingly heavy. I replaced mine with 1/8" polycarbonate. I used double-sided foam trim tape to secure the plastic to lightweight box-tube frames. The quarterlight assemblies are each held in by three Dzus (quarter-turn) fasteners, so both windows can be removed in a minute or so. After ten years they're still working fine. I just wish I'd done something to black-out the front door window trim to match.

Side marker lights and turn signals have been replaced with more modern and streamlined lamps.

GT rear hatch and plywood cargo lid are both really heavy... lightening them up would be a good idea.


Funny thing... no one has mentioned fitting spats to the rear wheels.

Funny this subject came up.
I was just thinking about trying to do a "mileage special" using an old spridget, and some kind of diesel, or turbo diesel, then converting it to run veggie oil.
Light weight diesel burner= great mileage, and I can get veggie oil for free, just need to start and purge the motor on diesel. I also know a guy who makes great aluminum tanks and has all the gear to do the swap.
Bill Mertz

Anyone ever seen any wind-tunnel test results for the 'B? I guess I could always try coast-down tests as a cheaper alternative.



Sebring cowls definitely reduce wind noise, so I assume that they reduce drag.

I've fixed mine with small circular magnets glued into the rim of the covers, I used 10 each side, more than adequate, but you need cover the face of the magnets with thin film to prevent damage to the paintwork.

I've got some pics if you send me your Email address, the magnets came from Eclipse, very small ,and very powerful.

M Barnfather

What would someone else's wind tunnel tests tell you anyway? You'd really like to have your own tunnel so you could test incremental design changes. Coast down is okay, but not so "controllable". Besides, what you really want to do in a windtunnel is wave a wand in front of the car while it emits smoke so you can look for turbulance, etc. Bits of yarn or magnetic recording tape adhesive-taped in a pattern over the car's body can tell you some things about airflow. The thing to do is take video footage from a second car driving parallel. It would be good to test at several different speeds too.

Hello Mike,

Thanks a lot. My e-mail adress is
I saw some pictures of alloy or chrome finished frames but never seen them on a car, although trying to find some since the late 1970ties.
Pics are shown on MGB MGC & V8 Gold Portfolio, page 92/93, reporting upon an Australian MGB with special GT Hardtop and improved engine and in THE MAGIC OF MG by Mike Allison, saying these frames were offerd by Layland Special Tuning (Definately they did not offer these) and othr suppliers.
As these items look very fine and stock, I am wonderung why noone ever offered any reproductions.

Anyway, I was not willing to fit the cowls as done on the works cars, so the idea with the magnets sounds good.


I think you can better improve mileage if you are interested in going with fuel injection; especially a closed loop system. A fuel injection system can adjust for so many factors and can help pin down fuel usage for all kinds of driving. If you have a closed loop wide band you can even experiment beyond what the EPA would require cars be built. EPA requires a relatively rich setting for cruise which could easily be leaned out a bit more. You may be more interested in playing with aerodynamics but I think there are a lot more gains to be made here.

gw mr

This thread was discussed between 23/04/2006 and 04/05/2006

MG MGB GT V8 Factory Originals Technical index

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