Fuel-injected MGB

Fuel-injected MGB
Fuel injection for the B T
Geoff Bradshaw wanted more modern
drivability from his MGB, Webcon
wanted to develop fuel injection for
the model. Put the two together and
is it a match made in heaven?
Geoff’s BGT has
been extensively
modified, but with
smooth running,
comfort and ease
of use very much
the goals in mind.
A brand new fuel
injection kit is just
the latest of these
changes.
24 MGE December 2009
Words and pictures: Steve Havelock
Subscriptions 01959 541444
Subscriptions 01959 541444
he car you see on these pages is the most refined,
most civilised road going MGB GT that I have
experienced. Part of that is due to it being the first
MGB to receive Webcon’s excellent new fuel
injection system, although that is only the latest
twist in a very long story. You see, owner Geoff
Bradshaw has toiled over this car and spent a small
fortune developing it, yet it was only supposed to
be a temporary relationship when he bought it eight years ago.
‘I had a Triumph Stag and was in the process of replacing the
Triumph engine with a 3.9-litre Rover V8,’ he explained. ‘My
wife Jane and I had planned to go on a motoring tour to Vienna,
but the Stag wouldn’t be ready in time and so I decided to buy
an MGB GT. It was supposed to be a short term measure and I
was going to sell it when the Stag was back up and running.
‘The car I found was advertised as an up together car, which
is what we wanted as we didn’t have much time to play with. It
didn’t have overdrive, which is essential for continental touring,
so I had that fitted and also a Webasto sliding sunshine roof.
Then we set off to Vienna with a smile on our faces and it got us
round. We loved it and decided to keep it. We subsequently did
a number of tours including a trip to New England in the USA.
Three years ago on a trip to France, someone ran up the back
of us. Nothing too serious, but when we got home I decided to
sort out the MG. That’s where it all started, really.’
Geoff stripped down the car and sent it off to a local body
shop at Selsey in West Sussex for a bare metal respray, opting
for Tartan in lieu of the original Flame red. Back home, snug in
his garage, instead of refitting the standard engine, Geoff
bought an Oselli 1950cc stage two engine with a fast road cam,
fitted with an aluminium backplate. He also ditched the MG
gearbox and overdrive in favour of a Ford Sierra five speed
gearbox and modified prop shaft from Hi Gear Engineering.
‘The gearbox is very neat and quite a bit lighter,’ he said. ‘It
really is a vast improvement and I would recommend to any
MGB owner that it’s the first thing they should do to improve
their car. It went straight in with no cutting or messing about. I
also fitted coilover front suspension from Hoyle Engineering in
Epsom, power steering from the MG Owners Club and a
smaller 14in Moto Lita wood rimmed steering wheel, stainless
steel exhaust and Kenlowe electric fan. The interior was
completely renewed with comfy black leather seats, also from
the MGOC, a wood veneer dash from Classical Dash and
magnolia faced Smith’s instruments from Holdens.
‘It went quite well,’ Geoff recalled, ‘but I did have a bit of a
problem with flooding carbs and it was never that good on cold
starts. On the other hand, my Stag had fuel injection and it is so
trouble free – you just switch it on and away it goes. So I began
to wonder if it was possible to fuel inject the MG and bring it
up to date. I phoned a few people who do this sort of thing and
got mixed messages. Some of them said you could, some of
them said you couldn’t and one firm who supply kits for other
models just didn’t want to get involved. I then phoned Webcon
at Sunbury. They were very positive and said: ‘Funny you
should phone because we are thinking about doing a kit for
MGBs. Can you bring the car up and we can have a talk about
it?’ So I did, last September.’
Webcon’s development engineers, Alan Collins and Peter
White, both with over 20 years of service with the company,
enthusiastically embraced the project. Indeed Alan, an ex-Isle
of Man TT sidecar racer, is currently in the process of building
an MGB GT track day car which will be used as a working test
bed for the company’s products. They explained to Geoff that
the main problem with fuel injecting an MGB was the standard
cylinder head’s siamesed (or shared) ports. As a result of this
design, one cylinder can rob another of fuel leading to uneven
running, and possibly even the complete cutting out of some
cylinders on idle. The solution lay in the fitting of an aluminium
crossflow cylinder head with four inlet ports, one for each
injector. These heads have been available for some time made
to Webcon’s specification, but previously they’d been mated up
to a traditional twin carb set-up.
Geoff, being a very competent home mechanic, wanted to
work on the car himself, so a collaboration was agreed. Webcon
December 2009 MGE 25
Fuel-injected MGB
Below: Crossflow
cylinder head
does away with
the B-series’
siamese ports
and opens up the
way to fuel
injection.
Bottom: Changes
to the interior are
extensive, but all
quite subtle and
certainly well in
keeping with the
character of the B.
would supply the parts they thought he needed based on years
of experience in supplying fuel injection and engine management
systems for other engines, especially in the kit car sector, while
Geoff would fit them and then report back with his findings.
First of all, Webcon put Geoff’s car on the rolling road so
that they had a benchmark to work from. The B was producing
just over 80bhp at the back wheels and about 100bhp at the
crank. Then, armed with a big box of bits that included a new
head, inlet manifold, throttle bodies, coil pack and ECU, Geoff
returned home and set to work installing them.
He was doing this for fun and didn’t want it to become a
chore, so it was a case of an hour or two here and there and the
odd weekend. After all, he still had his Stag to play with! As this
was effectively a prototype, the occasional tweak was needed.
Take the wiring loom, for instance. This was originally from
one of Webcon’s Ford kits. Geoff offered it up, made a note of
which wires were too long or too short, and sent it back to
Webcon who then remade it. This all takes time.
Then a solution had to be found for the high pressure fuel
system that is required for fuel injection. A high pressure pump
is needed, which has to be kept submerged under the fuel at all
times. This is because the fuel lubricates the bearings and any
sucking of air would lead to very quick failure. It wouldn’t do
much for the running of the engine, either! The initial thought
was to fit a petrol tank from a modern fuel injected car, like the
MG RV8 which has a swirl pot and high pressure pump built
in, but this seemed a rather expensive and laborious option. So
the thinking caps went on and the end result is neat, simple and
inexpensive. The existing fuel tank and its low pressure fuel
“Fitting wasn’t difficult for me
as a home mechanic; an MG
specialist could do it easily”
pump are retained, but instead of supplying fuel to the carbs,
it’s fed to a separate little tank, or swirl pot, which has a high
pressure pump within. This sits within one of the two battery
boxes. (Due to the efficiency of modern batteries, most MGBs
only have one fitted nowadays.) The fuel is then pumped
forward at high pressure to the throttle bodies and injectors, so
there is a low pressure circuit and a high pressure circuit.
The brains behind the fuel injection is the ECU, or Engine
Control Unit. This is a tiny computer loaded with thousands of
predetermined values. It analyses such information as throttle
position and engine revs, refers to its tables and issues
instructions on how much fuel to squirt into the engine and
when to fire the spark. The distributor is removed and a trigger
disc is fitted to the front engine pulley. Webcon had no detailed
data on MGB engines, so programmed the ECU with a set of
approximate values based on engine size, rev limit and power
output. This was adequate to get the engine up and running
safely. Geoff sited the ECU in the passenger footwell behind a
false footboard, an ideal spot away from engine heat, water
and dirt. He also fitted an Lambda sensor into the exhaust
which is wired back to the ECU. This was mainly for the
gathering of information for Webcon, and is not really required
for cars without catalytic converters.
‘The fitting was not difficult for me as a home mechanic,’
said Geoff, ‘but an MG specialist could do it easily. My MGB
has power steering, so I had to shorten the back of the pump a
26 MGE December 2009
Subscriptions 01959 541444
bit on my lathe because it fouled one of the throttle body
spindles. That wouldn’t be an issue on standard cars.’
Whilst in the garage, Geoff took the opportunity to fit Hoyle
Engineering’s independent rear suspension which incorporates
a Ford Sierra differential. As he explains: ‘It’s given the car
longer legs and allows me to keep up with fast lane motorway
traffic easily. I bought the complete kit with new hubs, disc
brakes and coilover shocks, but it meant yet another prop shaft.
It’s very well engineered and bolts straight in; there is no welding
involved. It’s very substantial and the overall weight is about
the same as the components that are removed, but the unsprung
weight is considerably less. I had to fit larger 15in wheels to
accommodate the brake calipers, though.’
Geoff had his car back up and running in March and the
ECU was programmed well enough for him to drive to
Webcon’s facility in Sunbury. There, Alan and Peter checked
the installation and fine-tuned the ECU. ‘They needed it for a
few days,’ said Geoff, ‘because they had to sort out cold starting
as well as warm running. There is a diagnostic socket on the
ECU – they connected their laptop while the car was running
and made the necessary adjustments.’
‘Having an oxygen sensor in the exhaust on Geoff’s car
helped us get the calibration right,’ said Peter, ‘but now that we
have the data, you don’t need one as it will run on predetermined fixed values. Nobody in their right mind would put
a cat on a car. They are a daft idea which the politicians thought
Subscriptions 01959 541444
of and we are all stuck with. But if you do need to fit one or
have one already, our ECU is capable of providing the fuelling.’
I asked if the fuel injection has increased power, to which Peter
replied: ‘To get more power out of an engine you need more air.
The fuel injection isn’t going to do that. The crossflow head is
better than the standard one because it overcomes the
limitations of the siamese ports, but the objective of what we’ve
done is to produce a nicely driveable car.’
Alan then added: ‘The Alpha system has been going for
about 20 years now and we sell a lot of ready-calibrated kits to
the kit car market. When Geoff approached us, we had already
been thinking about a system for MGs. We’d had feedback that
a lot of MG owners who wanted to use their cars frequently
were disappointed with the drivability compared to their
modern cars. We thought we could improve that and make a
car that was nice to live with.’
So, has it worked? ‘After this final fettling,’ says Geoff, ‘it ran
like a dream. We took the car touring to Austria, Italy and
Switzerland and did 1750 miles in nine days. We did 13 Alpine
passes in two days including the Stelvio, and it performed
amazingly well. It pulled like a train and was really quite
extraordinary. Its torque and drivability has improved no end
and we averaged 28.8mpg. I’ve now done about 2500 troublefree miles and even after days of standing, it starts first time.’
To see for myself, Geoff and I went for a spin. Sure enough,
from a dead cold start the engine fired on the first turn of the
Above: Once the
fuel injection was
fitted and
calibrated to suit
the B, Geoff
embarked on a
touring holiday to
the Alps to test it
out. He was not
disappointed.
December 2009 MGE 27
Fuel-injected MGB
key and instantly settled into a smooth idle. Pulling away and
accelerating through the gears there was no fluffing or hesitation
whatsoever. Even when the revs were allowed to drop right
down in a high gear, a prod on the throttle resulted in a clean
pick-up with bags of torque in evidence. Just like a modern car,
in fact. The suspension was also a revelation. It soaked up the
bumps admirably without any knocking, crashing and banging
and yet didn’t seem at all wallowy, although we didn’t really
push that hard. As Geoff reminded me: ‘This is a touring car. I
don’t like revving my engines too hard and I don’t like harsh
suspension. I’ve got it just as I want it and I’m very pleased.’
The complete system, which will be marketed through Moss,
costs £2865.95 (incl.VAT), with the swirl pot an additional
£200 or thereabouts. Webcon say that it can all be fitted by a
competent home mechanic in a weekend. Those with special or
highly modified engines should speak to Webcon because the
standard mapping may not be adequate. They did add that
recalibration should only be done by one of their authorised
Alpha dealers so they could control the standard of the work –
mistakes could leave you with a very damaged engine.
Is it worth it? Well, you get a lot of good quality equipment
for the money and it does what it says on the tin. But remember,
it is smoothness and driveability you are buying, not increased
power and performance. At the end of the day, it all depends on
what’s important to you.
28 MGE December 2009
Right: Full length
folding sunroof
was one of the
first things Geoff
had fitted to his
BGT – along with
an overdrive ’box.
Below: 15in
wheels were
needed to clear
new calipers, but
overall, the
changes have
all been very
discreet.
Contacts
www.moss-europe.co.uk or call 020 8867 2020.
www.hi-gearengineering.co.uk or call 01332 514503.
www.hoyle-engineering.co.uk or call 0208 393 2555.
Subscriptions 01959 541444