Forced induction
Introduction
Whilst many owners find the standard 1800cc engine
acceptable for country lanes and around town, the quest for more power is always
lurking in the background for the average owner. More to the point, by
comparison to today's traffic, a B can be frighteningly underpowered at times.
The Hi-Flow supercharger.
However, for a weekend's work, and the possibility of
power outputs similar to the original factory GT V8, one has the choice of
supercharging! Admittedly not as cheap as a V8 conversion, but, it
requires less effort to fit, and the car can be returned to standard in a short
space of time.
The Moss Supercharger unit.
The Moss kit by Michael
Beswick
Superchargers
are cheap - supercharger kits are not!
Buying
a supercharger off eBay is easy and will only cost a few hundred pounds. This
compares with about £2000 for a kit from Moss or even more from Hi-Flow.
However what you get with the kit is considerable. If you have the skills and
equipment to design and build the manifold, select the carburettor, produce all
the bracketry and pulleys then eBay is a cheap option. For those of us that do
not have the contacts, skills or equipment then the kit is a cost effective
option.
It
is also probably the most cost effective tuning option, provide you have a stock
engine and it is in good or rebuilt condition. Supercharging a tired engine will
end in tears.
I
fitted the Supercharger kit from Moss over a couple of weeks, though it could be
done over a long week-end, if you are lucky and with a well equipped garage. It
does not need specialist skills or tools. This is the key. Paying for an expert
to do headwork, polish and change cams all costs the labour rate (not much
different than for a modern car –if the firm is good). The supercharger kit
can be fitted by an amateur! The Moss kit is complete to the last nut and bolt -
complete with shims to match up the supercharger manifold to the various exhaust
manifold thicknesses. The only shortcoming was a US (so lhd and short) throttle
cable!
The
other main difference is the drivability. With a light throttle, it is a
standard MGB and perfectly happy driving through the local town centre. Bury the
throttle and it changes dramatically! Many raised compression, bigger engines
seem to be less tractable below about 3000 rpm. In comparison a supercharged one
will pull from 1500 rpm in overdrive top. Drop to third, and welly it and see
the difference. That thrusting BMW driver that allowed you into “his” lane
looks surprised as you disappear and pull in neatly!
So,
whats involved?
-
Remove
the air cleaners, carbs and inlet manifold
-
Remove
the radiator
-
Remove
the alternator and water pump (new units are supplied with heavy duty
bearings)
-
Lean
the exhaust manifold away from the block
-
Remove
the engine mounting bolts
-
Remove
the crankshaft bolt and the pulley (might be tough!)
-
Lift
the engine to remove the pulley
-
Fit
the new pulley, water pump, and fit the brackets for the idler wheels
-
Hang
the supercharger (complete with carb) onto the manifold bolts
-
Refit
the rad with the new shape hoses
-
Fit
the belt
-
Curse
the thing you’ve forgotten
-
Trundle
off to the rolling road to set it up
-
Enjoy!!
So
whats the effect?
Pretty
spectacular. The original B put out 65bhp at the wheels (about 95 at the
flywheel) when new. We measured 110 bhp at the wheels (probably about 140bhp at
the flywheel)! The manufactures claim a 40% increase.
But
driving is the key! It goes very well, “keeps up” with modern cars and gets
past people doing 60mph who won’t move over! It is happy around town, on
motorways or on the ubiquitous country lane!
The
downsides?
Well
its been in a year and 5000 miles. It does run a bit warmer –a problem in
France at >38° C.
This year a 7
blade fan was fitted to help (in addition to an after market electric one). My
guess is that it would be fine for the UK but maybe a problem in hot countries!
Just
after the French run, the head gasket went. However there is a suspicion that
the head had not been re-torqued after the rebuild, so we can’t determine if
it was caused by the supercharger. It wouldn’t have helped though.
I
fitted green stuff pads, but otherwise just checked the brake fluid and
“feel”. It stops!
Fuel
consumption may have changed - there is a temptation to use the performance!
Superchargers
Superchargers, the way to go! For
a weekend's work, and the possibility of power outputs similar to the
original factory GT V8, one has the choice of supercharging!
Admittedly not as cheap as a V8 conversion, but, it requires less effort
to fit, and the car can be returned to standard in a short space of
time.
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