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Engine Tuning
Ever since we started taking an interest in things fast and BMW, I don't think that anything, other than our own developed exhausts, have made more of an improvement in engine power and performance, than the current generation of "stand alone" engine management systems.
The main gain seems to be linked with the elimination of the airflow or flap meter, from the standard inlet system.
Removing this accursed component rids the intake of a "bottle neck”, which restricts the amount of air that can pass into the engine, releasing considerable power without any other modification!
These systems may be applied to your “stock" engine, naturally more air means more air-fuel mixture through too small valves, and more waste gases going out through an inadequate exhaust system so they really come into their own when installed to serve a modified power unit.
With improved management, comes other benefits. We have found that if you substitute coil pack ignition for the distributor-coil system, you can eliminate the vague, old fashioned, spark generating apparatus, from the equation, thereby getting rid of an source of ignition system faults.
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You now have TOTAL CONTROL of the engine management system, giving micrometer-like precision to fuel supply and spark occurrence, throughout the entire rev range of the engine. This ensures that you have the means to control, through a lap top computer, the exact moment that combustion takes place, allowing optimum tuning with long dwell cam set-ups, turbo and supercharged set-ups. These advanced systems will take most anything that we can throw at them. The motronic system, as originally fitted has 'holes" in the mapping, and of course built in restrictions, to limit the performance, and no amount of re-chipping would have any great effect, other than push the power band further up the rev range. Now however things are very different we can 'map-in" smooth power ramps all the way up the rev range, well beyond the motronic limit. The problem now is to live with the extra strain that must be exerted on the engine and drive train as a result. As an aside to this" those people out there who went for the idea of using a 2.7 525e crank and pistons in their 2.5 block, as a way to extra bhp, and were thoroughly disappointed with the results, may be interested to know that with the use of this advanced technology, all your dreams of greatness may yet be realised. It seems that much of the lack of extra go was and still is, mainly down to trying to use the ECU from the 2.5, which of course is not designed to cope with the longer stroke of the 2-7 crank This can now be mapped into the control system, and HEY PRESTO, superfast E30!! Obviously these advanced systems need professional installation, with the use of specialised equipment to effect the mapping procedure for the stand alone ECU. We are now able to provide these facilities, in house. We can supply, install, set-up, and map these installations on up to 1000 bhp vehicles using our rolling road. Power runs, tuning, and diagnostic services are also available with this machine, please telephone for further details of this and other facilities at your service!!
The heart of
any car, the bit we mostly lust after, the talk in any bar, is the
‘lump’.
Its
funny how things go full circle, a few years ago 2002’s only had 4
cylinder engines then there were sixes, eights, twelve's, but our
collective interest seems to be refocusing on the ancient and venerable
four once more.
Small,
light, and efficient for its basic design, easy to work on, cheap to
run.
What
more do you need?
Yes
I know, more cubes, right? More revs? More power? How? Leave that to us.
Want
to go bigger? No problem.
The
range of engines we cover is known as the M10, M20, M30 series.
That
is: 8 valve 4 cylinders
Or
12 valve 6 cylinders
The
M10 starts at 1600cc and can be extended to about 2100cc.
The M20
starts at 2000cc and goes to 2500cc without strain as standard
(I know about the 2.7 but
that’s another ball game)
The
M30 overlaps at 2500cc and goes to 3500cc but is much heavier in the
lower capacities than the M20.
The
interest always lies in the larger capacities, but there are other
considerations such as rev per min and torque.
These
two are related but only vaguely.
A
modified two litre six will rev until it wails like a wolf at full moon,
but its not a lot of good for towing the family caravan to Minehead!!
The
3.5 big six, however, as used by the forestry commission to pull tree
stumps out of the ground, will tow the caravan but takes some waking up
at a track day, the moral being, its horses for courses.
Although
this section is about engines and the appropriate tuning of them, the
rest of the chassis suspension, brakes, wheels etc must be borne in
mind, its easy to cram a big cube lump into 315 and head for the local
strip, only to find its OK to go, but won’t corner or stop, that’s
why we take the holistic approach.
The
fight is always for the balance, that is the balance between revs and
torque. We tend to tune for the best of both, this makes for an engine
that performs well and lasts a reasonable time, that both revs and pulls
but not to the limit or loss of either.
However
We
can build grenade motors if you want them, but going fast is an
expensive business both in time and hardware.
M10
the basis of all tuning is to make the engine “breath”. If you put
in more air/fuel, you have to be prepared to expel more waste gases.
The
standard induction can supply more air fuel mixture than your engine can
use at full revs, the governing factor is usually the size of the
valves.
An
e
The
E21 315 (yes 5) is a 1600cc engine with a small single choke carb
mounted on it, for economy.
Change
the carb for a twin 38mm choke Webber, you’ll spin wheels in first and
second, change the head for the one with 1800cc valves fitted, you’ll
do the same in third as well. Fit a four branch flowed exhaust manifold,
a longer dwell cam, twin 45mm Webber carbs, an induction kit and
you’ll be cooking with the gas, and lots of it, cos now the thing goes
pretty well and the idea of the original economic nice little car has
gone right out of the window.
Now
of course it won’t handle on those 13” wheels, won’t stop with
those un-vented disks on the front, and bounces all over the road on
those clapped out shocks,
So
what do we do?
Another
example
M20
engine
Designed
to produce silky smooth power this engine uses a tooth belt to drive the
cam, is quiet in operation, and good to drive, coupled to a five speed
manual or to an automatic it delivers good performance in a range of
sizes and guises.
The
later range (E30) engines breaths better, it has larger valves in the
head. The two litre can be made to rev to the roof and back but lacks
torque the two point three is the middle ground and the two point five
has bags of torque but relatively low revs.
Take
the big valves from the two point five, install into the two point three
head, slap on top of the two point three bottom end, triple Webers, long
dwell cam, six branch,
Yes,
but what about the ETA lump, the fabled two point seven, the big
capacity gift from the God’s?
M30
engine
Big
capacity, heavy engined 2.5
Here
we go again, all stages of tune from mild to wild.
Unlike the small six, forged pistons, and steel cranks are fairly easily found, long tract induction manifolds are also available, as are enlarged throttle bodies. All stages of cam tuning can be obtained we have six branch headers and flowed exhaust systems in stock. Triple Webbers on custom built manifolds are available if required, modified head (your choice of tune) can be installed along with heavy duty main and big end bearings plus HD oil pump.
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