RGMotorsport’s tech team has waved
its magic wand over the F90 BMW M5 and the results are spectacular.
In standard form the latest xDrive-equipped
Bavarian super sedan wants for little in the way of power and torque but that
doesn’t mean that more can’t be had. Proof of this is plain to see in a set of
impressive new numbers: on RGMotorsport’s all-wheel-drive dynamometer the
flywheel ‘after’ figures for our development car was an eye-opening 515kW.
We’ve found 74kW, or if you speak American, 100 horses.
Meanwhile, torque on the engine surges
to 907 Nm from 750 instock form and there’s no compromise on the delivery
either: at just 1 500 rpm torque has already climbed from 355 to 420Nm. At
6 000 rpm, there’s still 735 on tap, almost as much as the standard
engine’s maximum twist, which is achieved at 4 000 rpm.
When it comes to “next level” for
performance sedans, this is it.
The first thing to change on the
car was the exhaust: off came the standard item and in its stead the welding
gurus in the M workshop painstakingly built an RGM-Techniflow dual system. It starts
from the V8’s turbocharger downpipes and with a quartet of catalytic convertors
dispensed with, it is a pukka free-flow.
It measures 76mm in diameter and
follows the route of the original, though wherever possible the radii of the
bends have been opened as much as possible. A combination of mandrel bending
(which leave interior diameter unchanged) and pre-formed sections are used to
achieve this. Dozens of individual pieces of 304-grade stainless steel tubing have
gone into the construction, first being Mig-welded in situ and then removed for
final Tig-welding. This is where the ability of the man behind the mask really
comes into play.
It is labour-intensive and requires
quality equipment and skilled personnel...but the outcome warrants it.
The tail end, installed pre-assembled,
is a maze of intricate piping with a transverse silencer per bank of cylinders.
It continues to utilise the original dual-tone exhaust volume control (or M
Sound Control in BMW-speak) flap system which is integrated into the Techniflow
exhaust. For those who find the M5 a little too subdued, this bypass function
creates a deep and rich exhaust tone which leaves no doubt as to the car’s
performance credentials. One of the most obvious changes is more attitude on
the overrun…
To maximise the benefits of the
exhaust RGMotorsport turned to software experts, JB4. Their M5-specific
solution integrates seamlessly with the car’s CANbus wiring, maintaining all the
original drive-mode functionality including the aforementioned exhaust volume
control. It also allows for electronic wastegate control for superior boost
targeting, allowing maximum output to be safely achieved.
“The BMW brand remains very special
to me and it really has been quite an honour to be entrusted with upgrading the
latest M5,” says Rob Green. “We’ve made bigger gains than we hoped for and the
owner is thrilled with the outcome!”
Total cost of the conversion is
R110 000 excluding VAT.
