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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.
Sharp jump in power
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.
READ: RGMotorsport’s tuned Ford Mustang GT is a 600kW monstrous muscle car in SA
Meanwhile, torque on the engine surges to 907Nm from 750 in stock 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 000rpm, there’s still 735 on tap, almost as much as the standard engine’s maximum twist, which is achieved at 4 000rpm.
Image: Motorpress
When it comes to "next level" for performance sedans, this is it.
Quality and skill
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 converters 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.
Image: Motorpress
Dozens of individual pieces of 304-grade stainless steel tubing have gone into the construction, first being tacked 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.
Image: Motorpress
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…
Image: Motorpress
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!”
For anyone interested, the total cost of the conversion is R110 000 including VAT.
