The world’s most powerful four-cylinder engine in series production!” – This was the sensational headline used by Mercedes-AMG last year to announce the newly devel- oped M 139 engine, which provides impressive propulsion with up to 421 hp and 500 Nm in the A 45/A 45 S spearheads of the latest generation of A-Class models (W 177). Nevertheless: the power experts from POSAIDON in Mülheim-Kärlich still dis- covered some huge potential for even more performance, even in the world’s most powerful four-cylinder engine in series production, and got straight down to work on releasing this.
The result that was presented last spring is the POSAIDON A 45 RS 525, which now – it’s in the name – generates up to 525 hp and a mighty 600 Nm from the M 139 four- cylinder engine following the installation of a more efficient turbocharger and an opti- mization of the engine control unit’s map. Paired with the parallel optimization of the control unit for the eight-stage AMG SPEEDSHIFT DCT 8G transmission as well as the drive train (CPC), the four-wheel drive rockets from 0 to 100 km/h in just 3.4 sec- onds and reaches a top speed of 324 km/h. This makes the POSAIDON-optimized hot hatch just as fast as 1990s hypercars such as the Ferrari F40 and Lamborghini Diablo. So it hardly has any opponents to fear on public roads. POSAIDON thus set itself some different goals: on the basis of the A 45 RS 525, the tuners introduced the first tracktool that had been specially optimized for the race track in the company’s history.
Unlike the “civilized” A 45 RS 525 version, the tracktool is also equipped with chassis, brake and safety technology that has been optimized for motor sports. The A-Class was given a wheel/tire combination of OZ Formula HLT rims, each of which weighs in at just 9.8 kg in the dimension 9×18 inch ET35, and low-profile Nankang AR-1 semi-s- licks, that stick to the road like old chewing gum when they reach their running tem- perature, to optimize the mechanical grip as well as the unsprung and rotating mass- es. To ensure the wheels stay in contact with the road at all times, POSAIDON’s track- tool upgrade also includes the installation of a KW Clubsport 2-way coilover suspen- sion with independently adjustable compression and rebound damping, which also comes with parallel adjustable, aluminum Unibal top mounts. The latter can be used to adjust the camber to track conditions so that the tread sticks to the asphalt in the best possible way. An equally popular and plausible motor sports dogma goes something along the lines of: he who brakes later, drives faster longer. POSAIDON fitted the A-Class tracktool with a motor sports brake system to allow drivers to move the braking points as far back as possible during tough track use. The front axle is decisive when it comes to braking, which is why forged AP Racing calipers, each with six pistons, act on 362 mm disks from the same company. Motor sports brake linings with a higher friction coefficient as well as steel-flex brake lines are used all round. These prevent a “wan- dering” pressure point to give the driver a more reliable pedal response. The rear seat in the POSAIDON A 45 RS 525 tracktool has been replaced by a braced Wichers clubsport roll bar with cross to protect passengers from the worst if they come off course. At the same time, its cross strut also acts as fixture point for the red Schroth 4-point safety belts.
A couple of quick rounds in the “Green Hell”
But the big question is: what is the POSAIDON A 45 RS 525 tracktool really like on the racetrack? The best way to answer this is to drive the car where the wheat is fa-
mously separated from the chaff: in the “Green Hell”. So we take a seat for a round or two on the legendary Nürburgring North Loop alongside someone who knows the A 45 RS 525 better than almost anyone else: Patrick Schneider. The 31-year-old pro- fessional racecar driver, who currently sits behind the wheel in the Audi R8 LMS Cup and also regularly passes on his know-how as a track instructor under his firm’s Up- 2race label, is responsible for the dynamic test and development work in the PO- SAIDON motor sports division together with his colleague Alexander Rölleke: when- ever you see the yellow “Fake Taxi” out and about on the North Loop, one of the two racing professionals is usually behind the wheel.
The man in the hot seat knows exactly what he’s doing and how he can get the most out of the POSAIDON tracktool under the prevalent conditions – around 17 degrees C and patches of damp asphalt. A benchmark is soon found too: right alongside us at the entrance barrier is a Porsche 991.2 GT3 RS, which is probably off for a quick round of the North Loop too. Wait a moment: GT3 versus A-Class, a thoroughbred sports car versus a compact class – the comparison’s surely unfair! But is it? The Zuf- fenhausen model has 520 hp, so they’re equal in this respect. The AMG model is around 200 kg heavier, which obviously reduces its power-to-weight ratio. What’s more, its tires are much slimmer than those on the Porsche. But in contrast to this, it has four-wheel drive – advantage AMG. So let’s have a look how the POSAIDON tracktool fares against the iconic sports car …
The first impression after we leave the entrance cones behind us and Patrick acceler- ates through the “Tiergarten” section of the course: good grief, the POSAIDON A 45 RS 525 sets some alarm bells ringing for a four-cylinder engine! It’s hard to believe that there’s only a small two-liter engine under the hood. In the following bends of the “Hatzenbach”, it becomes particularly noticeable that we have set out with cold tires: the grip of the Nankang semis isn’t ideal yet. But it soon becomes clear how easy it is to handle the tracktool: Patrick brakes comparatively early to bring the relatively heavy car (a good 1,700 kg with two people on board) into position and then puts his foot down again very quickly. This is when the four-wheel drive come into play: the 4MATIC+ system ensures that the tracktool leaves the corners with an impressively neutral behavior, floating gently and controllably between under- and oversteer to, on balance, phlegmatically follow the steering angle. This means that the POSAIDON AMG very quickly picks up speed again coming out of tight corners. There follow some fast sections of the course: The AMG loses a bit of grip at “Flugplatz”, but steadies itself when braking into the following right-hand bend, which can be taken at speed. We enter the following left-hand bend at around 185 km/h, passing the 991.2 GT3 RS on the inside, whose driver has proven that he certainly knows his business through his clean, flawless drive up to then. We take the crest of the “Schwe- denkreuz” at an impressive 252 km/h. Then down we go into “Fuchsröhre”. The com- pression at the end is followed by the slow, curvy “Adenauer Forst”. What can clearly be felt here – and on the following sections of the course down to “Breitscheid” – is just how much more traction the tracktool builds up with warm tires compared to the first corners. In the meantime, we have let the GT3 RS past, but are now sticking like glue to his rear bumper and in some places Patrick could drive faster – if it wasn’t for the Porsche in front. We just want to make it clear here that we don’t know if the Porsche driver really did push his car to the limits. But there’s no disputing the fact that no third vehicle got near the unequal battle throughout the entire circuit. That speaks for itself. The North Loop goes uphill from “Breitscheid”, the lowest point on the track at 320 meters. Despite an upward climb of up to 17 percent, the RS 525 is by no means “starved” in “Exmühle”, “Bergwerk” and “Klostertal”: its abundant torque of up to 600 Nm, of which more than 95 percent is available over a broad revs range of approx. 3,300 to 5,500 rpm, provides constant thrust, even after changing gears going uphill. The Porsche can pull ahead a little here, but we catch up again in the approach to the famous “Caracciola-Karussell” and we take this slow banked turn together – one be-
hind the other at the bottom on the rattling concrete slabs, of course. What we notice here is that despite the sporty performance, the KW Clubsport suspension still dis- plays a workaday level of comfort. We continue over the “Hohe Acht” and “Hed- wigshöhe”, through the fast bends of “Wippermann” and “Eschbach” as well as “Brün- nchen”, where we see plenty of spectators on this largely sunny Saturday in Novem- ber. The flow continues at high speed in the company of the Porsche through “Pflanz- garten”, over the two crests and then through the “Schwalbenschwanz” and “Gal- genkopf” on the long “Döttinger Höhe”. Patrick eases off here to let the A 45 RS 525 cool off a bit before the circuit comes to an end. And before you ask: no, we did not time the lap, either on the lap described here or on the subsequent North Loop laps. This would have been irrelevant anyway on ac- count of the quite heavy traffic on the partially damp circuit. Patrick’s cautious esti- mate: “I think it was about 7:30 minutes today.”
This means that the A 45 RS 525 is well on its way to Maik Jakobs’, POSAIDON’s Managing Director, target lap time: after a few more details have been optimized and tuned, POSAIDON is aiming for a lap in the low 7:20s next spring, and set a new lap record for street legal, compact four-wheel drive cars. We’ll certainly be hearing from POSAIDON’s tracktool in the future …
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