Excell Racing’s XR700+ Package Maxes Out The McLaren M838T 3.8L V8

While this isn’t the normal territory for EngineLabs, there is no denying that the engine powering the McLaren 570S is quite an impressive powerplant, especially in a street vehicle. However, what is even more impressive is what our friends at Excell Racing are able to coax out of the engine with only a few hardware and software changes.

Properly referred to as the McLaren M838T, the engine is a 90-degree 3.8-liter (232 ci) V8 engine, with a flat-plane crankshaft and twin-turbochargers. The M838T has an interesting pedigree, with McLaren purchasing the rights to an engine architecture originally developed by Tom Walkinshaw Racing, which itself stems from a Nissan IRL Indycar engine which was never campaigned. That architecture was then used by Ricardo PLC to develop the M838T in only 18 months.

It is a highly oversquare engine with a 93mm (3.661-inch) bore and 69.9mm (2.752-inch) stroke. That configuration leads to a quite- high powerband, spinning to 8,000 rpm in this application, and up to 8,500 rpm in previous applications. As the name of the vehicle suggests, it is rated at 570 PS (metric horsepower; that’s 562 “regular” horsepower for us non-metric folks) at the brochure.

Here you can see the stock catted downpipes along with the OEM exhaust crossover, compared to Excell Racing’s fabricated (and black coated) replacement parts. Smoother bends and a lack of catalytic converters offer a big boost in performance.

On the dyno, besides sounding absolutely amazing with its twin-turbochargers and flat plane crank, the M838T puts down 510 horsepower and 425 lb-ft of torque to the wheels, in stock 570S trim. Respectable numbers no doubt, but ones that Excell Motorsports was sure they could improve upon.

What is really surprising is the amount of gains gotten with what equate to “bolt-on” parts in the XR700+ package. “We make a set of catless downpipes and an X-pipe which feeds into the factory tailpipe mufflers,” says Jay Healy of Excell Racing. “We then add sport filters on the intake and recalibrate the ECU.”

While the hard parts might seem formulaic, where Excell really excels, pun intended, is the ECU recalibration. “The actual theory behind tuning [the M838T] is the same. It’s still just an engine at the end of the day. But the software and dismantling the code is a different story,” Healy says. “You have to actually find the maps in the raw hex code before you can edit them.”

The McLaren ECU is an untapped market, with Healy needing to actually tap into the ECU itself, to access the raw code. Using the WinOLS software, Healy can locate and edit the hex code to alter the parameters required to squeeze all the performance possible out of the factory programming. As you can see, it's definitely not a plug-and-play proposition.

Besides altering the fuel and timing maps in the ECU, with having factory forced-induction, there’s an additional power-increasing parameter which can be altered – boost. “With our recalibration, the engine will see a peak of 17 psi, where the stock boost is 12-13 psi at those rpm points,” reveals Healy. “Full boost is reached by 3,650 rpm, and then it averages 15-16 psi from there.”

The results on the dyno are clear, with the XR700+ package putting down 631 horsepower and 563 lb-ft of torque at about the same RPM peaks as the OEM powerband for a 23-percent increase in power and 32-percent increase in torque, at the wheels. While that much power being left on the table from the factory is somewhat surprising, the upgrades do max-out the M838T’s potential, in stock form.

As you can see, the XR700+ pacakge (blue trace) not only makes more power overall, but there is a smoother power curve, The powerband is also shifted up between 200-300 rpm, with a final redline of 8,000 rpm. A 4,000-8,000-rpm powerband will not only be a blast to drive on the street, but make engine noises sure to snap a few necks as well.

“The limiting factor to the package is turbo size,” Healy explains. “Any more than 17 psi and the turbochargers just make heat. The engine’s internals are fine at these power levels.” With the limits found, Healy and team are working on resetting the limits.

“We are developing a drop-in turbo upgrade for the car that doesn’t require a core exchange and also we are working on an E85 calibration for the car,” Healy says of their current R&D. “The OEM fuel system has supported 670whp on E85 so far with no issues yet.”

So while the idea of modifying the engine of a brand new, almost-$200,000 car may seem ludicrous to some, seeing that the M838T can trace its heritage back to an engine designed for Indycars, it seems only fitting that it be pushed to its maximum ability. Personally, we can’t wait to see what happens with new turbos and E85.

XR700+ Mclaren 570gt

Finished up with another Mclaren 570gt XR700+ packages, This package consists of our decatted downpipes and xpipe constructed of stainless steel, a set of sport filters and custom dyno ecu calibration. Please contact us for more info.

Posted by Excell Racing on Wednesday, September 12, 2018

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About the author

Greg Acosta

Greg has spent over a decade in automotive publishing as Senior Editor of Race Pages magazine. In his free time, he is a firearms instructor and volunteer in the police armory.
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