Limited-slip diff, chassis tweaks and a power hike to 720bhp take the 570’s abilities to a new level
Among the vast array of models that McLaren has launched since the MP4-12C, it’s some of the less potent that have found most favour. We’re big fans of the 570S and GT, for example, models that don’t feel like they need any more than their 562bhp because in a sub-1500kg car that guarantees sensational performance. You’ll hear few complaints about their ride and handling, either.
Renowned tuner Iain Litchfield can spot an opportunity when he sees one, though. The market-wide shift to turbocharging over the last decade or so has played to his skills and he’s doing good business uprating Porsche 911s and BMW M models that, like those McLarens, are impressive straight out of the box. So why is he turning his attention to McLarens now?
‘Now that we can look after them and prices are around $80k-$150k we’re seeing a number of our good customers moving into them as a fun weekend car,’ says Litchfield. He got a great deal on one of the last 570GTs – optioned with the 570S suspension and slightly faster steering rack – and before deciding what to do with it he put lots of road miles and also some track miles on it, including visiting the Nürburgring Nordschleife.
Some things surprised him, the first being that the turbochargers used on the 3.8-litre, flat-plane-crank V8 are very old tech – the same items used on Saabs and early Impreza Turbos. However, before getting into the engine work proper, he did a simple ECU tweak, boosting power to 640bhp. ‘It was an eye-opener at the Ring!’ he says. ‘I found the chassis inconsistent and not helped by the open diff and the brake interventions that are supposed to simulate the effect of a limited-slip diff.’
His car now has a mechanical limited-slip differential. He went looking for one and found a German manufacturer that supplies them to McLaren for their GT racers, so it drops straight in and only weighs 2.5kg. Litchfield then designed new road springs that are slightly softer initially for ride and traction and then get firmer, with adjustable platforms to enable greater scope for set-up and corner weighting. There are also wheel spacers front and rear that work with the company’s own geometry to improve stability.
Litchfield has had a few McLarens through his workshops now and says that some have geometry that’s a chunk away from specification. He suspects this is because camber adjustment is by shim spacers, which can make for a time consuming and laborious job. Once it’s been set to spec it requires only minor annual tweaks, though. The final chassis element is a set of Michelin Pilot Sport 4 S tyres in the original sizes, replacing the OEM Pirellis.
Modifications to the engine are quite comprehensive but don’t involve breaking into the 3.8-litre V8. Litchfield’s vast experience with the Nissan GT-R’s 3.8-litre, twin-turbo V6 showed that the V8 ought to be much more responsive. The old-tech Mitsubishi TD04 turbos are replaced by bigger capacity, roller-bearing Garrett units with billet-machined, lightweight compressor wheels. Although larger, they spool up faster and require less boost to make the power, which means lower temperatures through the intercoolers.
The increase in power is almost a by-product of the pursuit of throttle response and control. The original Bosch ECU system is replaced in its entirety by a unit from Syvecs. ‘This gives us even quicker processing, detailed data logging, everything is adjustable and we can use a proper motorsport traction control system on the engine to intervene faster and smoother,’ says Litchfield. In Normal mode the output is 620bhp, and in Sport and Track that rises to a stonking 720bhp. More significantly and pertinently, torque swells well beyond standard, rising from 443 to 584lb ft and its delivered earlier, with an extra 128lb ft available at 3000rpm.
Litchfield’s geometry and wheel spacers give the 570GT (should that be 720GT?) a different, more purposeful stance, and it’s always a thrill to slip under the butterfly door into a McLaren cockpit with its low scuttle and panoramic view. Today doesn’t feel like a McLaren type of day, though: it’s barely above freezing, wet and grey as I point the 570’s shark-like nose down the road. Although the chassis changes have given it a little more weight, the steering still feels rather light.
I’ve driven lots of McLarens and I’m always a bit wary of goading them. I imagine it will be quite a few kilometres before I’ll have the confidence to go for full throttle with 720bhp. Not so, it turns out. The power delivery of the standard 570GT is a bit flat until you get beyond 5000rpm, whereas in the Litchfield there’s plenty of low-down punch. More than enough for the grip, which sounds tricky… but after a few kilometres traction control is off and the engine is whooping. The key is that limited-slip differential and how it works brilliantly with the grip, the engine management and the suspension. It’s revelatory.
On cold roads that occasionally look filthy like rally stages, the Litchfield 570GT can be driven like a rally car. That’s to say confidently, riding the throttle on opposite lock, pushing forward on a rising note and a steady throttle opening, with a kick more angle available if you floor it. I’ve never felt this confident in a McLaren. You can feel the benefits of the diff and engine management with stability and traction control only backed off rather than fully disabled. When the rear tyres start to overspeed you can hear the stages of intervention managing the torque. First the ignition gets knocked back, then the boost is modulated and finally the throttle is cut. All the while, the car is poised, balanced, and making progress. The standard electronic traction control is the last resort and if you’re playing the throttle precisely, often it doesn’t get involved. I predict that on warm asphalt the Litchfield 570GT will be superb, digging for traction and breaking away reluctantly and gently so you can play on the limit of grip. Given the conditions, I didn’t expect to experience all 720bhp but did on numerous occasions, which tells you all you need to know, really.
Litchfield has developed its own low-backpressure exhaust system that helps the turbochargers spool up faster, and it offers K&N air filters too, though the engine note remains businesslike. The ride feels composed and nicely tied down, even down difficult back-roads, filling in hollows and scalping big bumps to keep the car level and calm.
You can have the elements individually, with the springs, spacers and geometry set-up coming in at around $3122, plus the tyres. The engine work including turbos, engine management and full exhaust, installation, dyno tuning and an engine service, plus the limited-slip diff, is $35,615. That sounds expensive, but drive it and it feels worth every penny. I can’t wait to try it in the dry.
Litchfield McLaren 570GT specs
|Engine||V8, 3799cc, twin-turbo|
|Power||720bhp @ 7500rpm|
|Torque||584lb ft @ 5300rpm|
|Top speed||330kph+ (est)|
|Conversion price||See text|
This article originally appeared at evo.co.uk
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