Spin doctors

Motor Garage

Long term diaries

Great White gets a health check-up on the chassis dyno

HOSE who know me could argue I’ve driven as many L77 engines as I’ve met presidents.

Even so, I still think previous VF SS Commodores we’ve had in MOTOR’s garage didn’t spin with the same vigour and smoothness as the unit lurking in Great White.

This month I’ve noticed how our resident Redline has felt especially spritely. Sure, after a prod of the throttle there’s a miniscule delay in response, like it’s burdened with a heavy flywheel, but it soon shrugs off the weight and builds a slab of power that feels most deadly, also when the vi lur T res T engine sounds sexiest, at 4000rpm.

But I’m not the only person who thinks our L77 feels well fed. Not long ago I was in the passenger seat with contributor James Stanford at the helm. With a bootful of revs dialled up, he let out Great White’s clutch, the car twisted a little and then laid two thick strips of melted rubber. Then, as its 275mm Bridgestones found grip, it lunged down the road. As far as bum dynos went, we agreed this particular SS was impressive.

With almost 10,000km on its cluster, the engine’s well and truly run itself in and, in turn, freed up a little horsepower in the process – maybe.

To see if the numbers matched our seat-of-the-pants assessment, I contacted the guys at VCM Suite.

Based in Knoxfield, a stone’s throw from MOTOR’s Melbourne towers, VCM’s reputation as a tuning specialist means a fully-fledged chassis dyno lives on their premises. And Great White was welcome to spin ’em up.

Not only would this help us determine if we had a ‘healthy’ engine on our hands, but it would reveal what the final L77 is packing before Holden replaces it with GM’s LS3 engine. Holden has already paired the Commodore VF Series II with the LS3, and the only cars that will continue with the Mexican-built L77 are America’s VE Commodore police cars. So consider this a hallmark in V8 performance history.

There was going to be some guesswork, though. Chassis dynos reveal how much power makes it to the tyres after evaporating through various parts of the drivetrain.

Whether it’s the windage from thickshake-like gearbox oil, or the driveshafts and gears, they’re all sapping energy needed to turn the resistance of the dyno rollers.

If we wanted to know the exact power the engine was making we’d have it bolted to an engine dyno.

However, since Holden no doubt would like the SS’s engine to remain inside it, we used a more common chassis dynamometer.

While there isn’t any reliable way to deduce engine power from a chassis dyno, there are some general rules of thumb. One, used by Americans,

is the 15/20 rule: if there’s a 15 per cent driveline loss for manual transmissions, then it’s 20 per cent for automatics.

But Phil Genio from VCM Suite suggests that it’s more resolute. From his experience, he says most vehicles will see between 80kW to 100kW worth of engine power lost on VCM Suite’s Mainline chassis dyno.

With that in mind, Phil took the Redline through its paces. Like any other customer car, he completed three pulls in fourth gear, and that’s all he allowed, explaining any more and the engine’s computer starts to learn its environment.

After three pulls, the best Great White mustered was 195kW. Our first thoughts turned to disappointment; doesn’t Holden claim 270kW? Forget ‘healthy’, using the 15/20 rule would mean it’s as weak as a newborn.

But then it clicked. Add another 80kW to 100kW, like Phil said, and our long-termer is churning out between 275kW and 295kW.

After thousands of hard pressdriven kilometres, Great White’s bite is just as it’s supposed to be.

What about those possible extra 5kW to 25kW, you ask? Well, we’ve had Great White on the drag strip this month, and compared its run with another car to be sure.

It failed to best our previous efforts during Bang For Your Bucks 2014.

Rather, Great White crossed the finish line in a dead heat with the BFYB car, clocking 13.8sec at 168km/h.

It seems the real lesson here is that maybe I need to meet a few more presidents. – LC

After thousands of kays, Great White’s bite is just as it’s supposed to be