Logical LS1

With all the power-up options for owners of LS1 V8s, it’s difficult to know which way to go. When it came to modifying this 2003 Holden VY SS wagon, Andrew McKellar did his homework scouring the web and reading everything LS1-related he could get his hands on. This effort has certainly paid off. This car idles like stock, it’s relatively economical and it’s docile enough for anyone to drive.

Oh, and it just happens to crank out 445 horsepower at the wheels!

Okay, so let’s pass on the benefit of Andrew’s research and experience. What should the typical LS1 enthusiast go for – and in what order?

Well, when he decided he wanted more than the 235kW output in his M6 Holden SS wagon (a limited build) his first mods were the exhaust and engine management. “I ended up fitting a set of Pacemaker Tri-Y extractors and a Redback twin 2½-inch system with opened-up cats,” says Andrew. “The system isn’t too loud – it’s about right for street use,”.

The air intake was then enhanced with some simple tried and proven mods. First, the cold air intake to the airbox was enlarged and a King Dragon low-restriction air filter whacked in. From there, airflow into the throttle body was improved with a GTS big-bore pipe.

But to make the most of the improved breathing, you need to get stuck into the engine management system. Sam’s Performance in Sydney has tuned countless LS1s using LS1 Edit software and was called upon to tickle Andrew’s toy. Not only did Sam’s optimise fuel and timing to suit, they also ripped out the restrictive factory airflow meter and replaced it with MAP-based load sensing. This is the so-called “MAF-less tune.”

With only the most basic mods – exhaust, intake and tune – Andrew’s wagon showed a power increase that’s nothing less than remarkable. In stock form, the car made 245hp at the wheels on the DynoLog chassis dyno at Sam’s Performance. After the mods, this increased by 23 percent – to 302hp at the wheels! (Incidentally, the engine had only around 1000km on it at this stage!)

Note that Sam’s Performance are big believers in the average power output across the entire rev range - there’s not a lot of point examining only the peak power figure. The average power increase with these basic mods was around 18 percent. In other words, the larger percentage gain was in the top-end.

At this stage Andrew was a little unsure of which direction to take.

Some people were suggesting a head and cam package (the 300kW GTS uses a bigger cam than the 235kW-spec engine) and some people said he couldn’t go past a supercharger. Oh and, of course, there’s always those that swear by nitrous...

In the end, Andrew made up his mind when a too-good-to-miss-opportunity appeared in front of him. Extensive web searching uncovered a person in New Zealand selling a second-hand CAPA/Vortech supercharger kit for the LS1. The price was very attractive (even taking into account freight) so Andrew bit the bullet. Decision made!

What arrived was one near-new Vortech kit comprising all necessary brackets, pulleys, belt, additional fuel pump, blow-off valve, water injection and intercooler system. Installation of the kit was performed by Sam’s Performance and everything was pretty straightforward (for details on installing this kit see Boosting the LS1 ). The only variation to ‘the usual’ is a custom air intake into the back of the blower – there’s a big K&N pod hiding behind the front ‘bar. And, remember, there’s no airflow meter as is normally used in the Vortech kit.

With the ‘low boost’ pulley fitted as the starting point, Sam’s Performance again combed through the fuel and ignition mapping to find the right balance of power and reliability. At the end of the process, the car was pushing out 424hp at the back wheels – on just 7 psi boost! That’s a peak power gain of 40 percent. The average power increase, meanwhile, was even stronger at 43 percent. Note that the stock injectors were also flat-out at this stage.

With such a tremendous gain across the entire rev range, Andrew’s claim that the car was transformed is entirely believable. “After the supercharger went on it drove very well,” he says. “And I think that’s an understatement...”

Since then, Andrew has stepped up to a larger set of US-sourced injectors (with a retune) and the ‘high boost’ 9 psi pulley, which has achieved an impressive 445hp at the wheels. Average power also shot up to 70 percent more than stock. Andrew says there’s the potential for even greater power by upgrading the extractor/exhaust system – back-pressure currently goes off-the-scale near full noise!

Sam from Sam’s Performance advises Andrew not to push the standard bottom-end any harder due to reliability issues, so Andrew has been recently investigating a 6.3-litre stroker kit along with forged pistons. While it’s being ripped apart he’d probably also go for a bigger cam and some headwork – the all-out approach. “I love it as a streetcar, though, and the last thing I want to do is ruin that. My intention for the stroker kit would be to improve low rpm torque. I suppose it will also pick up a bit more at the top-end as well – and I wouldn’t say no to that...”

Visually, Andrew hasn’t felt the need to stray from standard. “The SS wagon really appeals to me,” he explains. The subtle body kit, 17-inch wheels and roof racks are all part of the standard SS package. The interior is also decked out in full leather and with all mod-cons.

The wagon has yet to appear at the drags but Andrew isn’t getting too caught up in the whole numbers thing. “With a set of Nittos under it I think it should do 11s without too much problem,” he says. A run at the drags would be to satisfy his curiosity more than anything. This is after all, first and foremost a street car – what works well on the track doesn’t always work well in normal use.

So, based on his experiences, what recommendations does Andrew offer other LS1 enthusiasts?

“It depends how far you want to go. You really need to work that out first – for example, I wouldn’t have fitted the Pacemaker/Redback exhaust if I knew I would be making this much power.

“If you’re after an effective upgrade the first mods I suggest are to improve the intake and exhaust and to see someone like Sam with LS1 Edit for a MAF-less tune. With these mods alone you’ll be making 210 – 220kW at the wheels with much better drivability.

“For a lot of power, though, I think the supercharger route has worked very well for me. It has given a strong boost all the way through the revs, it still idles beautifully and the whole package can be easily removed and sold later down the track. The supercharger conversion has been flawless – really outstanding.”

Contact: Sam’s Performance +61 2 9772 3105