Pure LS1 Performance

Amid the scores of modified LS1 Holdens on Australian roads, this sinister looking ute can stand proud. Why? Well, with a 10.7-second pass under its belt, it is the country’s fastest ‘unassisted’ LS1!

How can a 10-second pass be achieved without a blower or nitrous, you ask? Well, the basic ingredients are plenty of cubic inches and thoroughly maximised intake and exhaust flow.

When Criso jumped into modifying his Holden ute (a limited edition SS50 Signature) he went straight for a 383ci stroker kit - you know the saying about there being no substitute for cubes. With various other breathing mods, the stroked LS1 made considerable power – but not nearly enough for Criso.

This is where the ever-experienced Sam from Sam’s Performance enters the picture.

Sam took a look at the existing engine combo and instantly recognised that he could do better. The first move was to tear down the motor and start with a new slate. The virtually new Lunati 383ci stroker components were retained but Sam reassembled it using Manley pushrods, a Rollmaster double-row timing set, Crower solid lifters and T&D rockers. The compression ratio is 11.5:1. The heads were also swapped for LS6 items, which flow better than LS1 heads. Sam came up with the appropriate cam specs – a solid unit delivering 270 degrees at 50 thou and 600 thou total lift. This cam is best described as “purposeful”! An aftermarket oil breather catches any blow-by rubbish.

The focal piece of the engine is, of course, those trumpets that stand proud of the bonnet.

According to Sam, the standard intake manifold is restrictive at high power. That’s why he developed this ram-tube induction set-up that uses eight 50mm butterflies. The length of the ram-tubes was also critical to get the right spread of torque.

Exhaust flow is ample thanks to DeFillipo 4>1 1 7/8-inch headers leading into DeFillipo cats and a Starr Performance twin 3-inch system. Note that the entire exhaust is kept on for drag racing.

Sam believes almost anything can be achieved by reprogramming the factory ECU so he’s spent many hours LS1-Edit tuning this wild engine on his engine and chassis dynos. Obviously, it’s a MAF-less tune...

Fuelling the beast are 42lb injectors feeding from a custom rail, a Barry Grant 1100hp fuel pump and pressure reg and a Mood Motorsport surge tank. The ignition system remains standard – amazing stuff!

And the power output, you ask?

Try 630hp at the flywheel and, depending on the chassis dyno, well over 500hp at the treads! The torque curve is pretty broad for such a highly tuned atmo engine. A 7200 rev limit is enforced to ensure good engine durability and Criso tells us he usually up-shifts at about 6800 rpm. This drops the engine back to its ‘sweet spot’ for the next gear.

Surprisingly, Criso retains the factory 6-speed manual gearbox – there’s been no need to switch to a high-stall race-prep’d auto trans. The clutch is a no-slip job sourced by Sam’s Performance.

Out back, Criso moved to a new aluminium 9-inch diff that works with the existing IRS layout. Aside from its tremendous strength, the benefit of this diff is the wide choice of ratios that are available – a 4.11:1 centre is currently in service.

Launches are enhanced using a combination of Bilstein 90/10 front shocks and adjustable Konis at the rear. These team up with the factory springs, which allow some weight transfer over the drive wheels. Mickey Thompson slicks are used at the track, while 19-inch Tak rims wearing 245 and 265 Pirelli P-Zero rubber are used for street duties. Look behind the rims and you’ll see DBA slotted replacement rotors.

One of Criso’s main priorities has been to keep the vehicle kinda useable. That means no tubs and no interior stripping. Criso tells us the car weighs just over 3600lb (about 1650kg) without a driver.

The body remains 100 percent stock, with the exception of an aftermarket fuel filler and HSV Clubsport R8 add-ons that provide some extra individuality. The bonnet is also a custom fibreglass job with an opening for the ram-tubes, and grilles to release engine bay heat.

The only weight-saving measure has been to replace the factory seats with Sparco Pro2000 race buckets. “These were intended to give improved safety as much as to reduce weight,” says Criso. The interior is finished with HSV R8-spec trim, harnesses, a Blaupunkt high-end head unit and a shift light. A roll cage is also about to be installed under the direction of the drag racing officials. Ahh, the problems of owning a car that’s too fast...

Since a cage is now required for the car to see any more track action, Criso has recently decided to progress to the next level of mechanical development. Whaddaya do when more than 600hp isn’t enough? Simple – you plonk in a C5R race motor that displaces a massive 441ci!

The goal?

More than 700 ponies and, who knows, maybe even a 9-second pass. It seems Criso now has his sights set on the world record for unassisted LS1 performance!

Contact: Sam’s Performance +61 2 9772 3105