LS1 TT Ute

Danny Milton’s Holden VU ute represents of the cutting edge of LS1 enhancement. The ball started rolling with upgrade throttle bodies, mysterious airflow meter modifications and the usual bolt-on breathing mods. The scene then shifted up a gear with the introduction of off-the-shelf supercharger and stroker kits. And now we have this – today’s flavour is to cram a pair of turbochargers under the bonnet.

Add a couple of turbos to your LS1 and monster power is guaranteed!

Danny’s ute is the first twin-turbo LS1 developed by Melbourne’s Advanced Vehicle Operations (AVO). This was the proving ground for the newly introduced off-the-shelf twin-turbo kit which retails from AUD$11,275 plus fitment and tuning.

AVO has plenty of experience developing bolt-on turbo kits and, like previous kits, the LS1 package employs high-temperature cast exhaust manifolds. The manifolds are designed to mount the turbochargers close to the block and leave plenty of space for servicing. Terry Wilson from AVO says it’s a bloody tight fit and the easiest way to install the kit is to remove the engine from the car. This isn’t a quick job...

Danny’s car runs a pair of AVO Garrett-based turbos which are rated at 550hp (410kW) each. Oil for the turbos is distributed from a custom adapter on the rear of the engine and coolant comes from the heater hoses. The turbos use internal wastegates and connect to a pair of cast high-flow dump pipes.

An AVO pod filter feeds each turbocharger and the nosecone is crammed with a 3 ½ inch thick air-to-air intercooler (similar to the item AVO uses in high-power Nissan Skyline GT-Rs). As seen here, there are twin entries to the intercooler and a single large diameter outlet. A cast aluminium pipe routes air from the ‘cooler into the throttle. Hidden from view is a 50mm AVO blow-off valve.

Danny’s ute exhales through an AVO fabricated exhaust which uses twin 3 inch pipes from the dump pipes merging into a single 3 ½ inch pipe. High-flow cats and an AVO muffler are installed.

Previous AVO turbo kits have used an additional ECU to drive the injectors – but the LS1 TT kit is different. For this project, AVO use VCM Suite software to remap the factory ECU – an approach which gives excellent tuning flexibility and enables modification to automatic transmission behaviour.

The remapped ECU is configured with a 2 Bar MAP sensor and fires a set of 43lb injectors. An adjustable pressure regulator and ‘800hp’ Bosch pump complete the fuel system. The ignition is stock aside from replacement spark plugs and leads.

With boost pressure conservatively set to 6 - 7 psi, the standard internals of the LS1 should perform reliably. Terry says you could probably run 9 psi given a very safe tune and maybe upgraded head gaskets. Upgraded head gaskets were fitted to Danny's ute as one was found to be leaking before fitment of the turbos.

Unfortunately, the power output of the ute cannot be 100 percent confirmed.

On the AVO DTS chassis dyno, the twin-turbo automatic transmission ute has pushed out 320kW at the wheels - but Terry has doubts as to the accuracy of this reading. A manual gearbox car is currently being built by AVO – it is expected that this car will give a more representative power figure.

The auto trans in Danny’s ute has been rebuilt twice since fitment of the turbos and the latest build incorporates heat-treated shafts, upgrade clutches and pretty well every trans tricking technique known to mankind. A slightly higher rpm stall converter is also fitted. Fingers crossed, it’s a combo that lasts.

Danny is very enthusiastic with the overall level of performance, flexibility, fuel economy and reliability achieved by the twin-turbo set-up. There’s barely any noticeable lag and from about 1500 rpm there’s substantially improved thrust. Torque remains strong all the way to the 6000 rpm limiter (which is set slightly lower than factory as a precaution). Fuel economy is also improved over standard in normal driving conditions – but use the available power and you will pay for it!

With the ute’s twin turbochargers installed for around 12 months and 20,000km there have been no reliability issues and AVO is now releasing the kit in an off-the-shelf configuration. For AUD$11,275 (supply only), you’ll receive the same twin-turbo system fitted to Danny’s car except you don’t get an upgrade exhaust and ECU tune – Terry explains that many buyers outside of Melbourne will want their local performance workshop to perform final tuning. Upgrade head gaskets will probably be available at extra cost.

But let’s get back to Danny’s car!

Despite the addition of twin huffers, Danny has retained of the VU ute’s standard appearance. The ride height is subtly brought down thanks to a Pedders spring and damper combo and the stock wheels are replaced by HSV 17 inch items. Peer behind the front wheel spokes and you’ll find AP Racing 4-pot calipers and upsized slotted rotors. The rear brakes remain standard but Danny does plan to fix that shortly.

Aside from these bigger rear brakes, Danny doesn’t have anything further in store for his ute - it’s reliable and economical to drive on a daily basis and it performs exactly how he dreamed it would. If the opportunity arrises, he might but he might whack on a pair of slick rear tyres and hit the quarter mile. All signs point to a 11 second pass with traction permitting. And then there’s the possibility of bumping up the boost pressure oh-so-slightly using a wastegate bleed...

Eleven second performance with even more speed available with a simple wastegate bleed?

Let’s roll out a big welcome for the current flavour of LS1 modification!

Contact: AVO (Advanced Vehicle Operations) +61 3 9584 4499

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