Own a GU/GUII series Nissan Patrol with the
4.5-litre petrol six? Wish it had more grunt to lug its 2300-odd kilogram kerb
mass? Well, you’re not alone! In answer to growing public demand, Gold Coast
based Taipan XP offers a dyno tested exhaust upgrade and, if you want max
performance from it, ChipTorque can extract even more using a Xede
Let’s take a look at the specs.
The Nissan Patrol’s exhaust is typical of what
you’ll find on most mass produced vehicles – it’s a compromise between
production cost, emissions, durability, noise and performance. Standard pipe
diameter is around 55mm (just over 2 inch), which is quite small for a large
capacity engine. The standard pipe is also extremely wrinkled in some sections.
The Taipan XP exhaust upgrade replaces the entire
exhaust - including headers. At the start of the system you’ll find an
off-the-shelf Pacemaker Tri-Y header with its final collector bolting to a
larger diameter 64mm (2 ½ inch) engine pipe. The new exhaust employs constant
diameter mandrel bends to ensure maximum gas flow around the rear axle.
Interestingly, the OE cat converter is retained -
back-to-back dyno tests showed there was no power gain using an aftermarket cat.
At the centre of the system is Taipan XP’s Vortex muffler which is claimed to
swirl exhaust gasses and help suck gasses from the engine. At the rear you’ll
find a relatively small straight-through resonator which eliminates drones.
The complete header/exhaust upgrade can be
purchased starting from AUD$1590 in mild steel form or you can step up to a
stainless system costing AUD$1890. Fitment is typically a hundred dollars
depending where you have the system installed.
So what’s the gain?
Well, power typically climbs from around 90kW at
the wheels (standard) to 105kW at the wheels. (Power figures obtained from an
automatic Patrol on a Dyno Dynamics chassis dyno). That’s a gain of 17 percent,
which is very impressive from relatively straightforward header/exhaust upgrade.
The new exhaust has a noticeable aftermarket growl but it doesn’t get much
louder with increasing load/rpm and there are no significant resonances.
Note that this particular vehicle (owned by Kerry
Haines of Taipan XP) had already been equipped with a stainless steel mandrel
pipe between the airflow meter and throttle. It is not known whether this
achieves any performance gain over standard – it was fitted to eliminate a
previously installed LPG mixer which was strangling airflow. A K&N washable
filter is also fitted inside the standard airbox.
Engine Management Upgrade
After fitment of the new header/exhaust package,
the air-fuel ratios recorded at full load are slightly on the lean side. Lachlan
Riddel of ChipTorque says the full load air-fuel ratio is around 13.5:1 – not on
the verge of meltdown but not 100 percent safe.
The solution is the fitment and tuning
of a Xede interceptor.
The interceptor is wired in conjunction with the
standard ECU and is programmed to achieve full load air-fuel ratios of around
12.5:1. Ignition timing is also revised across the rev range with the option to
go for a more aggressive tune optimised for premium unleaded. Alternatively, you
can opt for dual mode map switching – this allows you to select, say, a high
octane map and a low octane map depending on fuel availability.
Once tuned with the Xede, the header/exhaust
equipped Patrol responds with another considerable lift in power. As seen in
this graph, the Xede tuned engine (shown in blue) is stronger all the way
through the rev range and peaks at 112kW at the wheels (up from 105kW). Although
this gain is not as impressive as achieved with just the headers/exhaust, it
does give a noticeable on-road improvement. We had the opportunity to drive the
vehicle with and without the Xede unit and noticed stronger mid-range and
top-end performance. Throttle response is also improved in the all-important
2000 – 3000 rpm zone and the big 4.5 is happier spinning to around 4500 rpm.
Note, however, this particular vehicle was mapped for premium unleaded and had
been inadvertently filled with normal unleaded. Not surprisingly, we did hear
the ‘tink’ of detonation on one occasion.
In addition to the price of the header/exhaust
upgrade, the fitment and tuning of the Xede unit will set you back AUD$1490. An
extra AUD$150 is charged if you want dual mode maps. So, from around AUD$3200,
your Patrol can be muscled up by a total of 24 percent. No matter which way you
look at it, that’s damn cheap power!