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Cam-ing the Boss 260

We check out the gains of installing aftermarket cams in the Ford Boss 260 engine...

Words by Michael Knowling, Pix by Julian Edgar

Click on pics to view larger images

At a glance...

  • Atmo mods for the Boss 260 Ford V8
  • Upgraded camshafts and tuning to suit
  • 30+ percent power gain - on top of existing mods!
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The current Ford XR8 5.4-litre DOHC V8 (aka Boss 260) is a beaut engine. While the rival Holden V8 plods along with pushrods and a single cam, the Ford donk meets world standards with its DOHC 4-valve heads, cross-ram intake manifold, high-flow Cobra intake system and electronic throttle control. Producing 260kW and 500Nm. it epitomises everything that a modern V8 should be.

But what do you do if you want some more grunt? How do you improve on an engine that’s already pretty high spec?

In this article we’ll check out what can be achieved by whacking in some aftermarket cams - after you’ve done the usual bolt-on breathing mods.

Preliminary Bolt-on Mods

The demo car for this article is a BA XR8 5-speed owned by Steve Lansdowne.

Steve’s first modifications involved upgrading the air intake and exhaust system.

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The XR8 is already endowed with a high flowing airbox and intake plumbing so there has been no need to modify any of this. But the snorkel into the airbox is another matter. Steve has replaced the standard snorkel with a SS Inductions ‘Big Mouth’ item which has a custom enlarged entry. As seen in this photo, the modified entry to the snorkel is gigantic in terms of cross sectional area – very unlikely to cause any restriction (until the bonnet is shut, anyway!). A King Dragon high-flow filter is also fitted inside the airbox.

Click for larger image

The only other modification to the intake system is the fitment of an SS Inductions throttle body. The new throttle measures 80mm diameter while the standard part is 75mm. This represents a 14 percent increase in cross-sectional area.

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The factory exhaust system has also been replaced from headers to tip. Up front, the factory manifolds have been swapped for Di Filippo ‘Series One’ headers and a pair of high-flow cat converters has been bolted in. From the back of the cats is an off-the-shelf Redback twin 2½ inch mandrel exhaust.

Camshaft Upgrade

The next step for Steve was the installation of Crow camshafts and an accompanying ECU retune by ChipTorque.

Why take this route, you ask? Well, Steve says he enjoys the progressive output and heightened rev range that come with the bigger cams. He’s also a bit ‘old school’...

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Steve’s car served as a test bed for prototype camshafts from Crow. The supplied camshafts are best described as “mild street” – they offer greater top-end power while maintaining a good torque spread and acceptable idle quality. Interestingly, the high lift camshafts fitted to the FPV Boss 290 engine will not fit into the XR8 engine as they require longer valve stems and other associated modifications.

The following table compares the duration and lift specifications of the standard BA XR8 cams with the Crow items. As you can see, duration is increased considerably while lift is increased by a relatively modest margin. In comparison, the FPV Boss 290 cams deliver greater lift but less duration.

  Dur @ 0.050"Advert DurLobe Lift
Std XR8 In 177230 0.218"
  Ex 1772300.218"
Crow XR8 In 2002550.234"
  Ex 2002550.234"

Installation of the camshafts is a big job.

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ChipTorque was handed the task of fitting all four new camshafts and, because of the XR8’s limited under-bonnet space, it’s a process that involves removing the engine. Lachlan Riddel of ChipTorque says it’s easiest to drop the engine onto a cradle and install the new cams at ground level.

The new cams are installed using the standard valve springs and cam timing is set to factory specs. It’s a job that takes around 20 hours.

Tuning

With the long duration camshafts installed, Lachlan Riddel retunes the factory engine management using their X-Flash system.

X-Flash is a Windows-based software program that gives a wide range of ECU adjustment including fuel and ignition, rev limit, closed-loop parameters, diff ratio settings and auto transmission shift behaviour. The ECU is flashed via the OBDII port so there’s no need to cut any wires. However, like the EcuTeK programming software for Subarus, X-Flash does not allow real-time tuning - it’s a case of repetitively flashing new data into the ECU and making another dyno run.

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Steve’s XR8 has been tuned to run 98 RON high-octane fuel so you’ll find a few degrees of extra ignition advance pretty well across the rev range. The high-load air-fuel ratio has also been set to around 12.6:1, which is pretty safe for this type of engine. Lachlan says there’s probably another 8 – 10 percent of injector duty cycle left to play with.

To capitalise on the top-end kick of the new cams, Lachlan has increased the rev limit from about 6000 to 6800 rpm. Idle speed is also raised to around 800 rpm to enhance idle quality and drivability.

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Lachlan expects that, even with its aftermarket camshafts, the car should meet the emission standard which is applicable to the car’s date of manufacture (ADR 97/00). A wilder set of cams would make it extremely difficult to control hydrocarbons at idle. This is partially because the Boss 260 engine uses MAP-based load sensing from factory - a mass airflow meter would make the tuning task easier.

Results

This Dyno Dynamics chassis dyno graph compares power and torque achieved before and after fitment of the new camshafts and ECU tune (the ‘before’ curves are shown in blue and the ‘after’ curves are shown in red). Note that the ‘before’ curves were performed with the preliminary bolt-on mods in place.

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As you can see, the standard camshafts maintain steady torque until about 5000 rpm. Top-end torque then tails off and peak power output is 198kW at the wheels. With the new cams and ECU tune, the torque curve is a similar shape but is much stronger across the rev range. Top-end torque also holds strong past 6000 rpm and, as a result, peak power output is now 263kW at the wheels – a gain of 33 percent!

Interestingly, peak power is now achieved at 6400 rpm (up from 5250 rpm) and peak torque arrives at around 5000 rpm (up from 4250 rpm). On face value, this would suggest the engine is now quite peaky – but that’s not the case. Sure, the biggest improvements are found at high rpm but output is increased across the entire rev range.

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Steve is very happy with the result. Grunt is delivered progressively and the car's much quicker than before – quick enough to run consistent low 13 second ETs with a very gentle launch. Idle quality is well within his boundaries of acceptance and fuel economy remains reasonable depending on driving style. Steve says it’s possible to achieve 9 – 10 litres per 100km consumption on the highway.

We had the opportunity to drive the cam’d XR8 and can vouch that it’s considerably quicker than the standard Boss 260 and quicker than a FPV GT. Throttle response is strong, it’s very driveable and much more willing to rev. Our only criticism is a surge that occurs at small throttle openings - but we’re assured this has since been eliminated with further tuning. The cam’d idle is much lumpier than standard but still acceptable.

So what’s the cost?

Well, ChipTorque charge AUD$4450 for supply and fitment of the camshafts and ECU tune. This is in addition to the cost of preliminary bolt-on breathing mods. In Steve’s case, he’s spent around AUD$7000 in total and has achieved a net power gain of 42 percent (starting with a base output of around 185kW at the wheels).

There’s no denying you can achieve greater overall performance with a bolt-on centrifugal blower kit but this upgrade should certainly appeal to those who aren’t fans of forced induction. At least there are now a couple of options for tuning this already great engine...

Update – Steve has now changed the diff ratio of his XR8 to maximise the performance from its new camshafts. The standard 3.23:1 diff ratio has been swapped for a 3.73:1 unit and we’re told this has improved drivability and better utilises the high rpm power output. In short, it’s made a big difference.

The FPV Boss 290 Engine – Where does its Extra Power come from?

The FPV Boss 290 engine generates an extra 30kW over the standard XR8-spec Boss 260 - but how?

Well, the 290 engine has more aggressive camshafts (giving a definite shake at idle), different valves, followers and springs, a balanced steel crank with reengineered rods and domed pistons. These pistons provide a 10.5:1 compression ratio that requires 96+ RON fuel, while the 260 engine has a 9.5:1 compression ratio that’s happy to run on normal unleaded.

Output is of the FPV beast is 290kW at 5500 rpm and 520Nm at 4500 rpm.

Note that this represents a 12 percent power gain and 4 percent power gain over the Boss 260. The cam’d engine seen here produces w-a-y more than that!

Contact:

ChipTorque +61 7 5596 4204        www.chiptorque.com.au

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