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We test JMM's bolt-on upgrade for the naturally aspirated Ford BA 4.0!

Michael Knowling

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At a glance...

  • The first aftermarket development of the local Ford DOHC non-turbo six
  • Dyno-developed intake, headers, exhaust and UniChip kit
  • Up to 180kW ATW
  • Good on-road performance gains
  • Cost effective
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With all the ranting and raving over Ford’s BA XR6T and quad-cam V8 engines, the run-of-the-mill 4.0 litre DOHC straight six is being completely overlooked. But after a drive of a BA Falcon 4.0 equipped with Jim Mock Motorsport’s DEV3 kit, we can assure you there is some go-fast potential!

With double overhead camshafts, infinitely variable cam timing, 24 valves and the latest engine management system, the BA 4.0 six offers substantial power from the factory. Peak power is an impressive 182kW at 5000 rpm.

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After Ford’s mammoth engineering effort with this engine, it should come as no surprise that there’s limited scope for the aftermarket to achieve peak power – at least, not without adding forced induction or nitrous... However, it is achievable to increase the average power output and to sharpen throttle response.

And that’s exactly what we found behind the wheel of the Jim Mock Motorsport BA Falcon XT.

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The throttle response of the JMM BA Falcon (with its manual gearbox) is wonderfully crisp. In fact, we can’t think of another car we’ve driven that offers better response – except, perhaps, the Mitsubishi Magna VR-X with manual trans (believe it or not, the Magna has stunning throttle response). The JMM Falcon’s crisp throttle response is immediately followed by a mountain of torque, which is greatest between 2000 and 4000 rpm. Performance falls away toward 6000 rpm - a result of the standard camshafts.

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Despite weighing 1700kg+ and with two people onboard, we hand-timed the JMM BA to 100 km/h in the mid-to-high 6s. That’s decidedly quick and, unlike other modified performance cars, we found it very easy to get off the line. Just don’t be too eager when you pop the clutch...

According to JMM, a stock BA Falcon makes about 140kW at the wheels on their Dyno Dynamics chassis dyno. Autos are generally a couple of kilowatts below the 140 mark and manual versions are a couple of kilowatts above. Once brought up to DEV3 spec, output jumps to a claimed 180kW at the wheels – just 8kW behind what they’ve seen from a stock XR6 Turbo under the same conditions.

The subtleties to the upgrade are also impressive.

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The engine fires into life with just a tiny amount longer cranking on the starter motor and the high-flow exhaust is completely resonance-free and quiet at cruise. Give it a bootfull and the exhaust howls, but it’s not offensively loud. The engine is also happy to trundle along in carparks in second gear with absolutely no surging, stalling or general misbehavior. Jim Mock suggests filling the tank with premium unleaded for maximum performance and, as we noticed, there’s no sign of detonation.

Okay, so that’s the result of modification - what exactly are the modifications?

The Jim Mock Motorsport DEV3 BA upgrade builds on the modifications involved in the DEV1 and DEV2 kits.

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DEV1 begins with a 2 ½ inch cat-back mandrel exhaust with two large-body mufflers. The precise details of the system are a secret as DMM has invested a lot of R&D in achieving a broad torque curve without resonance or excess noise. Note that the exhaust for BA Falcon utes is slightly different to those for sedans and wagons.

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DEV1 also includes a high-flow air intake, which comprises a Tickford over-the-radiator snorkel and a pod filter hidden inside the standard airbox. A custom plastic adaptor is required to secure the filter to the airbox. JMM defends their choice of installing a pod filter inside the factory airbox by citing their dyno development figures.

Another interesting component of the DEV1 kit is performance spark plugs sourced from America. Again, these are dyno tested.

The entry-level DEV1 upgrade for BA 4.0 Falcons retails for just AUD$695 (AUD$50 more for utes). JMM have seen this kit reach 148kW at the wheels – about 8kW more than stock.

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DEV2 – the mid-level kit – employs everything found in DEV1 and adds JMM’s latest “Scavenger” headers along with a high-flow cat converter and adjoining 2 ½ inch pipe. The headers are the result of extensive dyno testing and JMM tells us their design ended up being about halfway between their scavenger and race series headers used in SOHC 4.0s. We’re told that the Ford six is extremely sensitive to combustion chamber scavenging. Note that the headers are also HPC’d to keep heat away from the nearby engine bay wiring.

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DEV2 adds a significant AUD$885 to the price of the DEV1 kit, bringing the total to AUD$1580 (AUD$1630 for utes). However, the power gain justifies the extra cost – JMM claim about 168kW ATW. That’s a full 20kW more than DEV1 and 28kW more than stock.

Note that a slightly different version of this kit is also available – the DEV2A upgrade. DEV2A incorporates a 3 inch mandrel exhaust and cat converter (an early prototype is shown here), instead of the 2 ½ inch arrangement used in the usual DEV2 kit. The bigger exhaust adds AUD$260 and provides an extra 4kW, for a total of 172kW at the wheels.

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DEV3 – the kit that we tested on the JMM BA Falcon XT – introduces one relatively expensive component. A UniChip interceptor module. JMM is tight-lipped about the specific air-fuel ratio and ignition timing changes they’ve made, but cam timing and electronic throttle control strategies remain unchanged.

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In addition to providing improved drivability thanks to the UniChip, the DEV 3 upgrade ups the ante to 180kW at the wheels (see graph). The UniChip module contributes AUD$990 for an all-up cost of AUD$2570 (50 bucks extra for utes).

And the 3 inch exhaust upgrade? Well, at the time of writing, JMM were yet to see any extra power over their 2 ½ inch system. At around 180kW at the wheels, we’re told the DOHC Ford six is crying out for a new set of camshafts. JMM is currently working on this.

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For now, though, the DEV 3 kit is a very well behaved and cost-effective upgrade for anyone with a naturally aspirated BA six. Fear not – you are guaranteed to feel the difference over a stocker!

Ford’s atmo engine does have some potential!


JMM (Jim Mock Motorsport)
+61 3 9399 4401

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