The background of Ford Australia's Gordon Barfield:
"I've been in Ford for over thirty years. My most recent experience from about 1995 is time with Tickford, or FPV as it is now, as the program manager and planner; so I've been involved in all the XR products all the way from EL, GTs and T-series. I was involved in getting the turbo engine and the 4-valve V8 up and running - it was my involvement really that made it all happen.
"From a planning perspective I need to know the market and be aware of where we want to move in our long-term plan. I also program manage it, so - once we've defined what goes into a specific vehicle - I need to then work with FPV and Ford to configure the cars that we want as a mother car. Ford builds the mother car and sends it to FPV in the spec that we require - the rest of it is done by FPV and their assembly process. The engine, for example, on the XR V8 is built at FPV and is sent to Ford to be put into the car. The turbo engine, on the other hand, is built by Ford to the specs of FPV.
"With the BA launch we've integrated the XR more into the base Ford manufacturing process."
What were the market influences to produce a turbo six?
"We were going through the development process of the Dingo engine - the new six-cylinder - and the architecture of that was pretty much defined. With the twin-cam head on it there was really very little potential left in naturally aspirated form; we had 182kW targeted for the base engine (which is more than any of the XR6s had had up until then) and we felt that we were in a situation where we still wanted to offer a six-cylinder that offered better performance than the standard model.
"With its twin cams, multi-valves and [being] naturally aspirated we're in a position where you can optimise small areas and pick up 10, maybe 15kW. So we realised that we were going to have to force induce it to get any reasonable extra amount of performance.
"First, we had to decide whether we'd turbocharge or supercharge it. The supercharger didn't appeal too much because the architecture of the front-end drive of the engine - the belt drive and the ancillaries - are all optimised in a location as close as possible to the centreline of the engine (so that vibration isn't an issue). If you're going to put a supercharger on, you need to relocate one or more of those components and we really didn't have the space. And, look, supercharging - to us - was a technology that didn't have a good name, particularly in the six-cylinder market that we were in. The turbo scene was seen as much younger in terms of potential market - the Subaru WRX obviously had its influence on that market. It was much more contemporary.
"The turbo XR was seen as something that would really open the market. We were going to provide ourselves with an alternative to the V8 - for those people that consider them low-tech or dinosaurs - even although we were changing that anyway with the new multi-valve 5.4s.
"We looked back and, sure, we had the XR6 VCT versus the standard engine in AU but people had a degree of difficulty in picking the difference in performance. This time around we really wanted a significant change so you could notice the difference in the first 50 feet of driving."
Why not tune the atmo six to rev higher and make better top-end torque?
"Reciprocating mass is always a limiter on revs and we use a fairly long stroke engine. And, look, the DOHC engine now has a lot more high-speed torque than it had and we're not looking to high rpm stress the engine any more - it has very good longevity in its current form. We didn't want to sacrifice that for top-end performance - especially when you can achieve even more performance with a turbo or supercharger.
"Australian customers are also predominantly automatic transmission, low rpm drivers - they've got used to that. Engines that are strong low-down are the epitome of the Aussie engine; they want what is effectively a lazy engine. You'd lose a lot of that going for higher specific output - take a BMW M3, for example. It has a very high specific output naturally aspired but it needs revs, which is contrary to the liking of the average Aussie Falcon or Commodore driver. Gearing these days is also focussing toward fuel economy and, again, that is contrary to high rpm engines."
Talking of fuel efficiency, we believe that some of Ford's competitors are about to be released with extremely low Cds. Where does Ford - or FPV - stand on aerodynamic Cd?
"We did a lot of aero testing with the BA and, as you probably know, aerodynamics are more important at higher velocities. What you really have to consider when it comes to fuel economy is the car's ability to coast down - to roll with minimal frictional losses from the brakes, gearbox, diff, tyres etc. This mechanical friction, if you like, also has an influence on the ability to get off the line and do lower speed work as well. The worst economy areas are starting and stopping - you can do all sorts of things once the car is up to cruise.
"Our engines have always been up there in terms of volumetric efficiency and we're into lower grade oils now thanks to reduced frictional losses such as ring drag. Fuel economy is also inextricably related to the displacement of the engine, but you have to weigh that up with market demands. We're not all running around in 600cc cars and, personally, I don't think that hybrid vehicles will start selling in any real numbers - realistically - for 10 or 15 years.
"I think what we've seen so far is complete antipathy towards the fuel economies that some other manufacturers are talking about. The same with emissions - I don't think people are really prepared to put their hand in their pocket to reduce emissions. And, at this stage, there's no incentive to downsize or do anything else."
What were some of your XR6 Turbo design goals from the outset?
"We laid those down in a very early stage. We didn't want a car that was going to scare the pants off people when the turbo came on boost but we also wanted something that gave strong performance improvement. It had to be progressive - we didn't want any alarming driving patterns. Actually, we really like the Saab low-pressure turbocharging process and we felt that we could benefit from that on a big engine; we've got a lot of inherent torque so we had a good base. We wanted not a necessarily huge turbo, because we wanted something that would spin up very quickly. We didn't want to have a lag issue or any sudden change in torque - we were after a more high-tech, European feel."
What constraints are there on a project such as the XR6 Turbo in terms of cost, servicing, emissions, fuel, towing, etc?
"Whatever we came out with had to be a durable package - we set our own standards and said we weren't going to compromise any of Ford's durability, so the turbo engine did all the same testing that the naturally aspirated engine did.
"Of course, there's a lot of dynamometer durability testing - like 300 hours going between maximum torque and maximum power - and the engine still has to be completely serviceable and making reasonable power by the end. There are other dynamometer tests that check valvetrain, piston scuffing and all sorts of other characteristics.
"Then you've got to put the engine into a car and evaluate the driveline. So you do development on the dyno, durability testing on the dyno and then move into the vehicle.
"From the start we maintained that whatever we did it'd have an intercooler in the package. We had seen other packages without intercoolers and we weren't prepared to take the hit that high ambient temperatures created on the car's performance - we've got to be able to give then performance people expect whether it's cold or hot. Without the intercooler, we would have been severely detonation limited - you have to back off spark to avoid detonation - and high temperatures itself limits power as well. The intercooler would also help a lot for towing, because the greater the temperature build-up under the hood, the worse it was going to get.
"We knew when we went into the program that heat was going to be our biggest issue. We would have to heat shield a lot of things and insulate a lot of parts - that's probably the biggest effort in the program, not only to get the characteristic right, but to make it live in a real-world environment. The steering shaft, exhaust system and all the other components have to live."
How did you arrive at the chosen compression ratio and turbocharger size?
"The compression ratio was assessed in a number of tests. You make an assumption to start with that we'll lower the compression ratio by X amount and see what the spark characteristics were like. We knew we were going to be spark inhibited with the standard compression ratio - it needs a lower compression ratio, otherwise you give yourself a too-hard time. You need to get into very high quality fuels and we wanted to make sure - using a knock sensor - we'd have the ability run on standard unleaded. That was a prerequisite. There is a performance benefit on premium unleaded, however.
"We were pretty fortunate in that we nominated a compression ratio and it turned out pretty close to what we wanted - we didn't have to go through a whole gambit of ratios. Don't forget we've got a lot of basic 6-cylinder technology already intrinsic within the company - like where you need to go for detonation borderline characteristics and MBT (mean best timing relating to torque) so the characteristic of the engine was pretty well known before we got into it. It wasn't really a guess; we ran with 8.7:1.
"We worked very closely with Garrett for the XR6 Turbo - they do a lot of the turbo sizing for us. The A/Rs and that sort of thing was all developed from their data, plus the characteristic we were after.
"The other torque characteristic we were aware of was the driveline - we needed to maintain a torque characteristic that was consistent with the gearbox and the rest of the driveline. We also wanted to keep the driveline as common as we could with the basic Falcon - it made a lot of economic sense. The powertrain manufacturer gave us the limits of their products and we held it to those limits."
So the XR6 driveline is what's holding back greater output?
"Well, yeah, you've got to work within the constraints given. We could have gone to all sorts of different gearboxes, but we had a pricepoint that we wanted to go in with. The potential is certainly there for more - it depends what you want to pay. The sky is the limit, quite frankly. What we wanted was the torque curve to muscle into the old V8 market."
How many different turbochargers were tested?
"We started off with a recommendation from Garrett and that turned out to be a little bit wrong - we had a bit too much low-speed performance and not enough top-end. They did a minor tweak to what they had given us and that got us where we wanted to be - it was only two turbos we tried in the end. It's a roller-bearing GT40 we're using."
Why did you decide on a boost limit of around 6 psi?
"The governing factor was our torque limit. The driveline was the issue - we didn't want to overstep the manufacturer's limits."
Tell us about the XR6 Turbo's exhaust manifold design.
"We started off using a re-cast version of the standard two-piece manifold - it was an upgraded material spec. We were quite happy with the performance characteristics of that manifold - it gave us the distribution we wanted, but the issue was durability.
"We were getting a lot of heat and expansion and the slip joint that we had between the two manifold pieces just wasn't durable enough. We then actually went to Volvo and talked to others about where they were going with their exhaust manifold specification and we were advised to cast the manifold in stainless steel. That gave a few problems for the manufacturer, though, because [the material] is so hard there were initial machining issues. We also went to a one-piece design - you still need to allow for expansion and contraction, though, so we still have effectively slip joints around the bolt locations. We've never had any more problems.
"We then had to package an exhaust system that would keep backpressure down. We ended up using 3-inch off the dump pipe, modifying the catalyst flow and we went for a dual pipe system - similar to what we were running on the V8s at the time. This was a fairly major packaging exercise in the BA - with the change in the fuel tank and the new IRS, we had a bit of a challenge in terms of space, but we got there.
"The turbo accentuates certain types of exhaust noise, though, and we had a situation where we had a gas rush noise. You can't sell a car like the XR if it sounds like a gas cooker, so the guys had to do a lot of work to tune the exhaust to give the note we wanted. We do that with the V8s as well - it's essential to have aural feedback."
In Part Two of our interview we delve into some more technical aspects of the Ford XR6 Turbo...
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