One will often find that there is more fun and reliability at other than simply the maximum bhp one can achieve. Even manufacturers do not shoot for the latter. They want tuning that will cause the least warranty claims within government regs. gmg
A 2.0 Duratec four cylinder is by design a very strong and reliable engine with plenty of tuning potential left of the table by its designer, its well accepted you can tune it to 220hp without touching any internals, and still retain the well proven 200,000 mile Ford reliability and durability.
Actually, it's the emissions targets that manufacturers are forced to meet that stops them realising the true power potential of their engines. For example, valve overlap is good for performance but bad for emissions, conversely catalytic converters are good for emissions but very restrictive. Manufacturers also tend to cheap out on exhaust and inlet manifold design, and again for emissions reasons they add further performance limiting features such as exhaust gas recirculation and swirl flaps.
The 2.0 Duratec is such an easy and rewarding engine to tune because it was designed correctly in the first place, at just 100kg it's also very light for its potential output so offers excellent energy density, indeed if you study a Duratec in detail what you'll find is actually more akin to a competition engine which sits massively at odds with its dull Ford Focus, Mondeo, Mazda 6 origins.
In our favor a rear wheel drive vehicle gives a lot more space to fit better exhaust and inlet manifold designs, if you also don't need to meet those emissions targets you're now free to realise the engine's true potential. When carefully curating the list of tuning components for my Duratec Plus 4 I simply looked at what was out there that's also proven to work well as a recipe, then copied it over to Monty.
Tuning the 2.0 Duratec is such well trodden ground only a fool would try to reinvent the wheel, so the recipe I chose was really a function of plagiarism over innovation.
1. Replace the restrictive exhaust manifold with something better - I asked my fabricator to copy the excellent exhaust manifold used on the Plus 4 Superport, but also allowed him the creative freedom to improve upon it if he felt he could
2. Replace the Ford FWD plastic inlet manifold with something better - I asked my fabricator to build me an adapted version of his proven Fiesta ST150 manifold that looks a lot like it was inspired by the no longer available but legendary Mountune MR200 inlet manifold. The inlet manifold was just one part of a proven tuning package guaranteed by Mountune to release 200+ horsepower from the 2.0 Duratec. The kit worked so well even Ford themselves endorsed it, this meant after having Mountune fit their MR200 to your Fiesta ST150, Ford would continue to warranty the car
3. My new fabricated inlet manifold also meant we were able to completely remove the very restrictive swirl flaps, and the exhaust gas recirculation system - Actually anyone can make these two improvements to their existing plastic inlet for next to nothing, feeding an engine it's own exhaust gasses dulls throttle response and the swirl flaps are definitely a big restriction
4. Fit a better air filter arrangement - Probably on minor gains here but the Mondeo filter box does have a very small inlet port so does look rather restrictive to me, I went with an AEM DryFlow filter that seems to be working well enough so far
5. Replace the factory emissions based camshafts with something with more overlap, a little more lift and duration - Again I followed what everyone in the ST150 world seems to use, Newman Phase Two cams are the go-to option for any seeking a noticeable lift in performance while retaining daily drivability, I'd speculate the cams that came with Mountune's fabled MR200 kit would have been more or less identical to Newman Phase Two cam spec
6. Replace the factory valve springs with a set of 60lb beehive type valve springs - These were installed as a precaution against valve float that can occur at the higher engine speeds my Duratec is now capable of reaching
Tuning is all about understanding that an internal combustion engine is really just an air pump, so the objective is simply to get it shifting more air. However, when you do that you will need to add more fuel to match all that extra air or you won't make any more power, indeed you may make less power and you will definitely be putting your engine in grave danger too because lean mixtures are the cause of many a catastrophic engine failure!
As I fully predicted, at the end of my tuning journey I was left with a Duratec that was shifting so much more air the engine was now running dangerously lean, it also fell flat on its face if you dumped the throttle open or asked it to venture above just 3,000rpm. At this point it soon became clear neither the stock injectors or the Ford Mondeo Visteon ECU that controlled them were up to the job, so a set of Bosch Green Giant 440cc injectors we added and control of them was handed over the excellent EMU Black from ECU Masters.
With some careful calibration work from yours truly my Duratec absolutely came alive, the difference in performance from the standard Plus 4 engine spec was nothing short of astonishing, never before have I tuned a naturally aspirated engine and seen such huge gains!
But best of all is the car has not lost one bit of its super smooth and flexible drivability, indeed the engine is now noticeably more flexible than it was, finally I was astonished and delighted to discover that if driven in the same way Monty had retained his very frugal 38 mpg on a run. The car is way faster and nicer to drive with significantly crisper throttle response, yet when driven sensibly uses absolutely no more fuel than it did before I tuned it.
The process delivered an win win with zero downsides, well I say no downsides, if the truth be known you never get something for nothing in this world. The one area where the engine will almost certainly have gone backwards is tailpipe emissions, forfeiting tailpipe emissions for performance is the payoff anyone considering tuning their Duratec must accept. Saying that, I opted for a 200 cell sports catalytic converter, aftermarket cats that will get you through the MoT are available or you could repurpose the Morgan original, but as I have a friendly tester this all seemed like further pointless restrictions to allowing the engine to breathe as the talented Duratec designer intended.
