what's Ford's latest engine really capable of? FF dishes the dirt
on the Duratec.
and photos: Jon Hill
probably know, there's a brand-new four cylinder Ford engine in town.
Currently powering the Mondeo and soon the all-new Focus, the Duratec
is the engine of the moment as far as Ford's top bods are concerned.
But just how good is it? How does it compare to the Zetec it's replacing,
and will it be a match for the mighty Cosworth YB? Even more importantly,
how much power can you squeeze out of it on a shoestring? To really
nail these questions (and plenty more besides), we've visited SB Developments-
the company which is currently investigating the release from Ford's
engine is referred to as a Duratec, which stands to reason really -
that's the name on the rocker cover. That said, its other official title
is an I4. Now, there's the first bit of confusion we're faced with, because
of course Ford already has an I4 - the twin-cam jobbie that used to
power the last of the Sierras, remember? As we know, this went on to
spin the tyres on the RS2000 MkV Escort in 16-valve form. This I4 has
nothing to do with the old one, which is why it's called Duratec and
will be from now on. The only real thing it has in common is its chain-driven
cams. In fact, it isn't really a Ford engine at all; it's a Mazda. Which,
of course, Ford owns - quite handy really.
of the motor is that it's going to be produced in simply vast numbers.
Yep, they said that about the Zetec - that was supposed to be the first
Ford 'world' engine - but this one really is. And the word production
is the key to the whole thing, although it owes a lot to race track
tricks too. The only downside is that it isn't of the Ford family, and
therefore won't fit where a traditional Ford engine will. Look at it
and you'll see it breaks with years of Ford family bellhousing tradition
in that the pattern is completely different. As a result, no rear-wheel-drive
box will bolt straight on like virtually all past Ford engines; you now
need a purpose-made one to do the job instead. The engine mounts are
like nothing we've seen before and the whole thing is, well, efficient.
you can get over 200 bhp from it without touching the engine internals,
which sound a bit more like it. But how?
what have we got then? First off, all-alloy engine - alloy block and
head, four cylinders, twin cams and 16-valves. All fairly normal, modern,
great stuff. But the motor is designed entirely with production in mind,
to the extent that it'll pass emissions without even trying - it's that
good. Everything has been designed to be a light and svelte as possible,
which can't be anything but efficient. Consequently, many of the components
within the engine bear a striking resemblance to race parts.
the pistons, for example. If you didn't know they were cast, you'd think
they were the very latest slipper pistons with Teflon inserts. Yet,
although they will produce more horsepower that the standard Mondeo-rated
145 bhp, they simply aren't up to the standard of monster power. True,
they are being used fairly conservatively and will take a touch more-
but literally only a touch. And there lies the key to this engine. Everything
is designed to produce the power of a smooth, reliable, moderately high
performing rep-mobile/family car that's totally cost-effective and nothing
else. Arece car weiting to happen - like the Cosworth - it ain't. But
don't despair - you can get a fair old whack out of it. As Clint Eastwood
famously growled: "A man has to know his limitations" - and
this applies in engine terms too. For the right application, the Duratec's
a cracker. We'll show you why.
key to producing horsepower is excellent breathing, with big valves,
huge part and good induction all contributing to the process of getting
lots of air/fuel mix and gas in and out respectively. The downside of
an engine like the Zetec was that it was designed to be as compact as
possible, especially in bore size. Consequently, everything was crammed
in; the valves were too small with no real scope for a size increase,
and the ports weren't much better either.
the name of great emissions, the Duratec has whopping valves - 35mm
inlets and 29.90mm exhaust, plus huge, well-designed ports. Both of
these contribute to producing horsepower. The valves have nice , thin
stems- meaning the guide bosses don't have to be massive and therefore
obstruct flow thought the ports. The valves are also stainless although
they're of two-piece construction and have lovely thin valve seats,
again, optimising gas flow. Physically there really isn't anything you
need to do to the head design to improve it.
the method of opening and closing the valves isn't hydraulic but
mechanical. Being of overhead cam design, of course, means that
the cam is directly acting on the followers - also known as buckets,
as upturned they assume that configuration and carry the springs.
Modern cam thinking is different to that of old, where loads of
duration was used along with low lift, producing lots of overlap.
This is a real baddie as far as emissions go because fuel is literally
dumped down the ex has ut valves, resulting in horrendous backfires
and sky-high lambda readings.
cams are dialled in the direct opposite way, with large lift and
small degrees of duration. The Duratec's dimensions therefore
are inlet 257 degrees, with 9.87 mm of lift, and exhaust is 252
degrees and 8.45 mm of lift. Not huge in terms of lift, but they
don't need to be - the valves and ports are whopping, so why do
they really need to open by huge amounts if they can get the gases
in without doing so? True to the emissions-friendly ethos, just
enough is about right and consequently there is room for improvement.
the crank is cast to be svelte; to do its job and no more. The bearings
are of a tin aluminium construction and though capable of plenty of
miles in a cruiser, high revs and bhp will see 'em fail. Like the
pistons, the connecting rods are also pretty feeble and, compared
to more traditional rods, look like on good burst would knacker them.
like everything else, they designed for low-mass reciprocation, basically
meaning that it's all about the efficiency.
like many modern engines, they're also of broken big end cap design.
This means that the rod is cast as a one-piece unit, machined to tolerance
then broken in a totally controlled way across the bid end journal
hole to form the big end cap. The cap can therefore only fit one rod
and one rod only.
a Vauxhall XE engine - which SB Developments is most famous for
developing - the bore/stroke ratio is pretty much square on the
Duratec. You have an 87.6mm bore which is actually slightly bigger
than an XE and a 83mm stroke. America, as usual, is blessed with
something of larger girth - 2.3 litre version of the Duratec.
This has a slightly larger bore size but in comparison a far greater
stroke . It stands to reason that these engines will produce more
power, but it comes at a price. The Duratec version is harsher
and less able to rev - ideal for turbo applications, you would
Duratec blocks have some great design features built in, although
it could be argued that they don't look too hot. Most guilty culprit
are the exterior oil-carrying gullies cast into the block, but
obviously there's a reason for this. See it's no secret that oil
dropping onto the crank, whilst returning to the sump, produces
drag. This, in an engine where efficiency is everything, robs
bhp. So by directing the oil down the outside of the block in
purpose-built channels, the oil returns to the sump completely
independent of the crank, therefore having no effect on it in
terms of hindrance. There's more too. The crank is mounted high
up in the block away from the sump, and is braced by a cast girdle
housing all the main bearing carriers. Thus, several components
are incorporated in one, cutting costs. The downside may well
be the need for precision machining and assembly - but we'll discuss
this later because it's significant.
some huge game on your PC, the Duratec is meant for machine assembly
aided by computer. Therefore, all the components are made to the most
exacting tolerances imaginable. There are no keyways locating the crank
to front pulley/crank trigger, and nor are there any to locate the cam
and cam wheels. Instead the whole lot relies on friction joints - a
good method as far as fast production goes. As a result, every single
cam has to be made so it's exactly the same as the next, which you might
think would be a nightmare in terms of assembly. The truth is that the
valves are all made spot-on too, as are the valve seats. Any variation
is taken up in the bucket followers, which also double as spacing shims.
probably works like this - a CNC machine assembles the valves in the
head, then by laser measures the valve height then calculates and drops
in the relevant bucket/shim followed by the cam. And it's all done quicker
than you could eat a ham sandwich - although by then the machine's assembled
umpteen other heads as well. In short, the whole engine is meant as
an assemble once-only unit, which kind of highlights the modern dealership/garage
thinking. Long gone are the days of greasy overalls and blokes smoking
rollies with soft porn calendars up on the wall. Big ends and small
ends aren't meant to be touched anymore, and instead you have posh,
high-tech showrooms with matching high-tech cappuccino machines and
technicians that can change your oil or swap complete units only.
in your dealership are incredibly dear things these days, so anything
that can ultilise the system is used to full effect. The Duratec drops
straight into this with a role of fit and forget. And if it breaks,
slot in a new one - true throwaway mentality. The unit has a similar
role in motorsport too if you're smart, but we'll examine this in greater
detail shortly. In conclusion to this section then, the Duratec is built
to be an efficient unit produced in vast numbers. We will be seeing
it appear in not just Ford products but related makes and plenty of others
too, effectively meaning cheap engines.
there to be plenty of scope for tuning the Duratec. Well, good news
- there is. Up to a point anyway. Put simply, you don't have to do much
to wring out the power, as SB Developments has done back-to-back tests
all on the same day, after extensive preparation. By junking the standard
induction system, which is intended for serious emissions control only,
and replacing it with traditional induction methods, you can achieve
truly staggering results.
pair of 45 DCOE side draught carbs and managed ignition they got 170
bhp - that's 25 bhp over standard. By taking them off and fitting parallel
throttle bodies the figure then went to 195 bhp. Then, after replacing
them with SBD's own tapered throttle bodies, the power increased to
208 bhp. This, of course, is all on a completely standard engine with
no other mods. The Duratec engine we have run has been testing in two
forms, parallel throttle bodies which produced an output of approximately
195 bhp and then running the engine on tapered throttle bodies produced
203 bhp (this was used in the American SAE corrections). The implications
of this are obvious. The engine is effectively a plug and play unit.
If you want to compete in motorsport and are looking for an efficient
unit then the Duratec could well be an option. With secondhand low-mileage
units retailing at around £700, all you need after that is £1781.90
(plus VAT) of induction. It's kit that's unlikely to break or wear out
in a hurry either.
unfortunate enough to blow the engine then all you need do is unbolt
it and replace it with another. Compare that to tuning a traditional
Ford engine such as a Pinto. To get in excess of 200 bhp you'd need
eight grand-plus. And, if all you wanted was a good high powered plant,
you could do the dirty and switch to H**nda power - then all you'd need
is 'only' around five grand for a basic V-Tech unit. Put in these terms,
the Duratec seems like a cheap motorsport unit.
can obviously go beyond these figures, because until now we've
not even taken the cam cover off. Do this and fit higher lift
cams, which there's just enough room to squeeze in. That said,
pocketing the pistons and much better valve springs is necessary,
and this will provide up to 25 bhp more. The standard valve springs
are light in both weight and strength , as well as being progressive.
This makes for a very svelte, efficient drivetrain but can result
in coil bind because of their length. The problem is that space
is incredibly tight to get a bigger spring and follower in their
place. However , new ones are available from Kent Cams/SBD.
own cam design is slightly different to comparable aftermarket
makes in that duration of the intake valve is deliberately less.
Their theory is, you keep the combustion ratio up slightly higher
and produce more torque if you compress the gas you've got more,
rather than try and cram a greater amount in. If you examine cams
like for like, SBD's may not produce any more horsepower, but
it will give more torque. And that, as we know, is where the oomph
Another area that can do with a bit of attention is the flywheel,
which in standard form is a whopper, weighing in at around 12kg.
Again this is for emissions-friendly purposed. SBD's own purpose-made
unit weighs in at around half this, contributing to a freer-revving
still more you can do. But, as you'll have gathered by now, the Duratec
is primarily intended as a production unit. It certainly isn't a Cos
YB, which is really a race unit in seriously detuned form for production.
In this case you have a cast-iron block, made virtually bullet proof
in the 200 motorsport version - something you'd never get with any alloy
type. On top of this, everything's made with race in mind from the steel
crank and semi-steel rods to the head, which can be hogged out as much
as you like to produce the power.
the Duratec is great up to a point and the limit is around 245 bhp,
although we would suggest that the 2.0 litre should be rated 230-235
on standard rods and pistons. Yes, you can tune it further but this
breakpoint is significant because if you go beyond it the unit's cost-effectiveness
goes out of the window. Those spindly rods, cast pistons and acceptable
bearing won't take any more power than this safely. Consequently, the
amount of components that will need replacing beyond this point is huge.
You take the choice - parts are available but the unit becomes as costly
as any other race engine if you want to produce power beyond this point.
And that applies to turbocharging too - and no, we're not talking RS
Fucus either. It might say Duratec on the rocker cover but in truth
this motor is the final derivative of the Zetec. It isn't an I4 Duratec.
So retrofitting a blower and you would get gains from a very mild amount
of boost on an otherwise standard engine. Go beyond that 245 bhp figure,
however, and you're virtually guaranteed to get huge failures.
So in conclusion,
your best bet is the plug and play route, along with induction changes.
That isn't forgetting that you can upgrade the existing ECU in, say
your Mondeo - but don't expect wild bhp gains beyond the few you'll
get with a standard chip, filter and exhaust. The ECU in this case is
a central computer which is as much likely to control how long the interior
light's left on as the injector timing. The motorsport route on the
other hand, as we've discussed, is to bin the lot and start again with
a purpose-built unit controlling throttle bodies/carbs. This route is
currently the favourite in terms of Caterham/kit car applications but
as far as uprating your Mondeo - or new Focus - goes, controlling the
rest of the car remains open for now.
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