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The Duratec is capable of more power than it offers as standard. Read on to find out how to release it.

ound in the 2001-onwards Mondeo, Mk2

Focus and Fiesta ST150, the Duratec is the replacement engine for the older Zetec. The Duratec resembles the Zetec, but on closer inspection you notice that the two are nothing alike.

The Duratec belongs to the I4 family as found in twin-cam Sierras and Mk5 Escort RS2000 as a 16-valver. However, it doesn’t have a lot in common with those either. The only aspect they share is chain-driven camshafts.

There are also a few variations of the Duratec to contend with too. In the UK we get 1.8-litre and 2-litre capacity engines, but there is an American version too. The US Duratec, as found in their Focus and Ranger, is larger than its

duratecsF

How to modify

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Words: Jamie Photos: Jon Hill

As for cams there are a few options depending on what power you want. You will need to replace them, as the standard items are more concerned with meeting strict emissions laws than with making power.

You can choose from a number of different profile cams from all the major

manufacturers such as Kent, Piper, and Newman, and Cosworth even makes its own sets. Prices range from £300 for a pair of mild 220bhp cams, which will work with the standard injection system and original pistons, to around £500 for a pair of rev-happy power cams that will help make 300bhp. For the more lairy cams you’ll need to factor in the cost of uprated valve springs, top hats and followers.

Cam choice is a personal one, and different tuners will have their own preference on which to run at different power levels.

For example Joe Stevens of Bluesprint likes to use the Cosworth sets but agrees cams from the likes of Piper, Newman and Kent are just as good. SBD Motorsport’s Dick Hulbert says for its big-power engines it prefers to have cams ground to its own spec.

If you‘re planning to run silly high-lift cams Joe

Stevens recommends having the head machined to accept larger diameter followers. “As the followers, or buckets as they are more commonly known, are of a solid type all the discrepancies are taken up within them. You can get different grades to ensure the clearances are correct, but with higher lift cams you can find that the cam lobe will catch the side of the follower rather than the top of it when

rotating. To cure this on big-power engines we like to fit larger diameter buckets to give the cam lobe a greater area to make contact with, and ensure it won’t clip the side of it.”

One other thing that it is recommended to do if running high-lift cams is to pin the pulleys to the

camshafts themselves. As there are no keyways and the grip between the pulley and the cam depends entirely on the friction of a washer, it is a good idea to pin the pulleys to the cams to ensure they won’t move on high-revving motors.

“Cam choice is a personal one, and different tuners will have their own preference on which to run.”

British counterpart. An increased stroke and bore takes the displacement to 2.3 litres, which makes it slightly less revvy than its smaller cousins, but more torquey and more powerful.

The 2.5-litre V6s in the Mondeos and Cougars are also technically Duratecs, as they belong to the same family. However, the Duratec isn’t really a Ford engine at all; it’s a Mazda unit.

The idea was that the Duratec would be produced in vast numbers, and it can already be found in the UK and US cars mentioned previously in four-cylinder guise, while also being fitted to a few Mazdas including the Mazda 3, Mazda 6, and Mazda Tribute. The V6 version can be found in the UK Mondeo and Cougar as well as some Jaguars and Mazdas, and is fitted to many other American

motors including different Ford models and some Mercurys and Lincolns too. Confusing isn’t it?

For the purpose of this guide we will concentrate mainly on the larger 2.3-litre four-cylinder version, which can be sourced direct from the US for as little as £1200, but the same mods can be made to the smaller 1.8-litre and 2-litre variants, and similar power gains can be expected. We spoke to Duratec engine tuning gurus Joe Stevens of Bluesprint Motorsport and Dick Hulbert of SBD Motorsport to find out exactly what’s what.

CAMS

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One good thing about the Duratec

engine is the size of the valves and the

ports. Standard units have very large ports for

a production engine, and

the valves are fairly big with nice, thin valve stems,

meaning the inlet tract is free-flowing and unrestricted.

According to Joe Stevens at Bluesprint you should be able to see at least 230-240bhp on a standard head before you need to start opening up the ports. He also says that porting the head is quite a tricky job, as you don’t need to just enlarge the whole port, but

need to concentrate on opening the port throat to improve the flow into the cylinder.

As for nailing in bigger valves you need to think very carefully about exactly how much power you want before you start. You can achieve 280bhp on standard valves, but if you have got your heart set on a mental 300bhp motor you will have to pay to get larger valves fitted.

The usual upgrade is a 2mm larger exhaust valve, and a 1mm increase on the inlet valves. This means the

original valve seats can be machined to accept the bigger valves without having to fit larger seats.

SBD Motorsport offers a CNC-machined, big-valve head for £2110. This price is based on a 2-litre head that can produce up to 290bhp on a 2-litre bottom end. The good news is it will also fit the larger 2.3-litre bottom end and produce over 300bhp.

Performance cams are available from mild tune to wild custom-ground spec

Solid followers or ‘buckets’ come in different grades to take up the clearance

froM

150bhp to

300bhp

Standard cams will need replacing with performance items

How to modify duratec engines

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The Duratec block is quite advanced in its design, and so doesn’t need much tinkering to withstand up to 300bhp. Its aluminium block is light, making it a favourite with kit car and racecar builders alike, and features a few trick design tweaks taken straight from the race track.

The first is the Nikasil-coated steel liners, which the Duratec is blessed with

as standard. These will cope with most things

thrown at it in N/A guise, and Bluesprint Motorsport’s Joe Stevens reckons: “It will easily handle 300bhp without the need for further modification”.

The ally block also features exterior oil return gulleys that allow the oil to return to the sump without dropping back onto the crank. It is well known that the oil falling onto the crank produces drag, therefore lowering the efficiency of the engine. As the Duratec is built to be as efficient as possible, the oil galleries running down the side of the block mean

the oil return is completely

independent of the crank and has no

drag effect.Also, the crank

itself is mounted high up in the

block, and is held in place

with a one-piece cast girdle that houses all the main caps. This not only cuts production costs as it is one-piece item, but adds strength and stability to the block too.

One thing most tuners do, including those we spoke to, is replace the standard main cap/girdle bolts and standard head bolts with ARP stud and nut kits to aid reliability.

The headbolt kit costs £155, and the main cap/girdle kit costs £115.

piStonSThe factory items look neat with their Teflon coating but the 10.5:1 compression ratio is too low to produce anything over 220bhp.

Joe Stevens prefers Cosworth forged pistons to raise the CR to between 12:1 and 13:1 depending on your spec. They’re not cheap, costing £600 a set. SBD Motorsport prefers Omega pistons, which will similarly raise the compression and cost£470 a set.

There may be cheaper ones from America, however given the unpredictable state of the economy and the fact you’ll get clobbered with taxes and duties when they get here, they might not be such a bargain.

For a 250bhp engine you need to raise the CR to about 12:1, and for the ultimate 300bhp motor you’ll need to get that up to nearer 13:1. You can go for a CR somewhere in the middle, but you need to decide this when choosing your desired output in the build spec.

The crank has been designed to do its job, and no more. For an engine kicking out any more than around 220bhp you will need to bin the original item in favour of a stronger steel one.

This isn’t necessarily due to power, but more to do with the higher compression forces and high revs the engine will be doing to make that power. Cast cranks are notoriously weak at high revs, and the Duratec item is no different. At the sort of revs a 220-plus bhp engine will be pulling it will simply fall apart.

To stop this from happening a billet steel item

will be needed. There’s no need to increase the stroke, although a 2.5-litre stroker kit is available, as the increase in torque is often considered unjust against the costs involved and the revs lost in doing so.

Steel cranks are available and tuners have their own preferences. Joe Stevens prefers the Cosworth item as he believes it is the best quality one on the market,

and will cost £1300. SBD Motorsport prefers the more expensive Arrows crank, which costs £2120. To add to the mix further, there are cheaper alternatives from America costing around £800-900, but you’ll have to wait for it to be shipped, and unless you know someone who has used one before you won’t know the exact quality of it.

It’s worth having the crank and crank pulleys machined for a keyway. Like the camshafts, the crank

and crank pulleys are only joined by a diamond crusted friction washer, which in a high-power engine can be a weak spot. When running extremely high-lift cams the force put on the crank pulley during cranking can cause the chain to jump a tooth or move the crank pulley in relation to the crankshaft, throwing your valve timing out and potentially destroying the engine.

Joe Stevens can machine the crank and pulleys to allow a keyway to be fitted. The crank simply needs machining but the pulleys require a special ‘spark erosion’ process as they’re made of hardened, heat-treated steel. The lot costs £50, so you’d be well advised to carry this out.

Consider the crank bearings too. The original main bearings and big end bearings are of a laminated type and like the crank

itself have been designed on a budget to work in a standard motor but nothing more. Replacing them with a set of heavy-duty items is a must for high-revving engines making over 220bhp. If you’re replacing the crank you need to replace the bearings anyway. A set of main bearings c osts around £55 and the big end, or con rod, bearings slightly more expensive at around £70.

CrAnk

“The pulleys require a special ‘spark erosion’ process.”

Duratec block is very light and features a few racecar tricks

Adding a keyway to the crank and pulleys keeps everything where it should be

Main caps are all in a one-piece ‘girdle’ structure

Con rodS Like the rest of the Duratec, the rods have been made on a budget. They are fine at standard power levels but according to Joe Stevens, “are no good for anything over 220bhp”.

Also, the fact that the original pistons are a press fit on the rods means that if you are changing the pistons, which you will need to do in order to achieve bigger power outputs anyway, you will need to change the rods as well.

SBD Motorsport uses a set of Saenz

Higher compression is needed to make good power

H-section rods costing £750

which Dick Hulbert claims: “are very good

rods, and will take anything you can throw at them.”

Joe Stevens agrees, although he prefers to use Cosworth I-section rods which cost around the same for a set and are as good. Joe explains that uprated rods are needed because: “the standard items are weak, and can stretch at high rpms.”

There is no need to look for longer items as the

Duratec has very long rods as standard, contributing to the Duratec’s rev-happy characteristics. The 2.3-litre is capable of revving to 8500rpm and the smaller 2-litre unit can pull over 9000rpm, obviously dependent upon having the other necessary modifications to do so.

With uprated rods you don’t need to change the bolts, but if you are using standard items replacing the bolts with some uprated ones will aid the reliability of the engine.

Standard crank will fall apart at high revs

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The manifolds are probably the most important things on a Duratec that need replacing to extract any extra power. The other mods are there to keep the engine in one piece, but will all be wasted if you can’t get the air and fuel in and exhaust gases out any quicker than standard.

inletThere are a couple of options open to you. Carbs are a cheaper way of getting power, and if running them you don’t need expensive, complex engine management to operate them, simply need an ECU to control the spark timing. With a set of twin ’50s you can expect to see around 250bhp.

However, carbs are not as clinical or as accurate as a set of throttle bodies, which is a more common route when tuning Duratecs. SBD Motorsport offers bolt-on 45mm Jenvey taper throttle bodies as part of a kit for

£910. Dick Hulbert explains: “The kit is straightforward to fit, and works well in Fast Road and some competition applications.” The kit includes throttle bodies, manifold, ram pipes, fuel rail, and all the mounting bolts, and will make around 270bhp.

The next step in terms of inlet is a bigger 52mm throttle body kit which SBD Motorsport offers for a bit more at £1380. However, for the

ultimate 300bhp engines Joe Stevens of Bluesprint Motorsport prefers to fit a set of roller barrel throttle bodies. The lack of a butterfly valve means the inlet tract is uninterrupted, and offers a quicker acceleration response too.

Joe also explains that they are best used on race and competition engines. “Because of the way the roller barrels work you sometimes notice a slight judder at the bottom end of the rev range when you start to accelerate. It’s not so noticeable on a 2.3-litre engine because the increased torque counters the effect a little, but on a 2-litre you can notice it. Conventional butterfly throttle bodies are smoother and more progressive so are better suited to road applications, but they don’t make as much power as the roller barrel items.”

eXHAUStThe exhaust manifold is just as critical. Because the engine has been designed to be as economical as possible you can lose up to 30bhp without the right type of exhaust manifold. As Dick explains: “There is no point trying to get more air and fuel in, if you can’t get rid of the exhaust gases.”

Exact details of diameters and optimum primary lengths are a closely guarded secret, but we did find out that a 4-2-1 manifold works best on the Duratec. Exhaust design is influenced by other mods, so make sure you know the spec you’re going for before getting a manifold made up.

Throttle bodies are the key to big power

Throttle body kits include everything you need to fit them

MAnifoldS

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MAnAgeMent Engine management is down to personal choice. All tuners will have systems that they prefer to map and feel more comfortable with, and most engine management systems can do what is needed to run a Duratec.

Joe Stevens prefers to use the Life Racing or Pectel systems, and SBD

Motorsport favours the MBE ECUs.

The Duratec comes with a 36-1 trigger wheel as standard and the original sensors can be used so there is no extra expense there, but you will need a custom loom to work with whichever engine management you choose.

ContaCts Bluesprint Motorsport01621 7448811

Julian Godfrey Engineering01435 865999www.racetuners.com

Noble Motorsport Ltd01246 272749www.noblemotor sportltd.co.uk

SBD Motorsport020 8391 0121www.sbdev.co.uk

typiCal priCesForged high-comp pistons............£600 (set)Billet steel crank......................£1300H-section steel rods..........................£700Big-valve, ported head.......................£2110High-lift cams.. £300-500(Depending on spec)Throttle body kit.....£910Headbolt kit.............£155Main bearings...£55 (set)Con rod bearings............£70 (set)

turboteCh

next Month

How to modify duratec engines

It is possible to turbocharge the Duratec engine, although it has not taken off in that big a way just yet. Specialist tuners like Julian Godfrey Engineering are looking at what’s needed to make the Duratec capable of handling the immense power outputs required in rallycross to see if a turbo’d Duratec could be a possible replacement for the older Cosworth YB engine.

The first, and most major, problem is that the aluminium block is too

weak to deal with huge amounts of boost. It is something JGE is currently looking at in order to build big-power engines, but there are other tuners like Noble Motorsport who already offer low-boost turbo conversions.

As part of the conversion you will need to replace the crank and rods as per N/A tuning, but the pistons will need to be a set of lower compression items. A compression ratio of around 9.0:1 is good enough to keep lag at a minimum but

still hold together with 350bhp on tap.

The cams will also need binning, as the duration will be wrong. The N/A cams have a fairly long overlap period, which is a big no-no in forced induction tuning as all the boost gets blown straight out of the exhaust.

The exhaust itself will need to be a custom jobbie designed to hold the turbo. A hybrid T34 turbo will see 350bhp without any fuss and with the Duratec’s good low-down grunt won’t have too much lag either.

A set of high flow injectors will also be needed along with a mappable aftermarket ECU, but most tuners retain the original plastic inlet manifold and throttle body. Another good thing is that the head doesn’t require any work in forced induction guise.

You’ll be looking at parting with a handsome amount of cash for a turbo conversion like this, but they have been proven countless times and offer reliable bhp.

turboChArged

Turbo kits are rare, but work well

Aftermarket management allows much finer tuning