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turbocharging Ford's Zetec engine
Contents:
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Background
Zetec R & Duratec RS engines
Fitting
Turbocharging
Lowering compression
Headgasket
Bottom end
Turbo oil supply
Oil and water cooling
Inlet manifold
Management
Injectors and fuelling
Intercoolers and pipework
Breathing
Exhaust and turbo
Cosworth spark plugs
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This isn’t a definitive guide to turbocharging your engine; this is really just a collection of pointers and personal experience cobbled together into a couple of hundred words. Sorry for the lack of pics - I'll start looking for some!
If you have done this conversion, or are thinking of doing it and have been researching it, I would like to hear your views and experiences. If you think something I have written is wrong, or could be done better, I would like to hear from you.
A bit of background... | 
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The 16v Zeta/Zetec engine has powered Ford models from 1992 onwards. It was always fitted with a catalytic converter, and the engine management system was known as SEFi (Sequential Electronic Fuel Injection). The Series 1 Zetec engine ("DOHC" on alloy cam cover) and 2 ("Zetec 16v" on cam cover) engines used side-fed injectors and the management was heavily reworked compared to the EEC-IV EFi CVH 8v (click here to see the definitions page for an explanation of these terms) management to improve hot starting (by allowing flushing of cold fuel around the injectors), and driveability. The Series 3 (matt black plastic rocker cover, fitted to later Fords, exhaust manifold still at front of engine) uses end-fed injectors and a reworked inlet manifold design. All the Zetec engines can rev far higher than their CVH predecessors and due to their 16 valve heads, produce peak power at higher revs.
Fitted in Fiesta and Escort models, the series 1 and 2 engines mount into the same positions and are most compatible with the Mk3 Fiesta shell. The Zetec-R (commonly fitted in the Focus) uses a completely different mounting system to reduce torsional forces and as a result will require some welding to and fabrication to fit. |
Zetec-R & Duratec RS (Focus RS) engines |
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| In late 2002, Ford finalised their design for the Duratec RS engine, which powers the Focus RS. This is essentially a lowered compression version of the Series 3 (Zetec-R) engine with improved cooling, crankcase breathing and oil supply systems. In the Focus RS, the engine is powered by a water-cooled Garrett turbocharger and uses a chargecooler setup to reduce engine bay usage and boost pipework, which helps to reduce lag. Attention has been paid to the inlet and exhaust systems, with a new throttle body, uprated inlet manifold sealing, free-flowed exhaust system and a controversial cast exhaust manifold. Originally Ford had wanted to use a tubular manifold, but development problems, rumoured to be attributed to premature failure of the welds, resulted in the cast manifold being used. The end result is an engine putting out a book figure of over 200bhp. See The Focus RS website for more information. |
Fitting | |
| Fitting the Zetec-R engine is problematic in the Mk3 Fiesta shell. This page on Mark Stewart’s FiestaProjects website describes some of the steps necessary to fit this engine, including the removal of the existing rhs inner wing mount, and the welding-in of a new engine mount in front of the suspension turret, as well as the removal of a section of the rhs chassis leg which should be strengthened by the welding-in of a box-section. |
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Alternator: The alternator is rear-mounted on this engine. Due to a change in the pattern of the block casting, fitting the front-mounted alternator from an earlier Zetec is not thought possible.
Transmission: The transmission on the Focus RS is a strengthened MTX75 box with Quaife limited-slip differential. Space constraints and chassis design make it difficult to fit this pattern of gearbox in the Mk3 Fiesta shell and as a result a good compromise of gearbox is the fitting of the light to medium duty iB5 manual 5 speed box, fitted to many FWD Fords from 1995. This box was only fitted to engine producing less than 130PS (128BHP) and as a result isn’t particularly suited to a high-power turbocharged application. Ideally, the fitting of a strengthened aftermarket gear set, for example a Quaife kit, will increase the life of the transmission, although at a cost of several thousand pounds is often overlooked until the existing transmission dies.
The iB5 box is available with both rear- and front-mounted starter motors. For a turbocharged Zetec application, mounting the starter at the rear of the engine will improve it’s lifespan as it is less susceptible to heat damage from the turbocharger. For those of you with a CVH engine, the rear-breather on the block prevents the fitting of a rear-mounted starter without breather modifications – bummer.
Additionally, the iB5 was made in hydraulic and cable operated clutch variants. For compatibility with the Mk3 Fiesta cable-operated clutch, the cable-operated iB5 box should be used.
Note that the iB5 box is directly compatible with the existing driveshafts and mounts, although some ingenuity is required for the front gearbox mount. I found that fitting the 1100cc Fiesta front mount bracket allows some creative metalwork to be used to fit the horizontal bracing bracket onto the front of the gearbox. You will need to fit the iB5 clutch release bearing, which uses sealed bearing races. Despite being sealed, a lot of bearings have been reported as becoming noisy very quickly and as a result you should try to get some grease into the bearing races on fitting. A paddle clutch or similar uprated item is recommended for applications around and over the 200bhp mark as the standard 220mm item is normally unable to cope with the torque. For more information, please visit the transmission guide page | |
Turbocharging the Zetec engine |
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| When Ford turbocharged the Zetec-R, they weren’t the first people to do the conversion and the following information comes from a number of sources. Please see the links section on the left for a number of sites that provide turbocharging information on the Zetec. If you’d like me to add a link, please mail me. |
Lowering compression | |
You need to lower the compression ratio of the engine to run a turbocharger at boost exceeding around 6psi.
There are several methods of doing this:
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Spacer plate: This is typically a laser cut steel or aluminimum plate which sits between the block and head and effectively increases the area which is not swept by the pistons. One method of fitting involves using a second headgasket which is generally considered unsuitable for applications running boost above a certain level (typically around the 12-15psi mark). Another method is to bond the spacer plate to the block and use only one headgasket. Although theoretically stronger, extreme care must be taken to keep the metal-to-metal mating surfaces perfectly clean. The website which detailed this method of lowering compression made it clear that they did not intend to run high boost levels either. More information can be found at Richard M and TonyPastie’s Zetec-Turbo website which is extremely informative and well worth a read.
Skimming: Skimming standard (cast) pistons is really a no-no with one exception: the early 1800 Zetec pistons fitted to the Series 1 and 2 engines ("DOHC" or "Zetec 16v" on alloy cam cover) were cast a lot thicker than normal and careful skimming on a well set-up engine has produced some reasonably strong, reliable engines. The Series 3 pistons can also be skimmed but doing so removes the teflon coating from the surface. Otherwise, most people have heard the horror stories of holes in pistons and ruined blocks, heads and turbos from a piston going postal. Skim at your own risk.
Forged low-compression pistons: This is the only way to go if you want strength, reliability and the ability to handle high-levels of boost. There are plenty of other things you will need to do to make your engine extremely strong, but low compression forged pistons from the likes of Mahle, or taken from another car, for example the Focus RS, Vauxhall Calibra Turbo, etc, are well recommended.
Unfortunately, low compression pistons might well be the most expensive part of your new engine, weighing in at anything from £400 to £1,000 for a set, depending on the manufacturer and quality.
Specialist engine building companies will be able to take the necessary work on to fit these parts and you should expect to budget around £800 to £1,500 for the engine block work to be carried out. This work will normally include a bore and hone, calculation of the existing compression ratio, any specialist engineering work required to fit the pistons (including, for example, modifying oilways), and a reface of the block and head mating surfaces which is definitely well recommended.
Since there is minimal difference between the cost of lowering compression on an 1800 and 2.0L Zetec you should always aim to go for the 2.0L engine unless you have specific reasons to want to go for the 1800. Note that the 1800 and 2.0L engine use identical head castings afaik. Note also that the Focus RS uses sodium-cooled exhaust valves in its head which retail at approx £23 + VAT from Fraud's. | |
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Headgasket | |
| The Zetec R’s 2.0L Zetec engine is said to use a metal-based headgasket and has been claimed to cope well up to 2 bar (29psi) boost. Alternative headgaskets are available from racing parts manufacturers although it isn't for me to suggest that one make is better than the other, at least until I can speak from some experience. The Focus RS headgasket may well be a reasonably cost-effective choice although I would be interested to know if it is the same as the n/a 2.0L item. |
Bottom end strength | |
| The Zetec bottom end is remarkably strong – much more so than the CVH in many respects. One common recommendation is the fitting of ARP con-rod bolts to improve the strength of the bottom end. Uprated strength con-rods and cranks are available. However, if you are considering going for serious power then a reputable engine tuner will be able to advise you on whether the above are necessary (or even a good idea!). |
Turbo oil feed | |
You have to provide a high pressure oil feed and low pressure oil return for the turbocharger. The oil feed is commonly provided by installing an oilway t-piece in between the block and the oil pressure light switch, and running a high pressure hose to the turbo. When fitting the engine, an electric oil pressure gauge is always a very good idea as is an electric oil temperature gauge fitted in the sump.
The oil return should drain back into the sump. Ideally this will be as close to the oil level in the sump as possible without being below oil level in order to prevent a restriction occurring. Aluminium welding skills will come in handy here and again a good engineering firm will usually be able to help you. |
Oil and water cooling systems | |
Your oil and water cooling systems will need some thought on how to keep temperatures down as the turbo will put extra heat into these systems. An aftermarket oil to air cooler will be handy, although a thermostatically controlled take-off which sandwiches between the oil pump body and oil filter should be used to prevent the oil being cooled too much. Alternatively, an oil-to-coolant cooler can be used, such as the item fitted to the FRST and some XR2i 8v engines. Although this won’t need to be thermostatically controlled, the cooling system will have to work harder to cope with the extra heat.
The water cooling system will also need to be looked at. The FRST uses a smaller radiator than it’s normally aspirated counterparts in order to allow the fitting of an intercooler and this is one of the main reasons so many FRSTs suffer from overheating problems. Also, the Zetec engine has a fan control switch mounted in the radiator, whereas the CVH engine has a fan switch mounted in the thermostat housing. You will therefore need to work out a way of fitting the fan switch on the Zetec engine or, better fit the Zetec radiator and mount an intercooler in front of the radiator. I am planning to fit a 2wd Sierra Sapphire Cosworth intercooler low down in my front bumper, and one or two slim radiator fans in between the intercooler and the radiator. There will not be enough room behind the radiator to mount a fan because of the proximity to the turbocharger. There is just enough space at the right hand side of the Zetec radiator to run the charge air pipework to the intercooler if it is mounted as mentioned above.
A recommendation of many experienced tuners is to disconnect the water cooling on the turbo - generally speaking this is safe to do as long as you allow the engine oil to warm up to temperature and cool down again after every run, but it is worth noting that the turbo will continue to spin after the engine is switched off and if it is excessively hot, may be more prone to oil carbonisation which can lead to premature turbo failure. On a water-cooled turbo, the water will continue to circulate through the turbocharger by convection as the turbo cools down even with the engine off. |
Inlet manifold | |
The Series 1 and 2 Zetec engines fitted in the Fiestas and Escorts used an aluminium cast inlet manifold. Problem is, they use side-fed injectors which are difficult to obtain in higher flow versions. Most people have either fitted the ERST/FRST/XR2i 8v/XR3i 8v Efi (not KE-Jet) inlet manifold using 2 spacer plates which an engineering firm should be able to make up by providing the relevant gaskets (or by Ian Howells – see links page).
Alternatively, you could fit the Zetec (SEFi) inlet manifold, which has much wider inlet strakes, by having a custom fuel rail made up and by relocating the Zetec idle speed control valve (ISCV). See Richard M and TonyPastie’s Zetec-Turbo website for more info.
The ideal would be to obtain the Focus RS’s inlet manifold, fuel rail, injectors and throttle body. If you manage this, well done! Otherwise, using the Zetec-R inlet manifold and throttle body from the Focus, along with fuel rail (it uses end-fed injectors) might well be worth a go, but attention should be paid to making sure the mating faces can handle positive boost pressures.
An alternative is the fitting of the Rover inlet manifold, again through the use of spacer plates. Several tuning companies can provide one ready to fit, although, like a tubular exhaust manifold, they are usually only really required when squeezing every last drop of power out of your engine or for looks. |
Management | |
| The EEC-IV FRST OFAB management is well equipped to handle high boost levels and is commonly available for around £150 for the ECU, loom and sensors, but will require a custom chip fitting to take into account the uprated injectors, higher boost levels and increased displacement. Alternatively you could opt for an aftermarket management such as Pectel, OMEX, etc (everybody has their own opinion on which is best and you will usually find that the management is what will make the difference between a potent engine and one that feels flat and lifeless, or worse unreliable). |
Injectors and fuel system | |
As I’ve mentioned, the Series 1 and 2 Zetec’s side-fed injectors aren’t really suitable for use in a turbocharged engine because of the low availability of higher flow variants. The more common end-fed types are often categorised by being either hig or low impedance and then by pintle colour to indicate flow rate (often quoted as ccs of fuel per hour) and the colour is often quoted as being suitable for a certain power output. As an example, beiges are recommended as the minimum level for a 250bhp (4-cylinder, 4-injector) engine, and blues for higher power outputs. Again, a reputable tuner will be able to talk you through the various types and recommend a suitable injector.
A high pressure fuel pump, for example a Cosworth item, will also be needed as a minimum requirement to maintain pressure at the injectors. |
Intercoolers and pipework | |
There’s a wide range of intercoolers available. 4x4 or 2wd Sierra Sapphire Cosworth items are a good compromise between size and cost and are widely available. The RS500 intercooler looks awesome when well fitted but can increase lag slightly and may be overkill.
Companies such as Pace make welded aluminimum intercoolers which are much stronger and can handle higher boost than the standard items.
As a minimum, an intercooler setup with twice the capacity of the FRST/ERST IC is recommended, but again asking around before buying is usually the best way to find out what works well.
Charge air pipework will need to be made up to connect up the air filter, turbo, and intercooler to the throttle body. Silicone hoses are available in many sizes and shapes from a range of suppliers, for example Think Automotive and stainless steel pipework is available from a wide range of sources. |
Breathing | |
| The breather system on the n/a Zetec engines isn't really capable of coping with forced induction and the block's front breather port will foul the turbo housing for most applications. Blanking off this port and fitting one or, ideally two breather ports at the back of the block above the oil level, plus an oil drain return below oil level, will be much more useful. Breathing from the cam cover may not be necessary with this uprated sump breather system and indeed may be a bad idea as the blow-by gases venting up through the oil returns is said to restrict oil return to the sump. An aftermarket oil separator with internal oil baffling is recommended to cope with the high level of oil vapour being expelled from the engine. Again, FiestaProjects provides more information and pics on this. |
Exhaust and turbocharger | |
You will need to consider what exhaust manifold you want to run. The ERST item flows comparatively well until your power figures are pushing the 300+bhp mark, although fitting requires drilling and tapping of the head which involves breaching oilways, and some people have reported oil leaks from the studs. An alternative option may be to have the T3 turbo flange welded onto the late-spec Mondeo exhaust manifold, or the use of a tubular item if budget permits. Again, the Focus RS item would be almost ideal, although this manifold puts the turbo a long way over towards the gearbox, so clearance is an important consideration depending on your choice of turbo. A custom downpipe will be needed to mate to a T2-designed FRST exhaust. The exhaust design is down to your choice but as a guide, past 2.1L 16vT conversions have commonly gone for exhausts of 2.5" to 3" bore all the way down.
Turbochargers are carefully matched to the engine they are used on, and a lot of money is spent by R&D departments in the motor companies. Again, consulting a good tuner is your best bet. As a guide, some of the best results have been reported from the use of a Saab exhaust housing on a T3 (again, see FiestaProjects) for more ideas and info. |
Cossie spark plugs | |
| The plugs fitted to the Ford Cosworth engines run cooler than the Zetec plugs. This is recomended to reduce electrode breakdown from heat and prolong the life of your plugs. Again, a bit of engineering on the head will be necessary and you may have to experiment a bit with your plug leads to get a good watertight seal at the rocker cover. Again I would recommend discussing this with your engine tuner. |
That’s all for now, but I will be updating this guide as I find out more.
Al
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Information contained in this article is also applicable to the 1600cc Series 1, 2 and 3 Zetec engines and may also be of help to owners of the Yamaha-Zetec engine as well.
Note that the power available from the 1600 Series 1, 2 and 3 engines is a lot less than that available from the 1800 and 2.0L Zetecs despite the conversion costing you around the same amount. A good 1800 or 2.0L block can be found for less than £150 and it's well worth going for one of these engines instead :o) |
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