Words and photos: Jon Hill 

 

HMM, VAUXHALL. DON'T MOAN, IT'S A GREAT UNIT AND MORE THAN WORTHY OF A CLASSIC FORD ENGINE SERIES IN-DEPTH FEATURE. Yep, OK, it's a General Motors unit and nothing to do with the big, bad blue oval. But, wait a minute, yes it is because what we're actually talking about is a Cosworth KBA. 

 

You see it's not just Ford engines that the Northampton gods worked their magic on. The likes of Mercedes, Chevrolet, Panther and yes, Vauxhall have all given Cosworth their own blocks or cars, for them to turn into fire-breathing monsters. What we have here then is a unit akin to the current Duratec HE/i4 which is gagging to have the nads tuned off it for not much money. Right now there's a freight train load of Escorts out there, all running and rallying Vauxhall XEs. What's more, you can pick up a unit for virtually buttons at the moment. So let's ignore what it says on the rocker cover and examine how to wring out an easy 200 bhp, squeeze it all the way to almost 300 and better still, get one in you car – you know it makes sense, even if it is GM.

 

 

General Motors has had a lot of success in rallying with the likes of Vauxhall Chevettes and Opel Manta/Asconas and as such built up a good relationship with Cosworth to do the business for them. So much in fact that, smack bang in the middle of the hot-hatch craze, they commissioned Cosworth to produce a twin-cam 16-valve head for their 2-litre 'Family 2' engine block, for fitment in the MkII Astra GTE. If you've ever had one, that car's a legend and capable of ridiculous top-end speeds, stock. The year of 1988 then, saw the car hit the streets with an all-square 1998cc, 156bhp stormer, that's subsequently been fitted to several other cars in the GM range albeit a couple of years down the line – Cavalier, Calibra and Kadett in the Fatherland. With introduction of the Cavalier SRi in 1992 however, the job of casting the heads moved to General Motors plants instead of Cosworth. With this came a downgrading in the material used – as such Astra GTE, early engines have 'Coscast' heads whereas later ones are GM – we'll discuss this in a seconds. There have also been turbo versions of both the Cavalier and the Calibra if you fancied an instant 200-odd bhp and four-wheel-drive versions too.

 

The XE dream though, all came to end around 1992-3 when it was phased out in favour of the more emissions-friendly Ecotech. this is actually very similar – in fact it has the same capacity of 1998cc. However, the head is different – although an XE head will fit on – while the internal components were downgraded in the just enough strength is about right' vein. It's easy to tell the difference between the two engines, though, apart from the fact that the Ecotech has Ecotech written on it. But if you find yourself staring at an engine with the spark plug cover missing, this component is straight on an Ecotech and cranked like a hockey stick on the XE. 

The XE has a cast-iron block with an alloy 16-valve head with belt-driven overhead cams, which are hydraulic in operation. The induction is on the left, which is of course fuel injection, while the exhaust is on the right. The starter motor is also on the left-hand side of the engine. All engines were meant as front-wheel drive units although there is also a 4×4 Cavalier and Calibra. The Manta 1800 block is virtually identical and will accept the XE head. However, more significant is that Mantas are rear-wheel drive and as such, parts can be used to turn the engine round the right way – for use in classic Fords.

 

There shouldn't really be a question as to which engine you've got since all XE's are 2-litre – kind of reduces the risk a bit. The block is the same as the eight-valve although there are around five different types with minor variations – chiefly these are in the oil ways and some slight differences in the water passages. However, it's worth checking you haven't got an 1800 block, which should have 1.8 cast into it, whereas the XE has 2.0. There is also a system of casting marks on the top of the block – HH or HG, followed by a number. This corresponds to the block version, i.e. HH1 being the first, these were produced up to HH9 and HG1 being the first of then going to HG4, with each block having improved over its predecessor. XEs have cast cranks and connecting rods although Coscast engines have forged pistons. These have flat skirts all the way round, which is different to cast types. Rev limit on a standard engine 7250 rpm, and bore and stroke is equal at 86mm.

 

As we've mentioned, early heads are Coscast and as such, have this cast into the rear – GM ones surprisingly have GM cast into them. There's absolutely no performance difference in either type of head, although, since the later heads are of poorer quality material, they are prone to problems with porosity. The main area for concern is the oil ways, of which there's three – two running down either side the length of the head, while the problem one's the single tract running across the head, in the middle of the unit. Specifically, where this gives problems is the centre head bolt area, which can be bored in manufacture so that there's little material between it and the oil way. Both Coscast, but more likely GM head can be machined like this but the downgrading in material quality seriously increases the problem with the latter casting. The porous casting can be sorted by either re-tubing or generally re-sealing the area but according to specialists SBD, nothing is truly guaranteed. the safest solution is to seek out a Coscast head and use that. You'll know when you have the problem, though – your water will go brown/mayo and you'll think you keep blowing head gaskets. 

 

Ports are big and don't need a great deal of work to release further power, although the main area for work is the port-to-throat area. Cams, as you'd expect on a standard road engine, are quite mild with plenty of room for improvements. However, the main concern is cam drive because there are two types depending on which engine you have. Basically, the later SRi (and onwards) engine has a square section to the bottom to the teeth, whereas early engines have a U-section. You obviously need to know which engine you've got if you're fitting vernier pulleys. The belt-tensioning systems also different on the later engines using two, closer together, idler pulleys in the centre which give more wraparound of the belt round the exhaust pulley. Of further consideration is the method of ignition because there are two main types. Early engines use a distributor, which is driven off the back of the head via the exhaust cam – it's therefore longer than the induction cam.

 

 

However, later SRi engines use a crank trigger, which is 60-minus-two-teeth type and fitted on the end of the crank, internally. There are again two types of these as well. Ideally, you need the early type since these are machined from one-piece steel whereas the later types are pressed steel and crack. The ignition question is a concern, which we'll discuss later on, since the distributor clouts the bulkhead of a classic Ford when turned the right way. For classic Ford purposes, all the rest is junk – induction and especially exhaust which is truly restrictive in standard form. Since this is front-wheel drive anyway, you;ll therefore need a new one.

We mentioned earlier that the XE was very similar to the current Duratec, which it is, in that to gain superb horsepower all you really need to do is swap the induction for carbs/throttle bodies and the exhaust for something that's better flowing and less restrictive – then you've got an easy 180 bhp. In terms of straightforward, cost-effective power then the XE's stupidly cheap, although there's plenty more available, all the way to nearly 300 bhp in normally-aspirated form.

 

Power and Torque 

Model	Bhp/rpm	lb.ft/rpm
Astra 16v GTE	153/6000	150/4800
Astra GSi 150 PS	147/6000	144/4800
Calibra 2.0 16v	147/6000	144/4800
Calibra Turbo 4×4	201/5800	206/2400
Cavalier MkII Sri	147/6000	144/4800
Cavalier GSi	147/6000	144/4800

Blocks are tough as old boots and of no real concern. However, the oil feed to the head can get blocked up and most specialists such as SBD modify this area. Basically, the oil feed consists of a ball-bearing device which gets stuck so it's removed, the hole blocked up with a bung, through which a 3/32 inch hole is drilled – the head doesn't need much oil in these engines. Extra capacity potential is there and pistons are available up to 88mm, which is maximum bore. This will give 2.1-litres and plenty of torque, although the most common is an 87.5mm combination for several reasons. First, standard head gaskets are available to this size and second, it still gives room for one more life in the block before it dies.

Again, most components of the bottom end are very strong, and there's not much worry on the crank side unless you're doing serious racing where steel ones are available. It's true, though, that earlier cranks are heavier – the balance weights are a different size – which is good for idle although they'll need lightening in a serious engine. Rods too are I-beam and capable of abuse, although the bolts are the main weakness. It's because of these that the rev limit is 7250. Swap these for Cosworth/ARP and you'll safely raise that by 500 rpm. Again, further revs and racing and you'll need steel components. It's common to use these rods to around 235rpm and SBD has used them to 250.

 

Coscast engines use forged pistons, which can be retained successfully with higher lift cams – a safe cut-off point is anything hydraulic – start going solid lifter and you'll need to swap to better pistons. The same watershed applies to the rest really. The problem is the valve cut outs, which are only around 0.5mm and need to be deepened by 2mm to cope with extra lift. This is a maximum on these pistons since the crown is quite thin. The cast type piston isn't suitable for pocket deepening and therefore isn't used in performance engines.

 

We've already discussed the potential problems with the head so most stick with the Coscast version to steer clear of these. There's no performance gain though, which only comes from mild port work plus the usual head modifer's tricks in the throat area. Certainly, Andy Weston of Cylinder Head Developments concentrates on this area but admits that he dramatically opens up the inlet side, while the exhaust is opened 'to the gasket line'.

 

It's in the port-to-throat area that the most work is done, as this tends to close up a touch. Andy opens this out but also leaves certain angles in to direct the flow round the back of the valves more efficiently. Most heads can retain the standard-size valves, although it's best swap these for better stuff such as Paul Ivey stainless jobbies, made from 214N. Everyone knows that these are a work of art; seriously waisted, super-slim stems and thin seats – Andy uses 1mm inlet and 1.5mm exhaust. For ultra performance, you can raise valve size to 1mm bigger all round – 24 and 30mm respectively, although Andy does do a head, which he calls his Racer, which has plus 2mm all round valves. These need bigger seat diameters and a subsequent increase in head machining to cope.

 

The standard compression ratio is 10.5:1 and the chambers can be reduced by skimming the head, although you'll need to deepen the oil feed as well. As a guide, 7 thou removes 1cc from the chamber volume, but the CR you'd need depends on the cam you're running.

SBD has its own series of around 12 different cams. However, they're very similar to Kents profiles ( they've just been tweaked to SBD's Steve Broughton's preferences). Mostly these have different duration figures on each cam whereas Kent's seem to be the same for the pair. As a guide, SBD's hydraulic 'road' cams will release up to 225 bhp on tapered throttle bodies and 200 bhp on carbs – you should this on a fairly standard head combination – i.e. porting and standard-size valves.

 

A pair of race-spec cams such as Kent's AST1616 with 314 and 296 degrees duration or Piper A16VBP320M (although these have less duration but a similar lift) or SBD CM16V1195/304 should release power to at least 280 bhp depending on compression. The most SBD has got was a tad shy of 300 bhp.

It's safe to say that most people would really only look at an XE with a view to binning the standard induction. Inlet manifolds are available to fit either DCOEs or parallel throttle bodies, while for the ultimate, SBD can supply tapered throttle bodies – these need their own inlet manifold however, since the units are individual. Standard size is 45mm for all units. Obviously, if you're fitting a Vauxhall in your car, the distributor is a big question, so if you're swapping induction it's probably wise to switch to crank-trigger ignition at the same time – we'll look at the distributor removal in a second.

 

Consequently, you'll need an aftermarket ECU system to complement your induction – ignition-only with carbs and full engine management with throttle bodies. As we've discussed, a standard Vauxhall crank trigger is already available. Obviously ECU choice is personal, although SBD favours its own MBE units, while others use DTA, Emerald, Weber Alpha, Omex, the list goes on.

This area is a true restriction and there's loads of room for power gains, while the standard manifolds are totally unsuitable for rear-wheel drive anyway. The choice is already quite large for aftermarket performance stuff – SBD stock manifolds are 4-2-1 configuration also of equal length (although these are mainly for kit cars). Ashley has manifold on the shelf specifically for the XE-into-Escort swap. This has 1 inch primaries, 2 inch secondaries and a choice of either 2 or 2.25 inch tails. These are meant to slot into an Ashley Escort system – easily sorted. If it's the ultimate you want, though, Simpson Exhausts can make you bespoke, super-sexy performer at reasonable cost.

You can slot a Vauxhall in your classic Ford quite easily since SBD stock a universal kit that chassis mounts the engine – it's quite cheap too. The standard Astra sump is actually at the back of the engine, although it's really Manta parts you need to properly sort the conversion. This unit alloy and has big wings to further increase oiling. They are getting scarce now but use your head and they aren't impossible to find. It's an expensive option but SBD and Pace also do dry sump kits for these engines too.

 

Other considerations are gearbox adaptation and again you can use a Manta box, although it's only four-speed and has an integral bellhousing. It's not particularly strong and the ratios aren't particularly good. SBD again stock parts to the rescue; it stocks an alloy bellhousing available to adapt a Type 9, five-speed to the engine, which of course allows gear kits to be used too. As far as a clutch goes, the standard Vauxhall pressure plate is retained, although you'll need a special clutch plate with Vauxhall outer and Ford-splined centre – SBD can sort this though.

 

Next is the distributor question, which can be sorted with Manta parts and a custom-made bracket but we'd recommend using a crank trigger from an early SRi – the machined type – and blocking up the distributor hole. This needs some thought because you can't just lop the end of the cam to suit – there's an oil feed that runs up the middle that need sorting. The easiest way is to fit an aftermarket fast road cam – as if you needed an excuse. Or, you can drill and tap the end and Loctite a suitable bolt/bung in there.

 

Ideally, you'll also need the rear flanges on the head machining flat and an aluminium plate made to cover the area. As far as the rest goes, you might have to dress the lip back on the bulkhead for clearance. You should get away with a standard Escort radiator for mild engines while there's plenty of performance alloy types that'll slot straight in from the likes of Pace and Prefab.

 

So. the ideal engine you need, then is an Astra GTE, Coscast unit, with steel crank trigger and distributor conversion.

 

Reproduced with permission from Classic Ford Magazine