History

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 strenght 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.

Tuning

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.

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 weaknes. 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.

Head

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.

Induction

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 probabley wise to switch to crank-trigger ignition at the same time - we'll look at the distributor removal in a second.

Consquently, 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.

Exhaust

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 amaifold 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.