TECH FEATURES INSIDE THIS ISSUE:
Getting technical with the best in the business. Here’s everything you need!
Block and internals
The general consensus from the tuners we spoke to was basically to leave the bottom end alone.The standard block and internals aren’t bomb proof, but are more than adequate to cope with mild increases in power and torque. Of course, aftermarket forged con-rods and pistons can be fitted for out-and-out race engines, but for most people with fast road cars this is just overkill – plus if you’re going to that much expense you’d probably be better off starting out with a better-performing engine in the first place, such as the Cosworth 24-valve unit.
One issue worth addressing is engine revs. Both the 2.8 and 2.9 can rev safely to around 6000 rpm, which can be increased to over 6500 rpm with the addition of shot-peened con-rods and ARP bolts, but the potential consequences of overrevving the V6 means an aftermarket rev limiter is a wise investment.
As both the 2.8 and 2.9 have the same bore size, both can be increased marginally to slightly increase capacity, about 1 mm overbore is the excepted limit.This will give slight improvements but it does require aftermarket pistons. Some money can be saved by using 94 mm items originally intended for the Pinto but it will require some machining to get them to fit.
The biggest capacity gains come as a result of stroking the bottom end – this has been done in the past by
The earlier 2.8 (and 2.3) versions differ significantly from the later 2.9 versions.The main difference is that the earlier engines featured siamese exhaust ports, which are clearly visible when you look at the exhaust manifolds; they only have two headers!The 2.9 heads have three exhaust ports each.There are other minor differences such as the way the camshaft is driven (gears on 2.8, chain on 2.9) and the fact the 2.8 has a slightly shorter stroke than the 2.9.The next major difference is the induction systems: the 2.8-litre was available with either a carburettor or injection system, using the Bosch K-Jetronic set-up, whereas the 2.9 uses the Ford EEC-IV system — easily identified by the mechanical injection and square plenum chamber on the 2.8, compared to the twin MAF sensors and EFi plenum chamber on the 2.9. Both engines produce 150 bhp, but the 2.9 has more torque. Both engines respond well to similar tuning methods, but the two should be considered as completely separate engines.
either regrinding the original crankshaft, or fitting a modified version of the crank found in the Explorer 4-litre V6. Capacity can be increased up to 3.7-litres, and while it’s not quite as common a practice these days, Specialised Engines are still a good port of call to talk options.
It’s also worth noting that it is possible to fit the shorter-skirt pistons and con-rods from a 24-valve V6, which helps with engine revs — although this is a practice usually reserved for turbo conversions.
Heads and cam
As with most naturally-aspirated engines, the biggest performance gains can be found in the top end of the engine.The 2.9’s three-port heads are slightly better flowing than the earlier 2.8’s siamese exhaust port units. However both respond well to porting and a cam upgrade. Burton Power offers three different stages of tune for the 2.8 cylinder heads (they can also port 2.9 heads), as well as a selection of cam profiles.They reckon that a Stage 1 heads with appropriate cam will see around 165 bhp, but big-valve Stage 3 heads with a more lairy cam will see over 200 bhp.Tuning the 2.9 takes a similar path, and from past experience Burton say that it will be around 10 bhp up on the 2.8 at any given level of tune, due to the better-designed cylinder heads.
Induction
One of the biggest limiting factors of the Cologne engine is the standard induction system.The older technology of using a carburettor is actually the preferred method for many of extracting more power. The standard Bosch K-Jet system is awkward to tune, and the later EFi system from the 2.9 also has quickly breached tuning limits.You could bin the whole lot and fit a set of throttle bodies and an aftermarket management, but the expense involved means it’s usually reserved for competition engines. Road-goers are more commonly converted back to a carb set-up where similar power levels can be easily reached.