Building a 2.0 Duratec for 260 bhpLast on December 31 2015
I intend to rebuild the 2.0 Duratec engine in my Mk1 Fiesta....
I suppose I'd better start with the reasons why, so I can justify pulling a perfectly good working engine apart.
Reason 1: I'd like more rpm, for a higher top speed, better acceleration (fewer gear changes to get to 60mph)
Reason 2: I'd like more torque, for pulling the car up the steep inclines at some of the UK hills. Loton Park being a particularly steep hill in places.
Reason 3: I need more power to compete with the ultra high performance cars already in my class.
Reason 4: Reliability. I am revving the standard engine, on standard internals, to 7600rpm, and although I am running ARP rod bolts on the Ford conrods already, the rods are considered a weak link in the engine, and I'd hate to ruin a block from a breakage.
Note: Brake horsepower (bhp) is the measure of an engine's horsepower before the loss in power caused by the gearbox and drive train.
So lets just think about what the options are for the Duratec engine
I could go for a turbo charger. That would still require the engine to be rebuilt. I would need to lower the compression ratio, and fit a stronger bottom end to cope with the torque and power that a Turbo generates. I however, am not a great believer in turbo charging an engine. The extreme heat that a turbo charger generates, stuck underneath the bonnet (hood) just soaks in to everything around it, and contributes to component failures and reliability issues. I've seen turbo charged engines on saloons at hillclimbs, and they appear to be all or nothing with a very sudden power delivery. Hence they're not popular. Nick Mann's home built hill climber is the only real application of a turbo charger that appears to work properly in hillclimbs. He uses a Helicopter Auxilliary Power Unit, which runs at 100,000 rpm, and the exhaust gas from the APU drives the turbo, which effectively provides full boost, all of the time. This is a good solution for hill climbing. The BDA engine exhaust gasses are not used to spin the turbo, and the engine is therefore freed up to produce incredible levels of power, lag free. However I am not an aero engineer and I wouldn't have the faintest idea where to start with such an installation. And I'm not a fan of turbo lag on a conventional setup, nor the pipes, wires and plumbing required to get a turbo to work.
I could go for a super charger. These clever bits of engineering are belt driven, and therefore as the engine speed increases, the air pressure provided by the compressor also increases, in a fairly linear manner. They often also require an engine be rebuilt to lower the compression ratio (to avoid detonation), and have one major draw back. And that is driving them from the crankshaft. In my Mk1 Fiesta there is precious little room for any additional belts and gizmos, and although there are kits to supercharge the Duratec readily available (for example Pumaspeed have off the shelf kits for the Mk6 Duratec fiesta), I simply dont have the room to install one. And once again, they introduce more pipes and wiring, and potentially, a level of unreliability.
So the next option is simply to rebuild the engine, to increase the compression ratio, change the cams for high duration and lift race profile items, and port the head to encourage better flow of air in to the engine, and encourage the exhaust gasses out.
Given I already have a very good exhaust manifold, made by Tony Law, and a set of direct-to-head Titan roller barrel ITB's, I think its best to spend my money on the components that spin inside the engine, to allow it to rev higher (8200rpm), and to make more effective use of those higher revs, without introducing lost of external parts, weight, and potential reliabiilty issues.
Gathering the parts (February 2013)
After some discussion on Turbosport.co.uk I've taken the advice of a couple of fellow Duratec engine enthusiasts, and I've started going down the path of a 260 BHP budget build.
For the build project, I shall be using the following parts:
K1 Duratec conrods (supplied with ARP rod bolts), FH5758BRF, from www.part-box.com
Supertech 12.5:1 compression race pistons (and rings) P4-DU875-P7, from nolimitmotorsport.com
Cosworth CAMSHAFT DURATEC HE I4 250/280BHP INLET YD0718
Cosworth CAMSHAFT DURATEC HE I4 250/280BHP EXHAUST YD0719
Dunnel engines single valve springs
Dunnel engines water pump cover
Engine purchased (March 2014)
I have bought a brand new 2.0 Duratec block assembly, and this will be the basis of the new engine.
Fortunately on my 2008 Fiesta ST Duratec, there already sits the 'High Flow' Focus cylinder head, as can be identified by a casting number RF3S4G on the rear of the cylinder head (Exhaust side). Engines without the High Flow head make 10-15BHP less, and require more work to produce the same BHP. (See the article here how to identify your head).
This means that the head needs very little doing to it to make the 260BHP. Just double valve springs for the race cams, and simple port matching should do it.
When I say I'm aiming for 260 BHP, it is just that. I aim to reach 260 BHP. I'll be suprised if I make that much, as its very dependant on the fuel used, induction, exhaust, and mapping. So anywhere between 240 and 260 BHP would be great. So long as I end up with higher rpms, and more torque, I'll be happy.
So this is where I am. I'll document everything I've done, lessons learnt etc, as I go along.
I've created a Picasa album for all the engine rebuild pictures. The album can be accessed below:
|Duratec engine build 2013|