Turbo and inlet
The turbo dominates theYB like a massive anchovy on a baby pizza, and many people think it is the business end of engine — when in reality it is just another component, and as such needs to be carefully specced to work with everything else in the engine.The standard GarrettT3 found on the Sierra and Sapphire Cosworths is good enough to see you with around 300 bhp, and tricks like cut-back blades, and 360 degree thrust bearings will all help improve performance. The traditional upgrade is the Escort’s larger T34 turbo, which can be utilised to give 350-400 bhp. From there aT38 hybrid will see you well into the 400s, and aT4 robbed from the RS500 will take you the rest of the way up to 500 bhp — these upgrades have been proven to work time and time again with great results, but with the development in technology and newer turbos now available the choice has opened up even further.
The roller-bearing GT range of turbos have been used to great effect on theYB, and the new Borg-Warner series of turbos are also going down well.With so many custom options available turbo choice is virtually endless and it is best left to the experts to decide what will work best with what. On the other side of the engine, the inlet manifold choice has also improved over the years.To start with the RS500 eight-injector manifold was a must, then the ‘Swedish’ inlet was everyone’s fancy, and now nearly all big-bhpYB builds feature a Hart inlet.There are slight differences in performance between them, but all that really matters is that they all perform much better than the standard inlet which becomes a restriction at around 500 bhp. Roller barrel throttles have also been used to good effect in many applications, but as they were only ever designed to work on 300 bhpWRC cars when you start to push enough air for 500 bhp and more through them they don’t like it.Another option is to fit a set of individual throttle bodies which can be used with a plenum chamber — these will have performance advantages but considering a single throttle body gives such good results they are only used when people are looking to eke out every last bhp possible.
“THE TURBO NEEDS TO BE CAREFULLY SPECCED TO WORK WITH EVERYTHING ELSE ON THE YB”