Hi All…

I’m pretty new to the whole ‘Cosworth’ thing, so please bear with me whilst I ask what might seem like pretty basic questions!
I’m not about to purchase a sierra Cosworth, but am seriously looking into using a YB_ for powering my next road/drag racing project. I’m therefore after a ‘crash course’ in the facts and to dispel some dubious rumours I’ve heard about these great engines.

Firstly, what are the ‘official’ power outputs of the 2wd and 4wd sierra YB_ engines, and at what boost level was these power levels achieved? Also, what is the correct designation for the 2wd, 4wd and Escort Cosworth engines? I know they are the YB_ range, but just for interests sake, what is the last letter for each one!

Was the turbocharger, ex. Manifold, and inlet manifold the same on the 2wd and 4wd versions – if not, what were the differences, and were they all basically interchangeable?

Do all the 2wd and 4wd engines have valves / valve seats and ECU’s that mean they will run ok on Unleaded (Optimax) Fuel?

I understand the loom and ECU is different between the 2wd and 4wd. Why is this? Is the 4wd ECU more refined, is the 2wd ECU more easily tuned? Are the looms the same? Will the looms and ECU interchange (I assume they are all Weber/Marelli based???)

I hear the 4wd head is different from the 2wd. Is it a huge difference, is it better porting, larger valves, better cooling, thicker deck, etc? Is any better or more suited to bigger power outputs?

Block: what is the ‘205’ block that I keep hearing mentioned? Are all the blocks pretty robust for moderate power increases anyway?

Aside from fitting a ‘chip’ is there anything else that needs doing to achieve a reliable 280-300 hp – eg, rod bolts, head gasket, improving cooling, plugs, etc… Intercooling will not be an issue by the way, it’ll be much better than standard…

Finally, if I was to scour the small ads, how much do you reckon I could find a fully dressed engine in reasonable health for (i.e. turbo, inlet, plenum / fuel rail, flywheel, loom, ECU, etc)???

Many thanks, and apologies if it is stuff you’ve been asked a million times before!
Dave