news for those still vaguely interested..
the car is at barbz where he is fitting a standard modded manifold and a bit of kit we are hoping is going to make our life easy..we have a solution that as yet i think no one has used in uk.. we got it from usa and apart from a drag bike there is no other known use(we could find or any turbo company i spoke with whilst trying to buy one over here ,can find) of this set up.. so we may break new ground for coupe tuning ..the only problem will be the manifold..as yet we don't really know what its limits are..we soon will! whatever the car makes we will run it at that untill we can get a definate gaurenteed 600+ capable manifold built by whoever can gaurentee thiers will make the power..anyway this solution will be great for the 2l as it will give quicker spool than your standard set ups with far better boost control and allow the turbo to give its all without having to resort to a bigger housing...watch this space for results week after next..
on another note i have something to add to the debate regarding whether a 2l will be putting the same amount of gas through a manifold as a 2.5 to reach the same power..
ihave been speaking with a well known turbo builder/supplier who assures me they do not.. he went on to say he does a lot with subarus and when he puts a 3076 on a 2l he achieves 480 or very close everytime with his given set up..when he does same on a 2.2 he gets about the same usually a few bhp less but when he puts same set up on the 2.5's he struggles to get 430! but gets loads more torque as it chokes the turbo, when he fits a bigger housing then the turbo gives more the 480 as it can then flow the extra gasses..his words not mine..he thinbksd the manifold designed for the 2.l may well do 600 but with a 2.5 not as it caan,t shift volume of gas...can anyone explain to me whats going on in that real situation he comes up against every time he works the 2.5s? if they make same power with same gasses?

rmouthaan...i am 100% sure they can make what i need, thier fabrication and materials are top drawer but it's the design i am not sure on .. if i say just do what you think will work.. and it doesn't.. i am spending a load more money i can't afford to waste.. so it needs to be right ..unfortunaterly there is no concensus and everyone seems to have there own ideas..i am trying to absorb all i can so as to make descisions and give them some instruction..thanks for the good will.

I think you have answered your own question. He only swaps the housing to make the same power on a 2.5 litre - which also makes more torque. So, from what you have just written, the manifold MUST be able to flow 480BHP on a 2 litre, 2.2 ltre and a 2.5 litre as the ONLY thing he changes is the turbo housing.

you mention POWER, rate of doing work...

you don't mention revs ?

thus a larger cap engine will make more power lower revmlikem for like, thus choke itself higher up ? No ?

I agree, BHP is a measurement of power which is the rate of doing work. So, I don't need to mention revs as we are talking about a BHP limitation, not a revs limitation of the exhaust components including the turbine and housing. Though it is obvious that ALL OTHER THINGS BEING EQUAL a 2.5 litre engine will make the same power as a 2 litre engine, at lower revs. Having said that, the amount of fuel consumed per unit of power, and therefore the amount of air consumed, and as a consequence the mass of exhaust products per unit of power, will be the same for a 2 litre engine and a 2.5 litre engine producing the same power.

If this wasn't so, a 2.5 litre engine would consume more fuel per BHP than a 2 litre engine per BHP, so the BSFC would be 125% higher in the larger engine. This plainly isn't the case.

what i was hoping someone would explain was why the housing has to be swapped and why it cant make power with a smaller housing when a 2l can.. he hasn't got manifold issues so that wasn't my point

taz he did mention he works on some cosworths that rev to 9k and explained something relevent about revs which i have duly forgotten but there was a connection with the housing issue..
sorry not much use that i know..
we do have something up our sleeve that will be right up your street though..