fingers99 wrote:Almost certainly some combination of the above.
All the talk is that these engines are less amenable to tuning than the old Fiat twin cam and the 20v Coupe engine (which a few people have put into HGTs).
I think the final set of BTC Alfa 155s used the 2 litre version of the Alfa/Fiat twin cam -- the precursor of your engine. It would be interesting to know how much power they were putting out -- they were fast enough to be the car to beat.
The 155 BTCC used a 16V head like on the Delta 16V and an 8V engine (no balance shafts). The head was reversed so the inlet ports would be on the front of the car. It's a totally different engine and the rebuild time on those was 30 running hours max. Usually, they would start each race with a fresh engine, or have it used just one race before. A 280 BHP figure for a 2.0 sounds impressive, but is not comparable to something you'd put in a car you are driving on the streets and that has to last for more than a week.
Try the (Dutch) Alfa 156 challenge, they had roughly 200 BHP from "almost street" engines and I know of a road car that had one of these engines put in after the competition ended. Almost street still means fully flowed head, custom cams, and custom exhaust. Mind you, that's a 2.0 and this HGT engine isn't. It is however almost identical, minus the CCs and 4 spark plugs for the Twin Spark in the Alfa.