[tpepmeie]

Well, I know Dom started a thread on this already, but I am blown away by what GM has done with the LT6. To get 670 bhp from 5.5L is astonishing. Flat plane crank, as has long been known. But, mechanical valvetrain with what appear to be finger followers. Valve sizes and cam specs not disclosed. Bore is 104.25mm, or approx 4.100". Stroke must therefore be in the range of 80.5mm (3.170") for 5.5L.

For comparison, i've calculated the hp/liter, and the BMEP at the rated peak power and peak power engine speed for a handful of the highest hp N/A engines.

LT6....121.9 hp/L....12.98 bar BMEP at 8400 rpm
Ferrari 458 Speciale.... 132.8 hp/L....13.20 bar BMEP at 9000 rpm *** Highest specific output N/A engine***

458 Italia....125 hp/L....12.43 bar BMEP at 9000 rpm
Porsche GT3 RS....130 hp/L....14.12 bar BMEP at 8250 rpm
Merc SLS AMG....100 hp/L....12.11 bar BMEP at 7400 rpm
Ferrari 430 Scuderia....117 hp/L....12.29 bar BMEP at 8500 rpm

So, it appears they have succeeded in the highest absolute hp for a N/A V8. But not quite the level of specific output of the 458 speciale, which is probably the pinnacle of production N/A engines.

For fun, a 368 LT5 would have to produce:
685 bhp on the engine dyno @ 7500 rpm to equal the BMEP of the LT6
(assuming a very conservative 4.5% difference between the steady state SAE certified conditions with full accessories and exhaust compared to the normal aftermarket Superflow STD conditions and open headers)

for a 415 LT5:
775 bhp on the engine dyno @ 7500.

for a 427 LT5:
800 bhp on the engine dyno @ 7500.

I only wish they would release this as a crate engine!!!!
Todd