OVERKILL
$100 Site Donor 2021
Originally Posted By: turtlevette
Yep, I see it. It's more of an oblong chamber so the piston will come real close to the head on both sides. The dual spark plugs must help too. With valves that big you'd think they would out power the ls engines.
As has always been the issue with the design, even with a quench area, meeting power targets whilst maintaining acceptable emissions and drivability is a serious juggling act. The dual-ignition is part of that formula but I would hazard camshaft design is more of a compromise in this platform than it is for a wedge. The huge valve area and ports probably have poor velocity characteristics at lower speeds which hamper emissions performance and I know historically did, due to poor low-speed swirl, for both Ford and Chrysler back in the day with their fully hemispherical chambers, cause serious low-speed performance issues. That was the primary reason the street version of the BOSS 429 had a small quench area on one side of the chamber.
I would posit that Ford has similar issues with the big 6.2L "cammer" which shares a very similar chamber design. The BMW DOHC mill on the other hand, with the 4 smaller valves and full pent-roof style chamber would have superior low speed fill and velocity characteristics. Also, with the ability to manipulate both intake and exhaust camshaft profiles independently, can be more finely tuned throughout the power band when compared with a cam-in-block setup.
Now, you add boost to it and all of a sudden you seriously change things. Hence the 840HP Demon. I have no idea what the stock ceiling is on that mill but an honest 840HP emissions-legal engine is wild.
Yep, I see it. It's more of an oblong chamber so the piston will come real close to the head on both sides. The dual spark plugs must help too. With valves that big you'd think they would out power the ls engines.
As has always been the issue with the design, even with a quench area, meeting power targets whilst maintaining acceptable emissions and drivability is a serious juggling act. The dual-ignition is part of that formula but I would hazard camshaft design is more of a compromise in this platform than it is for a wedge. The huge valve area and ports probably have poor velocity characteristics at lower speeds which hamper emissions performance and I know historically did, due to poor low-speed swirl, for both Ford and Chrysler back in the day with their fully hemispherical chambers, cause serious low-speed performance issues. That was the primary reason the street version of the BOSS 429 had a small quench area on one side of the chamber.
I would posit that Ford has similar issues with the big 6.2L "cammer" which shares a very similar chamber design. The BMW DOHC mill on the other hand, with the 4 smaller valves and full pent-roof style chamber would have superior low speed fill and velocity characteristics. Also, with the ability to manipulate both intake and exhaust camshaft profiles independently, can be more finely tuned throughout the power band when compared with a cam-in-block setup.
Now, you add boost to it and all of a sudden you seriously change things. Hence the 840HP Demon. I have no idea what the stock ceiling is on that mill but an honest 840HP emissions-legal engine is wild.