Penguin
Active Member
we warmed up a p6 3.5 for a client with mildly reworked 4.6 heads ph1 newman cam, standard hifs6 with just the poppet valves removed and freeflow air filters in the standard p6 air box ( its going back to the USA so has to look standard) that produced a little over 200lbft and 173bhp.
the same engine now has had an upgrade, i swapped out the 3.5 bottom end for a 4.6 same cam, carbs, airbox etc, power only rose to 188 bhp, but torque is now an immense 288lbft @2600 rpm, im now worried about the rest of the drive train!
looking at the way the torque curve for the 4.6 falls away it is desperate for air, even with free flow cone air filters in the air box the air box on its own so strangling air flow so much that if you run it without the air box the AFR at light load changes for 12.5 to 17.1! obviously you could correct that but as the car cant be used without the airbox there was no point in going down that route. graph below for you enjoyment, 3.5 in red 4.6 in black
the same engine now has had an upgrade, i swapped out the 3.5 bottom end for a 4.6 same cam, carbs, airbox etc, power only rose to 188 bhp, but torque is now an immense 288lbft @2600 rpm, im now worried about the rest of the drive train!
looking at the way the torque curve for the 4.6 falls away it is desperate for air, even with free flow cone air filters in the air box the air box on its own so strangling air flow so much that if you run it without the air box the AFR at light load changes for 12.5 to 17.1! obviously you could correct that but as the car cant be used without the airbox there was no point in going down that route. graph below for you enjoyment, 3.5 in red 4.6 in black
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