The P51 models normally thought of had Rolls Royce Merlin 1650 cube V-12's.The earlier P51's had Allisons 1710 cube V-12's.By the way,V type aircraft engines are called inlines.Merlins and Allisons can turn over 4400 rpm and produce upwards of 4000 hp for short duration racing.Thats with 100 Hg of supercharger boost and 6 inch stroke.
Let's look back at fairly hi performance inline 6 cylinder engines,not the new ones with variable cam and induction systems.
What comes to mind is Jaguar,early Datsun Z cars,BMW's and the 3.0 liter 6 used in the Austin Healeys.Did these engines use crossover pipes? I'm not 100% sure,but I believe they all did,either 2 into 1 with a single exhaust or 2 pipes with a cross over.The old Jags in particular were very fast in their day,about 250 real stock HP from an ancient DOHC long stroke from 3.8-4.2 liters.The original 240Z sohc engine was good for 150 HP from 2.4 liters. The BMW's had similar HP from various engine sizes.This was back with crude combustion chamber designs and mild cams by todays hi po standards.
Do ya think these engine designer knew something?
