To be honest I'd need to research how a Honda C engine reacts to the balancing effect of single pipe versus the splint bank design,
Joining the exhaust banks makes for a more balanced flow between banks although position, piping and diameter are critical.
V6 engines like ours generally run 6-2-2 or 6-2-1 in OEM, 6-2-1 being technically cheaper and would in basis be more high revving that a 6-2-2 that would make more torque but weigh and cost more.
Now how that translates in to real world figures on a NSX is something that would need some further calculating, (see how the exhaust pulsations and firing order align between banks)
I'd need to dig up my notes on Acura Legend exhaust design as i recall 6-2-2 with a X pipe improving torque down low versus there standard 6-2-1 layout.
The odd firing character of the V6 and especially our '90 degree ones make it a tad more complicated.
A Straight 4 engine running a conventional flat plane crank would require 4-2-1 for optimum balanced performance & torque, although a long primary 4-1 setup improves high RPM capability and max power.
Cylinder numbers 1 & 4 are joined down line and 2 & 3 are joined as the first merger of the primary runners, secondary would combine 14 and 23 together (generally near the oil pan of a transverse engine)
Straight 6 engines must run 6-2 manifold setups to give satisfactory performance due cylinders cross breathing badly in 6-1 manifolds, then you'd traditionally run a 6-2-2 without H or X pipes.
Although there are examples by Toyota and I recall on classic British cars running 6-2-1.
A V12 can be seen as a dual straight six although often running 12-4-2 exhaust lines, Older V12 Ferrari's have very heavy 12-4-4 layouts.
V8's in traditional American/German cross-plane layout run differently to straight 4 engines there heavily off set cranks & firing orders negate the need for 8-4-2 manifold and thus nearly all would run a 8-2 manifold in performance applications,
Most V8 cars have 8-2-2 exhaust systems, often with H or X pipes in the middle to balance the left and right bank this improves smooth running and torque curve.
Side pipe's on for example a old Big Block Corvette run a 8-2-2 setup with out any gas equalization, you can hear the much rougher idle as well.
V8's in Italian/Racing flat-plan configuration are comparable to two straight 4 engines driving a common crankshaft, as you'd see on a Ferrari's and certain GP engines they run a 8-4-2 layout with each cylinder head having a 4-2-1 crossed layout.
These engines have very high RPM potential and very low rotating mass yet do suffer from low torque out put in low revs and higher idle speeds, this makes these engines undesirable in anything other than a race or sports car.
Boxer engines run different yet again on a H4 you'd run 4-2-1, there isn't any cross breathing as the engine runs in a crisscross pattern canceling it out.
I'm not going to bore you guys further with inverted induction engines (like new BMW V8's and 1.5 V12 Honda engines) these have the exhaust on the inside and the intake placed on the outside.
Last edited:
