Does an increase in airflow (intake or exhaust runner) move peak torque up or down the RPM band?
Or is the torque band strictly dictated by engine displacement and camshaft?
Let’s start by keeping it simple. An apples to apples comparison. We will take the engine, any engine, in dead stock form, dyno it, get the graph then run it again with headers as the only change. For simplicity, we will say both engines have a 2-1/2 H piped exhaust system properly connected to the exhaust manifolds & headers like you would in a car. Each engine tuned for each system tested.
The headers will increase power on both the Tq. & HP due to the improved breathing. With the efficiency going up, from start to finish, the light will shine best at the top side of the run. Headers alone will increase the power and add a few RPM to the curve due to the increased efficiency of breathing.
Adding an upgraded intake will also increase power all over for the same reasons as I said above. If the air pump can breath in easier, then the power and rpm band will increase slightly.
The camshaft dictates the rpm band in which the engine operates in. Again, starting at the top like we did with the headers first and intake second, the only change is the new cam is installed first for testing, the cam will changed the operating rpm band but also show a power gain because (most of the world) goes with a bigger cam. Adding the exhaust and intake will only up the anti.
If you have a dead stock engine and your looking for mileage gains, then of course the bigger cam is skipped but the intake and exhaust can still be upgraded will good results.
Retuning the carb & ignition for best results along with a multi spark box will show good improvements.
Don't believe the need for back pressure myth. Size the exhaust tube for intended power output.
