me3@neuralfibre.com wrote:Obviously the resonance frequency matters (see 2 stroke petrol) BUT
I was thinkign of simple differential flow, and EGT's variance.
What in a petrol would lose you some power, in a diesel could kill the motor.
I would like to know which is more significant, flow restrictions, or resonance patterns.
I suspect the resonance would be the same boosted or not, but the points and benefits would change.
Boosted doubles the pressure diff between cylinder and manifold, so 10% from resonance is less critical (to my thinking)
Then again - 10% of doubled mass is still significant.
It would be interesting to measure EGT variance with OEM vs custom "adhoc" manifolds.
I know the 1HZ manifold has some "tricks" up it's sleeve for what looks to be a very small, simple log design.
Paul
anyone with an EGT gauge could help here, multiple probes in the exhaust manifold through a switch to select witch probe is being displayed on the gauge.
You would want to see reading from either the front 3 or back 3 cylinders.
Boosted engine where full throttle power is the concern out right flow and even flow would be the most important part.
Ford went down this path with it turbo 6cyl engine. The manifold looks the same from the outside but is not fitted with any of the runner switching hardware.
But with petrol engines air flow is limited to control engine speed, so any gain from runner tuning is pointless at cruise.
Diesel engines are different. they don't limit airflow at all (most not all diesel engines anyway). so runner/plenum tuning takes on a whole new role. Even if your engine makes boost at cruise speeds you could still benefit from a tuned intake. If you can get more air into the cylinder by good intake design the engine doesn't have to work as hard.
Obviously there is a lot to consider and it not something you can just knock up in a day and have it work. But thats not to say there is no benifit.
What in a petrol would lose you some power, in a diesel could kill the motor.
Can and does kill petrol engines too. port injected EFI will still go lean on the cyls getting more air.