Using a pts flow bench to simulate engine exhaust

[gte]

So I just purchased the plans and while I'm waiting for them to be mailed ... I've been told that there is a provision in the plans to make the bench a positive pressure bench.

How conducive would this be to trying to simulate the exhaust volume of an engine? I'm theorizing that I can calculate the volume of exhaust flow, based on the amount of fuel used at an rpm, multiplied by the desired a/f ratio and then divided by the average of 33% of the potential energy in gasoline being wasted out of the tail pipe.

Does this sound reasonable?

[Otto]

but where are you taking into account exhaust temp, blow down timing, under scavenging or over scavaging, gas speed, pipe restriction, wave or mass tuning of exhaust. retarded timing will raise exhaust temp and change pulse timing by changing mass speed and wave pulse velocity.

Just food for thought

[larrycavan]

Interesting concept GTE. What exactly are you driving at? Is this is for header sizing or exhaust port development?

I'm not knocking your concept. I'd like to understand exactly what you're driving at for application though.

[gte]

I want to simulate exhaust gas mass flow to pressure and then see how different changes effect that, basically more of a question of how exhaust back pressure effects turbocharger response, and how the pressure varies inside of different manifold designs. Other variables will just be considered givens.

@ Otto, this is for a turbocharged application where scavenging vacuums created via pulses is not something that applies.

I cannot simulate gas speed and temperature will not matter in this case as I'm looking to baseline, and temperature will be close to the same in all ports, so having it at 1500F or 100F will just be a given variable either way, same thing with timing.

[blaktopr]

I'm going to just throw this out there. First for the heat. Would there be anything from a test if you were to put a heating element in the cylinder adaptor "tube" and recalibrate for that flow loss before installing the head or a basline "cold" before turning on the element? Not that it will be close to an engine but to see a change? And with the speed through a tubine, can there be a way to test velocity by the rpm of the wheel?

[gte]

I think that'd be worth trying after getting a baseline, to heat the air as much as possible, and then see if pressure readings changed with the heated air, I may be able to come up with a scale if so

[blaktopr]

Here is a way off base thing that may show exhaust airflow vs speed and how it responds through a turbine. And it may show head and manifold design efficiencies. If you were able to make a mini "dyno" for the turbo. Then after you made some changes and calculated flow and velocity. You record them and then put the turbo/turbine with dyno on. Go through the lift range and see the torque generated by your port for that particular trim. Or am I in dreamland! ???

[gte]

Yes, that's kind of what I'd like to do, and also possibly test for pressure differences across the manifold and tricks that can increase or decrease that

[jsa]