scion header interchange?

[soros151]

Originally Posted by DTM_Yaris

This one is very wrong. Exhaust theory still applies. Regardless of the fact that it has a hairdryer attached to it.

Well, u would want the turbo to spool as fast as it can to achieve the boost u want. So there is no lag, if u don't believe me then, do the research, and then answer me back. It may not seem right, but u would need to deal with backpressure in N/A trim. For turbo, flow efficiency is the right point. Why do you think a 2.5" to 3" piping for a turbo tC (2.4) is a good idea? Because u need to let the turbo move the exhaust gasses faster to help spool time, also N/A needs thermal capacity in the piping to retain exhaust velocity, that's why backpressure is still needed. Go turbo... no need for too much backpressure since thermal capacity is there with the gases and temps from the turbo itself.

[DTM_Yaris]

Originally Posted by soros151

Well, u would want the turbo to spool as fast as it can to achieve the boost u want. So there is no lag, if u don't believe me then, do the research, and then answer me back. It may not seem right, but u would need to deal with backpressure in N/A trim. For turbo, flow efficiency is the right point. Why do you think a 2.5" to 3" piping for a turbo tC (2.4) is a good idea? Because u need to let the turbo move the exhaust gasses faster to help spool time, also N/A needs thermal capacity in the piping to retain exhaust velocity, that's why backpressure is still needed. Go turbo... no need for too much backpressure since thermal capacity is there with the gases and temps from the turbo itself.

I've done the research for many years. Actually since 1990. Ive been turbocharging for over a decade and a half. I am pretty sure I have seen and developed a few things in my time.
I think you are misunderstanding the term backpressure. There isn't an internal combustion powerplant in this or any world that wants or needs backpressure to make power.
If there is ANY backpressure in an exhaust system, then there is something wrong. Meaning something is clogged or capped. Completely restricting flow in one direction. Pressure "backing" up towards is original source.

Now exhaust capacity, harmonics, velocity, thermodynamics, etc are completely different terms to concider.
There is absolutely NO rule book on exhaust size or geometry. It needs to be mapped and trialed.
When FI guys discuss large diameter downpipes, it isn't to say bigger is better. On a typical turbo application bigger is NOT better. It is about differential pressure. The pressure on the inlet of the turbine in relation to the exit side of the turbine. The bigger the "downpipe" the better does not work. It makes absolutley no sense, because you still need velocity to get you thru the rest of the exhaust system as efficiently as possible. Of course without limiting capacity. The SIZE of the downpipe will depend on how much airflow you need to process thru the engine. That is the only determining factor. NA or not.

Normally NA engines like to be a bit more conservative on diameter because they need to scavenge thru the ports. Limiting, predicting and "organizing" the exhaust pulses in such a way as to increase volumetric efficiency. On some cylinder head designs with Identical displacement engines, primary runner and collector sizing can vary 1/2 to 1 1/2 inches.

Again there isn't any concrete "this is what you need for na" rulebook on exhaust systems.

[DTM_Yaris]

Originally Posted by soros151

Well, u would want the turbo to spool as fast as it can to achieve the boost u want. So there is no lag, .

It doesn't matter if you have absolutely NO EXHAUST you will NOT get rid of "lag".
It is inherent to the size and design of the turbocharger. It takes heat energy to spin the rotating mass.
Heat energy needs to expand on the turbine blade. Having a two inch downpipe and having a 5 inch downpipe will not get rid of "lag"
Boost threshold (turbo lag) is dependent on the engines ability to produce the required energy to spin the turbine.
Now CAN you decrease the "lag" time slightly with a better pressure differential? Yes you can. If the ENTIRE system that is on the car is restrictive. By increasing the size of the downpipe off the turbo, it can aid in quicker turbo response. Very mildy however.