Active Exhaust - Meh?

[zpduff]

I don't notice any difference in throttle regardless of exhaust settings

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[Junkyard Dog]

….well so far, it’s 1-1 on observed difference in acceleration.
Me-yes,
Ryan-No

Uh, oh, now 2-1 against you.

No - zpduff
No - Ryan

Yes - Starship Enterprise

I'll try to remember to try this out myself.

 

[Cz_Ziemniak]

Not always, completely possible to overdo either and even both if done incorrectly.

False.

Backpressure is bad, period. What you're thinking of is scavenging

 

[Starship Enterprise]

Are we hinting / checking to see if exhaust mode modifies the tune and drive mode modifies the suspension?

IF the car doesn’t have Magnaride suspension I don’t think that’s possible.

And maybe like Ryan suggested, if anything, it might not adjust the tune, but maybe at the very least adjust the throttle curve mapping….or I’m an idiot. It’s one of the two…or both.

Uh, oh, now 2-1 against you.

No - zpduff
No - Ryan

Yes - Starship Enterprise

I'll try to remember to try this out myself.

OK, now questioning my own seat-of-the-pants driving judgement. And possibly my own sanity…lol.

The difference seems much more noticeable when gently pulling away from a stop. I don’t think an aggressive take-off shows the difference as much.

Look forward to your take, Dog!

 

[Zig]

False.

Backpressure is bad, period. What you're thinking of is scavenging

Wrong, open headers same as true dual 3”?

 

[Cz_Ziemniak]

Theres a very simple solution to this. Plug a scanner in and read the live data. Record the same exact pull in normal, and track. See if the recorded days changes timing

 

[Cz_Ziemniak]

Wrong, open headers same as true dual 3”?

This isn’t back pressure, you’re thinking of scavenging.

 

[Zig]

This isn’t back pressure, you’re thinking of scavenging.

Scavenging is the ability for the flow to generate pull, back pressure is the ability to provide gentle resistance, to prevent the flow from creeping through during the overlap

 

[Starship Enterprise]

Theres a very simple solution to this. Plug a scanner in and read the live data. Record the same exact pull in normal, and track. See if the recorded days changes timing

Great idea, but what if throttle curve mapped to the pedal is completely separate from timing? Like what if opening the exhaust to Track also adjusts the pedal alone But doesn’t do anything with timing? I don’t know how that can be measured….

Or like it seems so far with feedback here, I’m the only one noticing a difference….Is it possible just that extra bit more of open exhaust makes the engine that much more responsive all by itself?

 

[Cz_Ziemniak]

Scavenging is the ability for the flow to generate pull, back pressure is the ability to provide gentle resistance, to prevent to flow from creeping through during the overlap

Well in that case, you're just flat out wrong.

Backpressure is bad.

https://motordyneengineering.com/scavenging-and-the-exhaust-backpressure-myth/
"Back pressure rapidly reduces performance. The butterfly valve was attached at the end of the Y pipe and dyno tested at various levels of flow restriction. From wide open to almost fully closed, as back pressure increased, dyno performance rapidly decreased. "


https://forums.mightycarmods.com/fo...3416-backpressure-the-myth-and-why-it-s-wrong
"you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream"

https://www.dsmtuners.com/threads/exhaust-back-pressure-is-_always_-bad-long.71948/
"The easier the exhaust can get out, the better, no matter what. Back pressure in the exhaust is always bad, and just causes the engine to have to work harder to push the exhaust out, losing torque. Saying that the engine needs back pressure in the exhaust is like saying that you need vacuum in the intake."

 

[Cz_Ziemniak]

Great idea, but what if throttle curve mapped to the pedal is completely separate from timing? Like what if opening the exhaust to Track also adjusts the pedal alone But doesn’t do anything with timing? I don’t know how that can be measured….

Or like it seems so far with feedback here, I’m the only one noticing a difference….Is it possible just that extra bit more of open exhaust makes the engine that much more responsive all by itself?

Foot flat to the floor, it shouldn't make a difference theoretically.

Otherwise, most scanner show TB position %, you could try to match that as close as possible.

 

[Starship Enterprise]

Foot flat to the floor, it shouldn't make a difference theoretically.

Otherwise, most scanner show TB position %, you could try to match that as close as possible.

It’s in a gentle take-off from a full stop where the difference is most noticable. The lag/ hesitation is gone with the exhaust in Track, as opposed to the other 3 exhaust modes. It just seems the whole car wakes up with a simple exhaust setting change.

 

[Cz_Ziemniak]

It’s in a gentle take-off from a full stop where the difference is most noticable. The lag/ hesitation is gone with the exhaust in Track, as opposed to the other 3 exhaust modes. It just seems the whole car wakes up with a simple exhaust setting change.

That would be harder to match, then.

Not sure how I'd do it.

 

[Zig]

Well in that case, you're just flat out wrong.

Backpressure is bad.

https://motordyneengineering.com/scavenging-and-the-exhaust-backpressure-myth/
"Back pressure rapidly reduces performance. The butterfly valve was attached at the end of the Y pipe and dyno tested at various levels of flow restriction. From wide open to almost fully closed, as back pressure increased, dyno performance rapidly decreased. "


https://forums.mightycarmods.com/fo...3416-backpressure-the-myth-and-why-it-s-wrong
"you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream"

https://www.dsmtuners.com/threads/exhaust-back-pressure-is-_always_-bad-long.71948/
"The easier the exhaust can get out, the better, no matter what. Back pressure in the exhaust is always bad, and just causes the engine to have to work harder to push the exhaust out, losing torque. Saying that the engine needs back pressure in the exhaust is like saying that you need vacuum in the intake."

When was the last time you saw a 6” diesel exhaust on a mustang?

 

[Zig]

Well in that case, you're just flat out wrong.

Backpressure is bad.

https://motordyneengineering.com/scavenging-and-the-exhaust-backpressure-myth/
"Back pressure rapidly reduces performance. The butterfly valve was attached at the end of the Y pipe and dyno tested at various levels of flow restriction. From wide open to almost fully closed, as back pressure increased, dyno performance rapidly decreased. "


https://forums.mightycarmods.com/fo...3416-backpressure-the-myth-and-why-it-s-wrong
"you want make sure the pipe is wide enough so that there is as little backpressure as possible while maintaining suitable exhaust gas velocity. Backpressure in it's most extreme form can lead to reversion of the exhaust stream"

https://www.dsmtuners.com/threads/exhaust-back-pressure-is-_always_-bad-long.71948/
"The easier the exhaust can get out, the better, no matter what. Back pressure in the exhaust is always bad, and just causes the engine to have to work harder to push the exhaust out, losing torque. Saying that the engine needs back pressure in the exhaust is like saying that you need vacuum in the intake."

Psst: velocity is a byproduct of resistance

let’s not forget about overlap

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