World's first FT86 Anti-Reversion,(A/R) Header

[Ultramaroon]

rekt ☑ not rekt ☐

[Kodename47]

The AVCS doesn't impact the valve lift, in Subaru terms that's AVLS

[mig86]

This guy is a TROLL right? Has to be !

[Dimman]

Originally Posted by mig86

This guy is a TROLL right? Has to be !

No.

He's just stubborn and does incomplete research on ideas he has an insufficient grasp on.

None of the fundamental concepts he writes about are truly incorrect. But how he interprets them usually is.

For example, reversion is a thing, and it's bad. But physical anti-reversion systems can also interfere with another aspect of wave tuning that is good.

Make sense?

[boredom.is.me]

Originally Posted by Dimman

No.

He's just stubborn and does incomplete research on ideas he has an insufficient grasp on.

None of the fundamental concepts he writes about are truly incorrect. But how he interprets them usually is.

For example, reversion is a thing, and it's bad. But physical anti-reversion systems can also interfere with another aspect of wave tuning that is good.

Make sense?

Nope.

Well I'm gonna go show people how square wheels are better.

[KoolBRZ]

The strange thing about the anti-reversion header, was that it didn't suck any worse than it did. In fact, it didn't start restricting power till it got over 5500 RPM. What this showed me is that the place to make changes is in the ECU, not in the header.

I'm re-installing my catless midpipe right now. My MPG will go down, but with the right AVCS tuning I should be able to reduce the duration on the exhaust to compensate for having less back-pressure. I can change this just for the RPM range up to 3000, so I can still have performance when I need to, but better mileage when I don't.

For those snarky sarcastic bastards that just have to pick on everything I do, Here's some cannon fodder for you; I'm currently REMOVING the sway bars from my car to give it a better ride. How's that for an idea? Totally insane right?

[FirestormFRS]

[Andrew025]

Originally Posted by KoolBRZ

My MPG will go down, but with the right AVCS tuning I should be able to reduce the duration on the exhaust to compensate for having less back-pressure. I can change this just for the RPM range up to 3000, so I can still have performance when I need to, but better mileage when I don't.

I died after reading this.
Every time I see you say "back pressure", it shows you have a fundamental misunderstanding of exhaust.

[KoolBRZ]

Originally Posted by Andrew025

I died after reading this.

Why, to prevent yourself from breeding?

Reducing the exhaust AVCS retard amount closes the exhaust valves sooner, reduces overlap, increases cylinder fill %, and increases the compression ratio. I might even have to back off the timing a smidge also, since a higher CR increases the chances of detonation.

[Captain Snooze]

Originally Posted by boredom.is.me

Well I'm gonna go show people how square wheels are better.

A square wheel is much better than a triangular wheel because it has one less bump per revolution.

[Andrew025]

Originally Posted by KoolBRZ

Why, to prevent yourself from breeding?

Reducing the exhaust AVCS retard amount closes the exhaust valves sooner, reduces overlap, increases cylinder fill %, and increases the compression ratio. I might even have to back off the timing a smidge also, since a higher CR increases the chances of detonation.

To spare myself from anymore impending lack of correct knowledge.
You would think someone with your amount of "knowledge" would do some better testing as well considering you're trying to prove pretty much everyone on here wrong.

[Hyper4mance2k]

Originally Posted by KoolBRZ

Why, to prevent yourself from breeding?

Reducing the exhaust AVCS retard amount closes the exhaust valves sooner, reduces overlap, increases cylinder fill %, and increases the compression ratio. I might even have to back off the timing a smidge also, since a higher CR increases the chances of detonation.

Valve timing has aboslutely nothing to do with compression ratio. Small amounts of overlap exist for a reason; they increase cylender flow rates by allowing the intake ports to remain open longer. Thus, the incoming intake charge helps expell exhaust gasses.
Where do you learn these things? I suggest reading a book on basic automotive engineering, or taking a class before you go any further. I'm not trying to be a jerk, but seriously... Go take a class at your local CC, or UTI, or something, anything. You know the basic terminology, but your understanding is fundamentally flawed. I really am starting to think you might just be the biggest, most epic troll and you're just pranking everyone.

[SirBrass]

Originally Posted by Hyper4mance2k

No engine in the history of 4 stroke internal combustion needs backpressure. The exhaust needs velocity to scavenge all the spent energy from the combustion chamber. There are may ways to do this, but back pressure is not one of them. You are parroting misinformation and a lack of understanding of fluid dynamics.
For an engine to make peak torque at any RPM it must expell as much exhaust as it can at any given RPM. The key to doing this is exhaust gas velocity, not back pressure. Correct diameter pipes that maintain exhaust gas velocity, at the desired RPM and throttle position, are the key to making power.
The reason the back pressure myth continues is bacuse of people putting on too large of an exhaust system which is only effective at a small and high RPM range. At other RPMs and throttle positions too large of an exhaust pipe will cause the exhaust gas to have little to no gas velocity, and can add turbulant exhaust flow which will ultimately cause low RPM drivability issues; it's the reduction in velocity and flow rates that casue problems, not the reduction in back pressure.

It's times like this that make me wish I'd majored in mechanical or aerospace engineering instead of EE.

Thanks for the lesson (without the math... otherwise I'd need to go dig up my old college notes).

[himbo]

Hey, can't knock this guy. He had an idea, experienced with it, and reported. At the minimum, we all learn something from the discussion in this thread. Kudos for trying and getting ideas flowing. There's something to be said about experimenting and learning things first hand rather than from a book or a forum.