Time to go Stage II!

[Dusty Bradford]

I hope you plan to enclose all the area around the air hose so it doesn't bleed back out. Your using a small air hose into a much larger pipe. I can tell you from working with ejector systems that the paper should suck to the pipe. But it depends on if you can move enough air through the pipe to create a suction using only an air hose.

I have to laugh at those who think a gate mounted a perfect 90 degrees to the pipe will not work. Those are usually the same people who tell you a hairline crack in the crossover will absolutely kill spool-up. Somehow this hairline crack flows a lot more air than a gapping 40mm hole.

A wastegate will work mounted 90 degrees to the pipe. It will take a larger gate to get the boost to a low range vs a gate that has flow priority though.

 

[Alky V6]

Come to think of it, my set of Stage I headers are sitting on the floor, next to my bench.

What sort of bench testing should we do with them?

 

[Alky V6]

Wow. The results of the first test that I described earlier were even more AMAZING than I had predicted.
Specifics of the test;
The shop air gun being used in this test has a very good trigger control that allows very good modulation of the amount of air being delivered by the air gun.
I will be blowing air from the shop air gun into the turbo mounting flange end of an exhaust pipe. The rest of the opening will not be closed off.
There is a 1.5" wastegate mounting pipe welded to the exhaust pipe at approximately a 45 degree angle to the larger exhaust pipe. No part of the WG tubing extends into the main exhaust pipe.
I will be holding a small piece of paper about 1/2 to 3/4 inch from the opening of the WG mounting tube.
The shop blow gun will be positioned in the center and about 1/2 inch outside of the 4 bolt flange that will mount the turbo.

Results;
As I slowly squeezed the blow gun trigger, right away the paper began to suck to the opening of the hole it was being held close to. Even though the pipe size that I was blowing into was very large for a test like this, even the slightest amount of airflow caused the paper to move towards the smaller pipe opening. The more I squeezed the air gun trigger, the more force the paper had as it attempted to move towards the pipe opening. The force that the paper had as it attempted to suck up to the pipe opening was directly related to the amount of airflow I allowed to travel through the large pipe. The size of the large pipe seemed to have little to do with how well the paper reacted to even the slightest amount of airflow.
If I quickly blipped the air gun trigger, the paper reacted just as quickly by jumping towards the opening of the smaller pipe.
The more airflow through the larger pipe, the higher the force that the paper displayed as it attempted to suck up to the smaller pipe opening.

Conclusion;
A very telling test, to be sure. The pressure drop in the smaller pipe was directly related to the velocity and volume of air traveling through the larger pipe.
I was very surprised to see how little airflow it really took to get a reaction from the piece of paper.
Imagine if the airflow had been that of a quick high pressure and velocity exhaust flow pulse. Wow!

 

[Alky V6]

Any other conditions of the test that anyone would like to see tried?

 

[Alky V6]

Next question. Just what is happening in a typical tuned exhaust system collector when a high velocity, high pressure pulse is being expelled from one of the primary pipes connected to that collector?
Are the other primary pipes associated with that collector being sucked down to a lower pressure depression?
This is exciting stuff, guys.
I'm going to move to one of my Stage I headers and see what happens when I blow air into one of the primary exhaust flanges. I would expect that the other primary openings will suck the papers to them.

 

[Alky V6]

Holding my Stage I header so that the exhaust flange openings were perpendicular to the floor, and blowing air into one of the 3 primary pipes, a piece of paper was able to stay sucked to one of the other primary pipe openings without me having to hold onto it. This was all while the 3rd primary opening was simply left open.

Another test done with a piece of paper held to both of the other primary openings resulted in the papers being sucked to both openings and staying put without me having to hold them.

 

[Alky V6]

So now we know that the flow from one primary tube connected to a collector with other primary tubes will cause a pressure depression in the other primary pipes.
We know that the value of the pressure depression in the other primary tubes is dependent on the velocity and volume of flow exiting the one primary tube inside the collector.

What tuning variables need to be tweaked to make sure that this pressure depression occurs at just the right time to affect the best evacuation of exhaust gases from an adjacent cylinder?

 

[Alky V6]

Camshaft timing?
Primary piping diameters and lengths?
Collector design?
Collector diameters and lengths?
RPM range?
Exhaust mass volumes (boost levels)?

 

[Alky V6]

What if I were to pump up the atmospheric pressure in the whole room that I did the above test in? Let's say we pumped it up to 60 psi above atmospheric. What do you think the test results would have been?

Fascinating, isn't it?

Is this the variable that the engine simulator was unable to take into account, with the Stage I project? Like I stated earlier, the relationship of the exhaust pulses occurring with a 90 degree, bank to bank ignition, evenfire V6 is very unique to this configuration only.
In working with the simulator for the Stage II project, it was extremely apparent that camshaft and exhaust manifolding specifications were going to be the two main things that would have to be tuned in together in hopes of getting the most power out of my combination. And, not just the most power, but just to get the power in the upper section of a range of possible power levels that turned out to be surprisingly wide with this particular combination.

 

[norbs]

I really don;t see how your going to go from 800-1500 hp from 6000-8500 rpm, Does that seem right to you? Not sure I would put all the faith in to the sim, it maybe used to see differences in changing a part, but I don;t believe the hp numbers to be that accurate.

 

[Alky V6]

I really don;t see how your going to go from 800-1500 hp from 6000-8500 rpm, Does that seem right to you? Not sure I would put all the faith in to the sim, it maybe used to see differences in changing a part, but I don;t believe the hp numbers to be that accurate.

Norbs. Did you notice the boost level ramp up from 6,000 to 8,500 rpm? That is key to understanding why at 6,000 there would be 800 hp, then by 8,500 rpm there would be 1,500 hp.
There is a boost level trace line in that output chart. It's the light blue trace line at the bottom of the chart.

 

[Dusty Bradford]

That's what I expected from your test. Now pressure the inside of the header to 40 psi and see what happens. That's real world conditions.

 

[Alky V6]

That's what I expected from your test. Now pressure the inside of the header to 40 psi and see what happens. That's real world conditions.

That's why I mentioned the scenario of pressurizing the room to something above atmospheric pressure. I don't see why things would change if the stagnant average pressure in the exhaust manifold were 14.64 psi (atmospheric pressure at sea level) or 40 psi.
As long as a column of gases is moving down the pipe, no matter what the stagnant pressure level is, you will get the same effect. The only way you would not get the same effect would be if the stagnant pressure was able to stop all movement of gases in the exhaust tubing, and we know that doesn't happen.

 

[Alky V6]

Norbs. Did you notice the boost level ramp up from 6,000 to 8,500 rpm? That is key to understanding why at 6,000 there would be 800 hp, then by 8,500 rpm there would be 1,500 hp.
There is a boost level trace line in that output chart. It's the light blue trace line at the bottom of the chart.

I hope you also understand that there would be a similar ramp up of power tied to a ramp up of boost without the camshaft and manifolding being optimized. The power levels would just be different.

 

[Alky V6]

When it comes to the potential advantages of pressure pulse tuning, I would argue that the potential gains by optimizing pressure pulse tuning parameters increase with rising manifold pressures (intake and exhaust) and rpm levels. BTW, the sim outputs clearly show this relationship.

 

[geno]

After 774 replies and 30,363 views you need to put up a number on the board . All the high tech stuff is great but the number is what its all about..Get that thing to the track and show us how its done....

 

[Alky V6]

After 774 replies and 30,363 views you need to put up a number on the board . All the high tech stuff is great but the number is what its all about..Get that thing to the track and show us how its done....

All in good time.

 

[Alky V6]

The o-ring grooves in the heads will be cut .028" deep to allow the wire to protrude above the surface of the head .013". The .013" will be 21% of the planned gasket thickness. These are the same specs I used in the past with the Stage I engine.
It is recommended not to have the wire protrude above the head sealing surface by more than 25% of the gasket thickness.

 

[Dusty Bradford]

Your gonna have to stop sniffing the carb cleaner. Pressurizing the room does nothing. It's the differential pressure between the header pipe and outside of the pipe that matters. You'd have to move enough air through the pipe to pressure it up to 40psi to simulate a real world scenario. The header tube has to be at 40psi higher pressure than the atmosphere around it to show how things really work.

 

[Alky V6]

Your gonna have to stop sniffing the carb cleaner. Pressurizing the room does nothing. It's the differential pressure between the header pipe and outside of the pipe that matters. You'd have to move enough air through the pipe to pressure it up to 40psi to simulate a real world scenario. The header tube has to be at 40psi higher pressure than the atmosphere around it to show how things really work.

Still, it would not change a thing. The increased pressure differential that you are referring to would simply encourage more flow to exit through the turbo. You could pressurize the exhaust system to 100 psi and as long as the cylinder pressure is higher than the pressure occupying the exhaust system when an exhaust valve opens, or as a piston pushes exhaust gases out of the cylinder on the exhaust stroke encouraging flow through a primary pipe, you will still get the same effect. You will get a pressure depression in the other primaries associated with that same collector.
It more has to do with the movement of the gases. Not the pressure. In fact, as cylinder pressures and exhaust volumes increase with more intake boost, the effect increases, since velocity and volume through the primary would also increase. I already showed that in the simple bench test I did which showed that with increasing airflow through the primary, there was an increase in the pressure depression in the other primary tubes connected to that collector.

Better be careful about accusing others of doing drugs when it's clear that you yourself don't completely understand what's happening.