False dyno reports from magnaflow

[Red Devil]

Originally Posted by Jack B Red Devil: believe me I am not picking on you, but, the timimg issue is not there. These engines use the burn rate at WOT to adjust the combustion timing process. They only run 12-13% at WOT, that is commanded, therefore, what the factory dialed in.

No issues on my side. I don't know how the pcm is interacting with the engine so that was just a guess on my part.

[Jack B]

Originally Posted by Red Devil No issues on my side. I don't know how the pcm is interacting with the engine so that was just a guess on my part.

It really is kind of interesting, take a look on the posts that give the log of timing. It is so unusual, when the car hits approximately 4800 rpm's, the advance falls thru the floor, then levels out. On my car it is 12.5 degrees. The post with the logs from HPTuners software shows the timing.

[Red Devil]

Originally Posted by Jack B I agree 99%, but, you are talking about a DI engine that relies (to some degree) on scavenging by the exhaust - so your statement might have to be rethought.

All engines with overlap are relying on scavenging. Direct injection is beneficial for maintaining a cooler combustion chamber by not tumbling in the mixture and absorbing the heat of the cylinder walls...in effect. Also, because of superior atomization we see the capability to run leaner. These traits should make for great FI architecture - and we've seen it has! (I read your posts here and there, so I realize you know all of this)

That written, I still have scavenging in effect with a zero backpressure turboback, because the turbo itself is a huge restriction. That is why I'm saying that post-turbo the issue of velocity really isn't an issue, even with DI. We want to flow with maximum velocity into the exhaust turbine. After the turbine, the best thing for it to do is get out of the way - whether we're at 2500rpms or 6600rpms where exhaust cfm is clearly anything but the same.

If this were naturally aspirated, or SCd, it would be a different ball game.

I'm open to how this should further be rethought to accomodate DI.

[Jack B]

Originally Posted by Red Devil All engines with overlap are relying on scavenging. Direct injection is beneficial for maintaining a cooler combustion chamber by not tumbling in the mixture and absorbing the heat of the cylinder walls...in effect. Also, because of superior atomization we see the capability to run leaner. These traits should make for great FI architecture - and we've seen it has! (I read your posts here and there, so I realize you know all of this) That written, I still have scavenging in effect with a zero backpressure turboback, because the turbo itself is a huge restriction. That is why I'm saying that post-turbo the issue of velocity really isn't an issue, even with DI. We want to flow with maximum velocity into the exhaust turbine. After the turbine, the best thing for it to do is get out of the way - whether we're at 2500rpms or 6600rpms where exhaust cfm is clearly anything but the same. If this were naturally aspirated, or SCd, it would be a different ball game. I'm open to how this should further be rethought to accomodate DI.

I have some of the actual development curves (Bosch sells the CD) and they rely heavily on scavenging in the mid rpm range to increase torque. There are so many things happening that we don't know. I looked at that curve forever. I will look at it again a post again relative to this topic.

[Red Devil]

Originally Posted by Jack B I have some of the actual development curves (Bosch sells the CD) and they rely heavily on scavenging in the mid rpm range to increase torque. There are so many things happening that we don't know. I looked at that curve forever. I will look at it again a post again relative to this topic.

Ok...so in a nutshell, what you're saying is scavenging post-turbo, is beneficial due to DI?

What I'm saying is that scavenging is still taking place pre-turbo in the manifold - it's there that we should be concerned with velocity and there that we are getting it.

Are we on the same page, or am I missing something here? And who's on first?

[brentil]

Originally Posted by Jack B I have some of the actual development curves (Bosch sells the CD) and they rely heavily on scavenging in the mid rpm range to increase torque. There are so many things happening that we don't know. I looked at that curve forever. I will look at it again a post again relative to this topic.

The scavenging they're referring to probably between the engine and the turbo and not after the turbo. Because I would think that once it reaches the turbo and passes through it you're introducing a huge variety of varying conditions that would make pressures post turbo very difficult to calculate/rely on. Especially since the turbo itself will act as an agent to increase the back pressure. It's probably more important on NA DI engines, I wouldn't be surprised if they were even more sensitive to back pressure then normal NA engines.