Andy, Listen for what you are doing the wastegate location is really not a big concern. For an all out system it is critical. If you are just looking for a couple hundred horse anywhere is fine. Putting them to far from the turbo builds additional back pressure as the gasses have to travel down to the turbo build pressure then when released through the wastegate create all kinds of turbulence. It will make them not react properly due to fluxuations in gas pressure before and after the wastegate. As far as arguing with Former PFR you will be fighting an uphill battle. Highly educated person. He may not be the best mechanic in the world but him is pretty dag on smart.
By the way that is just the watered down explanation.
Hey Ed.
Ya You couldn't said it any better then myself. Totally agree with you.
I never realized it would be less turbulent closer to the turbo. Something new I learned from you i have to admit. The former FRP could've mentioned something simple as that but didn't and refused to give an answer.
But thanks for looking at the overal picture and explaining to the viper alley members that its not that big of a deal and is sufficient for the intended goals of my kit.
Ya that I already know. What you drew was CPE passenger side header. His Driver side is no where near like what you drew. It resembles a setup simliar to mine.
But thanks for taking the extra effort to draw it out.
Honestly If i had the space I would've done it like you mentioned. But there was no possibe way I can do it with the style headers I have. I know heffner has but thats b/c their air filters are not parrell like my air filters are. I'll take pics of my kit this weekend of the air filters to better explain it.
I was stuck with my header design so i had to pick the best spot possible.
The driver's side isn't quite as good as the passeger side, but it still has part of the pipe in the right location and is angled tangential to the outer radius of the pipe. Not 100% perfect, but I would give it a solid B+ if it was a turbocharging test. I know there is a reason it is angled different, I want to say its something with the hood latches...but there is a reason for it being constrained to that angle.
I guess I will comment on Ed's answer a bit, because I like how he put things. Right at the collector, unless you go tangential to a curve, or have a Y-pipe, scavenging will not be as good. Out of the headers, you see incredibly high velocity, best measured with mach numbers. As you may remember, Bernoulli would tell you that high velocity has low pressure. When you go 90 degrees off of an up pipe, you are primarily relying on pressure as your power source to scavenge. On a T3 system with lots of backpressure, this works pretty well. Now remember, as the exhaust travels into the up pipe, it is entering a larger pipe section and expanding, therefore slowing down based on a mass flow conservation model coupled with the perfect gas law (accounting for specific volume changes from heat transfer out of the pipe). Once again, Bernoulli tells us that a slower speed gas will have higher pressure. Consequently, pressure based wastegate scavenging will work best close to the turbo. You can artifically create pressure by having the wastegate in the path of flow. At the stagnation point right over a valve placed in the path of flow (done by having it tangential), velocity is transfered into pressure. This is why tangential placement is best, especially at the location you chose. Lastly, when flow exits through a wastegate, it will create a turbulent region (creates an artificially large boundary layer) which will slow the velocity that is able to exit the primarys near it. This of course increases backpressure in those cylinders compared to their brothers (and sisters). This is a bad thing because then it is harder to tune with uneven heating and, depending on cam profile, what besically becomes forced exhaust gas recirculation. These factors combine to cause varying detonation/preignition thresholds in those cylinders.
Damn...I gave it up. I always knew I was a whore. Well...at least it was only foreplay compared to how complicated the issue could be made.
I guess I will comment on Ed's answer a bit, because I like how he put things. Right at the collector, unless you go tangential to a curve, or have a Y-pipe, scavenging will not be as good. Out of the headers, you see incredibly high velocity, best measured with mach numbers. As you may remember, Bernoulli would tell you that high velocity has low pressure. When you go 90 degrees off of an up pipe, you are primarily relying on pressure as your power source to scavenge. On a T3 system with lots of backpressure, this works pretty well. Now remember, as the exhaust travels through the up pipe, it is entering a larger pipe section and expanding, therefore slowing down. Once again, Bernoulli tells us that a slower speed gas will have higher pressure. Consequently, pressure based wastegate scavenging will work best close to the turbo. You can artifically create pressure by having the wastegate in the path of flow. At the stagnation point right over a valve placed in the path of flow (done by having it tangential), velocity is transfered into pressure. This is why tangential placement is best, especially at the location you chose. Lastly, when flow exits through a wastegate, it will create a turbulent region (creates an artificially large boundary layer) which will slow the velocity that is able to exit the primarys near it. This of course increases backpressure in those cylinders compared to their brothers (and sisters). This is a bad thing because then it is harder to tune with uneven heating causing a lower detonation/preignition threshold in those cylinders.
Damn...I gave it up. I always knew I was a whore. Well...at least it was only foreplay compared to how complicated the issue could be made.
I guess I will comment on Ed's answer a bit, because I like how he put things. Right at the collector, unless you go tangential to a curve, or have a Y-pipe, scavenging will not be as good. Out of the headers, you see incredibly high velocity, best measured with mach numbers. As you may remember, Bernoulli would tell you that high velocity has low pressure. When you go 90 degrees off of an up pipe, you are primarily relying on pressure as your power source to scavenge. On a T3 system with lots of backpressure, this works pretty well. Now remember, as the exhaust travels through the up pipe, it is entering a larger pipe section and expanding, therefore slowing down. Once again, Bernoulli tells us that a slower speed gas will have higher pressure. Consequently, pressure based wastegate scavenging will work best close to the turbo. You can artifically create pressure by having the wastegate in the path of flow. At the stagnation point right over a valve placed in the path of flow (done by having it tangential), velocity is transfered into pressure. This is why tangential placement is best, especially at the location you chose. Lastly, when flow exits through a wastegate, it will create a turbulent region (creates an artificially large boundary layer) which will slow the velocity that is able to exit the primarys near it. This of course increases backpressure in those cylinders compared to their brothers (and sisters). This is a bad thing because then it is harder to tune with uneven heating causing a lower detonation/preignition threshold in those cylinders.
Damn...I gave it up. I always knew I was a whore. Well...at least it was only foreplay compared to how complicated the issue could be made.
thanks for the schooling, it was worth the 10 minutes to read it twice.
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