Goat Blower
03-03-2006, 02:30 PM
I think you're wrong on both ends here. From what I can see, there are about a half of a dozen (at least) running GT35+ series or SCM61 in this forum.
I wouldn't know why a turbo wouldn't be a restriction.
1. Generally the pressure in the exhaust side is about double of what is in the compressed side.
2. The combustion chamber divides the intake and exhaust tracts. More pressure is caused by the explosion (expansion).
3. The turbines are spinning, but they're creating some backpressure. Which is why after the turbo, the best exhaust system is no exhaust system.
I'll answer yours and Jakey's response since it's the same answer.
You're both forgetting that the turbo is a restriction to the exhaust pulses, and if the compressor side of the turbo didn't feed back into the intake as a feedback loop, you'd have a plain old restriction. It's a little different that the turbo creates positive pressure going into the combustion chamber, therefore creates higher cylinder pressures. The more pressure the turbo makes, the more of a "restriction" the turbine side of the turbo is. I just can't justify calling it a restriction though since the turbo itself creates more cylinder pressure and exhaust pressure than a NA engine would. I guess it's all semantics and maybe the engineering world would disagree. But I don't see something that adds more than it takes away to technically be a restriction overall.
And please, a GT35 or SCM61? Neither are capable of much more than 600 whp, and besides Shane and Cher, I haven't seen anyone here over that amount anyways. Just because half a dozen people have those turbos, doesn't mean they're all maxing out their 3" exhaust. You're looking for people at that power range or higher who have also done back to back comparisons with either timeslips or by measuring exhaust backpressure after changing exhausts. Do you really think you're going to get multiple good answers here?
I wouldn't know why a turbo wouldn't be a restriction.
1. Generally the pressure in the exhaust side is about double of what is in the compressed side.
2. The combustion chamber divides the intake and exhaust tracts. More pressure is caused by the explosion (expansion).
3. The turbines are spinning, but they're creating some backpressure. Which is why after the turbo, the best exhaust system is no exhaust system.
I'll answer yours and Jakey's response since it's the same answer.
You're both forgetting that the turbo is a restriction to the exhaust pulses, and if the compressor side of the turbo didn't feed back into the intake as a feedback loop, you'd have a plain old restriction. It's a little different that the turbo creates positive pressure going into the combustion chamber, therefore creates higher cylinder pressures. The more pressure the turbo makes, the more of a "restriction" the turbine side of the turbo is. I just can't justify calling it a restriction though since the turbo itself creates more cylinder pressure and exhaust pressure than a NA engine would. I guess it's all semantics and maybe the engineering world would disagree. But I don't see something that adds more than it takes away to technically be a restriction overall.
And please, a GT35 or SCM61? Neither are capable of much more than 600 whp, and besides Shane and Cher, I haven't seen anyone here over that amount anyways. Just because half a dozen people have those turbos, doesn't mean they're all maxing out their 3" exhaust. You're looking for people at that power range or higher who have also done back to back comparisons with either timeslips or by measuring exhaust backpressure after changing exhausts. Do you really think you're going to get multiple good answers here?