3" to 3.5" or 4" or 5" dp how much gain?
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I think the winner would be the one makes the most sense, economically. If you have a 3" DP, and then switch to the 5" one, and gain a tenth and 10hp, I would say the 3" would be the winner. Especially given that you wouldnt have that 5" one banging into every conceivable object under the hood, setting off the knock sensor. I hear its bad enough as it is with the 3" one.
I have no beef whatsoever with jason or RJC. I honestly thiink they've made some pretty awesome products. Someone over there had to know what they're doing on a flow generator, when developing the power plate. Ive been very impressed by that product since I first saw it. Plus, its at an unbeatable price. If a late model mustang vendor came up with something like that, they would rape everyone with some outrageous price. And people would pay it too! I'll bet RJC could have gotten alot more for that plate since the beginning. But given that price, and the work that was put into it, I think RJC is a company with integrity. This thread and the comments have gone to a place where they shouldnt have gone. When there is some new product that seems outrageous, its bound to stir up controversy. I think dyno and drag tests would help alot. Even if the 5" DP gains no power over a 3", so what. Someone may still want it and RJC has the right to sell cross drilled brake lines, line hone in a can and anything else if they want to.
Sorry for stirring the pot jason. We should just let the test results do the talking.
I have no beef whatsoever with jason or RJC. I honestly thiink they've made some pretty awesome products. Someone over there had to know what they're doing on a flow generator, when developing the power plate. Ive been very impressed by that product since I first saw it. Plus, its at an unbeatable price. If a late model mustang vendor came up with something like that, they would rape everyone with some outrageous price. And people would pay it too! I'll bet RJC could have gotten alot more for that plate since the beginning. But given that price, and the work that was put into it, I think RJC is a company with integrity. This thread and the comments have gone to a place where they shouldnt have gone. When there is some new product that seems outrageous, its bound to stir up controversy. I think dyno and drag tests would help alot. Even if the 5" DP gains no power over a 3", so what. Someone may still want it and RJC has the right to sell cross drilled brake lines, line hone in a can and anything else if they want to.
Sorry for stirring the pot jason. We should just let the test results do the talking.
bird
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norby, turn that boost up man! you havent maxed out your current combo yet. im still running a 3" atr and trust me i still have a little more left. your ride will go nines just turn it upnorbs said:
Thanks for the compliment.
I have no personal beef with Vader’s, I too admire his grammer skills. (chicks dig skills). I only have a problem with inaccurate posts regardless of who post them.
It has been a while since the fluid dynamics classes in college.I am a little rusty. You know how it is. You can only remember the practical application and not every formula and vocabulary.
A turbine works by taking two pressure differences and using this pressure difference to consume energy and create work on the compressor side. Heat absorbed during this process also aids in the amount of energy that can be consumed. If someone wants to go into more detail here please feel free. In other words everything you said about fluid dynamics is actually the opposite in this application.
The more pressure loss and heat loss across a turbine the better.
Another thing that you must consider is spent gases coming out of the turbo ideally should be flowing axially but actually will be rotating like a helix. The reason for this is the turbo is used over a broad range of engine speed and power and therefore the exhaust gases will sometimes be going faster than the turbine wheel exducer and sometimes slower. When they are going faster than the turbine they will rotate in the opposite direction from the rotation of the turbine and when they are going slower they rotate the same. In either case the path for the exhaust gases will be considerably longer than if they were coming out axially. For this reason, it is desirable to break up the swirl and change the gases to turbulent flow as soon as possible after they leave the turbine housing. One Way to do this is to have a sharp diffuser angle on the turbine housing. This requires a large diameter exhaust pipe from the turbine housing. Once the turbulent flow is established it is not important for the exhaust pipe to be that big. After about 18-24” a smooth reduction in the cross section of the exhaust pipe will not create much additional back pressure.
I have no personal beef with Vader’s, I too admire his grammer skills. (chicks dig skills). I only have a problem with inaccurate posts regardless of who post them.
It has been a while since the fluid dynamics classes in college.I am a little rusty. You know how it is. You can only remember the practical application and not every formula and vocabulary.
A turbine works by taking two pressure differences and using this pressure difference to consume energy and create work on the compressor side. Heat absorbed during this process also aids in the amount of energy that can be consumed. If someone wants to go into more detail here please feel free. In other words everything you said about fluid dynamics is actually the opposite in this application.
The more pressure loss and heat loss across a turbine the better.
Another thing that you must consider is spent gases coming out of the turbo ideally should be flowing axially but actually will be rotating like a helix. The reason for this is the turbo is used over a broad range of engine speed and power and therefore the exhaust gases will sometimes be going faster than the turbine wheel exducer and sometimes slower. When they are going faster than the turbine they will rotate in the opposite direction from the rotation of the turbine and when they are going slower they rotate the same. In either case the path for the exhaust gases will be considerably longer than if they were coming out axially. For this reason, it is desirable to break up the swirl and change the gases to turbulent flow as soon as possible after they leave the turbine housing. One Way to do this is to have a sharp diffuser angle on the turbine housing. This requires a large diameter exhaust pipe from the turbine housing. Once the turbulent flow is established it is not important for the exhaust pipe to be that big. After about 18-24” a smooth reduction in the cross section of the exhaust pipe will not create much additional back pressure.
FLYNRYAN87
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More technobable
Well since I believe that VaderV6 has been blowing so much mustang smoke around here I would like to put an engineering spin all of the technical jargon being thrown out with little to no science behind it. All the talk of velocity and momentum and is somewhat relevant; however you have to look at what is creating them. The TURBINE (not compressor) creates work that is directly connected to the compressor wheel. The reason that the turbine creates work is due to the pressure drop across the Turbine wheel from exhaust manifold pressure to down pipe pressure (work=massflow*(P2-P1)/density). This amount of work is directly proportional to the pressure that can be produced by the compressor taking in to account the efficiency of the turbo (i.e. more boost by creating a greater pressure drop between manifold and downpipe). By changing the down pipe nothing before the turbo is changed (that means VaderV6s “pulses” and his gas mileage). After the downpipe I am assuming it necks down to a smaller pipe which would act as a nozzle increasing the velocity of exhaust gases as they moves to atmosphere. I believe what RaceJase was referring to as pressure shape loss, is in fact the velocity profile. The velocity profile is very much affected by many aspects of the piping, which can only be decreased (i.e. removing cat, muffler, decreasing number of bends), but they cannot be eliminated completely from any pipe flow. This is caused by boundary layer development and the around the edges is all that’s affected. As far as VaderV6s resonating and “ reflecting” inside the exhaust affecting performance, I can only say… Well I don’t think anything has to be said. As far as Vaders Joule Thompson effect it just doesn’t apply to this system for 2 reasons: 1) the system is not adiabatic (adiabatic really means that there is no heat loss or gain in the system and we all know how much heat is given off). 2) There also has to be no internal energy change, which is not the case.
So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop (Bernoulli equation and conservation of mass). Where VaderV6 is correct; however, that there is a “loss” going from a smaller diameter to a larger one (k=1-(d1^2/D2^2))^2 , which is directly related to the diameter change). This loss is a pressure loss and in fact a loss that is beneficial because it is increasing the pressure difference which means more boost (Head loss coefficient hl = K*(vel^2/2*g))). I believe that a larger downpipe will in fact be beneficial in any application, but I too would like to see the numbers and know that science and engineering holds true. Sorry for bringing more technobable to the thread but be assured that is accurate and reliable from an engineering point of view. I am anticipating a response from vaderv6, but I suggest before you do you go back and read your fluid mechanics book again.
Jim Shae
Well since I believe that VaderV6 has been blowing so much mustang smoke around here I would like to put an engineering spin all of the technical jargon being thrown out with little to no science behind it. All the talk of velocity and momentum and is somewhat relevant; however you have to look at what is creating them. The TURBINE (not compressor) creates work that is directly connected to the compressor wheel. The reason that the turbine creates work is due to the pressure drop across the Turbine wheel from exhaust manifold pressure to down pipe pressure (work=massflow*(P2-P1)/density). This amount of work is directly proportional to the pressure that can be produced by the compressor taking in to account the efficiency of the turbo (i.e. more boost by creating a greater pressure drop between manifold and downpipe). By changing the down pipe nothing before the turbo is changed (that means VaderV6s “pulses” and his gas mileage). After the downpipe I am assuming it necks down to a smaller pipe which would act as a nozzle increasing the velocity of exhaust gases as they moves to atmosphere. I believe what RaceJase was referring to as pressure shape loss, is in fact the velocity profile. The velocity profile is very much affected by many aspects of the piping, which can only be decreased (i.e. removing cat, muffler, decreasing number of bends), but they cannot be eliminated completely from any pipe flow. This is caused by boundary layer development and the around the edges is all that’s affected. As far as VaderV6s resonating and “ reflecting” inside the exhaust affecting performance, I can only say… Well I don’t think anything has to be said. As far as Vaders Joule Thompson effect it just doesn’t apply to this system for 2 reasons: 1) the system is not adiabatic (adiabatic really means that there is no heat loss or gain in the system and we all know how much heat is given off). 2) There also has to be no internal energy change, which is not the case.
So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop (Bernoulli equation and conservation of mass). Where VaderV6 is correct; however, that there is a “loss” going from a smaller diameter to a larger one (k=1-(d1^2/D2^2))^2 , which is directly related to the diameter change). This loss is a pressure loss and in fact a loss that is beneficial because it is increasing the pressure difference which means more boost (Head loss coefficient hl = K*(vel^2/2*g))). I believe that a larger downpipe will in fact be beneficial in any application, but I too would like to see the numbers and know that science and engineering holds true. Sorry for bringing more technobable to the thread but be assured that is accurate and reliable from an engineering point of view. I am anticipating a response from vaderv6, but I suggest before you do you go back and read your fluid mechanics book again.
Jim Shae
I think the 5" section just after the turbo is a flippin sweet idea. The gas that exits the turbo is wanting to spin outward and almost gets flung out from the center at a 90 degree angle, and spinning. Then it needs plenty of room to get all "relaxed" and straightened out before it can calmly flow down the drain hole. Just like a toilet. :wink: I guess having the internal wastegate also creats plenty of turbulance with a straighter flowing gas blending into a spinning discharge. I also like the HP book "Turbochargers", by Hugh MacInnes.
I had a whole reply finished and my computer hung so I gave up. I'll try and remember what i said to the best of my ability.
The pressure diff pre-post turbine is an obvious one. What else would accelerate the turbine? No matter what DP you have on there, the pressure, pre turbine will not change. On the post side of the turbine, the lowest pressure you can hope to achieve is ambient. This will give you the greatest acceleration of the wheel. Quick spool, but not more flow into the motor, unless you can keep the pressure diff significant at a high rpm to get more rpms out of the turbine. Now, does the 5" DP get you closer to ambient, post turbine than the 3" one does in a useable rpm range? Thats the key question. Given the track results out there, it doesnt seem like there is much of a difference. I would bet on a 6000rpm street motor that the pressure, post wheel, wouldnt be much lower on the 5" DP vs. the 3" one. Only way to know would be to test it. Test the pressure diff between the 2, and the spool time to full boost. But who has time for that? Get it to the track or on the dyno and test it. But getting one pipe to have lower pressure than the other has its own set of problems. You would think that the big difference in pressure would be great for spool and all that, but a very short distance down the pipe, it becomes a hinderance.
"So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop"
Are you serious? You're an engineer? The velocity is momentarily accelerated through the turbine (it has to because it is squeezed), and then suddenly slows way down as the pressure equalizes with the outside, ambient pressure.
Ambient pressure against ambient pressure creates no work. does not move because there is no differential. If the pressure in that DP is at or close to ambient pressure, the gas cannot move. If the DP is huge, the pressure going down that pipe will reach ambient very soon. Then the gas flow will stall. Say the pressure differential is 50psi, pre/post turbine. The gas squeezes through that wheel, accelerates it, while the gas flow accelerates. But the DP is so large that the pressure drops very rapidly. The velocity of the gas slows way down because the pressure is now not that much different than the pressure outside (ambient) Say 10" down the pipe, it has dropped to 5psi above ambient. This gas flow is not moving very fast. Say another 10" down the pipe, it is close to zero...ambient. It cannot move. Now the engine has to push this huge mass of air out by creating a differential. Backpressure in the DP increases to create this diff. get it? You need to keep the pressure in the pipe high enough so that it knows where to go. If the pressure is too low, it moves slow. Your turbine does not spin.
About that helical flow pattern...the flow path will be much longer with a larger DP than a small one if the flow is spiraling out. The second half of your paragraph doesnt really have much to do with what we're talking about. The flow pattern between the 2 different diameter pipes is not addressed there.
The pressure diff pre-post turbine is an obvious one. What else would accelerate the turbine? No matter what DP you have on there, the pressure, pre turbine will not change. On the post side of the turbine, the lowest pressure you can hope to achieve is ambient. This will give you the greatest acceleration of the wheel. Quick spool, but not more flow into the motor, unless you can keep the pressure diff significant at a high rpm to get more rpms out of the turbine. Now, does the 5" DP get you closer to ambient, post turbine than the 3" one does in a useable rpm range? Thats the key question. Given the track results out there, it doesnt seem like there is much of a difference. I would bet on a 6000rpm street motor that the pressure, post wheel, wouldnt be much lower on the 5" DP vs. the 3" one. Only way to know would be to test it. Test the pressure diff between the 2, and the spool time to full boost. But who has time for that? Get it to the track or on the dyno and test it. But getting one pipe to have lower pressure than the other has its own set of problems. You would think that the big difference in pressure would be great for spool and all that, but a very short distance down the pipe, it becomes a hinderance.
"So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop"
Are you serious? You're an engineer? The velocity is momentarily accelerated through the turbine (it has to because it is squeezed), and then suddenly slows way down as the pressure equalizes with the outside, ambient pressure.
Ambient pressure against ambient pressure creates no work. does not move because there is no differential. If the pressure in that DP is at or close to ambient pressure, the gas cannot move. If the DP is huge, the pressure going down that pipe will reach ambient very soon. Then the gas flow will stall. Say the pressure differential is 50psi, pre/post turbine. The gas squeezes through that wheel, accelerates it, while the gas flow accelerates. But the DP is so large that the pressure drops very rapidly. The velocity of the gas slows way down because the pressure is now not that much different than the pressure outside (ambient) Say 10" down the pipe, it has dropped to 5psi above ambient. This gas flow is not moving very fast. Say another 10" down the pipe, it is close to zero...ambient. It cannot move. Now the engine has to push this huge mass of air out by creating a differential. Backpressure in the DP increases to create this diff. get it? You need to keep the pressure in the pipe high enough so that it knows where to go. If the pressure is too low, it moves slow. Your turbine does not spin.
About that helical flow pattern...the flow path will be much longer with a larger DP than a small one if the flow is spiraling out. The second half of your paragraph doesnt really have much to do with what we're talking about. The flow pattern between the 2 different diameter pipes is not addressed there.
You started off on the right track then you totally contradicted yourself (similar to your previous posts) and started getting mixed up. These cars are not propelled by the thrust of the exhaust coming out of the tailpipe so the speed of the exit is irrelevant. I think this is where you are looking at it wrong.
As for the helical flow being longer in a bigger pipe, you are misunderstanding this. The larger the pipe the quicker this helical flow becomes turbulent flow. Measuring the size of the helix is also irrelevant. This transition IS the most important part.
As for the helical flow being longer in a bigger pipe, you are misunderstanding this. The larger the pipe the quicker this helical flow becomes turbulent flow. Measuring the size of the helix is also irrelevant. This transition IS the most important part.
FLYNRYAN87
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I would first like to thank vaderV6 for helping me make him look like the A$$ he is, by quoting me then mocking me
. "So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop" - ME
Are you serious? You're an engineer? –VaderV6
Yes I am an engineer and yes this is a true statement. I knew that you would have a hard time grasping this concept and it is one reason I included it. So here is the explanation that I hope you will agree with. Say you have a tank with 30 psi inside and you have a similar tank next to it with 100 psi inside and you then open them both to “ambient” or atmospheric pressure approx 14.696 psi. Which tank is going to create a larger VELOCITY of air flow out of it? Correct the one with the larger pressure drop. Now Vader V6 is correct in that the air will eventually decrease to Patm and there will be no velocity but that will only happen when the pressure in the tank is equal to atmosphere and that will not happen in your Buick or Vaders mustang.
Now as far as whatever he is talking about with the poor lil’ exhaust gases getting lost in the big ole’ downpipe; the pressure difference between the dp and “ambient” will be sufficient and to increase this effect is the necking of the pipe which is a “NOZZLE” like I mentioned in my last post increasing the velocity of the gases.
. "So in conclusion the velocity is not decreased by a larger down pipe it is actually increased by the pressure drop" - ME
Are you serious? You're an engineer? –VaderV6
Yes I am an engineer and yes this is a true statement. I knew that you would have a hard time grasping this concept and it is one reason I included it. So here is the explanation that I hope you will agree with. Say you have a tank with 30 psi inside and you have a similar tank next to it with 100 psi inside and you then open them both to “ambient” or atmospheric pressure approx 14.696 psi. Which tank is going to create a larger VELOCITY of air flow out of it? Correct the one with the larger pressure drop. Now Vader V6 is correct in that the air will eventually decrease to Patm and there will be no velocity but that will only happen when the pressure in the tank is equal to atmosphere and that will not happen in your Buick or Vaders mustang.
Now as far as whatever he is talking about with the poor lil’ exhaust gases getting lost in the big ole’ downpipe; the pressure difference between the dp and “ambient” will be sufficient and to increase this effect is the necking of the pipe which is a “NOZZLE” like I mentioned in my last post increasing the velocity of the gases.
Since engineering and actual flow data is being totally ignored by vader here are a few suggestions.
How about if you install a GPS inside the big pipe to tell the gases which way to flow…..
Or we could get a jockey to ride the gases out of the pipe…..
Or better yet lets get a small family of hobbits to guide the air out…..
How about if you install a GPS inside the big pipe to tell the gases which way to flow…..
Or we could get a jockey to ride the gases out of the pipe…..
Or better yet lets get a small family of hobbits to guide the air out…..
Tell me....what flow "data" have you shown us? Nothing.Race Jace said:
I apologize for the mocking tone, but when I'm being ridiculed its hard to keep my mouth shut. The analogy with the 2 tanks wasnt necessary. I understand what you're saying. But the velocity will drop very very rapidly and now the pressure differential between the inside of the DP and the outside ambient air is not much. If there is a low differential, then what will provide the movement of air? Nothing else can! Velocity is gone, resonant pulses are gone, turbulence is very high, etc. Not that resonant pulses have a whole lot of significance with this motor, so we'll leave that out.
The 100psi tank will fill the 30psi tank very quickly, but the end result will be equilibrium. The downpipe isnt a sealed tank. Not that this is much of a point, but I'll continue.
Lets say you have the 100 gallon tank at 100psi, (simulating exhaust pressure in the headers, pre turbine) and it has a fixed diameter pipe coming out of it, (say 2") going to a flow control of some type (which will simulate the turbine restriction), and from there it exits into the atmosphere via a 3" pipe. The biggest restriction in this is the flow control, or simulated turbine. Lets pop open the valve and dump the air. Now lets replace the 3" pipe with a 5" pipe after the flow control. Refill the tank to 100psi. Now open the valve and dump the air out of the tank. Would the 5" pipe have dumped it faster? Not necessarily. If that 2" pipe and flow control (the turbine) remains the same, enlarging the post flow control side wont affect much beyond a certain diameter because the flow restriction is the flow control, not whatever comes after. Now if the post restriction pipe has 100 bends and sharp edges inside and what have you, the boundary layer will grow quickly and create so much turbulence that it can actually have less flow potential then the air through the flow control. Only in this scenario, will increasing the post restriction pipe's diameter help anything. But we're talking about 1 mellow bend here with the DP. That doesnt mean run a 2" pipe after the restriction. It means that you only have to keep the pressure below the pressure on the other side to keep it moving. But that flow control will limit the flow potential and anything you do after it will not be able to make the flow control, flow more air, faster. I hope someone out there gets this. If I had a dollar for every time Ive worked with an engineer, who had an "I know everything and the earth is flat" attitude, and could spit out tons of theory and math, yet needed an instruction manual to operate a screwdriver, I'd be rich. Its sad when you're double E masters engineer boss puts more faith in your design ability and grasp of common sense and even theory, than his whole staff of engineers...He would go to a "top" engineer, who would spend a week designing a solution to something, and then when he submits it, he would fine out that I had solved the problem in 10 minutes on monday. This has happened more times than I can count. It doesnt take dynamics courses and multiple degrees. It only takes a little common sense and an open mind.
www.tandis.com
Check out the videos. Thats all me and my former boss.
Buicks do not follow many theories. You build a dp and test it against RJC's and when it makes more hp and tq, then i can beilieve in your theories. Until then i am not believing any of this. I am not a rocket scientist, but more hp usually means a faster et, and a car is not going to go faster on a 2" dp compared to a 5" dp.
For once I wish someone would let what i say soak in, before having a negative kneejerk reaction to what i say. Did I not say, "That doesnt mean run a 2" pipe after the restriction. It means that you only have to keep the pressure below the pressure on the other side to keep it moving."norbs said:Buicks do not follow many theories. You build a dp and test it against RJC's and when it makes more hp and tq, then i can beilieve in your theories. Until then i am not believing any of this. I am not a rocket scientist, but more hp usually means a faster et, and a car is not going to go faster on a 2" dp compared to a 5" dp.
Have I ever said a 5" pipe is garbage and in no way should you run it? No. In many ways I explained why it may not be any better than a 3". As far as necking down to get a "nozzle" effect...whats the point? Is the velocity in the necked down portion (say it necks down to 3 1/2") of the 5" DP any greater than the velocity in the 3 1/2" DP that maintains that size end to end? No. If you're going to start at 5", then why not stay at 5"? Why not just start at 3 1/2 and stay there? Taking a given volume of gas and compressing it by going from 5" to 3 1/2" will get you the same velocity as a pipe that starts at 3 1/2 and stays there. It seems completely pointless. Like Ive been saying all along....Test one against the other, and dont fudge a bunch of data to prove me wrong. Jason says I ignore the data, but there hasnt been any! Lets take a TR that represents what most people have. Say a low 12, high 11 sec TR, and test all of them at the same A/F and timing. Same catback, same everything, same car, same track prep, same weather conditions. I started out by saying it was a cool product, but it would be nice to see comparisons on the dyno or track. I wasnt stirring up anything. I immediately was mocked for not believing the earth is at the center of the universe. I showed 6 second turbo cars that run smaller DP's and that was ignored. I think people just like to argue without actually thinking about a different way of looking at things.
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