For the short time I had my turbo running it sure seemed like I needed something larger than a satge 1 exhaust wheel.
I say this because my turbo would spool even under light load and seemed to choke out at high RPM even with the boost creeping upward. I also found that my super 60 will give 5lbs with the WG disabled and wide open. These seem more like small wheel issues than WG issues in my mind.
I don't know if it's good for a turbo to be spooling all the time when not in boost and I'd much rather have the exhaust flow passing through the wheel than having to fight it's way out of a WG.
What do you guys think?
Exhaust Stages
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hannibal
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A stg 3 wheel would spool a bit slower and be less restrictive. The trim of your std (stg 1) wheel makes it spin faster given the same amount of exhaust flow. This lowers the boost threshold and makes the car more responsive/smoother and less like a turbocharged motor. I think thats why most OEM turbos used the std wheel.
Then consider the size of your WG before your condemn your wheel. With a port about as big around as a nickel, it's hard to believe that whether or not it has been disabled, it still is only enough to move a small quantity of air.
So, if you get an external WG, you may find better luck with your problem. Or bore out your stocker, and put a bigger flapper on it.
So, if you get an external WG, you may find better luck with your problem. Or bore out your stocker, and put a bigger flapper on it.
Re: (Chezedik)
I thought about this but here is the problem.
The area of a circle is 3.14(r^2) right. This is not a linear equation, so increasing a .75" hole to 1" or so will yield only a fraction of the area increase that would be gained by increasing wheel size by .25"
Also, you want to think in terms of pressure Vs momentum. You want to spin the turbo using the momentum of the exhaust gas as much as possible. Of course the resistance of the wheel creates back pressure and it is the combination of the two that spin the wheel.
The WG, because of its physical properties, vents off only the excess pressure. I think it would be much better flow wise to try to minimize pressure as much as possible and capitalize on the force of the momentum of the flow.
Say you need 80% to make boost and the stage 1 uses 40% flow + 60% backpressure. Then the WG bleeds off ~20% to hold boost steady. Here boost will hold using 40% flow and 40% backpressure.
A stage 3 might use 70% flow and 30% pressure due to it's larger wheel area and of course empty space. Now our WG bleeds off the same 20%pressure and achieves the 80% needed to hold boost but 70% is force of flow (momentum) and 10% is backpressure.
In the first situation, venting more pressure will not work because it would only drop you out of boost faster because the smaller wheel uses backpressure and not force of flow to generate boost. Also, sufficiant quantities of gas can never escape through a WG untill their area has been sufficiantly reduced via backpressure. Think of adding an extra .5 " tailpipe to a 1" exhaust at a 90* angle - not gonna cut it.
Obviously the stage 1 is going to spool faster but the stage 3 wins in the high RPMs. At least that is how it works in my mind.
I think my super 60 with a stage 3 would be a great combo if I could find one cheep.
I appreciate the suggestion though - can you tell I thought about it a little bit?
The area of a circle is 3.14(r^2) right. This is not a linear equation, so increasing a .75" hole to 1" or so will yield only a fraction of the area increase that would be gained by increasing wheel size by .25"
Also, you want to think in terms of pressure Vs momentum. You want to spin the turbo using the momentum of the exhaust gas as much as possible. Of course the resistance of the wheel creates back pressure and it is the combination of the two that spin the wheel.
The WG, because of its physical properties, vents off only the excess pressure. I think it would be much better flow wise to try to minimize pressure as much as possible and capitalize on the force of the momentum of the flow.
Say you need 80% to make boost and the stage 1 uses 40% flow + 60% backpressure. Then the WG bleeds off ~20% to hold boost steady. Here boost will hold using 40% flow and 40% backpressure.
A stage 3 might use 70% flow and 30% pressure due to it's larger wheel area and of course empty space. Now our WG bleeds off the same 20%pressure and achieves the 80% needed to hold boost but 70% is force of flow (momentum) and 10% is backpressure.
In the first situation, venting more pressure will not work because it would only drop you out of boost faster because the smaller wheel uses backpressure and not force of flow to generate boost. Also, sufficiant quantities of gas can never escape through a WG untill their area has been sufficiantly reduced via backpressure. Think of adding an extra .5 " tailpipe to a 1" exhaust at a 90* angle - not gonna cut it.
Obviously the stage 1 is going to spool faster but the stage 3 wins in the high RPMs. At least that is how it works in my mind.
I think my super 60 with a stage 3 would be a great combo if I could find one cheep.
I appreciate the suggestion though - can you tell I thought about it a little bit?
All good points, but time and again we hear of people using the internal gate with boost creep issues. And while you still hear about them on externally gated cars, they are not as common. Also, the Stage 3 wheel should behave exactly as the Stage 1 wheel once it is moving, with the exception of moving more volume. It could still very easily be an issue at boost.
The reason to do the gate is because while we may well be talking about a small increase in area, we are discussing flow. Flow, like horsepower, is a measure of something OVER time, in this case volume. Since time is effectively out of our control we can only change flow by means of changing area. However tiny the amount, it is undeniable that it will lead to a rather significant flow, since you just want to take it to the edge of where the flow is not enough to maintain the spinning blades.
Also, you are having boost creep when the gate should be open, this should always indicate the need for a bigger gate, or less gate restriction (in the case of an external). Or possibly the need to readjust your MBC, but this does not apply to you, just to those who may be reading. The common fix is to enlarge the gate. A stage 3 wheel will accomplish the same thing in lower boost settings. If you are changing wheels, I would at least suggest doing BOTH while you have the turbine housing off.
The reason to do the gate is because while we may well be talking about a small increase in area, we are discussing flow. Flow, like horsepower, is a measure of something OVER time, in this case volume. Since time is effectively out of our control we can only change flow by means of changing area. However tiny the amount, it is undeniable that it will lead to a rather significant flow, since you just want to take it to the edge of where the flow is not enough to maintain the spinning blades.
Also, you are having boost creep when the gate should be open, this should always indicate the need for a bigger gate, or less gate restriction (in the case of an external). Or possibly the need to readjust your MBC, but this does not apply to you, just to those who may be reading. The common fix is to enlarge the gate. A stage 3 wheel will accomplish the same thing in lower boost settings. If you are changing wheels, I would at least suggest doing BOTH while you have the turbine housing off.
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C-Kwik
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Re: (Edub1)
Seeing as how the WG is not a restriction, this is not a good way to look at this.Edub1 wrote:I thought about this but here is the problem.
The area of a circle is 3.14(r^2) right. This is not a linear equation, so increasing a .75" hole to 1" or so will yield only a fraction of the area increase that would be gained by increasing wheel size by .25"
Any momentum is largely attributed to flow and pressure differential across the turbo. While it is important to try and maximize momentum, it's effect is not going to be significant as flow and pressure differential.Edub1 wrote:Also, you want to think in terms of pressure Vs momentum. You want to spin the turbo using the momentum of the exhaust gas as much as possible. Of course the resistance of the wheel creates back pressure and it is the combination of the two that spin the wheel.
For a given boost level (assuming same efficiencies), a better set-up is one that flows more air through a WG. Doing so generally means the turbo is using less air to spin the turbo. This is one way compressor and turbine efficiencies are important in making power.Edub1 wrote:The WG, because of its physical properties, vents off only the excess pressure. I think it would be much better flow wise to try to minimize pressure as much as possible and capitalize on the force of the momentum of the flow.
Not sure exactly what you are trying to describe with the percentages. All turbos use the same physics to drive the turbine. All turbos use exhaust flow, heat, and pressure differential to drive it. Turbos can use varying amounts of each, but don't require a specific combination.Edub1 wrote:Say you need 80% to make boost and the stage 1 uses 40% flow + 60% backpressure. Then the WG bleeds off ~20% to hold boost steady. Here boost will hold using 40% flow and 40% backpressure
A stage 3 might use 70% flow and 30% pressure due to it's larger wheel area and of course empty space. Now our WG bleeds off the same 20%pressure and achieves the 80% needed to hold boost but 70% is force of flow (momentum) and 10% is backpressure.
In the first situation, venting more pressure will not work because it would only drop you out of boost faster because the smaller wheel uses backpressure and not force of flow to generate boost. Also, sufficiant quantities of gas can never escape through a WG untill their area has been sufficiantly reduced via backpressure. Think of adding an extra .5 " tailpipe to a 1" exhaust at a 90* angle - not gonna cut it.
The stage 3 would win in the high RPM's because it simply flows better and uses less exhaust energy to drive it in that RPM range. The motor sees less backpressure as a result freeing up some HP.Edub1 wrote:Obviously the stage 1 is going to spool faster but the stage 3 wins in the high RPMs. At least that is how it works in my mind.
I think my super 60 with a stage 3 would be a great combo if I could find one cheep.
I appreciate the suggestion though - can you tell I thought about it a little bit?
What you should consider is how the combinations of compressor and turbines work together. Matching their efficiency ranges to the same RPM's will yield the best results in terms of peak power over the range of RPM's where peak efficiencies occur. I'd suspect the Super 60 and Stage 3 turbine would be a decent match, but certainly not the best.
As far as your original post, it sounds like two things are going on. The choked feeling is simply not having enough turbo. A larger turbine may help, but stepping up to a T4 compressor would likely be a better solution. Compressor efficiency plays a large role in how hard the turbine has to work. Compressor efficiency is directly related to how aerodynamic the compressor is at a given flowrate and pressure ratio. IIRC, the Super 60 is dropping below 60 percent efficiency at redline at most boost levels on a KA. By contrast, a T04E 50 trim will still be in the 70's at redline. When the turbine needs to work less, more air will divert through the WG and consequently result in less backpressure on the motor. This results in more power at the crank.
Re: (C-Kwik)
I'm starting to see that my super 60 might just be too damn small. I should have stuck with my first turbo. Oh well, I can upgrade on the rebuild.
I'm not sure I got my point accross about the larger turbine though. Think of a log manifold Vs a tube style. The log style creates backpressure for obvious reasons. Forcing large quantities of exhaust through a waste gate is the same principal.
It is important to remember that flow and pressure are not the same thing. Hold you hand in front of a strong stream of compressed air - the force you are feeling is not pressure. Pressure is what occurs inside the closed container. When the gas is released its molecules are accelerated to a given velocity and this velocity times their mass create the force you feel against your hand. I know this is a subtle difference but it is an important one.
If you take your air compressor and fire a hard stream of air at your turbine, you can make it spin quite fast. Yet the pressure differential in this case is 0. You are using only momentum.
Now back to our manifolds. Both will spin a turbo right? Yet a tube manifold will spin the turbo while having less actual pressure inside of it. This is because the log mani, due to its design, can not maintain the force of the gases momentum, it must wait untill pressure builds and forces the turbine to spin. A tube manifold on the other hand maintains the momentum of the gas and actually uses the moving mass of the exhaust to spin the turbine. Now clearly both will build pressure as the turbine creates restriction. It's just a matter of how efficiant each is in using momentum Vs using pressure.
This is easily illustarted if you consider two exhausts. Both are say 2" but one is a straight pipe and the other has 8 tight 90* bends. The straight pipe will build less pressure because it doesn't interfear with the moving mass of the exhaust gases.
So, my point is that while a large WG will vent pressure it is better not to build pressure in the first place and to instead use the energy contained in the moving gases to their fullest.
Anyway, I'm sure there are people who use a stage III. I'd like to hear what they say.
I'm not sure I got my point accross about the larger turbine though. Think of a log manifold Vs a tube style. The log style creates backpressure for obvious reasons. Forcing large quantities of exhaust through a waste gate is the same principal.
It is important to remember that flow and pressure are not the same thing. Hold you hand in front of a strong stream of compressed air - the force you are feeling is not pressure. Pressure is what occurs inside the closed container. When the gas is released its molecules are accelerated to a given velocity and this velocity times their mass create the force you feel against your hand. I know this is a subtle difference but it is an important one.
If you take your air compressor and fire a hard stream of air at your turbine, you can make it spin quite fast. Yet the pressure differential in this case is 0. You are using only momentum.
Now back to our manifolds. Both will spin a turbo right? Yet a tube manifold will spin the turbo while having less actual pressure inside of it. This is because the log mani, due to its design, can not maintain the force of the gases momentum, it must wait untill pressure builds and forces the turbine to spin. A tube manifold on the other hand maintains the momentum of the gas and actually uses the moving mass of the exhaust to spin the turbine. Now clearly both will build pressure as the turbine creates restriction. It's just a matter of how efficiant each is in using momentum Vs using pressure.
This is easily illustarted if you consider two exhausts. Both are say 2" but one is a straight pipe and the other has 8 tight 90* bends. The straight pipe will build less pressure because it doesn't interfear with the moving mass of the exhaust gases.
So, my point is that while a large WG will vent pressure it is better not to build pressure in the first place and to instead use the energy contained in the moving gases to their fullest.
Anyway, I'm sure there are people who use a stage III. I'd like to hear what they say.
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C-Kwik
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Re: (Edub1)
Actually, the reason you can even get air out of your compressor is because of the pressure differential between the air inside the compressor and the air outside of it. None of the momentum you describe would exist without the pressure differential. The pressure differential in this case is not 0.Edub1 wrote:If you take your air compressor and fire a hard stream of air at your turbine, you can make it spin quite fast. Yet the pressure differential in this case is 0. You are using only momentum.
As for more momentum, noone said it doesn't help, but I think you are looking at it the wrong way. More momentum results in a higher pressure area building in front of the turbine housing. This builds a slightly higher pressure differential with the same airflow. Where the wastegate comes in is always when the desired boost is reached. This is where turbo operation is generally more critical. The higher pressure differential created by additional momentum would require the wastegate to bypass more air in order to decrease the pressure differential. Otherwise, the higher pressure differential will cause the turbo to boost to a higher pressure. Requiring less airflow to achieve the desired pressure differential will mean less pressure in the rest of the manifold, resulting in less backpressure on the motor. This has nothing to do with using a larger turbine. The properties exist on any turbo.
+1 for everything Ckwik just described. The important thing here is not to try and separate the different ways a tubine wheels is spun, but rather to see it as a whole, with the primary function being delta P.
Additionally, it's important to remember that, when running low boost pressures, a higher percentage of the total exhaust flow must travel through the wastegate. Having such large exhaust displacement as the KA24 run through such a small turbo with an internal gate is prime candidate for boost creep, especially when trying to maintain low boost pressures.
It's time to step up to a better turbo and probably an external 38mm gate.
Additionally, it's important to remember that, when running low boost pressures, a higher percentage of the total exhaust flow must travel through the wastegate. Having such large exhaust displacement as the KA24 run through such a small turbo with an internal gate is prime candidate for boost creep, especially when trying to maintain low boost pressures.
It's time to step up to a better turbo and probably an external 38mm gate.
Re: (C-Kwik)
I understand what you are saying. I do think you are confusing pressure with force though. Using a hard stream of air to spin a turbine has nothing to do with pressure, it has to do with force. Force is measured in foot pounds or newton meters, pressure is measured in psi, bar, etc...
exhaust gases exert both force and pressure. In fact, it is resistance to the force that generates pressure. A smaller wheel will offer greater resistance to force and hence cause more pressure to build. This pressure must be vented off. A larger wheel will allow more gas to flow through it, therefore creating less resistance and less pressure. The wheel is being spun by the force of the gas - this is not pressure, it is force. And there is less pressure that needs to be vented. An ideal situation would be to have the turbo just free spinning from the force of the gas like a pinwheel without creating any backpressure. Of course this doesn't happen but I think the bigger wheel comes closer to this than a smaller one. The bottom line, you can vent the gas through the wheel or through the WG. The WG is going to provide a lot more resistance than the a big wheel. I think it best to keep pressure to the minimum amount needed and derive as much boost as possible using the force of the air going through the wheel rather than the pressure.
This is why the smaller wheel gives faster spool. It has more resistance to force so it builds pressure quickly which in turn creates a lot of force. Then a good deal is vented from the WG.
The larger wheel spools more slowly because it has less resistance to force and builds pressure more slowly but is more efficient when the gas volumes get high.
If they both work based on the same backpressure, how does this occur?
A good way to illustrate the difference between force and pressure is to stick a fan or just your hand out of your car window on the freeway. What you observe is force, not pressure. There is no pressure difference on either side of the fan, only the mass of the air acting against the fan blade. This is force, not pressure. You can spin a turbine with force.
exhaust gases exert both force and pressure. In fact, it is resistance to the force that generates pressure. A smaller wheel will offer greater resistance to force and hence cause more pressure to build. This pressure must be vented off. A larger wheel will allow more gas to flow through it, therefore creating less resistance and less pressure. The wheel is being spun by the force of the gas - this is not pressure, it is force. And there is less pressure that needs to be vented. An ideal situation would be to have the turbo just free spinning from the force of the gas like a pinwheel without creating any backpressure. Of course this doesn't happen but I think the bigger wheel comes closer to this than a smaller one. The bottom line, you can vent the gas through the wheel or through the WG. The WG is going to provide a lot more resistance than the a big wheel. I think it best to keep pressure to the minimum amount needed and derive as much boost as possible using the force of the air going through the wheel rather than the pressure.
This is why the smaller wheel gives faster spool. It has more resistance to force so it builds pressure quickly which in turn creates a lot of force. Then a good deal is vented from the WG.
The larger wheel spools more slowly because it has less resistance to force and builds pressure more slowly but is more efficient when the gas volumes get high.
If they both work based on the same backpressure, how does this occur?
A good way to illustrate the difference between force and pressure is to stick a fan or just your hand out of your car window on the freeway. What you observe is force, not pressure. There is no pressure difference on either side of the fan, only the mass of the air acting against the fan blade. This is force, not pressure. You can spin a turbine with force.
I assure you, if you hold the fan out the window (as described in your example), there will be higher pressure on the frontal area of the fan blades than on the rear-most area.
Think of an airplane wing. Why does a wing create lift? It's a result of a low pressure area on top of the wing created by the aerodynamic design/shape of the wing itself. The airflow across the bottom surface of the wing has a greater pressure than that found on the top of the wing. Conseqently, the wing will "lift" toward the low pressure area.
As for the differences in spool times between a larger and smaller wheel, there are many other factors to consider besides open gas flow area through the wheel. You must take into account the pitch of each wheel, the difference in mass of the wheel/shaft assemblies, etc.
Think of an airplane wing. Why does a wing create lift? It's a result of a low pressure area on top of the wing created by the aerodynamic design/shape of the wing itself. The airflow across the bottom surface of the wing has a greater pressure than that found on the top of the wing. Conseqently, the wing will "lift" toward the low pressure area.
As for the differences in spool times between a larger and smaller wheel, there are many other factors to consider besides open gas flow area through the wheel. You must take into account the pitch of each wheel, the difference in mass of the wheel/shaft assemblies, etc.
Re: (KATwo40)
The wing example does use pressure. A jet engine uses force. Even in space which is a vacuum where no pressure is possible, a jet engine still produces thrust because force is different from pressure. I can understand how the two could seem very similar if one hasn't had the difference drilled into their brain though.KATwo40 wrote:I assure you, if you hold the fan out the window (as described in your example), there will be higher pressure on the frontal area of the fan blades than on the rear-most area.
Think of an airplane wing. Why does a wing create lift? It's a result of a low pressure area on top of the wing created by the aerodynamic design/shape of the wing itself. The airflow across the bottom surface of the wing has a greater pressure than that found on the top of the wing. Conseqently, the wing will "lift" toward the low pressure area.
As for the differences in spool times between a larger and smaller wheel, there are many other factors to consider besides open gas flow area through the wheel. You must take into account the pitch of each wheel, the difference in mass of the wheel/shaft assemblies, etc.
But that has been beat to death already. I probably will not swap the wheel because it is expensive and I'm worried about spool up time. I just can't see how you guys think it's better to create a ton of unneeded and unused backpressure and then vent it off though a tiny hole when you could increase the area of the turbine and leave it vent WITHOUT creating the pressure to begin with.
Anyway, let me see if I can understand what you guys are saying a little bit better because I'm still confused as to how the WG vents exhaust gas in conditions where it might not be open. Say for instance you are traveling at a high rate of speed with about 1/2 throttle. Say here your big wheel might create just enough backpressure to keep you in some boost but not enough to open the WG. The boost would only reach max when you floor it. So, here you have just enough backpressure to keep you rocking but no more than is needed.
Now, in this same situation let's say you have a smaller wheel. The smaller wheel will naturally create more backpressure and cause more boost which would cause the WG to open to vent the pressure.
So, your argument is that it's better to create a lot of unneccessary backpressure and just wait untill the wastegate vents it off? Or in other words, it's better to deal with the pressure than to try to avoid making it?
If this is so, why not just use a little 1" wheel and a huge 3" WG? Then you could stay in boost all the time and just let the overage bleed out of the WG. Or perhaps a two hole WG where one vents enough to keep it stable for normal driving and the other for a secondary?
I guess the way to measure it is if you are in boost before you want to be or at normal highway driving your wheel is too small.
Anyway, I've managed to confuse myself by all this. Why is it they make different exhaust stages to begin with?
Jet engines don't work in space. They are turbine operated and require oxygen to fire. Thrusters used in space use solid rocket fuel. Totally different from anything aerodynamic whatsoever, in terms of propulsion, pressure differentials and air velocities.
I'm not saying it's better to have the WG open all the time. In fact, I'm a fan of "properly sized turbos do reach full boost sooner than 1/3 of the max rpm." This way, the turbine wheel is passing the exhaust gases without spooling up the turbo everytime you start up a gentle hill.
You have the right idea, in the end. Your turbo is too small to do what you want it to do. Not only is the turbine side choking up top, but so is the compressor, with it's flow properties.
I'm not saying it's better to have the WG open all the time. In fact, I'm a fan of "properly sized turbos do reach full boost sooner than 1/3 of the max rpm." This way, the turbine wheel is passing the exhaust gases without spooling up the turbo everytime you start up a gentle hill.
You have the right idea, in the end. Your turbo is too small to do what you want it to do. Not only is the turbine side choking up top, but so is the compressor, with it's flow properties.
Re: (Chezedik)
I agree, there must be some guidline for turbine size.____________________________________________________
BTW, I didn't mean jet engines per se - yes, thrusters. But you are wrong about the pressure, they use pressure to produce force and only force makes the craft move - not pressure. Pressure is commonly used to mean force but it is something entirely different.
BTW, I didn't mean jet engines per se - yes, thrusters. But you are wrong about the pressure, they use pressure to produce force and only force makes the craft move - not pressure. Pressure is commonly used to mean force but it is something entirely different.
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C-Kwik
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Re: (Edub1)
Pressure and force are indeed different. But the point you are missing is that the pressure differential creates the airflow and air velocity needed to create the force/momentum you speak of.
Smaller turbos spool faster moslty because the smaller actual nozzle sizes require less airflow to create nozzle velocities needed to drive the turbine wheel. Smaller wheels generally have less mass (both the compressor and turbine wheels) so it's easier to spin them as well.
Larger turbos have larger nozzle sizes allowing more air to flow but require a higher airflow rate to achieve higher velocity gasses at the nozzle. Compressors require a certain amount of shaft torque as well (very closely related to the compressor's efficiency). Larger turbines have larger major diameters and perheps even minor diameters, which allows a given exhaust velocity to have more leverage over the compressor. A small turbine will generally require more velocity at the nozzle to drive the same compressor as a larger turbine. Where smaller turbos reach really high pressures in the exhaust manifold are when you are trying to push more air through the nozzle. Since the nozzle is a fixed size, you have to increase the pressure differential.
Noone here is saying higher pressure is ideal. In fact, I've said quite the opposite in this thread and in many other threads here. A pressure differential is necessary to create the airflow needed to drive the turbo. But when you can boost a given amount of air with less of a pressure differential, you can make more power as you get less loss in power due to backpressure in the exhaust manifold.
As for WG operation under low boost essentially, it doesn't. A WG responds to boost pressure, so if you are not reaching or nearing the set boost level, the WG stays shut. Boost in this case is regulated strictly by the throttle and the corresponding airflow through the motor. At lower throttle inputs less air is burned and the corresponding exhaust airflow and pressure is lower than you would find at full throttle at the same RPM.
Smaller turbos spool faster moslty because the smaller actual nozzle sizes require less airflow to create nozzle velocities needed to drive the turbine wheel. Smaller wheels generally have less mass (both the compressor and turbine wheels) so it's easier to spin them as well.
Larger turbos have larger nozzle sizes allowing more air to flow but require a higher airflow rate to achieve higher velocity gasses at the nozzle. Compressors require a certain amount of shaft torque as well (very closely related to the compressor's efficiency). Larger turbines have larger major diameters and perheps even minor diameters, which allows a given exhaust velocity to have more leverage over the compressor. A small turbine will generally require more velocity at the nozzle to drive the same compressor as a larger turbine. Where smaller turbos reach really high pressures in the exhaust manifold are when you are trying to push more air through the nozzle. Since the nozzle is a fixed size, you have to increase the pressure differential.
Noone here is saying higher pressure is ideal. In fact, I've said quite the opposite in this thread and in many other threads here. A pressure differential is necessary to create the airflow needed to drive the turbo. But when you can boost a given amount of air with less of a pressure differential, you can make more power as you get less loss in power due to backpressure in the exhaust manifold.
As for WG operation under low boost essentially, it doesn't. A WG responds to boost pressure, so if you are not reaching or nearing the set boost level, the WG stays shut. Boost in this case is regulated strictly by the throttle and the corresponding airflow through the motor. At lower throttle inputs less air is burned and the corresponding exhaust airflow and pressure is lower than you would find at full throttle at the same RPM.
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WDRacing
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You guys are all wicked smart, but at the SAME time, wicked dumb.
This is simple and requires almost zero research. Small internal wastegates suckass, they always have. Making them bigger almost helps control boost spikes and enhance flow. Even making the hole a little bigger has been proven to help on lots of stock turbo cars.
The concept behind the turbine section and turbine wheel is easy...c-mon, bigger flows more. Its as simple as that. Increase the turbine size and very the stg of the wheel and the flow increases and lag goes up or down as a result. It goes up or down because more or less air makes it past the turbine blades before they start moving. Less back pressure equals more power.
All together the smallish turbo's are only good for low boost for a simple reason...they are small and don't flow enough exhaust gas pressure.
I'm still failing to see why anyone would not buy a T3/TO4E as the first turbo with an external WG if you ever think you may possibly want to run more boost. Want less lag, run a .48 AR exhaust housing. AZhitman has instant boost and runs 15 psi all day everyday with the help of a standard 38mm Tial.
The key is finding a combo that will flow well...I have never condoned smaller turbo's for a reason and this is it. Instant boost is instant gratification, but you fall short in the long run.
WD
This is simple and requires almost zero research. Small internal wastegates suckass, they always have. Making them bigger almost helps control boost spikes and enhance flow. Even making the hole a little bigger has been proven to help on lots of stock turbo cars.
The concept behind the turbine section and turbine wheel is easy...c-mon, bigger flows more. Its as simple as that. Increase the turbine size and very the stg of the wheel and the flow increases and lag goes up or down as a result. It goes up or down because more or less air makes it past the turbine blades before they start moving. Less back pressure equals more power.
All together the smallish turbo's are only good for low boost for a simple reason...they are small and don't flow enough exhaust gas pressure.
I'm still failing to see why anyone would not buy a T3/TO4E as the first turbo with an external WG if you ever think you may possibly want to run more boost. Want less lag, run a .48 AR exhaust housing. AZhitman has instant boost and runs 15 psi all day everyday with the help of a standard 38mm Tial.
The key is finding a combo that will flow well...I have never condoned smaller turbo's for a reason and this is it. Instant boost is instant gratification, but you fall short in the long run.
WD
Re: (WDRacing)
I'll do a compressor upgrade. A guy here will do it for $200. What can you get for $350 the whole turbo or a compressor?
Are the fakes that bad? Realize that I will have two so it's no big deal if one has a little trouble.
Are the fakes that bad? Realize that I will have two so it's no big deal if one has a little trouble.
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Re: (Edub1)
Have you noticed an increase in turbo failures? Those wouild be the fakes. Until ebay started slinging cheap crap, I never saw threads about people smoking a turbo after a day of use.
Anyway, the $350 is for the whole turbo. KATwo40 gave me the link, but I lost it. Maybe he'll chime in or you can email him.
The turbo isn't waht concerns me though, its the wastegate. They are crap...
What are the exact specs of your turbo now?
Anyway, the $350 is for the whole turbo. KATwo40 gave me the link, but I lost it. Maybe he'll chime in or you can email him.
The turbo isn't waht concerns me though, its the wastegate. They are crap...
What are the exact specs of your turbo now?
You can upgrade your compressor to a T-66 and you'll still suffer exhaust choking issues that limit the power up top.
Use a T3/T04E. Get the whole unit here:
http://www.teamblindside.com
Tell them Jonathon sent you. They sell a T3/T04E 50 trim with a .63 A/R exhaust and .50 A/R compressor for about $350 w/ 1yr warranty. These are Garrett internals with offbrand housings.
How good are they? Just about every Honda in Knoxville, TN is using one, one of the guys at the shop is using one (made 290whp @ 9psi) and I have one sitting in my garage about to go on my car as a bottom mount.
Mind you, my $750 "REAL GARRETT" turbo from AGPturbo.com came with the following warranty:
"Yep, we guarantee it's a turbo when you open the box."
No warranty beyond that.
Use a T3/T04E. Get the whole unit here:
http://www.teamblindside.com
Tell them Jonathon sent you. They sell a T3/T04E 50 trim with a .63 A/R exhaust and .50 A/R compressor for about $350 w/ 1yr warranty. These are Garrett internals with offbrand housings.
How good are they? Just about every Honda in Knoxville, TN is using one, one of the guys at the shop is using one (made 290whp @ 9psi) and I have one sitting in my garage about to go on my car as a bottom mount.
Mind you, my $750 "REAL GARRETT" turbo from AGPturbo.com came with the following warranty:
"Yep, we guarantee it's a turbo when you open the box."
No warranty beyond that.
Re: (KATwo40)
I'm begining to think I should sell the T3 and get one of those GT32 for $650. Only thing is I don't want to have to fab up a new dump pipe. That was a real PIA.
If you're referring to the GT32 from AMS, you're going to be disappointed. They're out of stock, and when they do get more, the price is getting hiked.
Just get a T3/T04E 50 trim and be done with it. Why are you holding out?
BTW, we just turned out an SR20DET at the shop with one of these T3/T04E units I'm talkin' about and it made nearly 10psi @ 3700rpm...that's pretty freakin' good on that motor.
Just get a T3/T04E 50 trim and be done with it. Why are you holding out?
BTW, we just turned out an SR20DET at the shop with one of these T3/T04E units I'm talkin' about and it made nearly 10psi @ 3700rpm...that's pretty freakin' good on that motor.
Re: (KATwo40)
That's what I'm going to do. 50 trim or 57?