something happend to my turbo a few months ago. It whistles at anything lower than 10 vac. Its not the hoses or anything like that. Im 99% sure its the wastegate. I kno another person who had the same problem and it was a hole in the wastegate. Is now the time to get a bigger turbo and run it at a low psi, like 6.5 until i get the engine rebuilt. I have to do something about it, but i wasnt sure if a bigger turbo would hurt anything as long as its running at the same psi as the stock turbo. and i do plan on doing major things like engine rebuild and stabd alone fuel management too when I get home, if that makes a difference wither way.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
bigger turbo or not yet?
- Thread starter lncatch
- Start date
you could put your car back to stock and have the dealer replace inspect it. you could also take the car to a shop and have them inspect the wastegate/noise. might as well find the problem before you throw money at the car trying to fix it.
no one here is going to be able to diagnois the problem 100% but there are a few threads regarding the whistling at idle and during boost.
i wouldn't put a larger turbo on w/o a good EMS. then you can tune for the larger turbo and run that reliably before you build the motor.
no one here is going to be able to diagnois the problem 100% but there are a few threads regarding the whistling at idle and during boost.
i wouldn't put a larger turbo on w/o a good EMS. then you can tune for the larger turbo and run that reliably before you build the motor.
- :
- MP5T / 944
Ummm, 5 Psi is 5 Psi with the exception of the HEAT. An engine will only take is so much air weather the air is coming from a small or large turbo. Unless you are trying to make over or near the surge limit of the turbo, there is no added benifit...
http://home.comcast.net/~tarryo/kyle/compefficiency.html
Check out the link, it will explain in greater detal...
http://home.comcast.net/~tarryo/kyle/compefficiency.html
Check out the link, it will explain in greater detal...
- :
- MP5T / 944
Oh Hell, I'll just re-post...
______________________
Not my Text...Not My Text...
______________________
I originally typed this up for a DSM website, but due to popular demand, I have posted it here so people can link to it.
There are all kinds of misconceptions when it comes to turbo sizing, flow rates, and compressor efficiency, so I have typed this article with the intent of clearing some of them up.
I will focus this discussion on the most common DSM turbo upgrade, the 14b to 16g switch. However, due to all of the other options that people still use, I will bring up a couple others, such as the 20g, and the common Honda practice of using a huge garrett compressor wheel at very low boost pressures.
First, the common DSM upgrade beliefs. People think that if you upgrade from a 14b to a 16g, you will instantly flow more air due to greater compressor efficiency, making more power, requiring more fuel, and all this will take place at mundane 15 psi boost levels, on pump gas. Wrong!
The fact of the matter is, especially at the lower boost levels DSMs commonly run on pump gas (not to mention the lower boost levels that are run by Hondas), compressor efficiency differences do not create a large advantage in terms of mass-flow. It is the mass flow of the turbo and engine combination that actually matters when one is trying to find out fuel needs and power output, and with some semi-simple math, one can calculate the differences between the 14b, 16g, and any other turbo you so choose.
For the following examples, we will assume that the car is question is a 2 liter DOHC import motor, thus assuming very good volumetric efficiency, on pump gas, with a 60% efficient intercooler. With a good FMIC, you will see even less gains then those below. All boost pressures are measured at the compressor outlet, and all temperatures are measured in the intake manifold. The pressure ratio (PR) is taken from the turbo inlet pipe to the intake manifold, and assumes a turbo inlet pressure of approximately 14 psi (due to flow loss from the air filter and the intake piping.) and an intercooler and IC pipe pressure drop of 2 more psi. Compressor inlet temperature is 60 degrees farenheight.
Example one: 14b, 15 psi, 315 CFM, PR = 2.26
Compressor Efficiency: 73.5%
Charge temperature: 593R (133* F)
Example two: 16g, 15 psi, 317 CFM, PR = 2.26
Compressor Efficiency: 77%
Charge Temperature: 589R (129* F)
At this point, we can already see a couple of things developing. First, there is not a huge difference in compressor efficiency between a 16g and a 14b at a PR of 2.26. Second of all, the temperature difference is very small.
If you run a tad bit more math, you can figure out the mass flow rate, either by converting from CFM, or by using the ideal gas law. I prefer to use the ideal gas law, just because that way I do not have to use the same CFM number that I used to calculate the compressor efficiency, and I can check my numbers.
For the sake of information, in order to use the ideal gas law, we assume that the displacement is the volume of the motor (2 liters) times the VE (95% at 6000 rpm) times the amount of full cycles of the motor in the chosen time interval (1 minute). This is just half the rpm (3000). Pressure is the pressure ratio, 2.26 in this case. T is the temperature of the air in the manifold in Rankin (because you must use absolute). R is a constant, found by plugging in the base units of all of the above (22.4L, 1.0, 1.0, 460). N is what we want to find, because we can easily convert the number of molecules to the mass flow, by knowing the average molar mass of air.
Ok, after you crunch some numbers, you arrive at the following: The 14b is flowing about 25.2 lb/min, while the 16g is flowing 25.4 lb/min. Not a big difference, if you even want to call it that. This is about 2 horsepower, requiring a negligible amount of fuel (because the change in fuel flow is one-tenth the change in airflow).
Now, a more extreme example. It is common practice in the turbo Honda world to sell kits with large Garrett turbos, yet run at boost levels around 10 psi. The 50-60 trims Garrett turbos are the most common, so for this example, I will compare the 14b (again) to a 57 trim Garrett wheel, at 12 psi of boost.
The motor in question has now become a 1.8 liter, and I will increase the VE to 110%, because the Honda guys get all uptight about their higher flowing heads. I could write a whole article on how they cant be that much better than other import heads, like that of the 4G63, or the 3SGTE. All other numbers will remain the same as they did for the first example.
Example 3: 14b, 12 psi, 330 CFM, PR=2.05
Compressor Efficiency: 74.5%
Charge Temperature: 582R (122* F)
Example 4: 57 Trim, 12 psi, 330 CFM, PR=2.05
Compressor Efficiency: 76%
Charge Temperature: 581R (121*F)
This example obviously has an even smaller difference in terms of mass flow and power potential. There is no reason a 57 trim is necessary at this boost level.
So now the question is, why even go to a larger turbo? My intent was not to discourage people from upgrading, but just to clear up some beliefs about turbos that were not true. A 16g is a good upgrade over a 14b, because the 16g is capable of boost levels over 24 or 25 psi, while the 14b is stuck operating around 21 psi. This will bring very large power increases, especially on race gas, or on a well prepped car.
Also, it is important to note that there will always be some degree of VE gained whenever a switch is made to a larger turbine housing. While larger housings will create more lag and raise the boost threshhold, they also decrease the restriction seen by the exhaust gases, and thus decrease the pressure within the exhaust manifold. The larger the pressure differential between the intake and exhaust side, the better the VE gains. With a switch from a 6 cm^2 housing to a 7 cm^2 housing at boost levels around 1 bar, there will be a small but noticeable power increase due to this. Obviously, this is more effective as power and flow levels rise.
The same is true for turbine wheels, which I feel are an often overlooked part of the turbo sizing process. By making a switch to a higher flowing turbine wheel, you are decreasing the pressure ratio needed across the hot side of the turbo in order to generate a certain shaft speed, and thus a certain boost pressure. This means that, for the same post-turbo exhaust pressure, the exhaust manifold pressure (backpressure) will be decreased, and VE will be increased. Again, you can see very solid power gains, without taking the compressor wheel into account.
______________________
Not my Text...Not My Text...
______________________
I originally typed this up for a DSM website, but due to popular demand, I have posted it here so people can link to it.
There are all kinds of misconceptions when it comes to turbo sizing, flow rates, and compressor efficiency, so I have typed this article with the intent of clearing some of them up.
I will focus this discussion on the most common DSM turbo upgrade, the 14b to 16g switch. However, due to all of the other options that people still use, I will bring up a couple others, such as the 20g, and the common Honda practice of using a huge garrett compressor wheel at very low boost pressures.
First, the common DSM upgrade beliefs. People think that if you upgrade from a 14b to a 16g, you will instantly flow more air due to greater compressor efficiency, making more power, requiring more fuel, and all this will take place at mundane 15 psi boost levels, on pump gas. Wrong!
The fact of the matter is, especially at the lower boost levels DSMs commonly run on pump gas (not to mention the lower boost levels that are run by Hondas), compressor efficiency differences do not create a large advantage in terms of mass-flow. It is the mass flow of the turbo and engine combination that actually matters when one is trying to find out fuel needs and power output, and with some semi-simple math, one can calculate the differences between the 14b, 16g, and any other turbo you so choose.
For the following examples, we will assume that the car is question is a 2 liter DOHC import motor, thus assuming very good volumetric efficiency, on pump gas, with a 60% efficient intercooler. With a good FMIC, you will see even less gains then those below. All boost pressures are measured at the compressor outlet, and all temperatures are measured in the intake manifold. The pressure ratio (PR) is taken from the turbo inlet pipe to the intake manifold, and assumes a turbo inlet pressure of approximately 14 psi (due to flow loss from the air filter and the intake piping.) and an intercooler and IC pipe pressure drop of 2 more psi. Compressor inlet temperature is 60 degrees farenheight.
Example one: 14b, 15 psi, 315 CFM, PR = 2.26
Compressor Efficiency: 73.5%
Charge temperature: 593R (133* F)
Example two: 16g, 15 psi, 317 CFM, PR = 2.26
Compressor Efficiency: 77%
Charge Temperature: 589R (129* F)
At this point, we can already see a couple of things developing. First, there is not a huge difference in compressor efficiency between a 16g and a 14b at a PR of 2.26. Second of all, the temperature difference is very small.
If you run a tad bit more math, you can figure out the mass flow rate, either by converting from CFM, or by using the ideal gas law. I prefer to use the ideal gas law, just because that way I do not have to use the same CFM number that I used to calculate the compressor efficiency, and I can check my numbers.
For the sake of information, in order to use the ideal gas law, we assume that the displacement is the volume of the motor (2 liters) times the VE (95% at 6000 rpm) times the amount of full cycles of the motor in the chosen time interval (1 minute). This is just half the rpm (3000). Pressure is the pressure ratio, 2.26 in this case. T is the temperature of the air in the manifold in Rankin (because you must use absolute). R is a constant, found by plugging in the base units of all of the above (22.4L, 1.0, 1.0, 460). N is what we want to find, because we can easily convert the number of molecules to the mass flow, by knowing the average molar mass of air.
Ok, after you crunch some numbers, you arrive at the following: The 14b is flowing about 25.2 lb/min, while the 16g is flowing 25.4 lb/min. Not a big difference, if you even want to call it that. This is about 2 horsepower, requiring a negligible amount of fuel (because the change in fuel flow is one-tenth the change in airflow).
Now, a more extreme example. It is common practice in the turbo Honda world to sell kits with large Garrett turbos, yet run at boost levels around 10 psi. The 50-60 trims Garrett turbos are the most common, so for this example, I will compare the 14b (again) to a 57 trim Garrett wheel, at 12 psi of boost.
The motor in question has now become a 1.8 liter, and I will increase the VE to 110%, because the Honda guys get all uptight about their higher flowing heads. I could write a whole article on how they cant be that much better than other import heads, like that of the 4G63, or the 3SGTE. All other numbers will remain the same as they did for the first example.
Example 3: 14b, 12 psi, 330 CFM, PR=2.05
Compressor Efficiency: 74.5%
Charge Temperature: 582R (122* F)
Example 4: 57 Trim, 12 psi, 330 CFM, PR=2.05
Compressor Efficiency: 76%
Charge Temperature: 581R (121*F)
This example obviously has an even smaller difference in terms of mass flow and power potential. There is no reason a 57 trim is necessary at this boost level.
So now the question is, why even go to a larger turbo? My intent was not to discourage people from upgrading, but just to clear up some beliefs about turbos that were not true. A 16g is a good upgrade over a 14b, because the 16g is capable of boost levels over 24 or 25 psi, while the 14b is stuck operating around 21 psi. This will bring very large power increases, especially on race gas, or on a well prepped car.
Also, it is important to note that there will always be some degree of VE gained whenever a switch is made to a larger turbine housing. While larger housings will create more lag and raise the boost threshhold, they also decrease the restriction seen by the exhaust gases, and thus decrease the pressure within the exhaust manifold. The larger the pressure differential between the intake and exhaust side, the better the VE gains. With a switch from a 6 cm^2 housing to a 7 cm^2 housing at boost levels around 1 bar, there will be a small but noticeable power increase due to this. Obviously, this is more effective as power and flow levels rise.
The same is true for turbine wheels, which I feel are an often overlooked part of the turbo sizing process. By making a switch to a higher flowing turbine wheel, you are decreasing the pressure ratio needed across the hot side of the turbo in order to generate a certain shaft speed, and thus a certain boost pressure. This means that, for the same post-turbo exhaust pressure, the exhaust manifold pressure (backpressure) will be decreased, and VE will be increased. Again, you can see very solid power gains, without taking the compressor wheel into account.
- :
- 2001 Mazda MP3
i have my GT28R for sale which is a bigger turbo, but not TOO big.
Not totally right, a bigger Turbo will flow more air at the same pressure level.Brian MP5T said:Ummm, 5 Psi is 5 Psi with the exception of the HEAT. An engine will only take is so much air weather the air is coming from a small or large turbo. Unless you are trying to make over or near the surge limit of the turbo, there is no added benifit...
Example: A GT42 will flow a lot more air than a GT25 both at 5psi.
that page only compared a 14g and a 16g, probably both with a TDO4H comp housing, so the difference is very small.
also, something Beau told me last night, is the PSI on an engine is basically a measure of inefficiency of an engine, its backpressure that your engine builds up. (thats why more efficient ported heads and intake mani's can lower the PSI and make the same or more power, or increase the power at the same psi)
a more efficient PSI doesn't equal a less efficient PSI because turbos that are more efficient will more more air per psi.
also, something Beau told me last night, is the PSI on an engine is basically a measure of inefficiency of an engine, its backpressure that your engine builds up. (thats why more efficient ported heads and intake mani's can lower the PSI and make the same or more power, or increase the power at the same psi)
a more efficient PSI doesn't equal a less efficient PSI because turbos that are more efficient will more more air per psi.
- :
- MP5T / 944
That makes no sense. If you had 10 Psi in a sealed container, it would be a finite volume of air. As soon as the valve closes and the compression stroke begins, the turbo is done adding HP to your car. If the cylinder is pumped to 10 Psi by a T-25 or a T-5453 and all the other functions were the same (Intake Temp etc) you would end up with the same amount (Volume) of air in your compression stroke.
PSI and Volume are a linear ratio equasion.
I would agree that the T3/4 would make more power at 15 Psi than a T-25 because of Heat, Surge Limits, Spool... Whatever other factor you like. However, I don't think that the physics support the generalized accepted notion that a bigger turbo running the exact same PSI makes more HP, just because...
PSI and Volume are a linear ratio equasion.
I would agree that the T3/4 would make more power at 15 Psi than a T-25 because of Heat, Surge Limits, Spool... Whatever other factor you like. However, I don't think that the physics support the generalized accepted notion that a bigger turbo running the exact same PSI makes more HP, just because...
and i dont buy that if u took say a t25 and a larger turbo, put them on the same engine, with no major variables that they will make the same power. If i put my t25 to 15 psi and did the same on a gt35R it would blow my engine. It sounds like your saying that all turbos produce the same cfm but the difference is how efficient the turbo is. which is not true at all, some turbos send 300cfm some send twice that. And just cause your at 10 psi doesnt mean your getting 10 psi of air into the engine, isnt it ...@ 10 psi my turbo is pushing X amt of cfm, correct me if im misunderstanding.
maybe im not understanding you, but if it is flowing MORE air, and you are running 8psi on both turbos, 8 pounds per square inch, and there are more "inches" of air coming from a larger turbo, i think that is probably where the power comes from? i dunno, im just guessing.Brian MP5T said:That makes no sense. If you had 10 Psi in a sealed container, it would be a finite volume of air. As soon as the valve closes and the compression stroke begins, the turbo is done adding HP to your car. If the cylinder is pumped to 10 Psi by a T-25 or a T-5453 and all the other functions were the same (Intake Temp etc) you would end up with the same amount (Volume) of air in your compression stroke.
PSI and Volume are a linear ratio equasion.
I would agree that the T3/4 would make more power at 15 Psi than a T-25 because of Heat, Surge Limits, Spool... Whatever other factor you like. However, I don't think that the physics support the generalized accepted notion that a bigger turbo running the exact same PSI makes more HP, just because...
its not quite as simple as you want to make it, yes a PSI is a PSI, but it has just as much to do with the turbine as the compressor, and the matching of the wheels and housings.Brian MP5T said:That makes no sense. If you had 10 Psi in a sealed container, it would be a finite volume of air. As soon as the valve closes and the compression stroke begins, the turbo is done adding HP to your car. If the cylinder is pumped to 10 Psi by a T-25 or a T-5453 and all the other functions were the same (Intake Temp etc) you would end up with the same amount (Volume) of air in your compression stroke.
PSI and Volume are a linear ratio equasion.
I would agree that the T3/4 would make more power at 15 Psi than a T-25 because of Heat, Surge Limits, Spool... Whatever other factor you like. However, I don't think that the physics support the generalized accepted notion that a bigger turbo running the exact same PSI makes more HP, just because...
If twice the cfm is pushed out of the turbo at your engine your going to have twice the boost pressure. So your wastegate will open sooner. End result is going to be the same volume of air.terbow said:and i dont buy that if u took say a t25 and a larger turbo, put them on the same engine, with no major variables that they will make the same power. If i put my t25 to 15 psi and did the same on a gt35R it would blow my engine. It sounds like your saying that all turbos produce the same cfm but the difference is how efficient the turbo is. which is not true at all, some turbos send 300cfm some send twice that. And just cause your at 10 psi doesnt mean your getting 10 psi of air into the engine, isnt it ...@ 10 psi my turbo is pushing X amt of cfm, correct me if im misunderstanding.
- :
- MP5T / 944
Ok, To make 10 PSI it would take a certain volume... If you were pushing twice the volume of air...(CFM), don't you think that would be the same as 20 Psi at the TB... But the wastegate would open sooner and you would get the same amount of air... 10 PSI...terbow said:and i dont buy that if u took say a t25 and a larger turbo, put them on the same engine, with no major variables that they will make the same power. If i put my t25 to 15 psi and did the same on a gt35R it would blow my engine. It sounds like your saying that all turbos produce the same cfm but the difference is how efficient the turbo is. which is not true at all, some turbos send 300cfm some send twice that. And just cause your at 10 psi doesnt mean your getting 10 psi of air into the engine, isnt it ...@ 10 psi my turbo is pushing X amt of cfm, correct me if im misunderstanding.
You see my point. 10 Psi in a closed space like a pop bottle is still 10 Psi weather it was pumped in during 1 second or 2 seconds, the volume is the same, the simple fact is that once the valves are closed and the compression stroke begins, "X" (Value) of air volume of air is being compressed and burnt regardless of how it got there if they were both 10 Psi.
Last edited:
- :
- MP5T / 944
I'm super comfortable to say that it has alot to do with the effency of the larger turbine...but just to say that it's because the turbo is able to push more VOLUME over a period of time seems hard to believe. It's not like the Cylinder is expanding like a baloon to house the extra air, If you put more air in that place, the pressure would go up...therefore there is no more "Volume" in the cylinder just because the pump is better. It's got to be another factor...RyanJayG said:its not quite as simple as you want to make it, yes a PSI is a PSI, but it has just as much to do with the turbine as the compressor, and the matching of the wheels and housings.
Last edited:
As long as the power you will be creating does not overload the engine or make it detonate. You don't want to bend a rod!!lncatch said:ok, so ill ask again...if im going to get engine management, is it safe to run the same psi as stock on a larger turbo givin that its tuned correctly??
Similar threads
- Replies
- 1
- Views
- 697
- Replies
- 2
- Views
- 2K
Latest posts
-
2016~2023 CX-9 DIY Cylinder head replacement (workshop/service manual)
- Latest: Silly Wabbit
-
