wastegate
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And I have a question here also...(hope you don't mind Lan Evo for tumpang the topic)
As we all know, there are a few sizes for the wastegate, 38MM, 40MM, 45MM, 46MM....so how do we know which is the right one to buy.
Thanks.
As we all know, there are a few sizes for the wastegate, 38MM, 40MM, 45MM, 46MM....so how do we know which is the right one to buy.
Thanks.
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boost level depends on the wastegate size.
Lan_Evo
Got TT in Greentown next MOnday (31/1). Call Aloy!!
ANyway, the main Advantage of external w/g I believe is boost control. 2nd is exhaust flow.
Disadvantage ah?, "SHRAAAAAAAAAA" sound!! Most people will think your exhaust piping bocor liao :lol:
Got TT in Greentown next MOnday (31/1). Call Aloy!!
ANyway, the main Advantage of external w/g I believe is boost control. 2nd is exhaust flow.
Disadvantage ah?, "SHRAAAAAAAAAA" sound!! Most people will think your exhaust piping bocor liao :lol:
jethrel dont tink so ..
it just limits the boost rite
it just limits the boost rite
"A wastegate basically just controls how much boost the turbo is going to run," says Kenji Sumino of GReddy Performance Products (Dept. ETD, 9 Vanderbilt, Irvine, CA 92618, 949-588-8300, www.greddy.com). "Without any wastegate, the boost would just keep on climbing until the engine blows. What [a wastegate] does is it lets out the excess exhaust energy before it goes into the turbo.... If the wastegate is set at 10 pounds, once the turbocharger reaches 10 pounds, it will dump the rest of the exhaust gas out to maintain that 10 pounds of boost."
Sumino notes that there are two kinds of wastegates. "The internal type is built in the turbo itself," he says. "The external type is actually outside, and it's usually bolted on the exhaust manifold, but it serves the same purpose."
Sumino notes that there are two kinds of wastegates. "The internal type is built in the turbo itself," he says. "The external type is actually outside, and it's usually bolted on the exhaust manifold, but it serves the same purpose."
Valve Size Typical Power Level
1.250 inches Up to 400 hp
1.500 inches Up to 500 hp
1.625 inches 800-900 hp
2.000 inches 1,000-1,400 hp
1.250 inches Up to 400 hp
1.500 inches Up to 500 hp
1.625 inches 800-900 hp
2.000 inches 1,000-1,400 hp
Airflow in lbs per minute = diameter of wastegate in mm X boost correction factor
So let's apply it to your car;
300 rwkw = 480 bhp
480 bhp = 44 lbs of airflow = 44 mm wastegate
Now if you want to run 19 psi, then that's the right size wastegate.
But we need to apply the boost correction....
My experience indicates that to get 300 rwkw out of a GT3040 you would need to run around 1.5 bar (22psi). So using the formula...
44 / 22 X 19 = 38 mm.
So let's apply it to your car;
300 rwkw = 480 bhp
480 bhp = 44 lbs of airflow = 44 mm wastegate
Now if you want to run 19 psi, then that's the right size wastegate.
But we need to apply the boost correction....
My experience indicates that to get 300 rwkw out of a GT3040 you would need to run around 1.5 bar (22psi). So using the formula...
44 / 22 X 19 = 38 mm.
1. The wastegate size is relevant to how much horsepower you are targeting
2. If you want to run high boost, then a smaller wastegate is better than a larger wastegate. The idea being that in order to generate high boost you need most of the exhaust gas going through the turbine, not through the wastegate.
3. If you want to run low boost then a larger wastegate is better than a smaller wastegate. The idea being that in order to keep the boost low you need a lot of the exhaust gas going through the wastegate not through the turbine.
But what is high boost? Well for the sake of this discussion I have settled on 1.2 to 1.4 bar (18 to 21 psi) as being the divider, thus 1. 2 bar and under is low and 1.4 bar and above is high. How did I arrive at this number? Well based on the results of the surveys, this seems to be the most common point where the wastegate sizes change from theory 2 to theory 3 (above).
The next bit of theory is that it takes 1 lb per minute of airflow to make 11 bhp in a current generation 4 valve engine. This is a pretty well established piece of turbo sizing philosophy. But how do we relate this to wastegate sizing? Well referring to the results of the surveys, it seems a straight 1 to 1 relationship is not too far from the average, so 1 lb of airflow = 1 mm of wastegate diameter.
What I am trying to do with the formula is give a baseline, something to think about. An 85% fit type of thing. At the moment there seems to be a majority of guys wanting external wastegates who don't even know where to start. They have been told for big horsepower you need a big wastegate, which is not necessarily true. They have been told you can't have too big a wastegate, which is definitely not true. They have been told for high boost you need a big wastegate, which again is not necessarily true.
In order to do this there is one main assumption, that the turbo is pretty much the optimium size for the target power and boost. If it is totally wrong then whether the wastegate is sized correctly or not is really irrelevant. The turbo / engine mismatch is gunna kill horsepower / response anyway.
A a 50mm wastegate valve is going to weigh twice as much as a 35 mm one. So there is an inertia issue to be considered. I think that is really the crux of the problem. The diaphram has to move twice as much weight, in and out very rapidly. This has 2 undersirable effects incomparison to a smaller (more correctly) sized wastegate.
Firstly the too large a wastegate has to open and close more often, as it has too little exhaust flow when closed and too much exhaust flow when open. This wears the diaphram, due to the requirement for more movements and more weight.
Secondly all this opening and closing of the wastegate affects the amount of exhaust flow though the turbine, this leads to fluctuations in the boost control. eg; I have seen a relatively low powered engine, with a very large wastegate, move up and down 0.3 bar in its boost as the boost control circuit struggles to keep up with this open, closed, open, closed requirement.
2. If you want to run high boost, then a smaller wastegate is better than a larger wastegate. The idea being that in order to generate high boost you need most of the exhaust gas going through the turbine, not through the wastegate.
3. If you want to run low boost then a larger wastegate is better than a smaller wastegate. The idea being that in order to keep the boost low you need a lot of the exhaust gas going through the wastegate not through the turbine.
But what is high boost? Well for the sake of this discussion I have settled on 1.2 to 1.4 bar (18 to 21 psi) as being the divider, thus 1. 2 bar and under is low and 1.4 bar and above is high. How did I arrive at this number? Well based on the results of the surveys, this seems to be the most common point where the wastegate sizes change from theory 2 to theory 3 (above).
The next bit of theory is that it takes 1 lb per minute of airflow to make 11 bhp in a current generation 4 valve engine. This is a pretty well established piece of turbo sizing philosophy. But how do we relate this to wastegate sizing? Well referring to the results of the surveys, it seems a straight 1 to 1 relationship is not too far from the average, so 1 lb of airflow = 1 mm of wastegate diameter.
What I am trying to do with the formula is give a baseline, something to think about. An 85% fit type of thing. At the moment there seems to be a majority of guys wanting external wastegates who don't even know where to start. They have been told for big horsepower you need a big wastegate, which is not necessarily true. They have been told you can't have too big a wastegate, which is definitely not true. They have been told for high boost you need a big wastegate, which again is not necessarily true.
In order to do this there is one main assumption, that the turbo is pretty much the optimium size for the target power and boost. If it is totally wrong then whether the wastegate is sized correctly or not is really irrelevant. The turbo / engine mismatch is gunna kill horsepower / response anyway.
A a 50mm wastegate valve is going to weigh twice as much as a 35 mm one. So there is an inertia issue to be considered. I think that is really the crux of the problem. The diaphram has to move twice as much weight, in and out very rapidly. This has 2 undersirable effects incomparison to a smaller (more correctly) sized wastegate.
Firstly the too large a wastegate has to open and close more often, as it has too little exhaust flow when closed and too much exhaust flow when open. This wears the diaphram, due to the requirement for more movements and more weight.
Secondly all this opening and closing of the wastegate affects the amount of exhaust flow though the turbine, this leads to fluctuations in the boost control. eg; I have seen a relatively low powered engine, with a very large wastegate, move up and down 0.3 bar in its boost as the boost control circuit struggles to keep up with this open, closed, open, closed requirement.
Respect for u JINKL
EvolutionV7 wei dont respect me la ,
i cut and paste from a website.
Hehe , cos i also finding info about wastegates :)
Confused with the size currently. :)
i cut and paste from a website.
Hehe , cos i also finding info about wastegates :)
Confused with the size currently. :)
there is nothing more beautiful than the sound of a massive wastegate opening up as a car rips past... sounds like heaven to me.... :)
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