Making a turbo kit
Making a turbo kit
Ok so im planing on piecing my own turbo kit and I need some help. I want to use a Garret T3/T04E turbo, but I need help in choosing the trim. What is the difference from 40 trim compaired to 60 trim and how will it effect proformance? And what turbine housing should I use 0.48 A/R or 0.63 A/R, I dont really even understand what that means.What down pipe should I use? does anyone know where I can get a 3" (or one close to it) for a KA.And just one last thing, What is the difference between a wastegate and a BOV. I totally understand the function of a wastegate but not a BOV.
I'll have to give you the obligatory "SEARCH!!!!"
but also answer some questions.
the trims of the compressors have different efficiancy ranges which essentially determine how hot/dense the air is. You want something more efficiant (cooler.) The would be the t04e 50 trim, it is the best for street applications hands down. If you want to know WHY, you'll be in for the fun of learning to read and plot compressor maps.
Turbine - .48 is too small, it will choke out the motor, power will drop as well as the boost around 5000-5500 on a kA, it just isn't good. Most people here are using the a .63 a/r turbine. It's also the best choice for street applications here. There are different staged turbine wheels also, which basically tell you how angled the fins are, the stage 1 (what you would find on a turbo that came on a car from the factory) the fins will overlap, which make for quicker spool, but say on a more radical stage 5, the fins are almost laying "flat" in reference to looking in at the turbine outlet, they would appear thin, which allow for more air flow. a .82 a/r turbine is what people use for big horsepower, usually not needed until upward of 400whp.
The BOV releases the pressure from the system when you let off the gas petal (close the throttle plate), the reason you have to do this, is because the turbo is now blowing 7psi at a piece of metal, the air has nowhere to go but back toward the compressor through the charge pipes, and this creates compressor surge. It severly shortens the life of your turbo and de-spools it (to make up a word) also inbetween shifts creating more lag.
but also answer some questions.
the trims of the compressors have different efficiancy ranges which essentially determine how hot/dense the air is. You want something more efficiant (cooler.) The would be the t04e 50 trim, it is the best for street applications hands down. If you want to know WHY, you'll be in for the fun of learning to read and plot compressor maps.
Turbine - .48 is too small, it will choke out the motor, power will drop as well as the boost around 5000-5500 on a kA, it just isn't good. Most people here are using the a .63 a/r turbine. It's also the best choice for street applications here. There are different staged turbine wheels also, which basically tell you how angled the fins are, the stage 1 (what you would find on a turbo that came on a car from the factory) the fins will overlap, which make for quicker spool, but say on a more radical stage 5, the fins are almost laying "flat" in reference to looking in at the turbine outlet, they would appear thin, which allow for more air flow. a .82 a/r turbine is what people use for big horsepower, usually not needed until upward of 400whp.
The BOV releases the pressure from the system when you let off the gas petal (close the throttle plate), the reason you have to do this, is because the turbo is now blowing 7psi at a piece of metal, the air has nowhere to go but back toward the compressor through the charge pipes, and this creates compressor surge. It severly shortens the life of your turbo and de-spools it (to make up a word) also inbetween shifts creating more lag.
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hannibal
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OK...Those trims tell you the shape of the compressor wheel. Each has different efficiency pionts (combinations of airflow and boost pressure) where its best to operate. This info is shown on a compressor map found on Turbonetics' and Grerett's websites and all over the net. THeres a sticky at the top of this forum on how to read one.The A/R refers to the relative size of the turbo's housings. A exhasut housing A/R of 0.48 is 'smaller' than a 0.63 housing. Because its 'smaller', it doesnt need as much exhasut airflow to make it spin the turbine wheel inside. This means it will start producing boost at lower rpms (when only a smaller amount of air is going into and out of the motor). At higher rpms (and greater airflow), your trying to force a whole lot of air thru this 'small' turbine housing. This is where bigger housings like the 0.63 and 0.82 are better. They can handle larger amounts of airflow. But at low rpms (and low airflow) these bigger housings need more exhasut flow to make them start spinning the wheel inside.FOr example, say your 0.48 A/R housing gets the wheel inside spinning up to speed at just 2500rpms. A 'bigger' housing like a 0.82 might need 3500rpm worth of airflow to get the wheel spinning fast enought to produce boost. This can be generalized by saying smaller turbine housings (lower A/R) have less lag than larger housings. And, as described above, bigger exhaust housings provide better (more efficient) top end flow than smaller housings.Downpipes are usually custom made. The position of your turbine outlet (which the downpipe connects to) depends on the position the turbo which depends of the type of exhaust manifold used. Kits like Greddy come with a downpipe designed to be used with that particular turbo and manifold combination.A BOV lies on the intake side of the engine while the wastgate lies on the exhaust side. BOV's are used to keep the turbo spinng during while shifting gears. At the top of a gear (high rpms), your turbo is pushing a lot of compressed air into your motor. When you take your foot of the gas to shift, the throttle plate closes and stops air from entering the engine. Well now all this compressed air coming from the trubo heading to the intake has no where to go. Its like putting your finger on the end of a straw and trying to blow thru the other end. THis is not good for the turbo (or you). The BOV gives this air a way to escape the from the pipes. Its a valve that only opens when the throttle plate has closed.
check out http://www.howthingswork.com for more info. And read a book like Maximum Bosst by Corky Bell.... and search!!!
Damn that was long. Do you have an address where I can send my bill???
check out http://www.howthingswork.com for more info. And read a book like Maximum Bosst by Corky Bell.... and search!!!
Damn that was long. Do you have an address where I can send my bill???
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C-Kwik
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A/R is NOT, I repeat, is NOT the size of the housing. A/R or Area/Radius refers to the area of the nozzle divided by the radius of the nozzle's center from the axis of the turbo. The nozzle on a turbine is where the turbine inlet releases air to drive the rubine wheel. Generally, for a given turbine wheel the housing size stays the same, so the raduis stays the same. The nozzle however is usually what is varied in order to control the velocity of air hitting the turbine wheel. A smaller A/R, or effectively the nozzle forces the same amount of air through a smaller opening. This causes the air velocity to be higher which in turn helps drive the turbine. The problem with too small a nozzle is that as airflow requirements increase as boost and/or intake airflow increases, even more air needs to be forced through the nozzle. This is where a small nozzle can become restrictive. A larger A/R or nozzle can naturally flow more air, but at lower engine speeds where airflow is lower it may have low air velocity which results in a slower spooling turbo.
The turbine stages are actually determined by the physical dimensions of the wheels. On both a compressor and turbine wheel there is what is referred to as the minor and major diameters. The narrower measurement across the axis of the turbine shaft is the minor diameter. The major is then the larger diameter across the turbine shaft. With Garrett based turbos, referring to these exhaust trims as stages is only done by turbonetics. Other companies use the actual numeric value of the trim(ie 50 triim, 57 trim, etc). For a given turbine the major diameter usually stays the same. The minor is changed to construct the varying trims. Since the outer diameter is the same, they usually do not touch the overall size of the turbine housing itself. In fact you can take a smaller trim housing and machine it to accept a larger trim wheel. Most of the machining will be done around the area of the minor diameter and and will progressively lessen as you reach the major diameter. All said and done, the internal dimensions of a modified turbine housing will match that of one that is matched to a specific trim wheel from the manufacturer. Why? Because the manufacturer machines the trim size into the same castings.
The turbine stages are actually determined by the physical dimensions of the wheels. On both a compressor and turbine wheel there is what is referred to as the minor and major diameters. The narrower measurement across the axis of the turbine shaft is the minor diameter. The major is then the larger diameter across the turbine shaft. With Garrett based turbos, referring to these exhaust trims as stages is only done by turbonetics. Other companies use the actual numeric value of the trim(ie 50 triim, 57 trim, etc). For a given turbine the major diameter usually stays the same. The minor is changed to construct the varying trims. Since the outer diameter is the same, they usually do not touch the overall size of the turbine housing itself. In fact you can take a smaller trim housing and machine it to accept a larger trim wheel. Most of the machining will be done around the area of the minor diameter and and will progressively lessen as you reach the major diameter. All said and done, the internal dimensions of a modified turbine housing will match that of one that is matched to a specific trim wheel from the manufacturer. Why? Because the manufacturer machines the trim size into the same castings.
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Checkered-Member
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blacks13ek
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C-Kwik
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Checkered-Member wrote:C-KwikWhich T3 turbine A/R will you recommend for a stock KA24DEthe .48 or .63?
Depends on several factors. Which T3 turbine? There are several trim levels. Secondly, what do you feel is more important? Good low-end turbo response or more top-end power? What are your power goals? And what compressor are you going to use?
Keep in mind I have a bias towards larger turbos. I'd use a smaller trim T4 turbine myself for a street KA(which is what I had on mine). So, as objective as I might try to be, I may end up pushing you towards a larger turbine or A/R.
It's also hard to really describe turbo response as well. Many people confuse turbo response and boost threshold. Larger turbos aren't necessarily unresponsive. The larger size is of course more weight to have to push around, but the biggest factor is that larger turbines need more energy to spin it. But at low RPM's where the exhaust flow is lower, there may not be enough energy. So until you reach an RPM where there is enough energy, the turbo will not spool fast enough to make boost. But once you are above the boost threshold, turbo response is pretty good. You can go from part throttle cruising and smash the gas and as long as you are above the boost threshold, the turbo will respond pretty quickly. I'm talking relatively here though. Larger turbos, again, do have more weight in the moving parts so there is a very small delay, but on a track, you can hardly tell. In exiting a corner, you should be easing onto the gas anyway in the transition from turning to accelerating, you'ld likely never be able to tell.
Honestly, though, the best way to know is to test it out yourself. If you can try to drive or get a ride in various turbo cars, especially cars like your own. Watch how the car responds to the throttle inputs at various RPM. Ask about the specs of the turbine and compressor. If the compressor size and trim are close, the differences will probably be negligible. You'll have an easier time comparing different turbine specs against similar compressor wheels. Comparing 2 different turbines with a T4 and T3 compressor wheel would be a lot more difficult.