Questions about turbos
Questions about turbos I've been reading about turbos over here and have a better understanding about what makes turbos different from each other and how to choose a turbo for differnt applications but I am still a little unclear about a few areas.
1. Surge. How I understand it is when the turbo is compressing too much unusable air. The opposite of choke, when there is not enough airflow. I assume this because when looking at a compressor map they (choke and surge) are on opposite sides of the efficency islands. Other than having a big turbo on a small engine, what causes surge? I guess it sounds like the compressor is "barking"?
2. Trims. I understand that it is a ratio between the inducer and exducer on the compressor and turbine wheels. But I always see 'T trim' 'Q trim' or 'P trim' being used injunction with turbos but don't understand that when in that writeup it describes the trims as being a number ie: '56 trim'. For anyone explain this?
3. Tangential. What does this mean? I know it has something to do with how the exhaust gas enters the turbine, but that's it.
Edit: I also forgot to ask about turbo names. Example: T76GTS, the compressor trim is a 76 to my understanding, but waht does 'GTS' stand for or GT-40 88RL, etc?
1. Surge. How I understand it is when the turbo is compressing too much unusable air. The opposite of choke, when there is not enough airflow. I assume this because when looking at a compressor map they (choke and surge) are on opposite sides of the efficency islands. Other than having a big turbo on a small engine, what causes surge? I guess it sounds like the compressor is "barking"?
2. Trims. I understand that it is a ratio between the inducer and exducer on the compressor and turbine wheels. But I always see 'T trim' 'Q trim' or 'P trim' being used injunction with turbos but don't understand that when in that writeup it describes the trims as being a number ie: '56 trim'. For anyone explain this?
3. Tangential. What does this mean? I know it has something to do with how the exhaust gas enters the turbine, but that's it.
Edit: I also forgot to ask about turbo names. Example: T76GTS, the compressor trim is a 76 to my understanding, but waht does 'GTS' stand for or GT-40 88RL, etc?
Last edited by SantaCruz163; Aug 28, 2006 at 05:07 PM.
Originally Posted by SantaCruz163
I've been reading about turbos over here and have a better understanding about what makes turbos different from each other and how to choose a turbo for differnt applications but I am still a little unclear about a few areas.
1. Surge. How I understand it is when the turbo is compressing too much unusable air. The opposite of choke, when there is not enough airflow. I assume this because when looking at a compressor map they (choke and surge) are on opposite sides of the efficency islands. Other than having a big turbo on a small engine, what causes surge? I guess it sounds like the compressor is "barking"?
2. Trims. I understand that it is a ratio between the inducer and exducer on the compressor and turbine wheels. But I always see 'T trim' 'Q trim' or 'P trim' being used injunction with turbos but don't understand that when in that writeup it describes the trims as being a number ie: '56 trim'. For anyone explain this?
3. Tangential. What does this mean? I know it has something to do with how the exhaust gas enters the turbine, but that's it.
Edit: I also forgot to ask about turbo names. Example: T76GTS, the compressor trim is a 76 to my understanding, but waht does 'GTS' stand for or GT-40 88RL, etc?
1. Surge. How I understand it is when the turbo is compressing too much unusable air. The opposite of choke, when there is not enough airflow. I assume this because when looking at a compressor map they (choke and surge) are on opposite sides of the efficency islands. Other than having a big turbo on a small engine, what causes surge? I guess it sounds like the compressor is "barking"?
2. Trims. I understand that it is a ratio between the inducer and exducer on the compressor and turbine wheels. But I always see 'T trim' 'Q trim' or 'P trim' being used injunction with turbos but don't understand that when in that writeup it describes the trims as being a number ie: '56 trim'. For anyone explain this?
3. Tangential. What does this mean? I know it has something to do with how the exhaust gas enters the turbine, but that's it.
Edit: I also forgot to ask about turbo names. Example: T76GTS, the compressor trim is a 76 to my understanding, but waht does 'GTS' stand for or GT-40 88RL, etc?
As fas as companies calling their turbos certain things this can get very complicated. The "76" designation usually means in inducer size of the compressor wheel. Now some other manufacturers use the exducer to make it sound impressive such as the Greddy T88 which in reality has a (from memory)74 mm inducer. The "GTS" designation is the turbine wheel, same with the "p", "Q" & "O". <------These are the 4 most common turbine wheels available for the T4 frame turbo.
To me calling a compressor wheel by it's trim doesn't mean much because a 56 trim wheel could be 90mm or 50mm. The GT series from Garrett can complicate things even more. There may be mulitple options in a certain GT series such as a GT40 may have 10-15 different iterations of that family. Typically they will have a secondary # defining it a little better. Go to their website and check out what they have available. www.turbobygarrett.com
Tangential vs on-center Bascially the tangential housing has a more uninterrupted flow path into the scroll area of the housing.
Tangential
on-center
