Different turbos
06-18-2005, 02:06 PM
#1
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Different turbos
could anyone enlighten me on the difference between a t3 and a t4 turbo. I understand the concept. Correct me if im wrong, but as a generalization: the t3 spools faster and provides less overall boost, the t3/t4 spools fast with more boost, and the t4 has less response and yet more boost. Im just curious what the mechanical differences are besides the shape of the flanges. Any help would be great. Thanks!
06-18-2005, 07:11 PM
#3
T3 helps with the powerband down low. If you had a t4 for instance you'll get ultra power up in the 5k+ range. V8's can use t70's and such as they have a great exhaust output system that spools the turbo.
06-18-2005, 09:25 PM
#4
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yeah, thats what ive come to undertand. Thats why im thinkin the t3/t4 would be the best choice cause you would kinda have a little of both worlds. Decent spool and decent boost if i understand correctly.
06-19-2005, 08:39 AM
#5
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OK, now ive got another question. Does anyone know a good reputable place to get a turbo at a reasonable price. I see all kinds of them on ebay and some actually look pretty good like this one: http://cgi.ebay.com/ebaymotors/ws/eB...category=33742 but im hesitant to buy such an important piece of equiptment from there since there is always the risk of getting skrewed over.
06-19-2005, 09:51 AM
#6
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Join Date: Apr 2004
Posts: 521
Try www.PHOENIXTURBO.COM they have good prices, and great customer service
06-19-2005, 10:00 AM
#7
That looks like a good site, I got mine from www.full-race.com they have good prices and you can customize a size however you seem fit to your needs.
06-19-2005, 10:39 AM
#9
The designation T3 or T4 doesn't have anything to do with how much boost pressure you run, just so you know. T3/T4 is a bit small for our cars I say, unless you get a really big AR on the T3. Or alternately if you are an auto and want to come off the line with boost by brake torquing, a t3 hot side might be a good idea too.
06-19-2005, 11:12 AM
#10
Originally Posted by Nealoc187
The designation T3 or T4 doesn't have anything to do with how much boost pressure you run, just so you know. T3/T4 is a bit small for our cars I say, unless you get a really big AR on the T3. Or alternately if you are an auto and want to come off the line with boost by brake torquing, a t3 hot side might be a good idea too.
06-19-2005, 12:01 PM
#11
Correct me if im wrong but a larger turbo will flow more air into the engine then a smaller turbo at the same psi rate. Example: a t3 and a t4 with exast same boost levels, the t4 will produce more hp over the t3.
06-19-2005, 12:17 PM
#12
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man, i think i just need to invest in corky bells book. Then maybe ill understand this stuff better. Im not going to start on the kit until i actually know im making an informed decision on what im buying and i guess i still have a lot to learn.
06-19-2005, 01:29 PM
#15
Any bookstore will have it or can order it, or amazon.com.
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
Originally Posted by Brad92SE
Correct me if I'm wrong, but wouldnt the only difference between a T4 and T3 turbine be that the T4 is harder to spool? At our boost levels, we arent going to max out the T3, and niether one is going to flow more air into the engine. Or would the T3 just produce more heat than a T4?
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
06-19-2005, 01:40 PM
#16
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Originally Posted by Nealoc187
Any bookstore will have it or can order it, or amazon.com.
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
06-19-2005, 04:25 PM
#18
Originally Posted by Nealoc187
Any bookstore will have it or can order it, or amazon.com.
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
I'm talking about hot sides here, not cold sides, for clarification. A larger turbine and wheel requires more exhaust flow to start spinning the wheel to speeds at which it can make boost, bernoullis principle and the fact that a larger wheel is just heavier than a smaller one. Thus a smaller exhaust side will start to spool earlier than a larger one, but it will also become a restriction earlier too. hurting your high RPM power. Perfect evidence of this is when mardigras was using his .58 a/r, his dyno dropped like a rock after about 5000rpm. He switched to his .81 A/R and he said the topend difference was night and day, and the spoolup didn't suffer either. .58 a/r t4 was just too small for the amount of air going through his engine, and it became extremely inefficient above 5000ish rpm. Too small a turbine can become a bottleneck in your exhaust system, just like too small a downpipe will.
The same basic principle applies to the cold side too, in that too small an A/R or wheel might not have the capacity to flow as much air as your engine wants to at higher RPM. As pretty much everyone knows intrinsically, people upgrade to larger turbos because their current turbo cannot flow the amount of air, either efficiently, or at all, as the larger one they want to upgrade to. Of course you can go too large and that leads to other problems, like a turbo that spools too late to be useful, or a turbo that surges.
06-19-2005, 07:05 PM
#20
A .81 A/R T3 is physically larger than a .63 A/R T3 and will thus ultimately have the capacity to flow more air/exhaust. I don't understand what you are saying/asking about heat?
The only thing I can think you might be thinking of with regards to heat is that once you get way out of the efficiency of a turbo compressor side (usually an issue when you are trying to flow MORE air than it can efficiently handle). Compressing air always will generate heat. The difference is how efficiently you compress it. Compressing it inefficiently produces more heat than compressing it efficiently. That is why it's important to properly size your turbo. There is a certain range of boost pressure and airflow amount in which a turbo is most efficient, that is what a compressor map is charting.
When I say speed I am talking about shaft RPM of the turbo incase I wasn't clear on that.
The only thing I can think you might be thinking of with regards to heat is that once you get way out of the efficiency of a turbo compressor side (usually an issue when you are trying to flow MORE air than it can efficiently handle). Compressing air always will generate heat. The difference is how efficiently you compress it. Compressing it inefficiently produces more heat than compressing it efficiently. That is why it's important to properly size your turbo. There is a certain range of boost pressure and airflow amount in which a turbo is most efficient, that is what a compressor map is charting.
When I say speed I am talking about shaft RPM of the turbo incase I wasn't clear on that.
06-19-2005, 08:31 PM
#23
Several people have said the GT35R is a very good turbo for our cars. The GT series are more expensive but spool more quickly and are more effecient.
That being said DO NOT just buy a turbo just because other people run it and say it is good. Research. Read. Maximum Boost by Corky Bell is a very good start. Read the FAQs. Read howstuffworks.com . It is better to take your time and figure out what you need now than to buy it and have problems and then try and figure out where you went wrong and why you are not making enough power. Taking shortcuts in the research especially if you are starting from scratch is a very bad idea. Even if you are buying a kit you need to know how to work on it, for repairs or upgrades.
That being said DO NOT just buy a turbo just because other people run it and say it is good. Research. Read. Maximum Boost by Corky Bell is a very good start. Read the FAQs. Read howstuffworks.com . It is better to take your time and figure out what you need now than to buy it and have problems and then try and figure out where you went wrong and why you are not making enough power. Taking shortcuts in the research especially if you are starting from scratch is a very bad idea. Even if you are buying a kit you need to know how to work on it, for repairs or upgrades.
06-20-2005, 05:19 AM
#24
Originally Posted by Nealoc187
A .81 A/R T3 is physically larger than a .63 A/R T3 and will thus ultimately have the capacity to flow more air/exhaust. I don't understand what you are saying/asking about heat?
The only thing I can think you might be thinking of with regards to heat is that once you get way out of the efficiency of a turbo compressor side (usually an issue when you are trying to flow MORE air than it can efficiently handle). Compressing air always will generate heat. The difference is how efficiently you compress it. Compressing it inefficiently produces more heat than compressing it efficiently. That is why it's important to properly size your turbo. There is a certain range of boost pressure and airflow amount in which a turbo is most efficient, that is what a compressor map is charting.
When I say speed I am talking about shaft RPM of the turbo incase I wasn't clear on that.
The only thing I can think you might be thinking of with regards to heat is that once you get way out of the efficiency of a turbo compressor side (usually an issue when you are trying to flow MORE air than it can efficiently handle). Compressing air always will generate heat. The difference is how efficiently you compress it. Compressing it inefficiently produces more heat than compressing it efficiently. That is why it's important to properly size your turbo. There is a certain range of boost pressure and airflow amount in which a turbo is most efficient, that is what a compressor map is charting.
When I say speed I am talking about shaft RPM of the turbo incase I wasn't clear on that.
06-20-2005, 06:44 AM
#25
guys...go buy the book.
understand what your "goal PSI" and what your car can handle. then learn to read compressor maps and understand them. once you do that you'll know EXACTLY what you want in your turbo. trust me...the turbo size is key here. you want to be in the sweet spot of the turbo and produce the right boost at the right RPM that you want and can live with.
understand what your "goal PSI" and what your car can handle. then learn to read compressor maps and understand them. once you do that you'll know EXACTLY what you want in your turbo. trust me...the turbo size is key here. you want to be in the sweet spot of the turbo and produce the right boost at the right RPM that you want and can live with.
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