# Turbo sizes



## scrub brush (Dec 31, 2002)

I felt this would be a good place to ask, and no, I couldn't find this anywhere else on here...

How are turbos sized? I see names like T3, T25, etc., but what do they all mean? Do they refer to the size of some part? What's the smalles turbo that can be used on cars? Please don't flame, I'm just curious.


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## 180SX-X (Sep 21, 2003)

this has been discussed(i noe b/c i asnswered 2 of em), but n e wayz...
turbos get bigger as the number goes up in the T-series turbos(at least Garrett and Mitsu), so T3 is smaller than T4...
if you see T3/T4 turbo...IIRC its the Turbine side is T3 size and Compressor is T4...


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## Rama (Mar 8, 2003)

Is there a formula as to how they come up with the numbers?


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## TheVodKA (Sep 19, 2002)

Within each specific make, the higher number represent bigger wheel sizes usually, but on an overall scale, no


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## 96sentra (Apr 9, 2003)

how is t4 bigger than t28?


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## chimmike (Oct 17, 2002)

it just is. what do you mean how is it? it's made bigger, that's how.


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## covertpolarbear (Oct 31, 2003)

the compressor is bigger, meaning that it can push out alot more air, or suck in, and push out alot more.. a few cheap tricks people pull would be get a T4 compressor housing, and slap it on a T20 exhaust housing, so the turbo spools up Very fast, and it would be compressing alot, because the compressor has to spin as fast as the exhaust wheel.. so if the exhaust wheel is very very small, it spools up quick.. the compressor has no option but to spool fast


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## Rama (Mar 8, 2003)

Chimmike what 96sentra was asking is if there was a rhyme or reason in the difference in size for the T4 be sized T4 and T28 to be labeled T28, like some sort of relative difference. I mean we all grasp the concept (well at least I do) that the T28 is bigger than the T4 but the questions being asked is there a reason for the number 28? is it 7 times bigger than a T4 or is the 28 representative of something? Because really I have only seen the sizes T3 T4 T25 T28 I havent seen too many other sizes not to say that their aren't any other but why the jump? Are there T6's and T7's? T8's? How of a difference in size a T4 to a T28?


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## 96sentra (Apr 9, 2003)

pretty much thats what i was askin.^^^


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## covertpolarbear (Oct 31, 2003)

well the AR of the T28 is like 56 or something.. the T4 has an AR of around 84.. i believe the AR is the size of the compressor wheel inside the compressor


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## chimmike (Oct 17, 2002)

covertpolarbear said:


> *well the AR of the T28 is like 56 or something.. the T4 has an AR of around 84.. i believe the AR is the size of the compressor wheel inside the compressor *


there are 56 AR t3/t4's so that logic is erronous.


there are T2s and there are T88s. 

the T2 is the flange size to be used, then there's T3 flange, T4 flange, etc.

as far as I know, the number labelling is arbitrary but logical. think about it.....the smaller the number, the smaller the turbo. 

It doesn't matter how they're numbered.......as long as you understand that the T designation isn't the only determining factor in the actual size of the turbo.

there are many different sizes to each turbo. You can have small T3s that will make 300hp, and then large T3s like the T3 super 60 that will make 400hp.......it all depends on the housing size and wheels.

There are hybrid turbos, i.e. the t3/t4 that uses a t3 exhaust housing and t4 compressor housing, faster spoolup with the smaller exhaust housing and more power out of the larger compressor housing (flows more cfm than a straight t3 would)


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## Rama (Mar 8, 2003)

Thanks to both covert and chimmike for the info. So basically it's an arbitrary number which clears somethings up because I think some of us were overthinking and figured it was representative of something else. Also with the info provided leads me to believe that the power of the turbo itself is indicative of more than just the T number when hybrid turbos are involved. What wheel and housing sizes are normally found in each?


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## chimmike (Oct 17, 2002)

depends. a good thing to do is find websites that sell turbos and look at the a/r and comp sizes for turbos to get a general idea...however there are many more.


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## Taffy (Oct 30, 2003)

www.limitengineering.com

There is a link on that site that explains how Garrett designates their turbos.

Also check out this post on Turbobuick.com for some REALLY good info on turbos: http://www.turbobuick.com/forums/showthread.php?s=&threadid=93074

Also check out www.howstuffworks.com They have some good info on turbos.


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