What is trim??????????

[rodknock]

I read all day long about turbo trims. I fake order turbo kits in hopes that one day ill get mine <dont ask> and they ask for trim specs. What is the trim, what effects do they create, what is stock trim? Any and all input would be appreciated.

[joemathews]

Read this technical novel by Kevin and you will understand a great deal more about turbos:

http://www.automotiveforums.com/vbul...d.php?t=156363

Trim= [(inducer squared)/(exducer squared)] x 100

...where the inducer size is the turbo inlet side of the wheel (usually in mm), and the exducer size can only be seen, as Kevin says when the wheel is not inside the housing (also size in mm).

So trim has no relevance to the sheer SIZE of a wheel, rather to the ratio. Read the article, it is terrific!

[kjewer1]

Good link Joe. The thing I love about this site is I can type this stuff once or twice, and I dont have to repeat it in every thread. Badass...

As mentioned above and in that thread, trim does tell you about some of the characteristics of the wheel, but not the size. If I remember correctly, and using some of my experience, it seems that lower trim turbos like low flow/high boost, while larger trim numbers are set up for lower boost but higher flow. Compare the maps for the TO4E 50 trim and the TO4E 60-1, and tell me if I'm off my rocker. I think that statement is correct though. Getting rusty in my old age...

[rodknock]

great thread Gsxracer if i could i would.......... Nevermind
thanx for the info joe

[JoeWagon]

I think it's also good to note that even though you can't tell the size of a turbo by the trim, if you are talking about a certain housing, most if not all trim indications are going to tell you exactly what turbo it is. For example, unless I'm mistaken, there is only one 50 trim compressor wheel (a commonly used one) in a T4 compressor housing. I may be wrong in that there exists more, but for DSM applications and especially from top vendors, a 50 trim T3/T4 is the same compressor wheel no matter where you buy it from.

Whether that is right or wrong, which I hate to sound like I DONT know what the hell I'm talking about, there are for sure several different T3 turbine housings, and to make it MORE confusing, a T3 and T4 turbine housing can have the same trim and be different of course, but also be 'equal' but I'm not sure if they mean flow and spool, or what. Too lazy to search. Not sure if I actually posted anything useful, though.

[kjewer1]

Youre right for the most part. For example, a TO4E 50 trim will be the same no matter where you get it from. And I dont know of any other garret 50 trims. They may list a to4B 50 trim, but I Think its the same wheel anyway. And of course the to4e etc is hte husing being used.