Clarifications: T04E Turbos

[BatmanGSX]

By looking at the compressor maps of these turbos, specifically the 50, 54, 57 and 60 trims we can see that the 50-trim has a max flow just left of 50lb/min. Both the 54 and 57 trim turbos are just right of 45lb/min. The 60 trim is just left of 50lb/min but operates happily at much lower PRs than the 50 trim.

So I'm wondering why some "popular" vendors lead people to believe the 50 trim is the "smallest", the 54 trim is a little bigger, the 57 trim is "the first step up to large turbos" and why they even sell the 60 trim at all? I guess they don't understand the concept that ratios (what trims are) don't necessarily indicate size. It must be pretty easy to sell turbos to people when you just line them up in numerical order of their exducer/inducer ratio. It probably would take to much time to be truthful I suppose.

 

[92awddsm]

You also need to take into consideration what the efficiency is of these turbos at a given flow rate. If you notice, the 60 trim might flow the same as the 50 trim in a particular efficiency range but that would also be at a lower boost level with the potential to flow more than the 50 is able to. There is a lot more to reading a compressor map than just what you have stated. I do understand what you are saying as far as compressor ratios are concerned but you should also look at all the variables when reading a compressor map, not just max flow rates. Actually, I think everyone should be able to read compressor maps before they just go out and get something bigger than what they are currently running.

I have personally seen someone go out and get a 57trim just because one of their friends had a 50 trim. Next thing I know, they wanted to know why the 57 wasnt as fast as joe blow's 50 trim. Even after explaining how to read a compressor map, the still said" well, its a 57 trim which is higher than 50 so mine should be bigger and faster"

 

[oddrob]

Yeah he'd probably kill me and my little 56 trim.