Originally posted by BStoneMega:
but how come my t-25 can run up to 15psi supposedly. I would figure the t-28 could go higher?


You are not seeing the entire picture.

Boost level and cfm flow are engine size & volumetric efficiency dependant. (using the "exact" same turbo - otherwise that adds a lot more variables!)

Also like stated the many turbo variables change the turbo's efficiency range. For instance a 50-1 trim "likes" high boost (~2bar max) and a 57-1 moderate boost (~1.4bar max) and they both max about the safe cfm level even though the 57-1 wheel is technically larger.
Just using the compressor maps and not taking the particular engine into account; nor is it taking into account the added heat and turbo rpm, nor exhaust wheel, nor... You get the picture.

Read my other very basic posts about it...

Even google search - IIRC there is a Stealth site that explains a lot about turbo sizing with more detail. (I.E. no way in hell I'm typing out even a layman's guide to it - my posts should be good enough to get the picture if you are going to get it easily)


Anyone who rates a turbo in "exact" cfm per psi or HP or whatever is not telling the whole story (I.E it's like marketing performance parts)


The T28 could probably support 15psi on the Zetec (2L vs 2.5L) thus giving you a 260FWHP Zetec... ZOOOOOOOM...

No I did not do "the math" it was just a "guesstimate" to be used as an example.

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.