1.32 A/R, 1.45 A/R, or 1.58 A/R - Which one do you have on YOUR Turbo?

1.32 A/R, 1.45 A/R, or 1.58 A/R - Which one do you have on YOUR Turbo?

The BorgWarner S400 and S410SX turbos are SUPER popular for CAT, Cummins, and Detroit trucks.  While these turbos are a little different, they share the SAME 96MM/88MMturbine wheel, which means all the exhaust housings are interchangeable. 

The available housings are: 1.15 A/R, 1.32 A/R, 1.45 A/R, 1.58 A/R, and 1.65 A/R.  

You will notice that the 1.15 A/R and 1.65 A/R housings are missing from the photos, that's because we virtually NEVER use these housings, more on that later..

1.32 A/R - This is a great housing for a sub 600WHP Truck (Stock CAT, Non VGT ISX, Hopped up Detroit or Mack).  It will spool up quick and provide plenty of peak power.  Very common and a good match to be on a 78MM or a 75MM turbo.  I have customers who will put the 1.32 on an 80MM turbo, and the best way I can describe it is "twitchy", this combo sort of has attributes of a 2-stroke dirt bike powerband.  

1.45 A/R -  This housing was never put on a factory/box BorgWarner turbo and has become the sweet spot for many CAT customers.  The 1.45 will support 650WHP-750WHP depending on what turbo its behind.  A 78MM with a 1.45 is great for a cat with a hot file and some extra fuel, and an 80MM with a 1.45 will easily handle a 750WHP CAT with Tune, Cam, Injector.  We have seen a few hopped up detroits have success with this housing, but we never really found an ISX that required a housing this size. 

1.58 A/R - A pretty big DOG housing.  You can get this housing on a box 80MM turbo.  The 1.58 breathes pretty good, but majority of folks in this range opt for a 1.45 for better spool up.  The 1.45 and 1.58 housings are pretty much identical from the outside, the difference in size is all internal.

Then the non pictured housings.....

1.15 A/R - This is a SUPER TIGHT housing.  I believe this housing was created more for the performance gasoline crowd or diesel pickup crowd.  I have only ever seen this housing successfully used on a few detroits, and these motors would have more likely benefitted from just going down to a K31 turbo.  

1.65 A/R - This housing is a PIG.  If you DONT want to party, this is the housing for you. By the time this mammoth housing actually spools, the wastegate will open around 26PSI and its all over. I believe the sole purpose of this housing was a "Catch All" for big horsepower applications.  Meaning that you virtually couldn't over spool a turbo with this housing on it.  Regardless, if you are at the point where you need a housing this large, you are likely better off jumping up to a large frame size turbo like an S500 or GT55

How To Tell Which Housing You Have

Visually you can tell if you have a 1.65 A/R, because its the only factory wastegated housing.  The 1.15 A/R housing is the smallest, so thats pretty easy to visually tell as well.  But the 1.32, 1.45, and 1.58 can get a little tricky - the 1.45 and 1.58 are near impossible to tell apart visually.  So how do we do it?

You will notice casting information near the T6 flange of these housings:

The one above is, you guessed it ! A 1.32 A/R Housing 

36.8 or 14961019064 is a 1.45 A/R

And finally 40.1 or 14961019063 is a 1.58 A/R

You can see this information WITHOUT removing the turbo, as this information will be facing the back of the truck near the exhaust pipe. 

11th Jul 2024 Joe Neill

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