Thread: randoom hole in t25?

so i am in the process of rebuilding my t25 for my car. a little background it came off a redtop s13 sr20. so i started to clean everything up and take it apart and i noticed these two bolt holes one of which goes all the way threw the housing, i am just curious as to why this bolt hole goes all the way threw and if it is factory. is anyone else's t25 like this? i will prolly plug it with teflon and a small bolt, but im curious. here is a picture, the one that goes all the way threw is the top hole. thanks in advance

Could've been for some sort of boost source signal, alot of times they'll put them right by the compressor outlet.

I'm pretty sure they are for some type of bracket. Probably the wastegate.

yea i think it is maybe a boost signal source like you said, deff dont think it is factory. i thought it was for the bracket at first but then i remembered the wastegate bracket is attached to the back of the housing, you can see it in the pic.

I lost to a Lada Niva

No way is it for a boost signal source. It wouldn't get proper readings there. You can see the boss for the boost signal provision to the left of the "M-24" casting.

I would plug it like you planned on.

What is the difference in placement from the cast bung that is plugged or anywhere else on the compressor housing? The pressures would be the same regardless?

I think it depends on the A/R ratio whether or not the pressure readings along the compressor housing will be above, below or match those found at the compressor discharge. Large A/R ratios cause relatively low boost readings at the discharge even if higher readings are found elsewhere. Smaller A/R ratios cause relatively high boost readings at the discharge even if lower readings are found elsewhere.

Mine was the same and yes wastegate bracket.
Chopped and re-welded that damn wg bracket in to many pieces to get it to fit a fwd setup lol.
Just put a bolt back in that hole for the bracket ala factory.

Yep. Indeed a wastegate bracket provision. Which is exactly why it's recommended if you are clocking the compressor housing that you seal the hole you expose when you re-affix the bracket.