I got a great deal on a t4 divided 6466 from MAP! Unfortunately it wasnt quite the one I wanted being that it is a t4 divided .84 a/r and I really would have liked the t4 divided 1.15 a/r but it was out of stock. The reason for wanting a 1.15 a/r is because this is a drag setup I'm building and from the information I've gathered it spools nice on the 2.0l setups but makes insane top end. I am guessing the .84 is going to spool even better but be significantly choked up in the higher rpm (8k+)


There might be positives to the t4 divided .84 a/r being that this is going to be on a stock block for a little bit while I build a 2.0l high revving setup, and it might suit the limits of the stock block better (better powerband/limited power) I just hope it can still flow 600whp with ease and without tons of boost.


Also if someone knows the correct formula to what t4 divided .84 a/r is equal or close to in open t3 that would be awesome

 

nothing? I found someone on the interwebs that said a t4 divided 1.00 equals roughly a .89 open(t4?)


So does that mean a .84 t4 divided equals a .73 open? They were not specific in regards to t3/t4

 

rule of thumb:

TS spools like 60% of a SS and has the top-end flow or 90% of a SS

so... a 1.00 AR TS spools like a 0.60 SS and flows like a 0.90 SS.

 

After doing the math, in theory it should flow like a .75 a/r, and spool like a .50 a/r (which is TINY) I am curious to see how well she does being such a big turbo with such a small a/r. I hope to see 30psi before 5000rpm.

 

Someone correct me if I'm wrong but I believe the T4 is still going to be larger than a comparable T3, despite having a smaller AR.

 

I was thinking the same thing, because a t4 .75 a/r is bigger than a t3 .75 a/r....which means it should still flow a ton of power.

 

You are incorrect. A 1.0 a/r T4 is phiscally bigger on the outside due to its split design but air volume wise it's actually around the size of an open .83.


i had a divided .84 with a big compressor wheel before. It did spool faster. It also surged like crazy in lower rpm's and choked up top. I Think it created to much back pressure because as soon as I went up to a divided 1.0 a/r the car performed completely different.

 

Well lets hope not because this has the anti surge cover, and regarding the choke up top this exhaust housing is going on a stock block. I wanna go with the magical 1.15 once I throw the built block in.

 

It just need hold steady till 8k MAX

 

Trade it for a GT55-91.

 

I'm good this turbo is all I need and more. This turbo is doing more work thks year than ANY other turbo in the evo community.