7cm housing to 8cm housing now won't build boost

[19gsx91]

Hey guys, some of you are aware I've been doing some research with the v1/v2 68hta and making some headway with comparisons.. well I decided to take the 8cm housing off my v2 on the shelf and throw it on my v168hta that is currently on the car to replace the 7cm housing to see what kind of differences it might make..

This was the only change made.. now I have everything back together and it will not build boost. WOT in 2nd or 3rd and I MIGHT hit 15psi by redline. whereas before I was hitting 25psi around 3500.

I know the 8cm was gonna be more laggy. but not like that..

Here's the short end of the question. I swapped hotside only, left the manifold on and just undid the v-band clamp.

is it possible it didn't seat all the way and the clamp still went on and bolted on like normal?

Because I have zero boost leaks to 30psi (none of the intake tract was touched anyway) and the only places I could have exhaust leaks are the manifold to turbo (I checked. I dont) turbo to o2 housing. also checked. and the o2 to downpipe.

I'm kind of lost here guys?

any suggestions?

 

[ErikTande]

Did the V2 have a TD06 turbine housing and the V1 have a TD05 turbine housing? If so, that's your answer.

I had the same thing happen by accident. I had a sleeper 20g that Jusmx built for me, and when I blew it up I swapped the turbine housing on to my spare 14b temporarily. It wouldn't build more than 17 or 18 psi no matter what.

 

[donniekak]

The v2 has a larger turbine than the v1. So, the turbine housing doesn't have the proper clearance to the td05h wheel on the v1.

 

[19gsx91]

Interesting. I might have to contact the guy I bought the turbo from, he advertised that it came from FP with the 8cm housing as they had (for whatever reason) "run out" of 7cm housings and that it ran and drove fine. I'm just gonna be frustrated if I tear everything apart again and find out it was installer error.

I had previous spoken to @JusMX141 about this very same thing and he said I was going to lose spool, which I was expecting.. but for it to be this laggy, I am surprised by. I am not getting above 5psi until about 5-6k although thinking about it.. you may very well be right donnie.

I'm tinkering with what I have on the shelves and trying to do research for the guys that want to stick to near stock frame turbo setups..

I never compared the INTERNALLY gated 8cm housing that I have (came off the v1 68hta I bought in favor of my 7cm external) To the externally gated 8cm off my v2 68hta.. Never even thought about that to be completely honest.

 

[19gsx91]

This honestly never even occurred to me @donniekak You are 100% right. I grabbed the INTERNALLY gated 8cm housing that CAME on my v168hta and I tried to fit it onto my v2 68hta that was sitting on the bench.. no go. so I would have to modify that internally gated setup in order to make it work. Pictures.. because I'm obnoxious.

It will not clear any farther beyond that. Thank you Donnie, I would of been chasing ghost leaks for some time for no reason.

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[JusMX141]

Current-version of the 68HTA uses a TF06-07 spec wheel which is a MHI wheel offered on Mitsu's 18KX3 performance lineup for Evo X and Subaru vehicles which is a similar size to the aftermarket-only TD06SL2 turbine but the blade profile is slightly different so the housings do not interchange. The TF06-07 turbines used on the FP 68HTA are not Genuine MHI parts, however.

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[19gsx91]

Yeah.. I goofed. I ended up modifying my OTHER 8cm housing (making it externally gated) that originally came on the v1 68hta that I bought and things are much, much better with that one installed. I cannot for the like of me figure out why I originally thought that the housing off the v2 would work properly. Physically it fits. but spooling? not so much.