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Discussion Starter · #1 ·
im running a pt67 with a .81ar p-trim is there anyone here that is running this setup and how is spool and what power are you making. what mods do you have if you have a p-trim with a .96ar with a bigger turbo state what turbo you have and power and mods. i love top end power and would like to go from the 81ar to the 96ar for more top end power but if im going to spool up alot later then i would not do it unless the amount of power gain is going to be like 30rwhp or better. also the pt67 turbo with a 96ar would almost be like having a greddy t78 but with a smaller compressor housing right or wrong? i have a fully built head and i plan to rev my motor to 8000k rpm my block has stock piston and rods with arp rod and main bolts i also have 264 cams and the fuel is done up fully. im on aem. i also have the aem truboost. i have 4in dp,mp,ex. i also put a 1mm hg to have some more low end power. so can anybody let me know if they have the 96ar also if you went from a smaller ar housing to a 96ar what did you noticed from the change and was it worth it thanks.
 

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there is no reason to up the hotside AR unless you are running out of exhaust flow and the turbo is the bottle neck.
 

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I gained 35 RWHP on my T-66 .70 to .81 AR..at 19psi and only 150 rpm more lag if that... For me it was Deff Worth it! Great Power Band to!

You may see different results with your cam set-up but, I'm not sure..

A T78 is not a 78mm wheel... I believe it is about a 66mm or a bit smaller...
 

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you have to figure out the tradeoffs....... if you feel like your current exhaust housing is too small and is restricting the exhaust flow excessively, then you can up the size. The trade off is more lag.

If you are coming on late already, then don't go larger.

the smaller the compressor, the smaller the hotside housing. There is a nice ratio between hot and coldside AR's. IMO stick with what you have.
 

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Discussion Starter · #6 ·
someone told me that you can check if you have to much back pressure by drilling a hole on the back housing and connecting a boost gauge on it with a 1/8npt and if the pressure in the back housing is more then what you are boosting the there is to much back pressure. i have my egt on my back housing so i could remove it and see what the pressure is. has anyone try this before?
 

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that doesn't hold true..... the pressure in the exhaust tract will rise proportional to boost pressure, but it's not going to be the same. This measurement would not be relevant.

What's got you thinking about going to a bigger hotside? Is the turbo coming on too soon? Is it running out of steam at the top end?
 

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Discussion Starter · #8 ·
in forth gear the turbo felt like it ran out of power but the motor was stock now the head is ported and has 264 cams so i dont know if i should change because now i have cams so the topend is going to be better now but i think the cams would like the bigger housing. the way i see it is alot of supra guys run .81 and bigger with a gtq and even a gts wheel that are alot bigger then my p trim wheel so if i run a 96 ar housing the car would make mor top end power and might just 200 or 400 rpm in lag and if i pick up 30wrhp i think thats a good trade off but i want to know what people think about there 96 ar and hows the spool like where are they making full boost at
 

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Honestly, just go pick a .96 housing and do it.... If you don't like it you can switch back very easily... Don't for get to post your results in this thread ... :bigthumb:
 

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I have a 96 hotside and I spool up aroudn 4500 on a T76. I went big so that I could work around it. On stock internals and stock heads.
 

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in forth gear the turbo felt like it ran out of power but the motor was stock now the head is ported and has 264 cams so i dont know if i should change because now i have cams so the topend is going to be better now but i think the cams would like the bigger housing. the way i see it is alot of supra guys run .81 and bigger with a gtq and even a gts wheel that are alot bigger then my p trim wheel so if i run a 96 ar housing the car would make mor top end power and might just 200 or 400 rpm in lag and if i pick up 30wrhp i think thats a good trade off but i want to know what people think about there 96 ar and hows the spool like where are they making full boost at
I think you're estimate on the 2-400RPM lag increase is optimistic.

Try it and post up what you get.
 

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I have a 96 hotside and I spool up aroudn 4500 on a T76. I went big so that I could work around it. On stock internals and stock heads.
4500 rpm 19-20psi or begin to spool? Curious what is your RWHP on 19-20psi 93 octane?
Thanks !
 
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