# Precision 67mm 12v vr6



## Deezy (Jan 3, 2009)

I picked it up for cheap and I'm thinking about running it but the high HP ratings scare me. 

Its a .68ar t4 exhaust housing and a 67mm compressor. 
Best I can find is it is a pt6768 maybe I'm wrong. 

Guy was running 450whp on a 2jz Lexus with it. 
The exhaust housing seems small on a vr6


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## Deezy (Jan 3, 2009)

Nobody has run this?
I found the quattro Audi runni g a 67mm but they have a bigger exhaust ar

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## VWallin (May 17, 2010)

A friend of mine is pushing 800whp on a 12v vr6 with a 6766 but it's a .82 housing.
.68ar seems a bit small.


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## Deezy (Jan 3, 2009)

That's what I'm thinking but understanding turbos is kind of hard for me. 
So I should spool quicker with a lower a/r exhaust but have the power fall off earlier as well. 

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## PapioGXL (Jun 3, 2008)

Deezy said:


> That's what I'm thinking but understanding turbos is kind of hard for me.
> So I should spool quicker with a lower a/r exhaust but have the power fall off earlier as well.
> 
> Sent from my XT912 using Tapatalk 2


With a stock 12v head, I wouldn't expect any power drop at higher revs to be noticeable or existent below 400 hp.


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## meximan (Jan 25, 2011)

im curious about this as well....i think that the lower the a/r the quicker the spool/lower rpm it comes on, the higher -the later. Or is it based on the ratio?




Deezy said:


> That's what I'm thinking but understanding turbos is kind of hard for me.
> So I should spool quicker with a lower a/r exhaust but have the power fall off earlier as well.
> 
> Sent from my XT912 using Tapatalk 2


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## PapioGXL (Jun 3, 2008)

Think of the hotside like a nozzle. The smaller the number, the smaller the nozzle. 

I had a bunch typed out, but these links are easier to understand. :laugh:

http://www.evans-tuning.com/tech-articles/turbine-housings-exhaust-sizing-and-back-pressure/

http://www.evans-tuning.com/tech-articles/compressors-turbines-explained/


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## Deezy (Jan 3, 2009)

I'm looking for maximum gains in the middle of the power band. Makes more sense to me. This isn't a track car. 
Basically say its an 1/8th mile car or a rolling start. 

Waiting for a turbo to spool can win or lose a race. If it was dedicated to a track or 1/4 mile than a larger exhaust housing would be necessary. 

Now the only problem I hear is people are breaking transmissions with lower rpm spools. :-( 

I will try this turbo out soon but I feel I will most likely part with it for a smaller more efficient to my needs sized turbo


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## Deezy (Jan 3, 2009)

What it boils down to is can this a/r exhaust spin the compressor up quick enough to create the boost I need. 

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## PapioGXL (Jun 3, 2008)

Depends on how much power you want. 
Cams
Head port work
Turbo manifold design
Wastegate spring pressure
Whether you run a boost controller, and if so electronic or manual

If all you do is rolls, brake boosting eliminates lag.
From a dig, launch control is amazing. Assuming you can plant the power that is.

My car has a PT6266 with a .84 divided hotside, tubular fully divided manifold. Wastegates have "7" psi springs in them and manifold pressure usually stays around 6psi. This is because of the wastegate location on the outside of a "U" bend, and the pressure drop across the intercooler.

1st gear if I roll into the throttle will see full boost around 5k.
2nd gear around 4-4500
3rd 3500-4000
4th and 5th rolling into it is around 3k 
If I'm going from a dig, I have launch control and flat shift, I never see vacuum from the time I stage till the time I cross the line.

If I were to increase spring pressure, boost would come on significantly faster.
If I hook up my electronic boost controller, the gates won't get pushed open as quickly and boost will come quicker.

I would imagine your turbo would spool slightly slower than mine given the same circumstances. But for a FWD car you don't really need much faster spool, 1st and 2nd are spin city.


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## zwogti (Jan 11, 2004)

.68 A/R on a 12V VR6 will give you full boost around 3200-3500RPM depending on how much boost you're running, intercooler and exhaust size, with a 67MM compressor wheel the .68 A/R hot side will start to choke up top once you go over 400WHP, also once you pass 350whp with boost coming in strong traction will be a big problem, when you pass 400WHP that's when 3rd gear may go. If you don't go over 380-400WHP I think all will be ok with a good set of drag radials up front.


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## Deezy (Jan 3, 2009)

zwogti said:


> .68 A/R on a 12V VR6 will give you full boost around 3200-3500RPM depending on how much boost you're running, intercooler and exhaust size, with a 67MM compressor wheel the .68 A/R hot side will start to choke up top once you go over 400WHP, also once you pass 350whp with boost coming in strong traction will be a big problem, when you pass 400WHP that's when 3rd gear may go. If you don't go over 380-400WHP I think all will be ok with a good set of drag radials up front.


I like your answer. I want in the area of 400hp which I could obtain 

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## PjS860ct (Dec 22, 2002)

Deezy said:


> I like your answer. I want in the area of 400hp which I could obtain
> 
> Sent from my XT912 using Tapatalk 2


he knows what he's talking about :thumbup:

you can always upgrade the exhaust housing with a .81T4 and have a later spooling turbo

post a pic of the turbo if you can...


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## Deezy (Jan 3, 2009)

PjS860ct said:


> he knows what he's talking about :thumbup:
> 
> you can always upgrade the exhaust housing with a .81T4 and have a later spooling turbo
> 
> post a pic of the turbo if you can...


Its a t4 now if that helps.. I might have noted that. 
But yea that's awesome. If I want to go over 400 I'll get a bigger exhaust housing 

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## PjS860ct (Dec 22, 2002)

Nope.. doesnt help


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## Deezy (Jan 3, 2009)

You guys have made my day. I bought this turbo on a limb thinking it was way to big. But the price was right. So in was planning on installing it but now I'm eager to install. 

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## V-dubbulyuh (Nov 13, 2005)

.68 T4 is not bad at all for a street/daily car (those 67mm turbos tend to be a bit laggy so on the street there is nothing wrong with helping it to spool a bit earlier). If you want something larger like a .81 T4 I should have something that I can trade you out for.


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## Deezy (Jan 3, 2009)

V-dubbulyuh said:


> .68 T4 is not bad at all for a street/daily car (those 67mm turbos tend to be a bit laggy so on the street there is nothing wrong with helping it to spool a bit earlier). If you want something larger like a .81 T4 I should have something that I can trade you out for.


To be honest this will be a street car. It seems as though the exhaust maybe larger than I was told. As well as the compressor outlet. 

Compressor is 2-3/4 which is OK.
Exhaust looks 4" but I'm new to vbands...









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## zwogti (Jan 11, 2004)

looking inside the turbine's housing it looks like that V-band got welded to the hot side..... is that the picture or me


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## Deezy (Jan 3, 2009)

zwogti said:


> looking inside the turbine's housing it looks like that V-band got welded to the hot side..... is that the picture or me


You are correct. Its welded inside and out. It was used after the weld and seems in tact so I assume the welder knew what he/she was doing. 

I'm going to be talking to a local guy about cutting this off and welding a 3" on. This 4" vband is conical down into the exhaust side and seems weird to me... 

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## Deezy (Jan 3, 2009)

up for another question...

Assuming people can change out the exhaust housing, i can change this one to a .68 AR exhaust (which is the same) But with a 4 bolt or 3" vband?
How hard is it? bolt on bolt off? The 4" vband discourages me very badly.


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## Deezy (Jan 3, 2009)

so.. i removed my exhaust housing. it says TH6839A and i cannot find jack, i want a replacement part number...

I prefer a .68 AR housing T4 with a 3" vband or a 3" 4 bolt but i prefer the vband.

Can anybody help?


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## o4rudeboy (Dec 8, 2008)

why not have the 4 inch v band cut off and get a 3 inch v band flange welded on where it was  thats what i would do ittle be cheaper


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## Deezy (Jan 3, 2009)

o4rudeboy said:


> why not have the 4 inch v band cut off and get a 3 inch v band flange welded on where it was  thats what i would do ittle be cheaper


I ordered a 3" flange and its not much to weld to... It would have to be welded from the inside. I'm going to talk to a welder and ask what he thinks...


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## Deezy (Jan 3, 2009)

So screw it I ordered a different flange kit which seems to have a much larger weld area. 

I will be cutting the 4" and having someone weld the 3"


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## Deezy (Jan 3, 2009)

So. Finally got it up and running. 12psi @4,000 rpm haven't tried more yet. Pulls like a beast! 

3" vband welded onto the .68 a/r housing. 
So far I think this turbo mated up perfectly with a vr6 everybody said it was too big. 


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## 1broknrado (Jul 6, 2005)

*FV-QR*

congrats :thumbup:


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## PjS860ct (Dec 22, 2002)

Pictures and videos


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## Deezy (Jan 3, 2009)

@vr6deezy Instagram. My buddy @b_radd took a few videos last night. Not the best. More to come. 

I raced a mustang svt that's supposed to be super sick and I got him 2 out of 3 50 rolls.  
Raced a Harley and won by a half a car 
New gt mustang I just left him and let off. 

Vr6deezy on YouTube as well. one small video of the new setup


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## DieGTi (Jun 19, 2001)

A .69 T4 hotside with a 67mm cold side I'd say is about perfect. I swapped from .96ar hot to .69ar hot because the .96ar wouldn't spool below 5k. Even with dual ball bearing it would drop boost on shifts and was not pleasant to drive.


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## Deezy (Jan 3, 2009)

It's a feeaking beast with a .68. In fact I'm in love. 


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