Precision Billet 6765- What are the benefits of different covers?

[mzunino]

Hey Guys
I am buying a turbo this week, finally got my short block tied up. I know I want to go with the 6765 with the .85 housing. Here is my combo

PTE SLIC
Girdled Stroker 9-1 Compression
80lbs
SD TT Chip
212/212 Roller Cam
3200-3300 Protorque 9"
GN1 Heads - Mild Port
Ported Intake
70mm Throttle Body

Question is not sure what cover to run. Is there really a benefit with going with a bigger inlets and outlet?
What are the downsides? Does it hurt spool? Any help would be greatly appreciated. Also the .85 exhaust housing are they worth the loss of spool for the top end gains?

 

[mzunino]

One more thing to add. This car will be driven on the street alot 20-30 passes a year at the track.

 

[John Wilde]

Get the S cover it has a 2.5 inch compressor outlet that will line up with your intercooler. You could also get the E which is a 3x2.
The H 4x3 has fitment issues with your combination and will have not benefit IMO.

 

[John Wilde]

Also what are your HP / ET goals?
The 6266 could be a better fit.

 

[mzunino]

I would really like an turbo that will go 10.7-10-5 all day down to 10.0 if I really want to push the boost. Again its gonna be a street driven car wanna buy it right the first time. What are your thoughts on the exhaust housing? is the .85 the way to go?

 

[bison]

The inlet and outlet sizes mean little. The diffuser design could show power on some applications. The diffusers in the various housings don't vary too much on these small turbos. You would have to be working the compressor hard to see the benefits. You aren't working the turbo if you are running 10.0 with a 67. There is little power benefit running a .85 on a 10.0 application. Nothing on a high ten sec application.

 

[John Wilde]

I would consider the 6266 S with w .63 turbine based on what you are saying.
If it wasn't for the 10.0 potential I would have told you the 6262 would work.
Considering you have cubes and compression the 66 turbine wheel should be a better fit.

 

[mzunino]

So Bison do you think the bigger exhaust housing would hurt me with my set up? Lag wise? I would like to push this setup as far as I can but remain street able. I tried to build the setup with the 67mm in mind. With what you see what do you think is the best fit?

 

[John Wilde]

It will impact the spooling, but what do you have for suspension, tires and boost control?
Some people like a little lag in their combinations so they can hook.

 

[mzunino]

I just have a HR Sway rest is stock. Been running 9inch 28 tall MT Slicks. Just stock style actuator for boost control.

 

[bison]

I would use a 62 compressor with a 65 or 66 turbine if you are going with a precision. I'd use a .63 housing no matter what. I made about 700whp with a 6265/.63. It was a journal and spooled extremely fast on the street. .78g from 70mph on hot m/t et streets. It will bitch slap just about any production car you will ever come across and most street bikes.

 

[mzunino]

Wow. I really feel like my set up is geared more to the 67mm. What kind of boost would I have to run with a 6266 to run a 10.5 versus a 6765 or even a 10.0? Reason I am asking is because I want to have enough Turbo in case I really wanna push it. Don't want to buy a smaller turbo and regret it..

 

[bison]

Wow. I really feel like my set up is geared more to the 67mm. What kind of boost would I have to run with a 6266 to run a 10.5 versus a 6765 or even a 10.0? Reason I am asking is because I want to have enough Turbo in case I really wanna push it. Don't want to buy a smaller turbo and regret it..

You don't have enough engine to use a 67 compressor effectively. The 62 and 67 will make the same power. It's hard to say at what boost. I had 10.0 power with the 62 at 25psi. If I wanted to run 10.50 or slower I'd run a smaller cam than I did and a 6262. You will need better heads, correct cam, converter and the tune working all together if you want to make the most power with a given turbo. The turbo isn't going to offset any area that lacking. Plan on running 30-32 psi to run 10.0 with a cleaned up set of iron heads with stock valves. If you have a race ported set of heads like I ran, CR 9:1 or higher, valvetrain up to snuff and the converter is working you could make the same power at 22-23psi.

 

[Quik Six]

I would use a 62 compressor with a 65 or 66 turbine if you are going with a precision. I'd use a .63 housing no matter what. I made about 700whp with a 6265/.63. It was a journal and spooled extremely fast on the street. .78g from 70mph on hot m/t et streets. It will bitch slap just about any production car you will ever come across and most street bikes.

Dang, Brian, reading this made really anxious to get to the track. My engine and tranny have really smoothed out and I'm tweaking it a little bit as I go and feel like I've found some more power in the process. Even though it's snowing here tonight, next Sunday is looking good for trip to the track.

Will see how far the 6265 will take the car into the 9's this spring.

 

[Detomaso71]

I had 6765 wth smaller housing on a stock engine and it was fun, excellent street fun, low elevens alky 93.
Once I went with a new engine like yours I went larger housing and 3 by 2 outlet and had no lag and runs into nines easily. Same turbo.
I did 3 by 2 because its class legal for THS if you wanna play with it!

 

[bison]

Dang, Brian, reading this made really anxious to get to the track. My engine and tranny have really smoothed out and I'm tweaking it a little bit as I go and feel like I've found some more power in the process. Even though it's snowing here tonight, next Sunday is looking good for trip to the track.

Will see how far the 6265 will take the car into the 9's this spring.

Its going to run the number if you can hook it.

 

[northerngn]

I have a 67/65 with a 85 housing and a 4 inch inlet
Engine is a 233 and it still spools up like a mofo
Took my car to 121mph at only 18psi...Then I ran out of fuel
I can only imagine its potential at 25lbs plus when I get the fuel system sorted out

just my 2 cents

-Dan

 

[Bent6]

Most people on here running 67s don't even come close to using them to their full potential. I run a billet 6765 on my street GN with S-cover and .63 a/r. Car has been 10.02 at 3700#s on a 1.42 60ft at around 28-30psi. This is a stock stroke engine with a mildly ported set of GN1 heads and is perfectly streetable. I'm not reaching the full potential of this turbo at the current boost levels but with only 8 bolt heads I'm not pushing this one much further. This turbo will do the talking at around 35-38 psi as long as the back pressure can be kept in check.

As stated above, the compressor covers don't offer any measurable performance at this power level and the boost levels required for your goals will be dictated by the cam and heads. The larger a/r turbine housings are a wash at this power level. If I were to switch to a .85 a/r my short times would likely suffer unless I upped the launch boost. There isn't enough advantage at the RPMs this engine turns to make the trade-off worthwhile on the top end.

 

[tonysmach]

Most people on here running 67s don't even come close to using them to their full potential. I run a billet 6765 on my street GN with S-cover and .63 a/r. Car has been 10.02 at 3700#s on a 1.42 60ft at around 28-30psi. This is a stock stroke engine with a mildly ported set of GN1 heads and is perfectly streetable. I'm not reaching the full potential of this turbo at the current boost levels but with only 8 bolt heads I'm not pushing this one much further. This turbo will do the talking at around 35-38 psi as long as the back pressure can be kept in check.

As stated above, the compressor covers don't offer any measurable performance at this power level and the boost levels required for your goals will be dictated by the cam and heads. The larger a/r turbine housings are a wash at this power level. If I were to switch to a .85 a/r my short times would likely suffer unless I upped the launch boost. There isn't enough advantage at the RPMs this engine turns to make the trade-off worthwhile on the top end.

I have a 6765HP. What cam are you running? I have a DLS 218/218 and XFI. See other specs in signature.

 

[KevinB]

I got a 3x2 on my 67. That's just because of the ths class. I think the 4x3 cover looks cooler