Precision PT7675 CEA, PT7675 GT42 Style, and PT7685 GT42 Style Differences

[karolko]

Hello Guys,

I am in the midst of building up my Stage II motor and I would like to know what the real dieeferences are between these 3 turbo's, the PT7675 CEA, PT7675 GT42 Style, and PT7685 GT42 Style

Patrick maybe you would be able to shed some light on this subject, along with anyone else.

Some real world experience would also be nice.

Adrian

 

[Eticket]

Really depends on what your goals are. All in all, the biggest exhaust side that you can stand and spool, the better. If you have a tuner aka Cal, let him pick your turbo.

 

[chris kirk]

Hi Adrian,
What does your build consist of? Block, heads, cam, intake, injectors, xfi..... How do you intend to use the car?

Chris

 

[karolko]

It's a Stage ii 153 on center block 271 or 274" motor, 9.5:1 compression, champion aluminum heads, ( I don't know if they are R heads) 224/224 solid roller, Champion race intake, 160lb injectors, xfi, xim, atr headers, Danny Bee Timing belt setup, AMS-1000, turbo 400 and ford 9"

All the good stuff

Intent of use, well I do still plan on driving the thing on the street, but by all means this car has become anything but streetable, if you know what I mean.

Adrian

 

[forcefed3.8's]

The GT42 style has a 5" inlet, v band outlet compressor cover. I am running the GT42 style 7675 with the 1.28AR exhaust housing. Mine is one of the first, and few billet wheel with journal bearing. Once spooled, it hits hard. BB might be better for the street, but I am learning how to spool it on the street, and even though the car makes more power than last year with the smaller turbo, the lag helps the car hook and go. The 7685 is probably too much turbine.

 

[karolko]

forcefed, Thank you very much for the info. It is real data that I neded to read. In speaking with Cal he also told me that the 7685 would be too much turbine.

You motor combination sounds to be very similar to mine ( based on your sig) and if you put down 990rwhp with that turbo and combination, it will achieve my goals.

This is kind of a hard question, but what type of lag times are we talking about here? For instance give me an idea of how long it takes you to get up to your level of boost, whatever it is, when you are on the tras brake and at the lights.


Adrian

 

[ttypewhite]

Spool up is not bad on a transbrake, probably 4sec to get it up to a 2 step. On the street it is a different animal when your on the roll. The more boost you have on it, the faster it will spool up. With a T400 there is no kick down, so this is where tuning comes into play. The lag actually works in your favor as it doesn't unload the tires on the instant hit. It builds up and gets nasty as the rpm comes up and works almost like a traction control. With a reverse manual valve body I manually shift it into a lower gear at higher rpm to get it going and pull the next gear when she starts trucking. A BB billet wheel version would be a better choice in terms of spooling on the street but it comes with a bigger price tag.

Real world data

 

[forcefed3.8's]

Like Mike said 4 secs or less to get to launch boost on the brake. On the street you need rpms. Either manually downshift or do a rolling brake torque. Starting in first from a stop isnt too bad even off idle with a good converter.

 

[norbs]

Like Mike said 4 secs or less to get to launch boost on the brake. On the street you need rpms. Either manually downshift or do a rolling brake torque. Starting in first from a stop isnt too bad even off idle with a good converter.

What is considered launch boost though? 10 psi? I can;t spool that in undeer 4 secs...

 

[forcefed3.8's]

11psi. This is full throttle on the 2 step.

 

[karolko]

okay great thanks a lot.

 

[norbs]

FYI the GT42 turbine is a 82MM wheel, smaller than the 85mm wheel but bigger than the 75MM wheel. The wheel diameter is more the choke point than housing A/R.

 

[karolko]

Norbs, where did you get that info from?

Here is what I pulled off the Precision Website:
PTE's PT7675 Turbocharger features the following:
• Exclusive CEA® (Competition Engineered Aerodynamics) compressor wheel machined from a 2618-aluminum forging
• Air-cooled, dual ceramic ball-bearing center housing rotating assembly (CHRA)
• Higher efficiency and faster transient response for maximum power and performance
• 76mm inducer compressor wheel
• "GT42 style" compressor cover with V-band discharge
• 75mm, 84 trim turbine wheel
• Turbine housing options:
- T4 Divided .98, 1.12, or 1.28 A/R with 4 5/8" V-Band discharge

It also says that the 7576 is a "GT42 Style" which I believe refers only to the fact that it has a divided exhaust housing.

Someone here can correct me if I am wrong.

Adrian

 

[2QUICK2B6]

ttype white is the combo maxed out or does it have a conservative tune ?