Gents, I did some searching and read for a while on the 6 but couldn't come up with a good write up to why lots seem to stick around 1 bar tunes instead of going a bit higher. Speaking in terms of stock turbos.

Having said that, I should be taking delivery of a 2002 996TT shortly with an EPL 1 bar tune, DVs, straight pipes, 200 cell cats, coilovers and GT3 sway bars. I am thinking about having the car tuned to 1.2, of course 93 would be the choice of octane.

Bottom line, seems like more stick around 1 bar rather than going a bit higher on stock turbos. Is this because most chose to stay safe or does the car need more injectors, 5 bar, etc?

Is this more effecient, less heat so numbers are across the curve and do not drop off or might it be fuel related?

Lastly, my first impression of driving a 996TT is by far one of the best of any car I have driven in my past. I can't wait and I feel like a kid on Christmas morning.


Cheers,
Allen

 

depends on what turbos you are running. most have standard k-16' good for 1.0 bar. if you have the GT2 or X-50 k-24's running at 1.2 is relatively standard and more optimal. larger turbo versions will run higher and that when other external and internal mods come into play.

 

The answer depends on the turbo you are running.

Air flow and heat produced will vary with pressure. Sometimes adding pressure (ie boost) does nothing and can go backwards if you exceed the flow capacity of the turbo compressor.

IMHO stock K16's should be limited to 1 bar.

Inexpensive (not UMW) compressor upgrades are available from blouch to get you lots more airflow. With (I like Protomotive) programming and 5 Bar FPR it is the best bang for the buck.

 

(assuming a motor's internals can handle the pressure) a larger turbo using the same boost as the smaller is moving more air and requires more fuel to keep AFR constant.

 

it isn't just turbo dependent, other hardware comes into play as does tuning. Different tuners have different pressures they like to run different turbos. For example, on stock injectors I was running 1.35 bar on UMW hybrids, UMW tune and 91 octane gas and it was very safe as UMW is very conservative in it's tuning, yet that is excellent pressure. I can't speak for other tuners, but they all tune to their specific turbos and know what they can do. Oh and cheap isn't always a good idea., often you get what you pay for. Also higher boost isn't good if your ECU has to pull timing and power can be lost instead of gained sometimes. Again, the tuners are the best ones to talk about this.

 

I seem to recall that you need stronger wastegate springs to enable them to HOLD the boost above 1.0

The DME actually can only release boost. They 'gain' boost by just stopping the wastegate from being opened. But the ultimate release value is dictated by the wastegate spring.

On a K16 you really cannot get much more that 1.0 but K24s will get 1.2-1.3 with an appropriate wastegate.


I sense hybrid turbos in your future...

A

 

Thanks gents, really appreciate the feed back!

Cheers,
Allen

 

Is the car you're getting silver? If so I was looking at that one. Nice vehicle.

 

Yes!

 

I run 1.2 bar with my 2005 Turbo S cab. It has K24's and GT2 intercoolers. I only run MS VP 109 with my 1.2 bar tune.

 

I also am running a 1.2 - 1.3 bar tune on 93 octane (Florida standard gas) with my 2005 Turbo S CAB with K24s. In fact I was spiking to 1.5 yesterday (when it is cooler outside). I am very happy with the tune I have. The car runs so smooth I cannot believe it, leaps and bounds ahead of stock. It took a little bit of time to get here, working with the tuner and applying certain mandatory mods, but now I think it is perfect for me. If I poodle around town in 4th and 5th, there is no hesitation at all. When I kick it in First and Second I get 1.2 bar with ease. When I kick it in 3rd and 4th I get 1.3 with ease and spike on occasion at 1.4/5 bar.

I have 1 bar waste gate actuators and have been tuning the adjustment for 1.3 bar sustained. It takes a few goes and experimenting but I am almost there. I actually need to back them off a bit as the 1.5 bar, even for the spike for me is a little too high. But I am getting 1.2 and 1.3 sustained.

Currently my Actuators are cracking at 13psi, I will most likely back them off to 12psi for peace of mind.

I am going to add water injection for extra in cylinder cooling, but other than that, my mods are complete.

This car is absolutely AWESOME, reliable and fast (enough for me). I do not track the car and never will, she is my Garage Queen, as are all the exotics I have owned.

IMHO this car iwith it's current mods, is a good compromise between power and reliability. BTW I am running the stock clutch with no issues.

I just clocked 6k miles on the car, it is like new. I will sell it next year, and most likely go for a 997 TT, till then, I am a VERY happy "P" Car owner. Getting a Turbo "S" was the best decision I ever made.

 

This makes complete sense to me.

Robert, You need some K24/20's for the way your car is "utilized"

(ex: think of white Proto car that resides in MPLS now).

Lots of tuning (many hours on Proto's dyno, specifically tuned for the
exact combination of mods).

As for the original poster, 1.0 are K-16's (they get a little wheezy above that and it does no good to push beyond).

MK

 

Allen you are welcome to ride in my TT at one of the next events. My car has the boost set for a touch more than 1 bar.

Congrats on the new ride. You will love the TT!

 

Thank you! I will get with you next time I can make it out.

Cheers,
Allen

 

Darn... back to the drawing board for me. Owner had to cancel sale.