porschedoc.. question about GIAC 996 tt
 

appreciate the help in advance.. i dont want to spend 5k on an exhaust, but would like to see solid gains from a GIAC which by what you say gives about 74hp.... how much hp is expected WITHOUT modifying the exhaust?

thanks.

RE: porschedoc.. question about GIAC 996 tt
 

Those are the gains on a stock car, 74ish hp and 78ish torque.

RE: porschedoc.. question about GIAC 996 tt
 

porschedoc... in a thread in the past you mentioned that doing the GIAC without the exhaust wont yield much gains... the thread was about a 996 NON turbo....

https://www.germanautoforums.com/m_14460/tm.htm

are you saying that on the non turbos exhaust MUST accompany the GIAC, while on the turbo the GIAC is sufficient alone for 74'ish hp gains?

im curious because i REALLY dont have an extra $5,000 do dump into an exhaust system, yet would love get at least 40 hp from a good tune. please advise.

also, PM me your shops details/phone. thanks.

RE: porschedoc.. question about GIAC 996 tt
 

You can not compare the gains possible with a turbo versus a non turbo, they are completely different animals. The reason you get the gains on the turbo, is there is so much to work with in terms of air/fuel and boost. You will get over 70hp from the tune on a turbo alone.

RE: porschedoc.. question about GIAC 996 tt
 

IM sorry but what is this GIAC that your speaking of? I have a 2003 996tt ANDI SEE THAT YOU CLAIM APPROX 70 HP FROM IT... I am interested.. please tell me what it is.. what is done.. and the cost.. My car is bone stock tiptronic at the moment..

thank you

RE: porschedoc.. question about GIAC 996 tt
 

GIAC is a company that specializes in ecu tuning for performance. www.giac-usa.com We are an authorized dealer for them.

RE: porschedoc.. question about GIAC 996 tt
 

PORSCHEDOC thanks for that clarity.. will be in touch very soon!

RE: porschedoc.. question about GIAC 996 tt
 

diverter valve it.... a must with the GIAC or not a must? what benefits?

RE: porschedoc.. question about GIAC 996 tt
 

I would highly recommend replacing the diverter valves with Billet units. I use EvoMS units, but there is also bailey and forge out there. The stock diaphragm is rubber and prone to tearing, especially under increased boost....the aftermarket billet units use a metal plunger instead....much more reliable.

Here is my write up on the diverter valve installs:
http://www.turbo911.com/showthread.php?t=287

RE: porschedoc.. question about GIAC 996 tt
 

Here is a writeup on the diverter valves I wrote a few months ago....


This topic came up over at 6speed, so I wanted to share a bit of knowledge with you guys. You see a lot of posts recommending EvoMS billet diverter valves on the market which are replacements for the stock units. This is one of the first things we recommend doing to the car, especially if you are thinking of flashing your ECU to higher horsepower levels. Why does this matter? What makes them better than the stock units?

Here's why: The stock units contain a rubber diaphragm in them that over time will tear, causing the valve to not function properly. Porsche, VW, and Audi have been using these Bosch valves in their turbo charged cars since the early 80's, and still are using them today. Sure they use an "updated" valve, but it fails in exactly the same manner as the old valves (as well as looking the same). Typically we see these valves fail by 30k miles. In cars that run higher boost levels, the Bosch valves will fail almost immediately, because the rubber diaphragm is not designed to resist the increased pressure. It will rip and fail, and all of a sudden that $2k ECU flash that you just paid for, will seem like you got ripped off (I.E. the car will produce less boost than stock).

What are the symptoms of a failed valve? Typically you will only be able to boost a fraction of what your car should. For example, if you are normally running 1 bar of boost with a good valve, well then with a ripped valve you may only be able to produce .4 bar. This is a significant decrease in horsepower.

Here is a picture of a stock Bosch valve that I cut open and pulled apart. The red arrow points to the rubber diaphragm which will split and cause the vacuum leak. What happens, is the air is not able to push the plunger up, because it travels right through the rip. If the rip is small enough, well then a lot of air will still partially be able to push the plunger up, which is where you might still get your .4bar of boost. Basically it is like trying to blow up a balloon that has a tiny hole in it. You might be able to blow it up a little bit, but you won't get it all the way. In the case of the DV valve, it is vacuum, but the theory of air movement is the same.
http://karl.wilen.us/images/BoschDV.JPG

And here is a picture of the Evolution Motorsports Diverter Valve. Notice the aluminum plunger, which is sealed tightly by the rubber o-rings on the side, eliminating the need for a rubber diaphragm. This virtually eliminates the valve failure. And since I know it will be asked, "Can the o-rings fail?" In theory yes, they could. In the last 2 years, I have had 1 valve come back with a bad o-ring, and this was a new valve, so I contribute that to a manufacturing defect. In contrast, last week alone, I removed 5 Bosch diverter valves that were shot from vehicles. A drastic improvement! With an Evo valve, you will also be able to run higher boost levels without fear of failure. We recommend them with all of our ECU flashes, as the boost is increased over stock levels. Replace the stock valves with billet units, and don't worry about them again!
http://karl.wilen.us/images/EvoDV.JPG