sdg1871

I ran my GIAC Stage 2/Europipe/IPD plenum with ADV1 wheels (stock suspension) Turbo S hard at Circuit of the Americas during GoldRush Rally 7. Ran full tilt during 4 20 minutes sessions. Pushed the car as hard as it would go, passing many cars (Ferraris, Lambos, etc).

I had zero issues. Not overheating and no suspension issues. Car handles the extra power perfectly. The instructor told me the car was just fantastic in terms of its performance.

speed21

This is the key point. So many try to fix what isn't broke in the first instance, paying good money compromising what was there to begin with. I personally find it impossible to extract the potential of the stock engine under hard point to point driving. Maybe I just need to go back for further driver training or something....or de-tune the car. It's just so damn quick stock, a phenomenal machine with seemingly limmitless capability. I'm keen to see if a 991GT3 RS 4.0 can hang with it on the open road. That will be the tell all for me.

Have you ever data logged your car under these types of sustained "flat out" driving conditions? It's just that I recall you repeatedly posting how your car is pulling timing from heat soak after just a few runs up the strip. It could well be the case that there is undue stress going on inside the engine which you are not aware of. The oil/water temp gauges showing as being within acceptable range won't tell you about your combustion temps. Also not sure what "full tilt means"? An instructors words is not an assurance that would comfort me personally...

sdg1871

Full tilt means I was pushing the car as hard as it would go. Late braking. Hard on the gas. Going as fast around the turns as the car would go. Not holding back at all.

With respect to the heat soak, there is heat soak at drag strips and roll race events as the time slips I have posted here have demonstrated. Even with heat soak the car's power is still above stock levels. The car does not go into limp home mode. It just does not produce as much power as when cold. GIAC has confirmed in writing on another forum that it's stage 2 tune is programmed to aggressively cut boost/timing to keep intake air temps within normal levels. This is because the stock intercoolers cannot handle for Long periods of time the excess best produced by the stage 2 tune which is a product of the tune's increased turbo boost. That is what the upgrades intercoolers will solve.

Stated differently, the heat soak from the stage 2 tune is not an engine malfunction but a deliberate part of the tune's programming to protect the engine/turbos from excess intake air temps.

speed21

I am very familiar with the engines defense mechanisms and the triggers behind their activation. Bottom line is the engine IS being pushed into the danger zone, hence why timing and fuel is being dumped. Neither being desirable situations. Regardless of the engine still producing above stock power levels is of no consolation least of all diminishes the fact the ECU has detected problems which require preservation/intervention against undue stresses being placed upon the internals. If you are operating your engine under these types of sustained driving conditions and experiencing these types of interventions I'd be flashing back to stock.... and then going hell for leather.

sdg1871

I hear what you are saying. That is why I expect lots of 991 TTS owners with tunes will be getting upgraded intercoolers so that the extra power can be produced without getting Intake air temps beyond the safe zone.

Tuners like GIAC who sell so many tunes cannot afford to blow up 991 TTS engines. It would kill their business. So they design their tunes so that does not happen or is extremely unlikely to Happen. That is why we are not reading reports on the forums of lots of 991 TT/TTS engines blowing up with a GIAC tune -- same for the 997 TT/TTS.

I can only speak for my car but it performs very strongly and I am very happy with it. Even more so when it has the enhances intercooling.

worf928

I do plan to track it a lot. Just not this instant.

One would hope that the higher RPM of the S is due to some lightening of reciprocating components in the engine. One of these days I might bother to install the latest version of PET and see for myself.

Right. I should have written "difference between my Turbo" and an S. In order to get the price of a Turbo and an S within ~$20k I think you either have to check some of the boxes that are standard on the S or pick every leather option I assumed the context was a Turbo with PDCC.

There is a lot of debate about PCCBs on the track and not just the older generations. My take away is that if you use your brakes properly on the track you can expect PCCBs to have twice the lifetime of steel brakes. But since the replacement cost is about 4x the life-cycle cost is 2x.

On the other hand, if you over-use the brakes - which a lot of newbies and high-hp drivers do - the PCCBs will not last 2x of steel.

speed21

I pays to be careful. Nothing is bulletproof unless it is tested properly to be so. Your engine may well appear to be performing strongly, or stronger than stock, but at what cost to the longevity and relieability of the engine?? Does anyone honestly know outside of the Porsche engineering division in Germany? Giac evidently don't appear to. Adding extral torques and HP by modifying the ECU which can cause the engine to enter any form of safety mode under sustained operation is basically unreliable and essentially useless HP. It goes against the entire grain of what this car was designed by Porsche to do. That is the beauty of the Porsche - it is a sum of its parts and WILL run reliably under sustained hard operation and, in all types of environments. This is where you need to ask yourself the hard question exactly how much do these tuners really know? Because if they really knew as much as you are hoping they know (or say they know) then why didn't they know (or at least advise you ) that the intercoolers amongst other ancillary equipment will fall over (and require up-scaling) under sustained use with their tune? Or did those details not matter? I can guarantee you Porsche knows exactly what their engines and the ancillary equipment will take because they have done the testing properly! I can also safely guarantee that if/when the 991GT2 surfaces it will have suspension modifications and up-scaled brakes amongst a range of items to accommodate for the additional performance that car will deliver....AND more importantly, deliver reliably. Once you up the hp in anything it throws everything else out of Kilter hence why it is so costly and time consuming to improve the car even by a few tenths.

Bottom line to this thread is you can pay more to option up a base turbo in a bid to match the output of turbo S but it will never be the same sum of its parts as a total car. Tuning the base engine just throws everything out, along with the warranty which is incinerated immediately. Doesn't make a lot of sense to me when you cant even effectively use what you've got. But by all means to each their own!

sdg1871

Yes tuning is not for everyone and it does have its risks. Those risks are much less if you use a top shelf tuner. I love the extra performance.

Would love the 991 GT2RS when it comes out. That will be near the end of the 991 lifecycle so it could be a bunch more years. And it will be super expensive and hard to buy anywhere near MSRP. In the meantime I am really enjoying my GIAC tuned 991 Turbo S.

speed21

I still come back to the testing (or obvious lack thereof) and, where the engine is presently up to in its overall life expectancy. Only way to find that out is to strip the engine. Fact is there has definitely been more heat and load stresses placed upon the internals. I'd personally be putting it back to stock immediately until such point you knew for sure the engine's ancillary equipment is up to spec, so to allow the engine to better handle the additional HP of the tune reliably without chopping the life out of the engine in the process. I guess it all comes down to how long you plan owning the car..

I'm sure it will be a beast and the one to own long term. But then I guess there will always be a gen 2 and an RS version so...all in good time.

FBA

I have tuned many cars and produced a ton of HP over the years. With a reputable tuner, or tuning company behind the product, risks can be quite minimal.

Often, tuning produces less eco-friendly results - which is why often, the vehicles come the way they do from factory, not simply because they can't handle the additional power.

The sky is not falling...and in fact, it's quite sunny out there!

speed21

Some of these tuners have become just like Hollywood movie stars! They could do no wrong. Maybe a Hollywood walk of fame is in order! Sorry fellas... had to laugh at the gay abandoned attitude that exists here amongst some of you. Truly beautiful! I take my hat off to you!

FBA

I'm curious, have you ever tuned or built an engine, or do you just preach the safety of staying stock to up your post count?

speed21

You would be surprised at how closely related my profession and area of expertise is on the subject matter but to keep you happy lets just say the latter....and let's just hope that sun keeps on a shining brightly for yas! You can always pay for my services in diagnosing your engine failure one day. Plenty do.

FBA

With all due respect, I doubt I'll be one of them, one way or the other...but thanks for the offer.

speed21

...well the offer stands. I promise to go easy on ya. We try hard to leave no stone un-turned.