Flat6Motorsports

We have a range of clients from street, drag strip and road course uses at varying levels (along with our own test vehicle). We do have one who is a top-tier amateur driver (PCA instructor for decades) who is running north of 600whp and uses it weekly on the track. He had a tire blow out if you want to consider that an issue. If I had to shoot from the hip, I know we have at least 20 folks running a Stage 3/4 on road courses with some frequency. Probably 75+ running a Stage 2 setup. I'm combining the 991.2 and 992 in one category but we certainly have more 992 clients. We also chat with many Porsche dealerships (sales, service, parts staffs) and have a pretty good pulse on issues/problems that Porsche is facing on the warranty side...(cough cough Taycan). By no means are we official experts on the matter, I'm just sharing some information from our relationships for the benefit of conversation.

Just my $0.02:
Porsche has a $38B market cap with $58B on the balance sheet. They are in the business of selling cars and factory warranties are expected with consumers. They have 650+ dealerships with thousands of factory trained technicians, part warehouses, etc. Most tuners and builders are small businesses carrying debt and trying to make payroll while following a passion of performance. There's just no way they could offer warranties remotely close to what Porsche does. The specification and quality control Porsche has is a big reason why they build very dependable cars. At Flat 6, we don't have defined warranties with our builds but we do provide service/support for years after purchase for our clients. We're in the business of relationships and look to take care of folks and make sure we're doing right by them. Porsche is able to ensure some level of standard and control through their service model. Most clients aren't shipping their car back to us for routine service. I don't want to throw out laundry on a public forum but I have zero concern about Porsche covering legitimate warranty claims. We have many examples of this happening with some pretty extensive build set-ups. They too are in the business of long-term relationships. At the end of the day, your Porsche is your Porsche, do what you feel comfortable with. This debate is as old as the forums and is splattered all around them. There's a lot of misinformation and opinions. One size doesn't fit all, enjoy your cars folks!

SapphireBlue981S

I really appreciate you typing this all out. You are the credible source with firsthand experience and real field knowledge. I’ve read endless posts about this topic but hearing it straight from the pro is relieving! I’m now sold on Soul 200 cell cats and ME stage 2. 75+ clients running stage 2 on the track with no issues is amazing 🍻
i also read through this thread and all the comments from Mitch @ ME and other clients are helpful.

recarv

This 100%. Even though flashing between maps only takes like 60seconds, it still was a surprise there isn't on the fly map switching. Its the only thing keeping me from running the ethanol tune the guys at Mengineering gave me - I have to plug the damn dongle in and carry my laptop with me etc...

BED997

Watched the Tommy L Garage video again on his 991 T blown turbo. $8,800 parts and labor. I have to think a 992 turbo isn’t any cheaper. Labor was something like $1,200 and he went through all the repair numbers.

It appears he installed a tune some time before the turbo went out.

lQUOTE=BED997;19298151]I’m hearing a single turbo replacement is over $8k. Wouldn’t be surprised a new engine is 60k + for a complete unit.[/QUOTE]

Patrick Pigulski

After the uninstall the tune you will still have crazy numbers on the turbo boost pressure which is how they can tell something’s up.

Mike Murphy

Sorry to dig up an old thread, but I just read that engine cooling is limited at higher elevation due to the thinner air. Basically, you’d need a lot more airflow across the radiator to get the same amount of cooling. So I wonder if this is the reason why some cars might limit turbo boost pressure at higher altitude?

Mike818

Just speculating, but the turbo has to work harder at higher altitude. Boost could be reduced to prevent the turbo from exceeding it's rated rpm limit.

Angryinch

Turbo engine is good for 900 whp, above that rolling the dice.

TheOtherDave

I posted a thread a while back about wanting to install the 3rd raditor
https://rennlist.com/forums/992/1397...r-install.html

I was basically branded as an idiot for wanting to do it....but anyway here is an analysis of how altitude affects cooling efficiency
that I wrote in the thread.

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

You basically lose the same cooling efficiency as the % loss of absolute pressure and loss of temp differential. Cooling (within limits) is all about how many molecules
you can pass heat to at any particular time. Lower atmospheric pressure means less molecules. The temp of the ambient air has 2 effects.
One is that the higher the temp the air then expands and again you have less molecules in a given space. The second is that thermal
transfer is relative to the temps of the objects transferring the heat energy divided by the thermal resistance of the interface.
In this case it is aluminum (radiator) transferring to an oxygen-nitrogen mix (air). The thermal resistance is measured in (in the EE world anyway)
in degrees C per watt. The lower the thermal resistance is and the lower the total thermal energy is the closer the hotter object will be in temp
to the cooler object but the larger the thermal difference is the more energy will be transferred.

So to make it easy if you have ambient air at lets say 20 deg C (68F so a nice day) and the cooling water is at 100 C (close enough) then if the thermal resistance
is 1 deg C per watt then the maximum thermal transfer is rate is 80 watts. Now a 992 C2/4S produces 330345 watts of mechanical energy at max HP and is (max) 40% efficient (so 60% of the
energy goes into heat) we now need to dissipate the other 60% which is 459967 watts. If you want to maintain the same temp differential you need a thermal resistance of 0.00017 deg C per watt.

So lets say the outside temp is now 40 C (104F which is probably low for most tracks in the summer) and you want to maintain the cooling water at 100C (which we do) we now have to
have a thermal transfer resistance of 0.00013 deg C per watt or an decrease of nearly 25%. This is why radiator fans run more when it is hot outside as they affect the thermal resistance.
Because when the fans are on you move more air and effectively lower the deg C watt of the interface (because more air is presented at the interface per unit time to move heat into).

Now we bring air density into it....at 5000 feet you lose approximately 17% air density and this is directly related to how much heat you can transfer to it.
Not to mention that the air density goes down with the higher temp (Pilots call this density altitude which is altitude and temp dependent...I used to be in the Air Force and this was a big issue)
which I have ignored in this.

Note that on a naturally aspirated engine you also lose approximately 17% of your max horse power....this is not accounted for in these calculations either.

So if you stack these together between 20C at sea level and 40 C at 5000 feet you need a cooling system with approximately 37% more cooling power to keep the same coolant temps

TheOtherDave

Technically the turbo has to spin faster to achieve the same absolute amount of boost (because of the lower input pressure/air density).
If your input energy (the exhaust) isn't enough to spin the turbo faster then the max boost pressure will be lower.

But the requirement for increased input energy and the higher required turbo spin speed is well represented by "working harder" in my mind.

There is also a max input to output pressure differential that any give turbo can achieve (regardless of the input energy) it is called the max compression ratio.

Basically you can think of it like a propeller in water where it starts to cavitate (i.e. produce bubbles under water because the propeller can't keep up).
In air cavitation means bubbles of low pressure. This is also related to an aircraft wing stalling. The airflow becomes disconnected from the wing
due to various factors and it produces no lift.

Mike Murphy

This post is brilliant! Thanks for sharing.

BTW, the whole 3rd radiator thing is a very common discussion point in the 996 world. Probably because, as a heat exchanger ages, it becomes less efficient (due to buildup of contaminants and deposits) and anyone looking to improve cooling can add that 3rd radiator. They could also replace their existing, aged radiators, with aftermarket ones that have better efficiency.

In any case, because Porsche designs these high performance cars with efficiency in mind (in this case, power to weight ratio), there probably isn’t all that much extra margin (extra cooling capacity) built into the design, because that just adds weight and cost. So in many cases, an older car, if tracked or modded, could probably use better cooling.

It goes without saying, too, the way the oil is cooled on a 996/997 is an oil to water oil cooler, which acts as an oil heater during warmup, and an oil cooler once up to temp. And so, improving water cooling at the front will also improve oil cooling in the engine.

And so if one were to tune any engine for more power, then cooling should be a consideration. If it’s just street power, the occasional 0-60 stoplight drag race, probably no biggie. But sustained output, different story.

TheOtherDave

One other thing that my manifesto doesn't consider when I wrote it is that some of the heat energy goes out the tail pipe
in the exhaust.

According to some research after I wrote it about half of the heat energy that an engine produces goes out the tail pipe.
So my calculations are definitely worst case. So my 60% number would become 30% of the total watts produced by the engine.

But that doesn't consider that the turbo uses some of that heat energy to produce boost....which is power and the energy
of the exhaust gasses drop....this I don't know what to do to represent because I can't find any numbers about it.

Dave

HOTCHKIS

Wow