991.two

Flat Eight, MFI and Slide Valves..........Love the Old School Engines.

R_Rated

could be new school too. Warning, this article is HIGHLY speculative.

https://jalopnik.com/porsches-ferrar...owe-1601962260

Petevb

1. Again it depends heavily on usage. My friend's got a highly modified 996 GT2 that we autocross and screw around with. For that use basic "normal" tuner packages for those engines (996 and 997 turbos) are fairly safe because heat's not nearly the same concern. The engine and especially bottom end is extremely strong (remember Porsche released nearly the same engine in the 997 GT2 RS with 620 hp in street tune and it wasn't even breathing hard) so as long as you don't overheat it or overspeed the turbos you're in pretty good shape. If we were going to take the same car to the track he'd probably crank the boost down and mix in race gas to stay on the safe side, but even then I guarantee the engine component and turbo life would suffer somewhat. Of course for him that might be an opportunity: "turbos and cats are cooked- I get to buy new ones!".
2. You tear down an engine (why- oil consumption?) and find wear. Say the valve guides are shot... but sooner or later valve guides are going to wear out, that's what they do. How do you prove that it was the tune that caused the issue? Especially when some other guy with a completely stock car wore his valve guides out in the same amount of time (maybe he used his car much harder in order to get the same wear, but how can you prove that)? The point is that unless it's a catastrophic failure you often don't get a smoking gun. But the laws of physics are clear: you don't get more power without creating more heat. That heat has to go somewhere, so things are getting hotter and that heat does cause things to wear out sooner. Porsche knows exactly how much sooner because they put their engines on dynos and test them to failure. Without that it's down to fuzzy logic.
3. When issues do occur (and they do) they are often handled discretely for obvious reasons. My friend recently sent his Porsche GT car ECU in for re-tuning. Something went wrong and the tuner bricked it and had to buy him a new (very expensive) ECU. His car's fairly valuable he could have lost engine data (over-revs, hours, etc) that are critical to resale value. Luckily he'd saved most of that and the tuner made it right so you never heard about it. But understand that's the norm not the exception.
4. All tuning is not created equal. A Ruf is a tuned car (technically also a manufacture). When they sell a Turbo package you're likely going to pay a lot for it compared to most tuners. On the other hand they're engineering with similar factors of safety as the factory, with safety margins, extra coolers, etc, and I'd have zero qualms running one of their cars flat out on the autobahn until the tank runs dry. Another manufacture might offer the same power with just a tune and turbos, but you can't have the same expectations. Horses for courses.

There are plenty of bad tuners out there, but luckily most of them don't last too long. There are lots more OK tuners, many of whom oversell to move product and don't properly explain the trade-offs to customers who'd need a lot of education. There are a handful of tuners who are pretty good; by definition not as capable as the factory but aiming for something different and able to exceed what the factory did in the area they're focusing on. I look for those guys, putting particular emphases on trustworthiness, and then err on the side of caution because I know I use my cars hard. These days I often don't feel the need to go beyond factory tune in any case- with the power available stock these days there's much less point. Stepping back Porsche first released 450 hp in the 4WD 959 supercar. A decade later you could buy the same power in a 993 GT2, a homologation special that had a widowmaker reputation. Now we're getting the same power in a run of the mill GTS. Sure tires and suspension have come a long way, but we're doing pretty well, so I feel much less need than I once did to make the tradeoffs to tune...

Though I must admit that I do still find the idea of 500+ hp in a narrow body RWD Carrera pretty tempting when they get that figured out. Maybe I can talk the wife into it?

Steve Cole

You're damned unlikely to have issues with just adding a bit more boost. Your biggest but unlikely issues are likely to be valve heat, engine heat and cylinder pressure. These are addressed in the tunes with:

a) a free-flow exhaust to carry the heat away from the head and valves
b) Porsche's over-engineering for engine heat
c) higher octane fuel requirement to prevent pre-detonation

If the engine isn't pre-detonating, and it's very difficult to do these days with head design, crank sensors, oxygen sensors, AIT sensors, EGT sensors... well, the lower end should be OK as long as the rods are strong enough to take the load. I'm betting that 500hp isn't going to kill the rods, they are likely tested to 650hp or more with today's materials and Porsche's engineering capabilities. I've seen the head and cylinder design of the Turbo cars and you'd have to build a whole lot more than an extra few pounds of boost to pop a head gasket with these engines, so that's unlikely too. Which leaves engine heat and valve heat ... the efficiency of the modern 911's cooling is amazing, have had my TTS idling in 40C heat in the pits after a track session and the fans hardly came on to keep the car right on target. Engine heat never went above 92C on track at a very high pace, which is roughly where it is on a highway cruise. If you're getting the heat out of the engine with an open exhaust and cooling the head well enough, you should be OK. Larger intercoolers are always a good idea for IATs.

Now, as to why I'd want a Cobb handheld... I'd want a mild tune to go on track with. Yes, the cars should be OK with hot lapping with a tune but for added safety, racing fuel of 110 octane would be advisable, or drop part of the power with a milder tune for track days. You don't want to hurt the motor .... unless you have the kind of money that can do a "that was a learning experience" kind of fixes. I'm probably paranoid there but for good reason. Either way, it's why I am waiting for a) the tunes to mature and b) a handheld that allows me to change between tunes.

There's my two cents from 25 years of racing cars and bikes, most of them modified.

Oh, and just as a "we're probably worried for nothing" kind of post, here is a ~750hp Turbo S that did multiple days at Road Atlanta, hot-lapping.

https://www.youtube.com/watch?v=I-PAVsPMIzs

Gary JR

Is that guy having fun in that video or what?

Steve Cole

How could you not?

Petevb

A few comments...
20% more power means 20% more hot gasses flowing past the exhaust side. Pushing that through a small turbo means those gasses are also at much higher pressure (and hence temperature). Porsche's approach of increasing the turbo size to reduce that flow restriction and get that pressure down is IMHO more effective than doing it after the fact with an exhaust. It also has the added benefit of lowing intake side temperatures as well...
Depending on usage... If you want to get back some of the ability to push your car harder you have a few options. First, if live in an area that doesn't get cold/ below freezing (ever!) consider playing with the coolant mix in your car. Antifreeze is not only slippery if it drops on the track, it's also less efficient at cooling, so switching to a water + corrosion inhibitor/ surfactant (ie purple ice, etc) mix will improve the cooling system's capacity, especially in hot spots like the head. Just don't forget to switch back before you ship your car over the mountains or you'll crack your block. If you're more serious the PET shows a center radiator option (I153) to improve cooling further.
As previously mentioned... However you do not want to simply run 110. There is much more to race gas than octane: ignition, burn rate and pressure build is all different (and varies from brand to brand). That's why race engines are tuned to run on a specific fuel. I would recommend never going over 100 (R+M)/2 in order to stay closer to what the engine is tuned for and avoid doing more harm than good. In a perfect world we'd have access to pre-mixed pump 96 to 98, but good luck with that. Second best would be straight pump 95 or 100, third would be a blend of street and race gas (not octane boost) to get to ~96. A real race engine guy will still cringe at this last option due to imperfect mixing and tell you to do that in jerry cans before putting it into your tank, but...

Also you reference the TTS a couple times, but keep in mind that's a very different beast. There has also long been a gap between how over-built Porsche makes its top models and its "cooking grade" mid-range ones. The Turbo's engine and cooling systems were clearly designed to support power through the range of at least 700+ hp (GT2 RS levels). Meanwhile there's no reason for the GTS not to top out before the Turbo starts- that's what the Turbo's there for.

Dan Nagy

Steve Cole

Sure, turbos are a huge factor. Didn't argue that. But I will argue your point about the gasses - yes it's more gasses passing the exhaust valves, but with stock setup you are also holding those gasses near the head longer and at a higher temperature unless you have an exhaust that allows them to pass more freely. Which is what is required for the tune that NM posted. This formula is as old as the ICE. You've got to get those hot gasses out of the head, the exhaust isn't just for sound.

I noted that I have raced for 25 years. Water and water wetter are all that is allowed in a track bike. Now you know. There are products like Engine Ice that provide better cooling, good freeze protection (-25F) and decent lubrication.

Pick and choose your race fuels. I run VP U4.4 in my race bikes. 116 octane, leaded, and needs about 8% more fuel than gasoline to achieve stoich. YMMV

All the concepts are the same. Yes the 3.8 9A1 is built to a different grade, but it's also making a lot more power on stock turbos whether stock or modified. I really wouldn't be worried about a 20% increase in the 3.0L engine, I'd be willing to bet that Porsche tests it at 150% or higher. As long as you deal with the basics of removing heat - as we both pointed out - you should be OK. But the smart owners will also look into better brake pads...

Petevb

I'm not saying an exhaust doesn't help at all, just that it's not your best **** to turn.
The Turbo is a pressure driven pump, and it requires a certain pressure difference to drive it. If you're using a turbo that's too small for the application you can easily see a ratio of 2:1, meaning making 17 psi on the inlet requires 34 psi of pressure difference on the exhaust side. Any exhaust back-pressure will add to this, so if your exhaust adds 6 psi of back pressure then when exhaust valve opens it's trying to empty the cylinder into a tube that's filled with 36 + 6 = 40 psi of compressed, hot air. Obviously that slows the exhaust process down, leaving denser, hotter air in contact with the exhaust valves for longer. I think we both agree up to this point- that's not a good thing, and if we can bring that pressure down it will be good for thermal management. What I'm saying, however, is that of these two contributors to high exhaust side temperature and pressure it's the turbo which is contributing much more. A larger turbo can bring the pressure ratio down to 1:1 or even below, meaning it's possible to reduce exhaust manifold pressure by 10 psi or more. Even a completely open exhaust can't reduce the pressure by that much, which is why I believe Porsche left the exhaust alone and changed the turbos when they bumped power in the GTS.

Same with many race groups for cars as well, though as you say there are better products than water wetter out there these days.

Yep, though best to leave the lead out of the cars. Just saying that unless you can re-tune more octane isn't better, it can actually be worse.

I suspect that you could do bolt-ons to the 3.0 and safely get it to ~550 hp (complete wag, for track duty) if you had proper control of the tuning. Bigger turbos, extra center radiator, exhaust, maybe water spray on the intercoolers. And I'd feel much better about tracking something like that than a tune-only 500 hp car; my read is that 500 hp is pushing it pretty far without any cooling upgrades for this platform.

Steve Cole

I haven't heard the larger turbo solution described in that exact fashion before. Good comment, cheers.

KenTO

Petevb