917k

Exactly my thinking. Didn't want to wait a year for GTS. Pretty much selected all the sports options so upgrade possible later.

sticky

For some reason my post you quoted was removed which makes it difficult to respond to you as well as have the correct information in place.

You're conflating two things, spool and boost threshold.

Let's start with this comment which I take issue with and you did not address but instead moved to throttle response:

WRONG. I'm amazed something like this would be allowed to be posted but refuting it with facts would not be.

This is a base 991.2 9A2. The difference between stock at 13 psi and increased boost shows no difference in lag. Actually, the tuned example looks to hit peak torque slightly sooner even. You can of course affect spool by playing with timing:


Right there, on the very car and engine we are discussing, you see there is a major torque benefit but no increase in lag due to increased boost. Why would there be?

You seem to be thinking of boost increasing in a linear manner as it would with rpm in a centrifugal system. With turbos you can have 13 psi, 14 psi, 15 psi, 16 psi, etc., at that same 3000 rpm point. There is more than enough exhaust gas to support those levels as the dyno shows you. Obviously if you push too far you will move the compressor out of its efficiency range.

What you wrote is simply wrong. More boost does not equal more lag and tuners don't dial down boost to improve spool. You don't shift the compressor map by removing a few psi.

Lag you feel is the delay in reaching a specific boost pressure. Increasing boost pressure will not create greater delay.

Regarding what you say about the 991.2 Carrera being 'sharper' than the Carrera S is baloney. A lower boost level does not mean it is sharper for the reasons already explained above. I can not believe someone claiming to be an engineer would type this.

The hardware, not the boost pressure, determines when it will start to spool. The only difference in hardware between the Carrera and Carrera S is a 2mm difference in the compressor wheels. The turbine wheels are the exact same size.

You are telling me you can perceive a spool difference due to 2mm in the compressor wheel and that this difference is so large as to make the Carrera more preferred?

Furthermore, as you can see in the graph posted above increasing boost pressure on the Carrera does not provide more lag. The stock curve is mimicked just with a substantial increase through the curve starting when the turbo spools.

sticky

You continue to spread this false assertion and it is downright dishonest. The owner no longer wants to post his slips here for this reason.

This is the timeslip:


How is there no improvement on this 991.2 C4S with 21 inch wheels? Are you saying stock C4S models run 11.1? They do not.

That is currently the quickest and fastest 991.2 3.0 on the planet. A distinction held by a tuned example.

I get the impression you do not want the 991.2 to be as quick and fast as it is. Additionally, that you are not able to discern between magazine GPS tested times and actual timeslips.

We barely even have a tune on the market and there is only one tuned run to reference. If the only run there is already shows a half second plus on stock cars and is the quickest and fastest to date on the platform, how is that not an improvement?

sticky

Heh, personally I find this post amusing as I'm the only person who dyno tested the IPD plenum on the 991.2 9A2. I found a mid-range gain as well.

So you're saying Porsche intentionally tuned out a part of the NA mid-range? First of all, that isn't engine tuning or anything due to software. It is a minor hardware restriction because Porsche uses a cheap, simple, and efficient plastic plenum.

Changing this plenum shows slight mid-range gains on the 9A2 and even some of the naturally aspirated models as well. Guess what? Eliminating cats will show gains too. That doesn't mean Porsche intentionally put catalytic converters on the car to reduce torque.

What you are saying about intentional tuning to limit torque is fake news.

R_Rated

That's 11.2 if you're going to round. Stock is 11.4. So that math equals .2 second improvement and not your grossly exaggerated .5 second improvement. I hope your power gains are a little more honest. Also, with that much power gain the trap is laughable.... if the power gain was real.

.2 seconds could be so many things and until you do back to back on the same night - same track.... it's all conjecture... especially given your liberal interpretation of rounding numbers.

sticky

You must be new to slips as when someone runs 9.9 you don't round to 10. It's a 9.9 and this is an 11.1.

It also is the quickest and fastest time so far. Don't worry, winter is coming. Times will drop.

Stock is 11.4? Show me that slip for a C4S. Go right ahead. There you go again quoting magazine times as if they are the same thing.

The quickest stock slip I've seen is 11.5@120 from a C2S. So, a heavier all wheel drive car on 21 inch wheels is still quicker and faster.

If you want to believe a 100 lb-ft gain at the wheels isn't making cars quicker, go right ahead. Better yet, line up with a tuned 991.2. Too bad you are far away from me but if anyone in SoCal wants to I'll gladly do it

R_Rated

That's the difference with my car and yours.... mine would make the trip cross country... a Giac tune may not!

sticky

I think the way you are characterizing the GIAC tune is unfair to GIAC and people who bought the tune. Immediately implying a car will have issues with it when you have no experience with it is just spiteful.

Not only can you count the number of people with it on one hand the 991.2 is very new yet I'm not seeing reliability issues that should make one wary of tuning?

Your tone is constantly negative against it. GIAC posts a tune with incredible gains and you say they are fake. A guy takes a tune to the strip and runs the quickest and fastest recorded time on the platform and you say the tune isn't doing anything yet the numbers show it is.

Furthermore, plenty of people on the 991 Turbo platform run GIAC tuning. As do those on 997 Turbo platforms. They even have 9 second cars with the GIAC tune and factory turbos.

The problem here isn't the tune or performance. It's your constant hatred of the 991.2 and the performance it offers. You even hate on the X51 kit. Look at your first post.

randr

Suncoast - when you get the chance can you please respond to your messages thanks.

R_Rated

Your making up fairytales. Yes, I made a crack at the new power kit being really expensive for 2 turbos... but have always given credit to the performance and gains of the .2.... even recommended it many times; publicly, on here.... depending on the intended use.

If you want to promote your product on here then why not sign up as a forum sponsor?

GIAC has a long history of questionable reliability. For every success, I can name an issue - including personal experience on a boosted car. Please stop trying to make things personal.

sticky

This powerkit is a great value. Suncoast is offering a good deal and you have to look at the kit in the context of Porsche.

$18,500 for the 991.1 X51 package which offers less torque, less power, and less headroom. It also comes with a much higher install cost and only is applicable to the 3.8 liter motor. These turbos will fit every 991.2 3.0.

You also get a factory warranty here for less than half the price it would cost on the 991.1!

What product am I promoting? I don't even have a GIAC tune. I'm not intentionally discounting a tuner or a platform as you seem to be going out of your way to do in yet another 991.2 thread.

Maybe let people who want to talk about the X51 package and tuning do so as you have nothing to add? I'd love to hear more feedback from people ordering as well as thoughts from those who may want to figure out how to get it working on a base 991.2.

Petevb

Actually I am not. He're the graph in question. I have labeled it to show where the boost threshold is. You can see that by before 2500 rpm you well past the boost threshold in every gear. When Ferrari calls out their "best in class .8 second response time in 3rd gear at 2000 RPM" you can see clearly what they are referring to.



You can also see clearly why they say having a unique boost map in each gear is key to improving response.
Have you asked yourself why in the above the stock car doesn't make peak boost/ torque until 3200 RPM? When Porsche quotes 1700 RPM, which would be well of the chart to the left?

This gives the game up. In all likelihood they used an inertia dyno and started the tuned car earlier rather than magically reducing the boost threshold by hundreds of rpm with timing alone.
Frankly if that's what the tuner had done you wouldn't want to run their software.

When you get full correct curves you get something like this when you tune, much like the Ferrari curve above of Porsche's own curves:

sticky

See, you're not understanding. What you posted was a graph of different load in different gears.

If you are in 7th gear at 2000 rpm yeah you bet it's going to accelerate differently than 1st gear at 2000 rpm.

Would you mind explaining how this shows increased lag with increased boost? The graph I posted showed the same gear and same rpm except one run with stock boost pressure and the second with increased boost pressure.

Mind explaining why there isn't an increase in spool or lag?

The graph you posted highlights the point. The spool is still the exact same.

I have no idea what you mean by 'tuning' for an inertia dyno as a Mustang dynamometer is eddy current based which is what GIAC has in-house. You don't know what you're talking about.

Furthermore, since you love the Ferrari motor so much here's a tuned example:



Where's the penalty? It doesn't exist.

Petevb

So what you're saying is that Porsche couldn't afford to make their newer flagship cars are good as the older 997 RS 4.0. Despite charging 180k that little plastic part was a deal-breaker? This despite years of development, a new finger-follower head, improvements in engine friction...

What you fail to realize is that virtually every Porsche made is de-tuned to hit a power target. Porsche develops their engines as a "kit" with various parts they can mix and match. 98% of the parts are interchangeable leaving a few key components they can mix and match to get their desired results:



When Porsche first developed the engine family they developed a range of bores and strokes, but they put the largest bore and stroke combo together only recently in the RS 4.0.

95% of the parts are shared between the 9A1s, from the bearings through the block, so each one costs almost the same amount to make (GT3s excepted). At any time Porsche could have made them all 4.0s for virtually no extra cost in the same way Porsche can simply turn up the boost in the base 991.2for "free". If they want more torque that's easy- they know how in any number of ways. They choose not to make more torque.

sticky

You're all over the place. I'd love to talk about the X51 for the 991.2 and how great it is and also how you can increase boost making the car more fun to drive without a sacrifice. But fine, I'll address this.

I have no idea where you come up with the thought I'm saying Porsche can't make the new GT3 motor as good as the GT3 RS 4.0. I will say I prefer the Mezger block but so what? What does this have to do with anything?

I fail to realize every Porsche made is de-tuned? Exactly how detuned is a motor making over wheel 100 horsepower per liter? What do you think you will be picking up here exactly? Is there some large pocket of hidden torque?



What is Posche de-tuning?

I would agree the Cayman GT4 3.8 is artificially limited to not step on toes but that certainly does not apply to the GT3 RS 3.8. Porsche themselves had to increase displacement, compression ratios, revs, etc.

The 9A2 architecture is modular and parts are shared. Porsche began more and more parts sharing when the motors became direct injected. And? How is increasing boost through software tuning the same as changing hardware? There are very different costs associated with these two things.

What is your point? Do you have one?