GrantG

They increased compression ratio from 12.0:1 to 12.9:1 (made possible by DFI) and redline (9k from 8k5 and peak power is made at 8,250 rpm in the 9A1 instead of 7,600 rpm in the 997.2 which is the part that matters). These are the two time-tested methods to gain hp from a given n/a displacement (assuming adequate breathing in intake and exhaust which are close to optimal in a GT3).

Remember the 3.6L 996.1 GT3 made only 360hp, the 3.6L 996.2 GT3 made 380hp and the 3.6L 997.1 GT3 made 415hp. This 55hp improvement with the same displacement came from raising the redline from 7,600 rpm to 8,400 rpm, lightening the internals made this possible and the compression came up too...

Making peak hp at higher rpm gives more peak power.

Raising compression ratio makes both more peak power and more torque across the power band. Today after DFI, we're making only small incremental gains on compression without improving pump fuel octane standards.

neanicu

You only remember the version Macca has " planted " on this forum according to his " sources ", in a desperate attempt to defend the car. Shortly after,mysterious reports started pouring in about engine fires and such. And then there's the " stop sale ".
The truth is,there's no official version of this and I can guarantee there was no tuner that had cracked the 991GT3 Siemens ECU at that point!

Nick

I am dumbfounded by this thread. Assuming the GT3 has more than 475 but less than 500 who in his/her right mind would play with the ECU and risk losing the warranty? The hp increase would be difficult to discern while driving the car.

Jimmy-D

^^Fair enough. But I have ECU flashed my Porsche before. I "get it" on a turbo engine but I would still recommend proceeding with caution on a NA engine especially the 991 GT3.

Tacet-Conundrum

I appreciate everyone's response. This post wasn't about if you would get an ECU tune or about making up imaginary scenarios about your said tunes.

I asked one simple question, and I wasn't asking if I should get an ECU tune and I wasn't asking if the members here would get an ECU tune; SIMPLE!

The only thing I asked was could the 991 GT3 get 500 horsies off the crank with just an ECU tune. Thats it - was't asking if it was a good idea or not, or if you would do it. Just one simple question that is all.

kosmo

^^^ I think 500 is possible w/ a simple tune given that I think P is sandbagging w/ its 475 figure.

0Q991

Agreed.

JasonAndreas

First you have to find an aftermarket tuner that actually measures torque and horsepower at the crank...

TrackFan

I don't think bringing the HP from 475 to 500 would be that noticeable on a road track. Maybe the drag strip?

Tacet-Conundrum

Thats a good point. We can only Infer how much power is coming from the engine because I don't know of many who would yank the engine to test the engine to get the power off the crank. Good point.

Now the only prudent way of measuring power is off the wheels and doing some math to figure power loss through the powertrain - and the numbers used to figure that out is a shot in the dark.

Many would tell you to multiply between 85% and 80% to come up with the 'round about true power figure. Sure may be if yoi're driving Chevy, Ford or Dodge. Not unless Porsche is Sand-bagging their power figures, Porsche's powertrain is far more efficient than the American Front engined rear wheel drive configurations. Doing the math Porsche's powertrain losses are closer to around just 10% and slightly less.

GrantG

Yes and I think using any percentage is only a rough estimate. I think the way to truly calculate power loss is a more complicated formula involving much more than choosing a percentage (involves constants and other terms as well).

Found this on Google, fwiw:
http://www.mwrench.com/Whitepapers/Dyno.pdf

http://www.sdsefi.com/techdyno.htm

http://www.carcraft.com/techarticles...in_power_loss/

RCMA991

A piggyback ecu (no cracking the edu required) that compensates timing and A/F for use with 100 race octane fuel. Then GMG's cross pipe or other AM exhaust upgrade could get the gt3 to 25+ crank hp over stock.
Just need Techart or TPC Racing to roll out this upgrade. Would it sell? Who knows; just for 25 HP? doubtful.

Tacet-Conundrum

Yup, I'm with you on that one but argue that point with the Modern day Muscle car crowd is a difficult proposition. They can barely see beyond the tips of their noses most time when you try to explain how much actual horsies are hitting the road.

I will take a look at those link when I get home. But when doing the simple math it seems Porsche does a better job of getting the power to the ground.

PS..

I read all the Articles and the one that really opened my eyes was the second article at sdsefi.com - where does all the extra power dissipate too even if some claims on a chassis dyno of almost 35% on an engine that is suppose to be cranking out 800+ BHP. Of course there are plenty of places that can heat-up and soak-up the lost power but the author does make a very good point. 37,000 watts heating up the transmission and differential on only a 200 BHP is a lot, around 36.92 horsepower, Can TODAY'S car parts soak up that type of power without causing a failure.

The third article "CarCraft" - Magazine and other outlets pretty much put's a tremendous amount of faith in it's acceptance of the Chassis Dyno which is mis-quided.

I don't know for some reason, I did say ENGINE DYNO and not Chassis Dyno. I wasn't really thinking about it at the time but it would be the absolute correct choice to truly get what an engines true potential really is. Even though it is a far, far greater undertaking. And none of us here would really put forth the effort in doing the job. Yet I would allow Sharky to take a 991 GT3, give it a tune, take it to where Dan and Alex like to do their Chassis Tuning and apply their wizardry to get the power number they can get. That's assuming they haven't done anything to such effect considering they keep a lot of what they do hush hush - really how many of us knew they had the 4.1 conversion in the first place? Not I.

Joe@Fabspeed

I will inform you that it is virtually impossible to flash tune the new Continental Siemens ECUs that are being installed on all the newest Porsche, Ferrari, McLaren, Maserati, Mercedes, BMW, and Bentley cars.

These new Continental ECUs are encrypted and have multiple layers of protection and are often rewritten by the OEM manufacturers and checked or re-validated by the OEM manufacturers. With wifi and satellite communication the OEMs can check the system at will. No company anywhere has been able to properly crack and tune these new ECUs and from what I have been told you dont even want to tamper with them as you can not get full control and when they KNOW you have been inside the ECU's software the OEM's can rewrite and VOID your warranty. From what has been described to me its like Big Brother taking complete autonomous control.

Also, the newest Ferrari V8 Specialie and Porsche 991 GT3 cars have 14.5:1 CR and 12.9 CR respectively. On pump fuel I cant imagine any tuner can advance the timing significantly and even with 100 octane unleaded may make a difference but at $10/gallon I may be getting old but see the law of diminishing returns on these super HICR engines.

One thing you can be sure of is that the new 991 GT3 engine employs virtually the same heavy exhaust system as all the previous 997 GT3 cars. I have analyzed the systems in person and in Germany and IMHO I would swap out the GT3 headers.

If anyone is looking for maximum street legal power I would get a set of equal length GT3 headers with HJS German tri-metallic sports racing catalytic converters as in the past +16HP was gained along with sports car sound. Dyno graph of a 997.2 GT3RS is on my website. I would then consider eliminating the very heavy twin side mufflers on the engine. This eliminates alot of weight off the rear of the car and this the best place to remove weight on any 911 for performance and handling dynamics. On the rear of the car my Fabspeed mini maxflo mufflers added +7HP on the previous generation 997 GT3 cars.

Fabspeed Motorsport uses HJS German tri-metaliic ultra short highflow catalytic converters for these headers. I actually switched over to McLaren Mp4-12C cats for these ultra highflow headers. I have supplied many of these HJS catalytic converters along with super tight radius U & J bends to Todd Zuccone at Evolution Motorsports for his big GT3 engine packages.

If the car did not have to be emissions legal I would try a set of headers with NO catalytic converters and keep the pipe OD outlet small for maximum exhaust gas speed. On the previous generation GT3 cars NO cats added a few more HP but made the car extremely loud and you had a CEL.

Its a shame as I had a Guards RED 991 GT3 ordered several years ago and my build was kicked back over & over, read everything on this forum, and I bailed. I had several local 991 GT3 customers and their cars all waiting for engines.

A chassis DYNO is perfectly suited to test any of these cars engines and actually gives you true data delivered to the rear wheels. You simply have to trust the OEM power rating and witness an improvement in power after making changes from a reliable baseline dyno. No one is going to be pulling engines from exotic cars to test bolt-on modifications.

TrackFan

Hasn't anybody dyno'd a new GT3?