RealityGT

I've gone down this road several times in the past 20 years.. And my reco is that you do 1 mod per year.. This way you won't get bored to quickly.
Not to say there aren't those who will be happy for many years with the full on NA + 3.99L stroker.. But I would get bored after about 2 seasons and would be searching for more..

My 2bits..

RealityGT

+1
I'm really eager to see how John@ BGB makes out with this.. I'm expecting a lot!

Mvez

Exactly.

There is already plenty of documentation with 981 owners gaining 13-15hp with JUST the TB/plenum after full adaptation. Since the GT4 already has a more free flowing exhaust than normal 981's, it should net a little more I would think.

Sure, all of these are part of the equation, but IMO, the biggest part of the equation is the TB/Plenum. It's pretty obvious.

Warranty concerns are valid, but people who keep pushing ONLY headers/cats as the best solution, are a bit blinded by their fear of warranty issues. I'm all for headers, I think they are great and part of the equation.
BUT, I'm simply saying, the best bang-for-buck mod for this car, and any 981 is the larger TB/Plenum, and it's the largest part of the "power" equation.

I do wonder though, even since it's DFI and should have plenty of fuel availability, if running the TB/plenum long-term on track, creates issues for the engine from running too lean for extended periods. Seems like plenty of 981's have been running them now without issue though.

I've also seen where plenty of 981 owners have had IPD plenums installed by their dealer and don't seem to have any problems with warranty. Not to mention, if something was to happen to your engine, it can pretty easily be removed prior to taking to dealer for fixing, if you are worried. Just sayin....

BGB Motorsports

If you want safe, round, conservative numbers...assuming the car makes 389 crank hp (proven on the dyno in Germany), i think it's safe to assume you could make around 408 - 410hp with those mods and NO ECU flash.

BGB Motorsports

I don't want to get into RS speculation or why the factory uses the 3.4L throttle body on the car so i will just stick to facts. It has been arbitrary to say the least, which cars are angered by the larger throttle body and which aren't on the 3.4L front. Since I am going with the X51 setup i will absolutely have to revise the file to expect larger air but if i wasn't, i am not convinced that the car wouldn't set off the whole MAP/MAF fault if you added an 82mm throttle body when it expects seeing a 74mm one. So at this point, we are suggesting the tune to people who don't like seeing CELs or we are warning them that a CEL could appear. I want to see a car with an 82mm throttle body and race headers run through an entire tank of gas without a CEL MYSELF before i tell anyone that it won't happen based on conjecture.

Please see above. Since i am not going to do just the throttle body itself, unfortunately I won't know if doing the TB upgrade will set off the CEL. It did not on the dyno in Germany but running through a full tank of gas is the only way to be sure.

This was back about 12 months ago when i had was trying to help people with the larger IPD plenum and throttle body. Some cars responded to this while others did not. Some cars had it go away and then some had it come back. It's very arbitrary to say the least.

YES! This is the path!

I like it...I like it!

There is no restriction in the GT4 for closing throttle and in fact, the file is more aggressive than the one in the 991 3.8L.

neanicu

This.

And I can add if I may...even if it doesn't set the CEL,it will not benefit from the larger throttle body if it doesn't know it's there.
People don't realize that especially in modern cars,even when installing a window switch,you'll need to tell the body control module a new switch has been installed or it won't work in most cases.

il pirata

Following this closely as I have a 2016 Spyder.

From the IPD page on the GT4 Plenum "But the 981 requires more ECU “adaptation” time than any other Porsche model so it may take over a hundred miles for the “adaptative” process to be fully complete."

CAlexio

Info from one of the tuners I received in response to my question regarding installation of the TB/plenum without adding a tune (and therefore presumably saving my warranty):"It would provide a little better throttle response and power, but the key is in tuning for it. You may also have to have Porsche calibrate the larger TB with the Piwis scan tool depending on how long it takes to adapt".

BGB Motorsports

Just to reiterate, it was all over the board with the outcome. I had 1 car that i was completely unsuccessful on; i had others that worked and then came back after the car sat and then there were others that always triggered the CEL and then after they sat for a while and started up again, the CEL went away. I just never thought the effectiveness was enough to ever tell people "you're good to go." A lot of people credit me for my honesty but at the end of the day I am just managing expectations because yours truly is the one whose phone rings at 8am on a Saturday when that little CEL pops up!

neanicu

Just to add to this and to the point BGB made very accurately : some people need to be reminded what " drive by wire " means. It means you are pressing on a computer mouse when stepping on the throttle. The throttle position sensor sends the opening command to the engine management which then decides to open the throttle plate by commanding a motor inside the throttle body. BUT and this is a big but,it will do so in correlation with multiple other information received from sensors throughout the car. Here's just a tiny list of PIDs the engine management is looking at : see below.

If you think you'll just bolt on parts in modern computer controlled engines and are good to go,just like you were in your 1980s carbureted Chevy,you have another thing coming...

Mvez

Regardless of whether it sets off CEL or not, or if they need a tune, it's pretty safe to still say, the single biggest contributor to power, across the entire range, and contributing to more efficient "use" of down stream exhaust components, is to FIRST, get the car breathing better through the larger TB/plenum.

Besides a cat-less header, I would be shocked if anything even comes close to the power the larger TB/plenum adds on an individual basis.

My original argument is NOT about what can be added that doesn't trigger a CEL, it's about what is the biggest contributor to power, bang for buck, type of thing.

It's pretty obvious that Porsche shackled this car, most easily, through the throttle body, so that in subsequent models, it can easily add Porsche typical, incremental power via a simple switch to larger TB and remap. Presto.

For all we know, Porsche may have already programmed the GT4 software to account/allow for the larger 82mm throttle body, further increasing the ease and profit of the next model. How do you think they maintain those 19% profit margins?

neanicu

Manufacturers are required by law to run a 15 to 1 air/fuel ratio to keep the O2s happy and running within stoichiometric....not too rich and not too lean. It means that for every gram of gasoline 15 grams of air are needed.

25/2O2+C8H18=>8CO2+9H2O is the ideal tailpipe emission result.

This is the manufacturers target when tuning an engine for fuel consumption and emission control.

Tuners change those parameters slightly to achieve more performance rather than emission control.

Getting more air into the engine will undoubtedly increase power,but the computer will need to be aware of all the changes been made to achieve that. I am sure there is a factory tune made to run with the larger TB,if one does not want to go aftermarket. The problem is : good luck obtaining it from the factory...

CAlexio

You can obtain it from the factory.. It's called "recalibration with the piwis scan tool"

That's required even with the Cobb.. The problem is the warranty.

BGB Motorsports

I guess one could say that 50% of the benefits are realized without tuning with the goal being ultimately to achieve a smooth curve AND make sure the mixture is achieving that which is being targeted, If the motor is sucking more air then it will make more power, BUT, it's being told to target a certain Air Fuel Ratio (a.k.a. mixture) and in theory it will compensate once it sees additional air volume via the MAP sensor. IF the ECU does not find a way to back down the Air Fuel Ratio and can't physically "fatten up" the mixture you do get an added bit of HP if you're on the fatter side of the magic HP mixture number. Most standard DFI Porsches from the factory run 12.7 on the Air Fuel Ratio at WOT when moving up and passed 6K RPM so if the added throttle body adds air and the ECU does nothing about it, it will in fact become leaner and approach 13.0 which is the magic HP spot on a Porsche from 6K RPM to redline. Going beyond this is going into aggressive territory just like adding a bunch of ignition timing would also be but that's an entirely different discussion.

Just so we are clear, I am not refuting what you are saying; yes, I agree with you 100% that the easiest way to make more power is to add more air to the giant air pump. I was just chiming in to defend the reason we suggest the tune with the intake mod. Outside of closing the throttle down via the ROM map, the single biggest way to mechanically restrict any car is to give it a smaller throttle body which is the same thing racing sanctioning bodies do when they give cars a "restrictor." If you make the hole smaller, it makes less power and less torque. Sure you can try and tune around some of it but the reality is that less air is less power. Furthermore, I am not assuming you don't already know any of the above, just adding color for the folks reading along.

Had i just stated that the car will make more power with a bigger throttle body and no flash then you probably would have seen the point I was trying to make.

I think you guys are talking about 2 separate things with the same protocol.

#1: CEL for Lack of TB Calibration: After you write to the DME on any of these cars, if it doesn't see the Throttle Blade Adaptation procedure completed successfully it will run in Reduced Engine Power mode. The DME commands a sweep of the actual throttle blade to get a reading for voltage ranging from closed to open. After that, every single time you turn on your key, when you hear a clicking from the engine bay, that is what is occurring. There is a fault in the DME if this is not executed after writing a new map in the car.

#2 CEL for MAP/MAF IMPLAUSIBLE: Using the same procedure, I kept trying this because i had installed the X51 Intake Manifold and Throttle Body on my 2014 981 R&D car but the resulting CEL that comes as a result of sucking more air happens once you mash the gas and run the car to redline no matter what you do. A lot of us have tried to use this procedure to reset everything after they install the larger throttle body with the hopes of getting the DME to figure things out but every single person i talked to said that it eventually came back. I could be wrong and there could be people out there with stock mapping and an 82mm throttle body on a GTS/S Cayman with no CEL but i am unaware of them. My car eventually went off for a long time but it took months and months of driving around without using full throttle. It was never consistent enough for me to draw any constructive conclusion. NOW...there is a good chance that since it's a larger volume engine in the 3.8L, in theory, the throttle body is introducing a smaller % relatively of air volume vs. what it's expecting but only a true controlled test would give us anything.

ChrisF

I'll bet a beer that Porsche did not make it so easy on an end user to just bolt on new parts and have the ECU adjust for a significant increase in airflow. If you're constraining a car, why would you leave so much headroom in the stock programming? I've done a decent amount of modding and tuning in my day and rarely has any car seen significant gains without tuning. That goes for a lot of very smart ECU's too.
Mvez, are you going to be the guinea pig for bolting on a TB/plenum with no tuning to see how it goes?