John@Fabspeed

Dyno data isn't always everything. The change in the drivability, throttle response, and overall feel of the powercurve is very nicely enhance by the plenum/tb package. All the feedback i've gotten from my clients are around the same lines...smoother powercurve that pulls more evenly and harder throughout the curve.

Extended Warranty just posted some nice insight on the plenum/tb upgrade here saying " Loaded up the Cobb Stage 2 OTS map last week, very nice bump in power.

Today I got the IPD Plenum/82mm GT3 TB installed. See it as my big '**** you' to Porsche for putting a 74mm TB on the GT4 when the 991.1S came with the 82mm TB stock. Impressions: The Cobb Stage 2 OTS tune integrated flawlessly to the IPD Plenum/82mm TB, no codes, no stumble, no knock The stock exhaust sounds 20% louder and there is a very nice bump in power in the mid-range and a smaller bump up too. There is an increased in air induction sound and the throttle response is more lively. The car pulls smoothly to no end without any dips in the midrange anymore (the Fabspeed headers themselves smoothed out 95% of it). Highly recommended modification to complete your bolt ons Don't just settle for that 74mm TB that Porsche purposely gimped the car with."

Looking forward to hearing how everything goes with the new upgrades!

Very well said! To add to this point, most clients aren't going to give shops permission to take their car to the nearest drag strip to whoop on their car. We don't even bother asking as we don't want that responsibility on our head.

May I ask you to elaborate a bit on this? I am quite familiar with all our dyno graphs, and to start I don't quite understand the "peak BHP at stupid revs one will never see". Peak BHP on these cars are seen at right around 6500rpm, and this doesn't change more than a few hundred rpm between different cars, upgrades, and dynos.

GT4_Driver

Well John, you wrote a lot, but still no numbers. Why is it such a huge problem to measure the car with a PB?

mrd_spy

to quote your manifolds

"Fabspeed's Sport Headers for the Porsche Cayman GT4 add 26 whp and 39 ft-lbs of torque at 3600RPM"

when infact at 4k revs fitting the manifolds would give lower than stock numbers !

and gains at 6.5k are 10bhp so just about worthless.

hence why in the real world people are not doing timed runs as the cars no quicker WOT !

who give a flying what a peak figure quoted at 3.6k revs is, I never see 3.6k revs !

remember these are fabspeed words not mine in the quote above

John@Fabspeed

Well I wouldn't really say its a big problem at all. Up until the last few days there was little to no request for such data to warrant the time and material to invest in a PB, along with the additional invested time in performing that testing on top of all the other R&D work and dyno testing we do on our products. In over two years I have only had one other person (a 991TT owner) ask for that kind of data.

John@Fabspeed

I take it you must not have seen the dyno graph by a third party PCS Motorsport, which is also on the Sport Header product page for your reference. If you are looking for maximum gains in the higher RPMs, you should looking at Race Headers and ditching your factory cats.

After countless inquiries and complaints of the factory powercurve having a performance dip in the 3200-3800RPM range and long gearing, our Sport Headers were developed to target that low end power dip. That is where the gains are needed to optimize the performance for majority street use, with a much stronger and smoother low-end/mid-range the get the car powering through the powerdip and the long gearing.

Again, if you never see 3-4k rpms then you should be investing in a set of Race Headers for your car. Different needs fit different products, just because yours don't match our Sport Headers doesn't mean the Sport Headers don't exceed the expectations of all our clients running them.

turbo8765

In the end, a quarter mile track is the best way to confirm power gains. It's a known verifiable location.... and there's always a large database of info to compare to.

Trap speed is a reliable indicator of power, and it's easy to correct for DA.

jmartpr

The more info we have available the better but I do agree with John on the application of sport vs race headers and what they really provide in the real world. Also, 1/4 mile times can give you some idea but I think too many variables come into play and very difficult to control them. Would love to see owners dumping clutches at 4-5K rpms on the drag strip....unless you do a roll. Again too many things that can change from pass to pass.

user1029

In contrast to modifying turbo'ed cars, debating about modification gains on a naturally aspirated platform is like fighting over meager table scraps.

'oh but that mod gained 10hp but is it really 10hp or it is just random dyno variation?!?!?!?!?'

Look at the overall gains underneath the curve and improvements to driveability if you want to scrutinize anything - headers are definitely a good bang for the buck mod for this platform

Peter_GT4

GT4, cargraphic sport headers, IPD, tune, 100-200 km/h between 9.1 and 9.5 seconds.

Performance box was borrowed from a fellow GT4 owner, his stock GT4 (same weight)
took 10.1 to 10.5 seconds. I assume that a 0.5 to 1 second improvement is to be expected
and realistic in relation to the claimed figures.

More important...it does feel right and defintely different, as often described here.


Peter

cox1974

Custom map uploaded.... Next Wednesday i will dyno my gt4 for the third time on the same dyno ...and will post the graph....

Alan C.

Thanks for your willingness to share your data and time.

jmartpr

Thanks for posting this info...first time I see something like this posted. Also, your test start at 100 km/h (60 mph) all the way to 200.....which is a good indication that indeed there's a good performance gain that shows on a very useful speed range.

Yargk

mrd_spy

nice gain in time that.

which tune was on that car ?

My Audi TTRS with a remap was 7.8 seconds 100-200 kmh.
So it makes you think , one does not buy GT cars for the outright performance.

user1029

One buys a GT car to not be mistaken for a hairdresser