Gibbo

Hi there

Managed to get myself an X51 carbon air box, so it fits better I've also gone with this:-

EuroCupGT 82mm GT3 Throttle Body & Plenum Kit for 997 Carrera C2S, they also sell hose which works with stock air box too, looks good especially the carbon fibre plenum, heres a link:-
http://www.porscheshop.co.uk/acatalo...induction.html

At the moment car has stock air box but I dremeled out the resonator and put in a BMC filter, also got X51 headers and PSE too. Also had softronic map but at this state of tune the difference between stock and softronic map was like 2BHP peak and no change elsewhere. Still the car made 358BHP at the flywheel.

Car now has NHP 200 cel cats and loading the softronic on the car with these fitted could be felt on butt dyno, so softronic no doubt working better with high-flow cats. Car goes to the dyno in one to two weeks to get a baseline figure with the cats fitted. Then the euro cup plenum, GT3 throttle body and X51 air box with BMC filters shall be fitted and car ran again on dyno, softronic shall then be removed to see if it is helping make more power or not with the above.

I shall post dyno plots all together when all done, but looking forward, be good to make 385-390BHP at flywheel.

Renzsport

Can you also post some pics of the intake installed please. Did you "add" the second intake scoop from the spoiler also?

Luxter

Hi Gibbo,
I have GT3 TB + Plenum installed too in addition to Cargraphic 200 cell high flow cats and their Euro exhausts.
No re-flash or other mods though. Stock C2S Air Box too.
My car feels "smooth" and "effortless" if you know what I mean, compared to stock 997S. That leads me to believe that Porsche did whatever they had to do to prevent cannibalizing GT3 range with C2S model. That's why X51 is SOOO expansive. Keep us posting, would love to see the results.
Cheers,
Luxter

Gibbo

Hi there


Got an X51 airbox, but its missing a part which Porsche can't locate for me as they need a partcode, I've circled the image in the part:-



Can someone please pull this part of their airbox, it just easily pulls off and should have a partcode stamped on it. Can someone post the partcodes which are stamped on it please to help me source a part.

If Porsche don't have it separately then I need to try and get something made up, otherwise my engine will suck in warm air.

Gibbo

Hi there

Managed to get on the dyno yesterday to compare the 200 cel NHP straight cats compared to the stock cats.

Car spec:-
997.1 C2S
Stock airbox, resonator section removed and capped off.
BMC panel filter
Silicone hose
X51 manifolds
Centre radiator
PSE
Stock cats VS 200 CEL straight pipe cats
Softronic


Dyno Comparison:-




You can see the cats are giving me what I felt on the butt dyno, little to zero losses down low, with increased coming 3500rpm upwards with a peak gain of nearly 30BHP at certain points in the rev range and approx 10lb/ft gains across the rev range.

So 200 cel straight pipe cats definetely work on our cars with softronic, no low-down losses and gains 3500rpm upwards. Removed softronic and the results were similar though it was helping with low/mid range for sure, but up top talking about 4-5BHP, not bothered to add comparison with and without softronic as its close, though it does help.

Think what this proves is a full de-cat does not work on our cars, it looses lots of power below 4000rpm, even with softronic, though gains above 5500rpm are large, shall add full de-cat comparison to 200 cel comparison in the week as need dyno shop to email me the PDF file of this.

In short, if you don't want to loose low-down power/torque go with straight pipe 200 cel cats from either NHP or AWE. The X-Pipe designs definetely loose low-down power/torque and also loose some of that classic Porsche sound track. An X-pipe 200 cel pipes will no doubt gain a little more up top, but as I say at dis-advantage of loosing down low. Full de-cat either way, your gonna loose low/mid range for sure.

Gonna try to get the plenum, throttle body and X51 airbox fitted within next couple of weeks and head back to the dyno.

I am happy with the results as the BMC panel filter, X51 manifolds, 200 cel cats and softronic have gained me 16-20BHP peak along with 35ish BHP and 10-15lb/ft at points in the rev range.

Hopefully the addition of the X51 airbox, throttle body and plenum will bring me upto true X51 power of approx 380BHP with good gains across the range.

Edgy01

Without changing your heads you can't approach the numbers of the complete X51 kit.

Gibbo

The heads Porsche hardly changed, plus when I fitted a full de-cat the car made 392BHP which is beyond X51 power.....

So yes you can.

Let's see what the plenum, throttle body and intake do before we say it's not possible......

Edgy01

So if you take a real complete X51 kit and then de-cat the car you can make even more!

utkinpol

I like softronic flash a lot, it adds quite some torque where it was lacking it and maked curve much more flat compared to stock one so car pulls very nicely. cats and bigger throttle body all adds up, bigger headers would also add a bit, you decide if you also want to do headers or not, I do not think it is overly critical unless you build a race car that should deliver same power as other ones in same class.

jrgordonsenior

If I'm reading the dyno correctly you're putting out corrected BHP numbers of 370.6. Is that SAE corrected? I also read only 276.6 "wheel power" which is almost 100 WHP less than BHP. Obviously I'm missing something, please explain....

Gibbo

Mahaa dyno, designed for accurate flywheel figures, it's wheel figures are in-accurate as it uses two contact patches. Some stock cars ran on the day and made bang on the book stock flywheel figures.

Yes it corrects to SAE.

Gibbo

Of course a full X51 car with 200 cel cats, BMC filters should be around 390ish at flywheel.

7500rpm

Gibbo, thanks for bringing us this report. I have a lot of the mods you are talking about and your result confirms my butt dyno. Looking forward to the plenum + larger TB result. I couldn't feel much change except for even poorer response around 1,800-2,000rpm.

Gibbo

For those interested, here is a comparison between the Sport Cats and the full De-cat X-pipe, which also sounded bloody awful!



Now you can understand why I thought the car felt gutless between 2000-4000rpm, because of the 45lbft and 30BHP loss as the plot shows, though gains beyond 5500rpm not bad. Still with a 911 sports cats is the way as the engine design requires some back pressure.

Gibbo

Hi there

Tonight I fitted:-
Carbon fiber plenum
GT3 throttle body (76mm upto 82mm)
X51 carbon fiber dual air intake

Installation was a bit tight but easier than expected, took my time to prevent any potential air/vacuum links. Made sure to disconnect battery etc. So ECU fully reset.

Connected back up, left for 30s so throttle body could sort itself out, started car and no idle issues, left it to idle for 5 minutes.

Went for a drive, throttle seems a little less responsive which is to be expected as at present air box has a pair of old stock paper filters in it and the right hand side intake does not have a hold cut yet in the decklid for cold air feed. Felt similar to the stock filter in the regular Airbox would do, as high flow panel filters really improve throttle response.

So jobs to do:-
1. Cut hole in deck lid so cold air feed works.
2. Fit performance BMC filters, due end of week.
3. Extend MAF wiring so can route maf cable neatly under Airbox and not over it.
4. Maybe buy shorter oil filler tube, as stock one is too long, but does fit.
5. Fit new plugs, current are 20k miles old.
6. Change oil to Millers Nano oil.
7. Go back to dyno.

A picture of course:-


Glad I did it myself, always more enjoyable, though only when it goes well.



Oh and finally the good point, no infact the sensational point, the noise OMG the noise, no word of a lie past 5000RPM it sounds like 10000RPM, sounds like a CUP car, I'd go as far as saying the noise in the cabin is GT3 beating. Seems to pull better too, but sure improve more with second hole cut along with fresh performance filters.