6SpeedOnline - Porsche Forum and Luxury Car Resource

6SpeedOnline - Porsche Forum and Luxury Car Resource (https://www.6speedonline.com/forums/)
-   997 (https://www.6speedonline.com/forums/997-31/)
-   -   Got myself an X51 air box, GT3 throttle body, plenum, before & after dynos (https://www.6speedonline.com/forums/997/305331-got-myself-x51-air-box-gt3-throttle-body-plenum-before-after-dynos.html)

Gibbo205 Apr 24, 2013 02:42 PM

1 Attachment(s)
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:-
https://www.6speedonline.com/forums/...ine=1366836157

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. :D

Gibbo205 Apr 25, 2013 09:42 AM

1 Attachment(s)
Second hole now cut by local garage. :)


https://www.6speedonline.com/forums/...ine=1366904527

JoelPirela Apr 25, 2013 10:08 AM

OMG, your car is immaculate!
Also, did they fit the longer MAF cable? I never got to doing that...

Gibbo205 Apr 25, 2013 11:04 AM


Originally Posted by JoelPirela (Post 3831790)
OMG, your car is immaculate!
Also, did they fit the longer MAF cable? I never got to doing that...

Yes longer cable fitted.

Might also get the shorter oil filler neck tube too, did you bother with that?

JoelPirela Apr 25, 2013 11:43 AM

nope... i just pushed the accordion part to the back and it actually fits...

Gibbo205 Apr 25, 2013 12:03 PM


Originally Posted by JoelPirela (Post 3831889)
nope... i just pushed the accordion part to the back and it actually fits...


Couple of questions m8:-

1. Can you post of picture of your oil filler neck pushed back and located please so I can see how far is safe to push it as I am scared of it breaking.

2. Did you have to calibrate the larger throttle body or anything, or did you just disconnect battery, fit it all, re-connect and just start the car and leave to idle?

SecretAsianMan Apr 25, 2013 12:19 PM

Thank you for sharing!

Too bad the x51 airbox is so insanely expensive for an intake, it is beautiful. I am a little surprised nobody has made a fiberglass or plastic replica.

Gibbo205 Apr 25, 2013 02:04 PM

Just a question please guys, as the maf cable is now extended, is there any way I can check the extension and maf is working ok?

greaser5 Apr 25, 2013 03:19 PM

Now that you have the deck lid hole cut, how's the seat of the pants dyno feel? Did you get the bottom end back?

Gibbo205 Apr 25, 2013 03:23 PM


Originally Posted by greaser5 (Post 3832137)
Now that you have the deck lid hole cut, how's the seat of the pants dyno feel? Did you get the bottom end back?

Don't think it's a lack of bottom end, but more reduced throttle response, shall see if the BMC filters give that back.

Past 5000rpm it seems to rev quicker and feels more powerful. The noise is amazing!

JoelPirela Apr 26, 2013 04:40 AM

1 Attachment(s)

Originally Posted by Gibbo205 (Post 3831922)
Couple of questions m8:-

1. Can you post of picture of your oil filler neck pushed back and located please so I can see how far is safe to push it as I am scared of it breaking.

2. Did you have to calibrate the larger throttle body or anything, or did you just disconnect battery, fit it all, re-connect and just start the car and leave to idle?

The tube is actually pretty bendable... I had to trim the little hook and the bottom of the pouring part in order to correctly latch with the X51 box

https://www.6speedonline.com/forums/...ine=1366972805

To calibrate the TB, disconnect the battery prior to taking the original TB out. Install new TB, connect the battery and switch to ignition without starting the car. wait 30 seconds, switch off, and now start the car. The TB will adjust to maximum opening and maximum closing during this procedure. If you don't do it, the accelerator pedal input may not reflect the true TB flap's position.

Gibbo205 Apr 26, 2013 02:41 PM

Hi there

Ok got BMC filters in, allowed throttle body to adjust and went for a good drive, I'd say what I've noticed is:-

Throttle response is now better than the stock paper filters, but marginally less slight than before stock BMC airbox and stock throttlebody, this is no doubt the effect going from 76mm - 82mm throttle body, is it an issue, well no, it's marginal and hard to notice.

Maybe a marginal torque loss sub 3000rpm but it could just be the fact the car seems smoother in power delivery now, as the car seems to accelerate faster.

4000rpm and above the car pulls harder, but at 5500rpm and above it feels like it's pulling way harder and would keep pulling so hard right upto 9000rpm if the engine could spin that fast. Put it this way floor it in 2nd gear at 4000rpm and you need to be very quick to get the change upto 3rd.

It seems 1-2mph quicker by a landmark I regular accelerate too on my route to work. If I was to have the dyno in my head I'd be thinking similar/same power upto 3500rpm but then a steeping upwards curve above 3500rpm with more top-end power for sure.

Onto the noise, sorry GT3 guys but from inside the cabin to my ears it's better, from the outside I'd say it's not, but on the inside it's like a race/cup car when the revs pass 5000rpm, infact 5000rpm now sounds like 7000rpm did previously, it's absolute music to my ears.

Shall aim to get on dyno next week and to see if there is any change power/torque. :)

P.S. Still need to sort rubber bellow on right side to seal against warm air but the gap is less than an inch so doubt it's having a noticeable effect on performance.

JoelPirela Apr 26, 2013 03:27 PM

For the mean time, I would buy insulating foam tube from a hardware store and run it on the lip of the right intake inlet, that way you can create the extra inch you need and being able to seal it...
btw, I love the intake sound of when you accelerate... like a power suction swoosh!

Gibbo205 Apr 27, 2013 10:33 AM

2 Attachment(s)
Dremel the bellow of my old Airbox and it fits perfectly over the X51 snorkel, so now it's only getting cold air. Noise and power vastly improved, get to dyno next weekend. :)

https://www.6speedonline.com/forums/...ine=1367080394

https://www.6speedonline.com/forums/...ine=1367080394

Looks almost OEM :)
Car is in need of a good clean now!

JoelPirela Apr 28, 2013 08:39 AM

awesome solution!


All times are GMT -6. The time now is 07:55 AM.


© 2026 MH Sub I, LLC dba Internet Brands