Fabspeed 996 Airbox Upgrade

I purchased the Fabspeed 996 Airbox upgrade and installed it over the Christmas holidays. After 110 miles of normal and some spirited driving (to let the computer adjust to the new mods) I re-ran the same performance tests I did before the upgrade. The tests that I ran before and after were done on the same stretch of road under the same weather conditions - I even made sure the amount of fuel in the tank was roughly the same to make sure the weight was not a contributing factor. Here are my results. Test 1: speed runs in 2nd gear from 3K rpm to 6K rpm Before: After: 1. 3.81 3.56 2. 3.53 3.37 3. 3.66 3.22 4. 3.56 3.38 5. 3.53 3.43 Average: Before - 3.618 sec Average: After - 3.392 sec Difference: .226 seconds faster Test 2: speed runs in 3rd from 3K rpm to 5K rpm Before: After: 1. 4.85 4.41 2. 4.91 4.53 3. 4.82 4.41 Average: Before - 4.86 sec Average: After - 4.45 sec Difference: .41 seconds faster Note: Stock air filter was replaced with BMC air filter at the same time. The sound after 5.5K to 7K sounds more Ferrari'ish now. The only problem I had was a slight install issue - the carbon fiber ring wouldn't stay in place on my airbox. I used 4 - 5 spots of glue from a hot glue gun and the problem was solved. The whole installation process takes about 30 - 45 minutes. I love the extra gain in power from 3K - 6K and the sound in the higher revs. I don't know exactly how many more horses the upgrade generated, but judging from my before and after results, Joe (from Fabspeed) is probably close when he said 8 - 10 hp more. Phil in CA

"The sound after 5.5K to 7K sounds more Ferrari'ish now. The only problem I had was a slight install issue - the carbon fiber ring wouldn't stay in place on my airbox. I used 4 - 5 spots of glue from a hot glue gun and the problem was solved. The whole installation process takes about 30 - 45 minutes." Hi Phil. Try my $13.66 box (less than people pay for shipping for Joe's model) which has no install issues.

"Hi Phil. Try my $13.66 box (less than people pay for shipping for Joe's model) which has no install issues." Ben. What parts did you use and is it an exact part for part replacement of fabspeeds 3 components? Phil

"What parts did you use and is it an exact part for part replacement of fabspeeds 3 components?" Only two parts and I listed there part numbers at: http://www.funcarsonline.com/frames/...d/996board.htm Go down to the thread that starts with: "Mike P. re: air box modification"

Ben, I had a look at the site and let me say, "very creative". Did you get a chance to run some tests before and after the mods to see if your solution gave you more power? And are you still running the stock filter? Cheers, Phil

No, I didn't measure before and after performance. I've had the mesh screen out for some time though. The only other improvement that box is designed to produce is remove the 1.5 litres of air the muffler robs. Yes, I'm still running the stock filter. I remember Mike P. doing a test on the stock one and the other one and finding no difference.

PHIL wrote: I purchased the Fabspeed 996 Airbox upgrade and installed it over the Christmas holidays. After 110 miles of normal and some spirited driving (to let the computer adjust to the new mods) I re-ran the same performance tests I did before the upgrade. The tests that I ran before and after were done on the same stretch of road under the same weather conditions - I even made sure the amount of fuel in the tank was roughly the same to make sure the weight was not a contributing factor. Here are my results. Test 1: speed runs in 2nd gear from 3K rpm to 6K rpm Before: After: 1. 3.81 3.56 2. 3.53 3.37 3. 3.66 3.22 4. 3.56 3.38 5. 3.53 3.43 Average: Before - 3.618 sec Average: After - 3.392 sec Difference: .226 seconds faster Test 2: speed runs in 3rd from 3K rpm to 5K rpm Before: After: 1. 4.85 4.41 2. 4.91 4.53 3. 4.82 4.41 Average: Before - 4.86 sec Average: After - 4.45 sec Difference: .41 seconds faster Note: Stock air filter was replaced with BMC air filter at the same time. The sound after 5.5K to 7K sounds more Ferrari'ish now. The only problem I had was a slight install issue - the carbon fiber ring wouldn't stay in place on my airbox. I used 4 - 5 spots of glue from a hot glue gun and the problem was solved. The whole installation process takes about 30 - 45 minutes. I love the extra gain in power from 3K - 6K and the sound in the higher revs. I don't know exactly how many more horses the upgrade generated, but judging from my before and after results, Joe (from Fabspeed) is probably close when he said 8 - 10 hp more. Phil in CA =========================================== Hi phil.......your results are just like we have found and anyone can feel in the seat of their pants on any 996. The Fabspeed Motorsport 996 cold-air hiperformance upgrade kit adds 25% better breathing ability and more capacity of airflow to any stock 996 airbox. The 3 pieces are and integrated package that maximizes smooth airflow and maintains air velocity through the airbox to the 996 engine. .226 faster acceleration is a significant improvement and great value. .41 seconds with the above and a BMC F1 airfilter is an outstanding performance gain. I should have dyno results soon by several sources. Regardless, a stopwatch and acceleration runs provide definetive proof that the Fabspeed airbox modifications work extremely well by providing more power and sportscar sound. In addition, the parts are beautifully finished parts that compliment a 996's engine bay and simple to install. Someone with an engineering background should take Phils cars weight and plug it into a formula and ascertain the resultant horsepower gains. F=MA can anyone help. Have a great day. Performance for the Next Millenium

Just curious, Joe, how did you measure the airflow to come up with the 25% improvement figure?

what a performance improvement you got there.. well, I just wondering how much is it cost and where to get them. also if it possible, do you mind to post or send me email about the dyno test(before and after)you install the airbox. I currious and interested to buy them too thanks for the info andy :

Indeed it is. Kind of miraculous that this $225 modification of a stock airbox "produces" more power than Porsche did in 2002 over 2001 from increasing displacement, changing the vario cam to the turbo's and redoing the exhaust

I'm posting this response to share information on my error during installation, so no one else makes the same mistake. At this point I'm hopeful that the problem is self inflicted or a sensor failure and not a FabSpeed problem. I installed the FabSpeed kit last Thursday (muffler and plastic screen removed) and drove about 200 miles for the weekend and the performance and sound change was great, the car roared over 4500 RPM's. On Monday morning my check engine light went on and I had my dealerhook me up to the Diagnostic computer and it showed a MAF sensor error. The tech suggested that I use some Vaseline on the red tubing to insure a good seal. I did that at the dealer and found that I crimped the MAF sensor wiring between the top and bottom of the air box which allowed some dirt/dust to get on the MAF sensor and the throttle body intake. My mechanic said that I may need to replace the sensor due to contamination and also that there has been a sensor modification and that I may have the old style in my 01 C4. I drove 70 miles and the light is on again. The sensors are on backorder. I'm hoping that replacing the sensor solves the problem. Any advice.

Hopefully the sensor when it gets replace will solve the problem for u> My car has the same Fabspeed intake(installed myself as well) and thru 700 miles-havent had the check engine lite ring up. Maybe but I'm just searching a bit but the cable that links to the MAf sensor maybe its not connected right> Just make sure its snapped in an all and free of dust that may impair the connection(air-duster). It is very possible the maf sendor could have been criped especially trying to take out that maf screen which was the difficult thing to do. Regards. Mike

It's not hard to accidentally damage the MAF upon removing it from your old box and installing it in your new one. Also, make sure there are no exposed wires as a result of the crimped MAF "cable". I can't imagine that the Fabspeed would cause this problem. Before making my "mods" (ie: muffler removal, etc), the screen had been out for several thousand miles without issue. Further, the bottom of my box was modified in the way "Mike P. from Long Island" suggested appx a year ago. Lastly, I've put nearly 1k miles on my car since the Fabspeed copycat. Could be that your MAF is just bad and it's going to act up until it is replaced since it's hard to believe it's the airbox causing the problem.

The MAF sensor is protected deep within the upper lid - it shouldn't be unbolted for any of these box mods.

For clarification, I did not remove the MAF sensor, however I did unplug the connector and when reinstalling the airbox the wiring got betwen the top and bottom of the airbox and created an air gap on the unfiltered side allowing dust to contaminate the MAF sensor. FDR

that wiring harness is 3/4 " thick with it's plastic protective sleeve - how could you even have bolted the two halves together ?- the screws wouldn't come close enough to seat more than a couple turns .

The harness has a loose covering that does flaten out to less 1/4" and the imprints were there. FDR

"it shouldn't be unbolted for any of these box mods." I mistakenly thought the Fabspeed box came with a new entire upper portion of the two peice airbox which would require moving the MAF. fdr, it's going to be hard to tell until the MAF is replaced if they're telling you it might be bad. Once it is replaced, your problem may go away.

Can the airbox be used with the 02 C4S?

If the airbox of the new c4s is exactly the same as with the 1999-01 models then yes is the answer. Regards. Mike