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Just put Fabspeed intake on my 09 997.2 c4s last night and car seems to feel more sluggish with decreased throttle response - thoughts?
Originally Posted by gasongasoff
There seems to be a lot of controversy about the CAI design. On the one hand, flow is supposed to be improved. On the other hand, people say that the design actually draws more hot air in. Is there a net performance benefit? One way to test this would be via a dyno. However, the only dyno results I've seen are manufacturer-conducted, and there has been a question about what conditions were used for each run. The dyno also does not really replicate real world air flow.
To settle this matter (for myself), I tested a Fabspeed CAI, purchased a from an online retailer. I have no affiliation with Fabspeed or that retailer. I then took tracings of MAF vs. RPM. MAF is measured in grams of air per second and already factors in temperature and air density. By comparing MAF readings for the CAI vs. Stock airbox, assuming no change in AFR or engine efficiency at a given RPM (just by changing intake pipes, which there shouldn't be), and assuming no change in MAF accuracy between intakes, the % difference in MAF should = the % difference in HP. I realize this isn't a perfect assumption, but here it is anyway.
One caveat is that the Stock airbox filters were not new and had some visible dirt accumulation.
Vehicle: 997.2S PDK Existing Mods:sharkwerks bypass, IPD plenum Measurement: OBDII data (~19 samples/sec) via OBDLink LX, and OBDAutoDoctor software Data Collected: includes MAF Mass Air Flow (grams/sec air) and RPM Test: same freeway onramp (done safely, no traffic laws broken) Repetitions:4 consecutive runs with STOCK airbox, followed by 3 with Fabspeed CAI, done on same day, similar ambient temps
Results: +2.5% to +4% in MAF between 4000-7500 RPM in 1st Gear +5% in MAF between 4500-7000 RPM in 2nd Gear +19HP (ballpark), assuming the relationships above and stock HP of 385 @ (+5%). My data did not show a difference < 4000RPM in 1st Gear
Mean MAF values within each RPM range:
These graphs are scatter plots of MAF vs. RPM. Again, MAF should be directly related to HP, given the above assumptions. Each line represents the 2-point moving average of a single run - this was done to smooth out the data points.
Updated the original post with my subjective impressions after 1 month:
- In my craziness, I also swapped in/out the stock airbox twice during this time just to be sure.
- I think there's definitely more "pull" from 4000-redline with the Fabspeed. To me, it's very noticeable in sport or sport+ mode. Plus the sound is just amazing in this rpm range.
- HOWEVER, during "normal" driving around (sport mode), between idle and 4000rpm, I THINK the car might feel just a bit more sluggish in terms of pull and throttle response. I'm not sure though.
One thing to know is that I have consistently observed (and recorded) the Intake temp and Ambient temp under various conditions. Here's what I can share:
- The stock airbox is not a 100% cold air intake (there are mesh panels that draw in engine air), but it does seem to draw in more ambient air than the Fabspeed (obviously).
- The "delta" temp (Intake temp minus Ambient temp) appears to be greater on the Fabspeed.
- At freeway speeds (65+MPH), the Fabspeed and Stock intake delta temps are basically equivalent (about 3-5*F).
- At lower speeds, the Fabspeed deltas are typically between +20-30*F, whereas the Stock deltas are more 10-15*F.
I notice the same exact thing.....bit anemic in lower end but definitely picks up from 5k on in sport or sport plus....last night I noticed my CEL went off, I popped the trunk and noticed my Fabspeed connection completely fell off - clamp somehow got loose, I also found another small air leak which we plugged up - disconnected negative side of battery and my CEL eventually went off - car seems to run like a beast after we reconnected - it's amazing the difference in "snap" the car has at 6am in the morning (50's) as compared to middle of day when it's more humid - big difference .......my Softronic flash I got about a week ago definitely pairs nicely with the intake ......and the sound at 5k plus is fantastic! New tires and spacers Friday and then I'm done putting $ in - now time to enjoy some summer driving!
I just received and installed my Fabspeed intake the other day. I agree with your subjective assessment. The place I really notice reduced throttle response is when blipping the throttle for downshifts during normal, around-town driving: before you barely needed to touch the throttle to get a blip, now it feels like it takes a more concerted jab.
The sound at WOT in the top half of the tach is intoxicating, though! Now I just wish it could continue for another few thousand RPM...
Buy it for your own reasons. Just don't make claims about it without proof.
If you feel you got gains. Great. Happy customer. If you don't see gains then fine. Not so happy.
There has been some bashing on the manufacture. Pros & cons. I have personal experience with it and decided that I didn't get what was "advised" when purchased so I sold it off.
Looked good in the engine bay!! Sounded good at WOT. That's what you want great!!
Everything is subjective these days. Like our future President to be. (That's another argument)
This whole thead was started to be OBJECTIVE -- so not everything is subjective. The whole point of running the numbers was to eliminate your very comment that ''everything is subjective...'. No, that's simply not true.
You're expectations might be off, but that's another issue all together.
This whole thead was started to be OBJECTIVE -- so not everything is subjective. The whole point of running the numbers was to eliminate your very comment that ''everything is subjective...'. No, that's simply not true. You're expectations might be off, but that's another issue all together. .
Subjective to opinions. Which can be objective.
Or not!!
We can always knit pick statements, opinions, test, results. All subjective. BUT the thread was objective. That I agree.
We can always knit pick statements, opinions, test, results. All subjective. BUT the thread was objective. That I agree.
People can post the usual butt dyno opinions all they want in this thread ("the car seemed faster/the car seemed slower/the car bogged down/the car seemed to breathe so much better/etc") but the data points so graciously measured and posted in this thread show repeated, quantifiable gains. You may not have liked yours but the data is there.
Updated the original post with my subjective impressions after 1 month:
- In my craziness, I also swapped in/out the stock airbox twice during this time just to be sure.
- I think there's definitely more "pull" from 4000-redline with the Fabspeed. To me, it's very noticeable in sport or sport+ mode. Plus the sound is just amazing in this rpm range.
- HOWEVER, during "normal" driving around (sport mode), between idle and 4000rpm, I THINK the car might feel just a bit more sluggish in terms of pull and throttle response. I'm not sure though.
One thing to know is that I have consistently observed (and recorded) the Intake temp and Ambient temp under various conditions. Here's what I can share:
- The stock airbox is not a 100% cold air intake (there are mesh panels that draw in engine air), but it does seem to draw in more ambient air than the Fabspeed (obviously).
- The "delta" temp (Intake temp minus Ambient temp) appears to be greater on the Fabspeed.
- At freeway speeds (65+MPH), the Fabspeed and Stock intake delta temps are basically equivalent (about 3-5*F).
- At lower speeds, the Fabspeed deltas are typically between +20-30*F, whereas the Stock deltas are more 10-15*F.
This all makes sense. The issue with the FS CAI is that it pulls in "hotter" air than the factory intake. This is easy to observe visually. So why does it improve power at the top end and (anecdotally) reduce power down low? Because of the flow of air.
At high RPMs, there is LOTS of air moving through the intake, thus, it doesn't have the residence time in the engine bay to heat up. Hence, the equivalent delta temps. At lower speeds, not only is the engine sucking less air through, thus providing MORE residence time in the engine bay for the air to heat up, you're also blowing less cooling air in / through / around the car altogether. Thus, "sluggish".
I would LOVE to see this same comparison with IPD vs factory plenums. Good job.
Amazing analysis! Looking for a job??? Always looking for analytical talent!
...this may be a dumb question. So, there is a square hole in the engine lid for the OEM airbox. Why not put a identical square hole on the opposite side to let that much more cool air in to power and cool the engine? Anyone seen this done?
Amazing analysis! Looking for a job??? Always looking for analytical talent! ...this may be a dumb question. So, there is a square hole in the engine lid for the OEM airbox. Why not put a identical square hole on the opposite side to let that much more cool air in to power and cool the engine? Anyone seen this done?
Turbo, GTS, X51. Yes!!
I am tempted to cut a second hole and get an X51 Airbox
...this may be a dumb question. So, there is a square hole in the engine lid for the OEM airbox. Why not put a identical square hole on the opposite side to let that much more cool air in to power and cool the engine? Anyone seen this done?
The template pattern is already there in the plastic. All you have to do is cut it out and buy the sane trim piece that's on the left side to install on the right.
05-21-2016, 11:27 PM
Just put mine on.....
