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Done. Swung by Home Depot and bought some Oatey plugs. To get the right fit I had to mix and match the end pieces from a 1.5" plug with the rubber gasket from the 2" plug. $10 solution.
It's definitely got a much raspier tone from 5-7k rpm. And I don't feel that momentary lag between 3-4k rpm. Im hesitant to say, but it feels like its got more high rpm zip.
Im unclear why this would reduce the lag (I was under the impression that was from the variocams). The only thing I can think of is the resonator works by creating a turbulent airflow and plugging it streamlines the flow.
I was worried the plug could get sucked into the throttle body but after taking the airbox apart I realized the airflow to the resonator goes the other way. The resonator is a sealed box so the air is coming from the main pipe and some turns the corner into the elbow pipe and resonator. It's that same principle as blowing into a bottle.
The next question is could I just remove the resonator all together to increase airflow? Its just glued in mine and the C2 doesn't have the baffles the C2S has.
How can the airflow go the other way when the throttle body is sucking air at a furious rate and that offshoot hose is angled to be part of that flow. Maybe the vacuum created by the airflow closes the resonance chamber by sucking something shut, but not running these stock boxes for years, I've not looked at the guts inside.
How can the airflow go the other way when the throttle body is sucking air at a furious rate and that offshoot hose is angled to be part of that flow. Maybe the vacuum created by the airflow closes the resonance chamber by sucking something shut, but not running these stock boxes for years, I've not looked at the guts inside.
I took the airbox apart to see what was going on and had a quick chat about it with an aeronautical engineer that works with me. The resonator is a sealed enclosure of air within the airbox so the throttle body sucks air from the path of least resistance, which is the main pipe from the airbox. A sound wave is created by the airflow from the main pipe flowing past the elbow pipe into the enclosed resonator, similar to blowing into a bottle. You can make different sound waves by increasing the size of the resonator or size of the elbow pipe. The engineering explanation sounded way smarter than mine :-)
Day 2 with it and its really loud as ****. Its actually a little harsh so I may take it out. Its really bangin at 5k and then you get a high pitch woosh of air at 7k, almost like a turbo. Im not sure if the C2S airbox has a different size resonator than the C2. I don't believe Porsche's design objective was to make the car quieter, it was just give the car more baritone at high RPM.
It is about the same as what you described except more pronounced throttle response and you really hear more air being sucked in due to the larger diameter. Around the 5k to 6k rpm in 3rd and 4th...and 5th if I get daring it really is loud and it sounds like a jet engine compared when mine was stock. I wouldn't have gotten the GT3 plenum and TB if I wasn't going to mod the exhaust and then do a tune. That's when the IPD comp plen and TB will give you the most bang for the buck.....I am basically doing what my indy suggests me to do. He races them so I assume he knows what he is doing....cause for me, I don't! haha … you can't beat this hack tho. So cheap and you do hear/feel a difference.
Don’t anyone get too excited about any performance benefits outside of it “feels faster” because it’s highly unlikely there are any gains doing this mod. The stock airbox is huge and flows well. These threads are recurring across decades with airbox mods. For Those who like the sound - this is an easy/cheap mod. For those who want a more powerful engine - not much can be done without five figure investments.
Don’t anyone get too excited about any performance benefits outside of it “feels faster” because it’s highly unlikely there are any gains doing this mod. The stock airbox is huge and flows well. These threads are recurring across decades with airbox mods. For Those who like the sound - this is an easy/cheap mod. For those who want a more powerful engine - not much can be done without five figure investments.
it does seem to eliminate the lag between 3-4k. I don't understand why. as for more power, yea agree. it just feels faster because it scares the crap out of you.
I disagree. The Castrol cap fits perfectly upside down and would be all but impossible to get sucked into the engine even if it managed to come loose (it can’t fit through the resonator). Worse case (and my one concern) was it aging and getting brittle over time. I doubt this would be the case, but didn’t even want to consider it, so I bought a $40 kit made by Topspeed off EBay that has a nice black hose, it works perfectly. Plus I do think flow has to be improved through the hose. If that wingnut somehow manages to come loose and get into your engine that is going to be a very costly mistake!
How can the airflow go the other way when the throttle body is sucking air at a furious rate and that offshoot hose is angled to be part of that flow. Maybe the vacuum created by the airflow closes the resonance chamber by sucking something shut, but not running these stock boxes for years, I've not looked at the guts inside.
There is another smaller hose connected to what I think is a solenoid that uses a vacuum to close the resonator (there is a flap below what he blocked off). I think the top portion of that box might act as a resonator although I didn’t look too closely when I replaced the filter.
01-05-2019, 01:44 AM
