diy exhaust project
#91
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The one I did has a full 3" path through it on each side, so I do not think its restrictive. Hard to tell if the one from alleykat is restrictive, depends on how they cut the pipes. It's also not on a 993TT. I think the one that Basal did actually is a bit larger and probably mixes more. Knight's is even larger given its really two 4" pipes facing each other. Mine is below.
Cheers,
Mike
Cheers,
Mike
#92
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Join Date: Nov 2010
Location: Central California
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The one I did has a full 3" path through it on each side, so I do not think its restrictive. Hard to tell if the one from alleykat is restrictive, depends on how they cut the pipes. It's also not on a 993TT. I think the one that Basal did actually is a bit larger and probably mixes more. Knight's is even larger given its really two 4" pipes facing each other. Mine is below.
Cheers,
Mike
Cheers,
Mike
#93
Excuse the rushed thru welding,since its a tester I didn't take my time.Also didn't bother brushing the tubing before welding.I'll do that on my final final version.
It flows pretty well actually.One way to tell if one side wasn't getting flow,it simply wouldn't be the same color.
#94
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Thread Starter
!1!
What are you talking about 'rushed' those welds look really nice, you must do this professionally (or could if you don't)!
#95
Here's 1 of my more fav pieces that was for a Lambo,test pipe in progress.
That piece I actually brushed the tubing first,I like the added touch.
#96
Post 2 has a sound clip but its far from the best quality.Just a cell phone clip from the passenger seat. I will get a real video once im happy with everything and finish adding the tips.
https://rennlist.com/forums/997-foru...y-911-c2s.html
https://rennlist.com/forums/997-foru...y-911-c2s.html
#97
I built a 3" with custom muffler/ resonators a while back. I'm currently researching methods to get rid of the drone at 2000-3000 rpms.Mostly 2400 rpms Can anyone chime in on the drone level with the different exhaust setups.
I can add a helmholtz tube or add tubing length after the muffler before the tip. Maybe a u turn in the old muffler location.
I plan on measuring cabin noise before and after.
does anyone have cabin noise readings?
I can add a helmholtz tube or add tubing length after the muffler before the tip. Maybe a u turn in the old muffler location.
I plan on measuring cabin noise before and after.
does anyone have cabin noise readings?
#98
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Join Date: Nov 2010
Location: Central California
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I built a 3" with custom muffler/ resonators a while back. I'm currently researching methods to get rid of the drone at 2000-3000 rpms.Mostly 2400 rpms Can anyone chime in on the drone level with the different exhaust setups.
I can add a helmholtz tube or add tubing length after the muffler before the tip. Maybe a u turn in the old muffler location.
I plan on measuring cabin noise before and after.
does anyone have cabin noise readings?
I can add a helmholtz tube or add tubing length after the muffler before the tip. Maybe a u turn in the old muffler location.
I plan on measuring cabin noise before and after.
does anyone have cabin noise readings?
#99
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Thread Starter
I could take some cabin noise readings, I probably have drone although I guess it's little bit of a perception thing (not quite sure what it is) and might be different depending on who is listening. It doesn't bother me. Capping off one of the twin tips like I did probably is a helmoholtz tube type of thing, it seemed to change the sound at lower rpm but I did't think it changed much at higher rpms (but that was before I added the inserts - haven't really had a chance to take it out since I put the inserts in).
Another option might be to make a tube that connects the two sides - like an H type (vs X over) where your exhaust crosses over which might change the sound too (although there may not be any space for that actually).
Here's a pic of your car from your thread:
#100
I should have time this month to experiment with different methods to get rid of the drone. First I'll try the helmholtz tube in the area of the stock muffler location. I'm using a phone app to measure frequency and decibels
I don't want to tie the two sides together at this point.
I don't want to tie the two sides together at this point.
#101
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Thread Starter
Was out at the track April 1 and had a chance to try it out on the track (and the 3 hour drive there and back). Car ran great, exhaust looks good after inspection with no loose or broken parts (was a little anxious about that). No check engine light with the O2 sensor spacers (for the distal sensor). Took it easy on the track for the first 1/2 of the day, then second half was driving a little faster. Sounded good, and afaik wasn't too loud (could hear the 991 gt3 in front of me and it shifting easily - that thing shifts so quick, it would shift through 3 gears while I'm rolling on the gas in one gear, I try to shift as little as possible while the pdk cars seem to want to shift as often as possible, very different approach to driving). No problems on the drive to and back, louder than my old exhaust (umw sport cats/roock mufflers) but not bad. Sounded great in the tunnel!