The Race Gas concentrate leaves an orange tint which has made clear there is no exhaust flow in the crossover tube connecting the two mufflers. At least not with the exhaust valve open because I am in Sport + mode all the time.
The ‘fancier’ factory twin exhaust exit has the twin tubes intersecting the merge pipe at almost a right angle.
I kind of think the base model single tip exhaust may flow better than the optional expensive and heavier twin exit exhaust.
My X-pipe is just a bit simpler than the factory twin-tip exhaust. And much lighter too! My X-pipe weighs roughly the same as the simple base Cayman exhaust tip. I would ballpark the pretty Sport Tailpipe at about five pounds heavier.
I used a bit of brake caliper lube to make it easier to install the X-pipe. Oh yeah, I painted my X-pipe with Krylon flat black high heat paint. Those days back in middle school spray painting the lexan bodies of R/C cars paid off. Please excuse the few caliper lube smudges; I cleaned those off later with Simple Green.
The stock tips are about 3” diameter. I used 2.5” for my X-pipe which makes it a bit leaner and meaner.
4 comments
Some of the aftermarket companies (I think Soul?) were claiming no power gains on the 718 with a straight piped catback exhaust. Different X pipe tip design than yours though. Any thoughts?
Anything the baby 2.0 stock turbo can put out, not going to see much with the going cat back. Maybe on the bigger S or GTS turbos. Even then, not much gains to be had in the exhaust until turbo upgrade in my opinion. The only real bottleneck in the stock exhaust is the stock cat. Replacing that with a high flow sport cat is the best place to uncork restriction. Otherwise, the downpipe is huge and then that splits into the two approximately 2.5″ exhaust pipes that go to straight through mufflers. At the exhaust tip, text book loss coefficient for a 90deg bend is 1.1. A 45deg bend is 0.4. Mine is 60deg but I think gain benefit by not having the pulsating flows crash into each. Regardless, need a tune to take advantage of any potential flow improvement at higher power levels. Otherwise the stock ECU will just keep on hitting the programmed in torque target. Or if on crap fuel, better exhaust flow should mean less knock. But for sure, the stock cat is the major bottleneck. The other bottleneck is the small compressor inlet tube. Raggdoll Motorsport has a good upgrade for that.
Nice design. A little surprised you didn’t angle the cuts on the tips. Hopefully the crossflow design helps with scavenging. I imagine there’s a slight change in exhaust note.
I thought about the slash tip for about a minute. But it added two more cuts along with another area to add error and visually see any misalignment of the tubes. I figured flat cut was good enough for a GT3 racecar, good enough for me.