Does anyone know what it takes to get the exhaust dB to be legal?
Should I go any less then 3" (300rwhp)? How much will two large silencers help?
Should I go any less then 3" (300rwhp)? How much will two large silencers help?
Exhaust system Thread.
- Thread starter D.J.T.
- Start date
Nick M;1653853 said:
What I mean is, it's not worth the cost/effort until you want to make tons of power. Plus, I can't think of any 4" turbo-back systems that will bolt or even weld to the stock ct26; turbine outlet is far too small and would cause the double expansion/turbulance mentioned before. Furthermore, it's the expansion of exhaust gasses that really gets a turbine going, not overall flow, which is why most systems are designed to retain heat at the turbine housing instead of sending it out the exhaust, and why the tubine inlet is smaller than the outlet. Best idea is to match your exhaust diameter to the turbine outlet, necking out a bit more in the downpipe if it's a divorced-reintegrated wastegate design. It should also be a bit larger than your intake piping, to maximize on the expansion effect and to support the overall air throughput of the motor.
Nick M;1653853 said:
I'm a Cali guy, smog testing is a way of life out here...universals tend to pass pretty well, seeing as you can't sell one that won't pass in CA. It really depends on how much your cat is clogged. Yes, a brand new stocker is pretty unrestrictive, but it's also 3 or 4 times the cost of a universal one that will also match your exhaust diameter, preventing turbulance and (more) backpressure. Simple fluid dynamics, there.
Nick M;1653853 said:
That was an rx7, though, which is a strange motor. They need a bit more backpressure than most motors because of the way the motor spits out exhaust; instead of gasses, the first few inches of a rotary's exhaust is actually a jet of flame. He changed out for the 3" when he did 3" from the turbo back...at the time, it really was his exhaust holding him back. He did gain a little with the test pipe, but again...emissions is a bitch out here, and he passed every time with the 3" magnaflow. Not to mention the backpressure from the cat was keeping it from backfiring...
I'm not concerned if you pick apart my post. It gives me a reason to further clarify my post, and learn more through discussion
scotty;1653898 said:
3" is preferable for plenty of reasons, read above. In California, your idle noise has to below 85dB, measured 4 feet from the tailpipe, I believe...not sure if there's a different measurement for applied throttle, though. Best bet is to look through your state's vehicle code. Either way, it's totally possible on a 3" exhaust, especially with a turbo motor. Turbos are quiet, almost functions like a muffler on its own...if it's too loud, a silencer will help. Doubt you'll be too loud with a 3" system without big cams, though.
