capt. bill1

Anybody else had their exhaust back pressure checked? I did today, 7 psi with a DP, N-Tech high flow( ha ha) cat and PFS cat back. Straight through is like what, 3 psi. 7 psi sucks. Don't really like how loud these cars are with out the cat. Anybody know of a true (read documenable) high flow cat or muffler system?

Swamp RX-7

Get a resonated midpipe. BTW, how do you check the back pressure of the exhaust?

JoeD

the PFS exhaust is one of the louder systems out there. run a resonated midpipe and a Racing Beat cat back, and you will be much quieter and flow more.

skunks

hey, a straight pipe is not that loud, im running a 3inch straight pipe and its not that loud, i always hear civics with louder exaust as well as nearly any V-8 that is moving!

REDLINE

I got an exhuast back pressure done at a rotary shop. He said normal stock readings should be around 5psi....doesn't sound right to me. I have an HKS DP and HKS cat back with somewhat clogged main cat giving me 8psi or back pressure. They said that its too much back pressure. Bad for the turbos and he said its one of the reasons I can't hold boost on 2nd. Turbo. He used a fuel pressure gauge placed where the 02 sensor should go in DP and took it for a quick spin.

maxcooper

I've always been interested in measuring back pressure because I think that it is one of the primary factors in how much power the car makes. For a given port configuration and manifold boost pressure, backpressure seems to be the only thing that will determine flow and thus power. I've read in Maximum Boost that exhaust backpressure should be no more than 2.5 times the boost pressure, but that is just a rule of thumb for properly designed turbo systems. I would like to know more about what the backpressure is on the FD.

Did you measure between the engine and turbos, or after the turbos? It seems like you could use a regular boost gauge as long as you had enough metal tubing to connect to the manifold without melting off and perhaps a few coils of that tubing in some air flow to cool the air down. Is this the method you used? I read somewhere that exhaust shops sometimes measure the pressure before the cat to see if it is clogged, and I assumed they used an apparatus like I described. Just a guess, though.

How did you do it, capt. bill? And did you test at full boost pressure (what was it) at high RPM?

Thanks,
-Max

JeffShoots

Just open that BadBoy up, I'm running the HKS Ti 4" open from DP back and Gas it, WHAT I said, GAS IT, YOU WHAT!!!!GAAAAASSSSSSSS IT!!

Later, Jeff

capt. bill1

maxcooper, You can get a pressure gauge from Snap-On (and others I would guess) that reads from 0-15 lb over a wide scale. It screws into your oxygen senser port. It was tested at max boost. Are you sure you mean "2.5 times boost pressure"? That would mean at 15 lb of boost you would see 37.5 lb of back pressure.

yzf-r1

iTrader: (1)

get a resonated MP...it's loud at WFO, but who cares?

sunnyxwala

isnt the point of the exhaust system to move the heat away from the motor, "jeffshots" said to let it out at the downpipe...isnt that bad for the motor, giving that it already produces soo much heat??