exhaust advice to increase backpressure
12-02-12, 03:13 PM
#1
20bwannabe
Thread Starter
iTrader: (2)
Join Date: Nov 2012
Location: san antonio tx
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
exhaust advice to increase backpressure
im not sure but shouldnt my NA have two catalytic converters? one right off the exhaust manifold then the one near the middle of the car with a pipe that leads back to the 5th and 6th ports? well mine only has the one in the middle. reason im asking is id like to make damn sure my 5th/6th ports are opening fully at wide open throttle. on ebay i found a magnaflow bolt on from the manifold to the center with a cat for around 100 bucks free shipping.
Ive heard people can just stick the 5th/6ths open which sounds like the easier and cheaper route but what could i expect as far as bottom end power and fuel economy? leaving the ports open all the time id loose intake velocity and fuel economy am i right? i dont like loosing fuel economy. also im premixing my fuel with twostroke right now and dont plan to stop, its just really good insurance to do so, which in turn can destroy catalysts right? any other thoughts? my mission here is not clean exhaust emissions but only to get my 5th and 6ths working properly.
Ive heard people can just stick the 5th/6ths open which sounds like the easier and cheaper route but what could i expect as far as bottom end power and fuel economy? leaving the ports open all the time id loose intake velocity and fuel economy am i right? i dont like loosing fuel economy. also im premixing my fuel with twostroke right now and dont plan to stop, its just really good insurance to do so, which in turn can destroy catalysts right? any other thoughts? my mission here is not clean exhaust emissions but only to get my 5th and 6ths working properly.
12-02-12, 07:57 PM
#3
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,829
Received 2,597 Likes
on
1,845 Posts
the 6 ports only take about 2-2.5psi to open, which means that they should be opening with a stock main cat....
you can always put a pressure/boost gauge in the 6 port hose and check
you can always put a pressure/boost gauge in the 6 port hose and check
12-02-12, 08:32 PM
#4
20bwannabe
Thread Starter
iTrader: (2)
Join Date: Nov 2012
Location: san antonio tx
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
ok question, do these cars have 3 cats to keep the exhaust from smelling? cause my cars smells like raw fuel all the time. wow smog pump will do that? haha! sweet let me go check it out!
12-02-12, 09:39 PM
#6
3 cats because 1980s technology for catalytic converters wasn't the greatest. One was a pre-cat, one was a main cat, and..
I really don't know what they all were to tell you the truth. All I know is that a single catalytic converter by today's standards can rock the world of all 3 OEM FC cats.
I really don't know what they all were to tell you the truth. All I know is that a single catalytic converter by today's standards can rock the world of all 3 OEM FC cats.
12-03-12, 08:33 AM
#7
Emerald Triangle for life
iTrader: (5)
Join Date: Jan 2002
Location: Fort Collins, CO
Posts: 552
Likes: 0
Received 0 Likes
on
0 Posts
I ran a S4 with a full exhaust (MT header, Bonez cat, RB mufflers) and it actuated just fine. As long as your actuators are in good shape and you have a remotely reasonable exhaust they'll work fine.
My current S4 has the actuators wired open, because the stock actuators don't open the ports all the way and I was chasing a slight HP advantage around redline. Power suffers a bit below 3000RPM and cruise mileage is down to 20MPG, but it has a strong surge from 5000RPM to 7500RPM.
My current S4 has the actuators wired open, because the stock actuators don't open the ports all the way and I was chasing a slight HP advantage around redline. Power suffers a bit below 3000RPM and cruise mileage is down to 20MPG, but it has a strong surge from 5000RPM to 7500RPM.
Trending Topics
12-03-12, 08:26 PM
#9
ANTI-REPUBLICAN
iTrader: (4)
Join Date: Feb 2008
Location: Strasbourg, PA
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Fuel economy will be horrible. I believe mine went from ~23mpg to about 12mpg. Acceleration at low rpm is nil. Noticeable power gains at the higher end rpm's, tho.....a blast to drive on the highway versus non-working ports.
12-09-12, 08:48 PM
#11
20bwannabe
Thread Starter
iTrader: (2)
Join Date: Nov 2012
Location: san antonio tx
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
great info thanks, ill keep the exhaust with the catalytic converter then use the grease trick and check if the actuators are working on there own. the rear one moves easily if pressed down on but the front didnt. upon inspection i found one of the screws is missing so it was binding. looking forward to getting this thing put back together and feeling the difference.
Thread
Thread Starter
Forum
Replies
Last Post
rx8volks
Canadian Forum
0
09-01-15 10:46 PM
