hey today my local shop custom bent 2.25" piping back to my single muffler (i sold one) and it seems like the 2.25" killed my power. like around 50 and up its decent but on takeoff it sucks ever since i got this catback on. i have a pacesetter ceramic header,catco high flow cat and custom catback exhaust and a intake and 59mm t/b on my 2.4l 4spd dohc. any tips guys?
how did they bend it?
crush bent will decrease performance
compression is better
mandrel is best
2.25 crush bent will flow WORSE then 1 7/8? I dunno...i call BS on that, but I'm no expert...lol
Are you boosted?
If not the 2.25 exhaust is too big and you are loosing all your exhaust velocity and your exhaust simply is able to get out of the engine fast enough.
If your running N/A the stock 1 7/8 is ok, but 2" is good. 2.25 is too much for N/A.
Most people who are boosted run 2.25, and I dont know of anyone with anything bigger.
You're reading my line-break, you are a loser. Lurch <3's the c**k.
im running 2.5, and have been since about the 2nd month i got the car. but now im boosted so it kinda works out lol
2000 Camaro V6.
| SLP Loudmouth | CAI Intake | HID's |
I have a N/A car with a 2.25" exhaust all the way and I didn't felt any loss of power, maybe I'm wrong but it's my opinion..
neoSandstorm (The Sandy One) wrote:Are you boosted?
If not the 2.25 exhaust is too big and you are loosing all your exhaust velocity and your exhaust simply is able to get out of the engine fast enough.
If your running N/A the stock 1 7/8 is ok, but 2" is good. 2.25 is too much for N/A.
Most people who are boosted run 2.25, and I dont know of anyone with anything bigger.
Um....i'm pretty sure most people who stick to N/A run 2.25 exhaust....and people who boost their car run a 2.5 exhaust.
neoSandstorm (The Sandy One) wrote:Are you boosted?
If not the 2.25 exhaust is too big and you are loosing all your exhaust velocity and your exhaust simply is able to get out of the engine fast enough.
If your running N/A the stock 1 7/8 is ok, but 2" is good. 2.25 is too much for N/A.
Most people who are boosted run 2.25, and I dont know of anyone with anything bigger.
you sir are wrong. 2.25" has been proven to improve horsepower N/A ..2 1/4 is twhat most people run N/A for boosted applications you would want 2.5" or bigger
Adding a free flowing i.e. oversized exhaust will allow the engine to breathe easier increasing Hp at the expense of low-end torque. if you reduce back pressure to much you will drastically decrease torque. Torque is responsible for getting you up out of the hole. Thats why the civic with the folgers coffee can from autozone falls flat at the light. Thats why i never put too big of an exhaust on my car cuz i like the light to light action where your 60' can win it all.
<a href="http://www.onlineshowoff.com/content/groups/226J3D19Y@!#$ATBYRGE3FO7Z683.html">Club 13</a>
The Magic Equation Torque = Fun
The Magic Number 5858
wich muffler do you use? Do you have a catalyst converter? I have the same car as your NA and i got 2.5 inches compression bent wich i'm happy with. I lost some low end but high end is really better than stock. If i have to redo i would go 2.25 compression or mandrel if you can get it cheap. All that dosen't change much if you dont have a 300hp monster.
You will get use to the lost low end and work from there. it's a long way to get a fast 4-bagner.
Good luck!
Its simple, like stated above, you have little or no back pressure now, so you've wiped out your low end power.
1999 Pontiac Bonneville "The Boataville"
3800 SFI V6 (L36)
intake w/ heat shield, relocated IAT sensor, 180 degree T-stat, blue reverse glow gauges...
and a bucket full of HP robbing KR!
Quote:
William Smith
Today 2:07 AM
Its simple, like stated above, you have little or no back pressure now, so you've wiped out your low end power.
with 2.25" piping???
is everyone reading the original post? 2.25" is NOT too big for n/a applications, in fact its optimal.
do you have a high flow cat and muffler?
something isn't right... when I bolted on my full exhaust the car REALLY woke up... cat back won't make much difference... when you do everything including header, you're def gonna feel it in the seat of your pants.
hmmm these are good posts....i have ordered a pacesetter ceramic header, 2.25 high flow cat, yet i only have a 2" in/out borla exhaust. is that going to keep my low end power good?
AkA joe m.
Ricer ELIMINATOR!
You may feel it in the seat of your paints in the high revs, but that size pipe w/ a header, high flow cat and catback is still the reason for the loss of low end power. These small engines do not need that much exhaust velocity unless your running forced induction.
1999 Pontiac Bonneville "The Boataville"
3800 SFI V6 (L36)
intake w/ heat shield, relocated IAT sensor, 180 degree T-stat, blue reverse glow gauges...
and a bucket full of HP robbing KR!
i dont know if this is true but i heard that if there is to much of a low presser on the back
end (exhaust) it sucks the input to much, so your sucking the gas out of the cylinder be for its burned all the way
or
did you have your mass air flow sens. plugged in?
<img src="http://server3.uploadit.org/files/QazQaz007-venom_banner.jpg">
some of the onfo here needs to go in the trash
see ya!
i have a 2200 with obx 4-2-1 header, high flow cat and vibrant 2.5" exhaust(cuz i'm gonna be boosted soon) ...but even with the 2.5" i see a good difference in how she's running
some of the boosted guys run as big as 3". But that's turbo ONLY. Turbos HATE backpressure...so, NA I say 2.25, nitrous/sc 2.5 should be sufficient...turbo...3"
as said in my first post, i have a header, high flow cat and now a 2.25" catback...should i invest in putting on a magnaflow oval muffler to create alittle backpreasure? thanks
neostorm you are wrong. 2.25" is perfect for NA cars. Ask anybody here.
Yea, Im pretty sure there is R+D that goes into the exhaust kit these companies are selling. And most of them are 2.25 or 2.50. No offense neoSandStorm and William Smith, but you wrong. 2.50 is debatably overkill. but 2.25 still leaves plenty of back pressure and provides power in a vast majority of its cases. As proven by the sheer amount of people all over the world that seem to buy them and make power. As also proven by the amount of time and money put in by these exhaust company THAT MAKE AND SELL AFTERMARKET EXHAUST. So from here on out I'd leave the back pressure to them.
Read, then process the info, think logically, than if you don't have a headache afterwards, post your response
jsunfireGT2000 wrote:hey today my local shop custom bent 2.25" piping back to my single muffler (i sold one) and it seems like the 2.25" killed my power. like around 50 and up its decent but on takeoff it sucks ever since i got this catback on. i have a pacesetter ceramic header,catco high flow cat and custom catback exhaust and a intake and 59mm t/b on my 2.4l 4spd dohc. any tips guys?
most shops dont crush bend...
most shops use compression bends...
the difference in crush and compression are VERY obvious.
crush leaves ridges... ridges not good.
compression merely changes the shape. which is fine.
for example on a compression bend, its merely changing the shap of a circle to an oval. the flow is basically still the same. its just distorting the perfect circle. so for people into shows its not gonna be as pretty and perfect underneath. for those into performance, you prob wont be washing nor showing the underside of your car.
now you say it killed your power? not really.... you then said, its great past 50mph....
you have a free flowing exhaust, which is good, and a 59mm TB. all of these things are good................... for upper rpm, but you lose velocity on the lower end.
its the same with camshafts.... different cam shafts work for differnt rpm band ranges.
cant believe there is still talk about needing backpressure.............................................
Quote:
BACKPRESSURE = TORQUE?
An old hot-rodder's tall tale: Engines need some backpressure to work properly and make torque. That is not true. What engines need is low backpressure, but high exhaust stream velocity. A fast-moving but free-flowing gas column in the exhaust helps create a rarefaction or a negative pressure wave behind the exhaust valve as it opens. This vacuum helps scavenge the cylinder of exhaust gas faster and more thoroughly with less pumping losses. An exhaust pipe that is too big in diameter has low backpressure but lower velocity. The low velocity reduces the effectiveness of this scavenging effect, which has the greatest impact on low-end torque.
Low backpressure and high exhaust stream velocity can be achieved by running straight-through free-flowing mufflers and small pipe diameters. The only two exceptions to this are turbocharged engines and engines optimized for large amounts of nitrous oxide. Both of these devices vastly increase the exhaust gas volume and simply need larger pipes to get rid of it all.
http://www.magnaflow.com/05news/magazine/05sportc.asp
back pressure is not what you need. velocity...velocity....velocity....
you basically lost your low end and gained top end.
basically you moved your powerband higher with the mods you;ve added. if you wanna gain some low end back, go back to the 52mm stock TB or maybe a 56.
adding a TB may increase air flow, but the larger the TB, the slower the air speed, especially when your engine is still internally stock and still takes in the same exact amount of air.
William Smith wrote:You may feel it in the seat of your paints in the high revs, but that size pipe w/ a header, high flow cat and catback is still the reason for the loss of low end power. These small engines do not need that much exhaust velocity unless your running forced induction.
^^^^^
novaracer wrote:some of the onfo here needs to go in the trash
exactly....
^^^^thank you event. i had the
when i read some of those post. Ignorant people passing on ignorant information.
2006 Cobalt SS 2.4L 9.6 @74mph 1/8th mile w/2.28 60ft
