DODGE RAM FORUM - Ram Forums and Owners Club! - Dodge Truck Forum

Go Back   DODGE RAM FORUM - Ram Forums and Owners Club! - Dodge Truck Forum > Dodge Ram Forum - Mod Zone - Custom Dodge Ram Mods - Dodge Ram Performance > Custom Dodge Ram Performance Mods - Engine - 4.7 Liter V8


Notices

Custom Dodge Ram Performance Mods - Engine - 4.7 Liter V8 Discuss modifying your Dodge Ram with Performance Parts and Accessories!
Factory Spec: 4.7-liter V8 engine - 310 horsepower, 330 lb-ft of torque.


Latest Vendor News
AutoAnything
Addictive Desert Designs!
United Radio
Bayou Goat Mounts

Reply
 
Thread Tools
  #1  
Old 09-24-2010, 12:03 AM
BigOrange BigOrange is offline
Dodge Ram Forum Senior Member!
 
Join Date: Jul 2010
Location: TEXAS
Age: 35
Posts: 174
Gender: Male
Vehicle: 2013 RAM 1500
Trim Level: EXPRESS QUAD CAB
Color: BRIGHT SILVER
Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
Rep Power: 0
Rep:10
BigOrange is on a distinguished road
Default New Muffler = Loss of Power???

2008 Ram w/ 4.7L
I just switched from an 18" XLerator Single 3" in, Dual 2.25" out with pipes straight out the back to a 14" Magnaflow Single 3" in, Single 3"out directly into a 3" to 2.25" Y-pipe into the existing 2.25" pipes out the back. I did this because the XLerator didn't produce the sound I was looking for. It actually made a terrible low bass drone from 1200-2200 rpm that was really annoying & really lound..... it didn't even sound like a V8!!! The problem is that I lost a noticable amount of power. The engine feels like it's working harder, and doesn't pull as much on the top end. Does this sound right for going from a 18" SI/DO to a 14" SI/SO muffler with a y-pipe? I didn't think it would make a performance difference, and the muffler guy said it would flow the same as well. Any thoughts on whats going on here? I'm also wondering if an 18" Magnaflow SI/DO would make that same deffening bass drone that the XLerator made under light ecceleration....
Also, I did unplug the battery for a while to do a computer reset, but that was 6 days ago when I had the muffler installed. Also running an Airaid Modular Intake tobe to the factory airbox with a K&N drop-in filter.
Any input, thoughts, or ideas would be great here! Thanks!
__________________
Magnaflow 14" SI/DO, No Resonators, K&N Drop-In Filter, De-badged.
Reply With Quote
Sponsored links
  #2  
Old 09-24-2010, 12:31 AM
moparmanicac's Avatar
moparmanicac moparmanicac is offline
Find em hot leave em wet

 
Join Date: Aug 2010
Location: nj
Age: 24
Posts: 1,287
Gender: Male
Vehicle: 12 RAM 1500 qc 4x4 HEMI
Trim Level: express
Color: bright silver
Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
Rep Power: 5
Rep:204
moparmanicac has a spectacular aura aboutmoparmanicac has a spectacular aura aboutmoparmanicac has a spectacular aura about
Default

hmm possibly the change in back pressure and the pcm needs to re learn just my 2cents
__________________
[SIGPIC] RIP 02 4.7 Dakota sport qc 4x4
RIP 05 Ram 4.7 rc 4x4
HELLO 12 Ram HEMI qc 4x4 and 94XJ
Reply With Quote
  #3  
Old 09-24-2010, 12:50 PM
4pnt7 4pnt7 is offline
Dodge Ram Forum Senior Member!
 
Join Date: Jul 2010
Location: New Mexico
Age: 30
Posts: 167
Gender: Male
Vehicle: 2008 4.7l Dodge Ram
Color: Graphite Grey
Engine: 2008-???? 287ci (4.7L) PowerTech V8 310hp 330lb/ft
Rep Power: 0
Rep:10
4pnt7 is on a distinguished road
Default

Samething happened to me. I bought a flowmaster 40 series. I lost all of bottom end. I switched to an Aeroturbine 30/30. Great mufflers.. it was a nice performance muffler. It did drone a little. Then went with an Aero Stealth 170. It was perfect for me. It was a smooth sounding muffler. I didn't loose performance. And it sounded great at wide open throttle. This was all on an 02 4.7l with more Mods.

On my 08 I'm going to use the bigtank 248. Its another stealth muffler.
__________________
Nicolas Chavez
2002 ram 4.7l qc (Totaled),60ft.-2.0,1/8-9.310,@76.mph,1/8-9.41,1/4-14.80,@90.94
Reply With Quote
  #4  
Old 09-24-2010, 01:08 PM
BigOrange BigOrange is offline
Dodge Ram Forum Senior Member!
 
Join Date: Jul 2010
Location: TEXAS
Age: 35
Posts: 174
Gender: Male
Vehicle: 2013 RAM 1500
Trim Level: EXPRESS QUAD CAB
Color: BRIGHT SILVER
Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
Rep Power: 0
Rep:10
BigOrange is on a distinguished road
Default

would the pcm re-adjust to make optimum power for the amount of backpressure that there is now? or will I just have to get used to not having the power I had with the SI/DO muffler?
__________________
Magnaflow 14" SI/DO, No Resonators, K&N Drop-In Filter, De-badged.
Reply With Quote
  #5  
Old 09-24-2010, 04:14 PM
Race1Mopar Race1Mopar is offline
Dodge Ram Forum Senior Member!
 
Join Date: May 2010
Location: Texas
Posts: 153
Gender: Male
Vehicle: 1995 Dodge Ram 1500
Trim Level: SLT
Color: Forest Green
Engine: 1994-1997 360ci (5.9L) Magnum V8 230hp
Rep Power: 0
Rep:67
Race1Mopar will become famous soon enough
Default

Back pressure is created by exhaust scavenging and how efficient it is. My guess is that's it's scavenging better and more than before, creating less back pressure. Not sure in tis engine, but in the magnum engines if you took too much of the back pressure away you lost your bottom end grunt.
__________________
1995 Dodge Ram 1500, bored, stroked and breathing fire.
Joe
Reply With Quote
  #6  
Old 09-26-2010, 10:14 AM
AIR RAM's Avatar
AIR RAM AIR RAM is offline
Dodge Ram Forum Member
 
Join Date: Jun 2009
Location: HOMESTEAD FLORIDA
Age: 42
Posts: 66
Gender: Male
Vehicle: 2002 4.7L QC RAM (9.49's 8th)
Trim Level: SLT
Color: SILVER
Engine: 2002-2007 287ci (4.7L) PowerTech V8 235hp 295lb/ft
Rep Power: 0
Rep:13
AIR RAM is on a distinguished road
Default

Quote:
Originally Posted by Race1Mopar View Post
Back pressure is created by exhaust scavenging and how efficient it is. My guess is that's it's scavenging better and more than before, creating less back pressure. Not sure in tis engine, but in the magnum engines if you took too much of the back pressure away you lost your bottom end grunt.

I hope you don't take this the wrong way but it sounds like you have Back Pressure and Scavenging mixed up to where they some how work together...

Back pressure is NEVER good... No engine on earth has ever needed or needs back pressure. Back pressure is a product of restriction, the words Back pressure and performance should never be used in the same sentence... the term back pressure does not belong in the performance minded vocabulary.

Back in the day when old timers did not understand the physics and dynamics of the exhaust system they would relate loss of torque to loss of back pressure simply because they went too large on the pipe they assumed they had lost some back pressure... There for they preach its importance and they have passed it on through the generations. Many people will speak about the importance of back pressure but have very little understanding on why or how it effects the system... they just know somone told them it was important. Understanding the theory of operation will help anyone put myths like that to sleep.

What they had lost was velocity. Velocity through the system is needed to keep the exhaust gasses flowing through the system... with high velocity you create vacuum... other wise know as the "scavenging effect". If you go too large on the ID of the system for the amount of air the engine can pump, you lose the velocity.... NOT BACK PRESSURE.

This velocity is pulling the gasses through the system. This effect is most important at the exhaust valve. The more vacuum your exhaust system makes the more toque you will make... but how? What is it about the vacuum and exhaust that makes toque... Hint... its not magic!

Most all NA cams are designed with an overlap of the exhaust and intake valves. This means that for a very short duration both the intake and the exhaust are open at the same time... Why? This is so your intake charge can benefit from that exhaust vacuum your system SHOULD be creating. Just before your exhaust valve closes the intake side starts to open... the vacuum on the exhaust side pulls the intake side into the cylinder effectively filling the cylinder with more air. This is a form of force induction... Not like a supercharger or turbo... but the same theory apply s. More air = more power! When you install an exhaust system that is too large it does not create the needed vacuum until the higher RPMs when the engine is moving enough exhaust to make create the scavenging effect. This is why you lose bottom end when you go too large. Its not the loss of back pressure, instead its the loss of low RPM velocity.

To get a better idea how the scavenging effect works, think of it like when draining a pool of water.
With a hose in the pool hanging over the edge from the pool onto the ground you simply create an initial vacuum on one end to get the water moving... BUT once the water is moving it continues to flow with no power source.

Think of the pool as the cylinder, the water as the exhaust gasses and the hose as your exhaust system. Go to large on the hose and it will not have the needed velocity to keep the flow moving go too small and it will be restrictive. But with the right amount of velocity in the exhaust system the vacuum created in the system continue to pull from the cylinder end.

Exhaust systems are not a one size fits all... But we are limited to whats available... so most of us have to make a sacrifice going either too large or too small. But never forget...

Back pressure = BAD (Restriction)
High Velocity = GOOD (Scavenging)

SPEED SAFE, NICK

Last edited by AIR RAM; 09-26-2010 at 11:29 AM.
Reply With Quote
  #7  
Old 11-16-2010, 06:43 PM
Atlantic Blue Atlantic Blue is offline
Dodge Ram Forum Newcomer
 
Join Date: Nov 2010
Posts: 2
Gender: Male
Vehicle: 2002 Dodge Ram - orignal owner
Trim Level: Sport
Color: Atlantic Blue
Engine: 2002-2007 287ci (4.7L) PowerTech V8 235hp 295lb/ft
Rep Power: 0
Rep:10
Atlantic Blue is on a distinguished road
Default Exhaust

AIR RAM
Thanks for the explanation - im about to replace my exhaust with a Gibson Single system.
Reply With Quote
  #8  
Old 11-16-2010, 08:00 PM
GTyankee's Avatar
GTyankee GTyankee is offline
Dodge Ram Forum Member

 
Join Date: Dec 2009
Location: San Diego East County, Ca
Posts: 19,042
Gender: Male
Vehicle: 2009 Dodge Ram 1500 2X4
Trim Level: quad cab SLT
Color: sunburst orange pearl
Rep Power: 20
Rep:2615
GTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond reputeGTyankee has a reputation beyond repute
Default

a few years ago during the BAJA 500 race, there was a vehicle that hauled ass across the flats it was close to the front runners on time, but, then they hit the hilly section & that vehicle fell well back, then that vehicle bottomed out & the exhaust pipes were partially dented.
that vehicle didn't finish first, but, that little bit of restriction, still let him haul a** across the flats & he didn't get passed on the hilly sections after that.
I don't know any technical stuff, but, i know that it worked
__________________
Ram 1500 SLT Quad cab, 5.7 HEMI(R) MDS VCT, 5 speed auto 545RFE, 3.55 differential gears, 18" Magnaflow muffler, EGR bug deflector, Bushwacker fender flares, customized Nfab nerf bars, CB radio, Autonet wi-fi router, custom soft tonneau cover, Line_X bedliner, DEBO Step, build date 10/15/08 a Wednesday built vehicle
Reply With Quote
  #9  
Old 11-16-2010, 08:36 PM
drivehard27's Avatar
drivehard27 drivehard27 is offline
Dodge Ram Forum Senior Member!
 
Join Date: Mar 2010
Location: queen creek , AZ
Age: 39
Posts: 536
Gender: Male
Vehicle: 2012 dodge ram
Trim Level: sport
Color: black
Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
Rep Power: 5
Rep:108
drivehard27 will become famous soon enoughdrivehard27 will become famous soon enough
Send a message via Yahoo to drivehard27
Default

man i dont now what to tell ya i have a flowmaster and i have tons of low end when it was stock i could not rip the tires now i can rip them allday and that is all i have right now no cai or programer just a flow master 40 and i had them just replace the muffler and weld up to the stock pipe .but i will say this if i were to do it again i would get a magnaflow a friend of mine has one and it sounds deeper .i think it might just be the computer mine took about a week and about 500 miles and then it ran better i even get better mpg now
__________________
2012 ram sport qc
Reply With Quote
  #10  
Old 11-23-2010, 05:39 PM
OldMoparMan63's Avatar
OldMoparMan63 OldMoparMan63 is offline
Dodge Ram Forum Member
 
Join Date: Nov 2010
Location: PA
Age: 51
Posts: 51
Gender: Male
Vehicle: 2002 Ram 1500 QC-4.7
Trim Level: SLT
Color: DK Blue
Engine: 2002-2007 287ci (4.7L) PowerTech V8 235hp 295lb/ft
Rep Power: 0
Rep:68
OldMoparMan63 will become famous soon enough
Default

Quote:
Originally Posted by AIR RAM View Post
What they had lost was velocity. Velocity through the system is needed to keep the exhaust gasses flowing through the system... with high velocity you create vacuum... other wise know as the "scavenging effect". If you go too large on the ID of the system for the amount of air the engine can pump, you lose the velocity.... NOT BACK PRESSURE.
Agree 100%. 2.5" to a 3" exhaust is the culprit. Exhaust velocity was lost, resulting in lost low end torque.
Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Advertisement






All times are GMT -4. The time now is 06:08 AM.


= Copyright RamForumZ.com a Gigathreads.com Network Site =Ad Management by RedTyger
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
vB.Sponsors


=Gigathreads Network=
CLUBS MOPAR NATION DSM GPMM MAMM JAM
DIESEL Diesel Forum      
CHEVY Chevy Camaro Forum Chevy Volt Forum    
CHRYSLER Chrysler 300C Forum      
DODGE Dodge Avenger Forum Dodge Caliber Forum Dodge Challenger Forum Dodge Charger Forum
  Dodge Circuit Forum Dodge Hornet Forum Dodge Magnum Forum Dodge Nitro Forum
  Dodge Ram Forum Dodge Dakota Forum Dodge Durango Forum Dodge Dart Forum
FORD Ford Raptor Forum Ford F150 Forum Ford F100 Forum  
JEEP Jeep Forum      
PONTIAC Pontiac G8 Forum      
SRT SRT Viper Forum SRT Cuda Forum