...you wouldn't gain that much hp going from stock to true duals..unless you added headers... 
pipe bending question
pipe bending question I am calling muffler shops to find out who uses mandrel bends and one of the shops who was highly recommended to me told me they used a pipe bender.
The question is: does pipe benders cause that crinkle in the pipe, causing a reduction in diameter and increasing turbulance or will it be smooth as a mandrel bend?
thx
The question is: does pipe benders cause that crinkle in the pipe, causing a reduction in diameter and increasing turbulance or will it be smooth as a mandrel bend?
thx
11 Second Truck Club
Joined: Jun 2002
Posts: 536
Likes: 0
From: Alvin, TX
If it's a press bender like most muffler shops use, you'll only lose alittle diameter in the bends. There will be no turbulence from the ones I've seen. I know the ones your talking about though with the ridges in the bends. I usually see those on factory or direct replacement exhaust. All the muffler shops I've ever used have the press benders w/ no ridges.
Although it is best to have mandrel bends, my track numbers recently show my press bent exhaust at the rear after the x-pipe did not affect my car power wise. I would say fully built 500+ hp cars would probobly be a different story though.
Although it is best to have mandrel bends, my track numbers recently show my press bent exhaust at the rear after the x-pipe did not affect my car power wise. I would say fully built 500+ hp cars would probobly be a different story though.
I went from 308 rwhp with a press bent 2.5" dual exhaust to 340 rwhp with a mandrel bent 2.5" dual exhaust...both dumping at the rear axle, both with x-pipes, and both with bullet style mufflers.
Press bends reduce the pipe diameter by about 25-30%.
Press bends reduce the pipe diameter by about 25-30%.
Originally Posted by NOBR8KSS
I went from 308 rwhp with a press bent 2.5" dual exhaust to 340 rwhp with a mandrel bent 2.5" dual exhaust...both dumping at the rear axle, both with x-pipes, and both with bullet style mufflers.
Press bends reduce the pipe diameter by about 25-30%.
Press bends reduce the pipe diameter by about 25-30%.
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The car had the same mods between exhaust switches and I have the dyno sheets to back it up.
My car dynoed 318 rwhp and 326 rwtq with a lid and an SLP Loudmouth cat-back
Then, I added the MACs with the off-road y-pipe to the Loudmouth and didn't dyno.
I hated the way it sounded, so I had a local muffler shop fabricate a 2.5" crush bent dual exhaust. They used a portion of the MAC y-pipe and fabricated their own x-pipe and dumps. They used 2.5" Dynomax Bullet mufflers. I have a video and a dyno sheet showing the run with those mods....308 rwhp.
Realizing that dual exhaust wasn't worth a crap, I ordered a 2.5" dual exhaust setup from Lane in Texas. He used Magnaflow mandrel bends, a Dr. Gas x-pipe, and 14" Magnaflow Magnapacks. I dynoed again to the tune of 340 rwhp and 340 rwtq...I have the video and dyno sheet for that run also.
All of the runs are on the stock PCM tune.
Go ahead and whine about differing weather conditions and all of that mess. Take it for what it's worth...I didn't respond to this thread to start a pissing contest. Those were my results, believe it, don't believe it, I don't give a crap. The locally fabricated exhaust was crappy...why is that so hard to believe?
My car dynoed 318 rwhp and 326 rwtq with a lid and an SLP Loudmouth cat-back
Then, I added the MACs with the off-road y-pipe to the Loudmouth and didn't dyno.
I hated the way it sounded, so I had a local muffler shop fabricate a 2.5" crush bent dual exhaust. They used a portion of the MAC y-pipe and fabricated their own x-pipe and dumps. They used 2.5" Dynomax Bullet mufflers. I have a video and a dyno sheet showing the run with those mods....308 rwhp.
Realizing that dual exhaust wasn't worth a crap, I ordered a 2.5" dual exhaust setup from Lane in Texas. He used Magnaflow mandrel bends, a Dr. Gas x-pipe, and 14" Magnaflow Magnapacks. I dynoed again to the tune of 340 rwhp and 340 rwtq...I have the video and dyno sheet for that run also.
All of the runs are on the stock PCM tune.
Go ahead and whine about differing weather conditions and all of that mess. Take it for what it's worth...I didn't respond to this thread to start a pissing contest. Those were my results, believe it, don't believe it, I don't give a crap. The locally fabricated exhaust was crappy...why is that so hard to believe?
Last edited by NOBR8KSS; Dec 14, 2004 at 03:01 PM.
11 Second Truck Club
Joined: Jun 2002
Posts: 536
Likes: 0
From: Alvin, TX
Originally Posted by TransAmJo
He must have had the 2.5 inch crush bent with stock manifolds and one crappy X. Then swapped to the mac mids and put on the 2.5 inch mandrel bent set up.
The only other explanation would be his 1st exhaust was cut and welded terrible with obstructions and massive welds blocking some flow.
Originally Posted by NOBR8KSS
The car had the same mods between exhaust switches and I have the dyno sheets to back it up.
My car dynoed 318 rwhp and 326 rwtq with a lid and an SLP Loudmouth cat-back
Then, I added the MACs with the off-road y-pipe to the Loudmouth and didn't dyno.
I hated the way it sounded, so I had a local muffler shop fabricate a 2.5" crush bent dual exhaust. They used a portion of the MAC y-pipe and fabricated their own x-pipe and dumps. They used 2.5" Dynomax Bullet mufflers. I have a video and a dyno sheet showing the run with those mods....308 rwhp.
Realizing that dual exhaust wasn't worth a crap, I ordered a 2.5" dual exhaust setup from Lane in Texas. He used Magnaflow mandrel bends, a Dr. Gas x-pipe, and 14" Magnaflow Magnapacks. I dynoed again to the tune of 340 rwhp and 340 rwtq...I have the video and dyno sheet for that run also.
All of the runs are on the stock PCM tune.
Go ahead and whine about differing weather conditions and all of that mess. Take it for what it's worth...I didn't respond to this thread to start a pissing contest. Those were my results, believe it, don't believe it, I don't give a crap. The locally fabricated exhaust was crappy...why is that so hard to believe?
My car dynoed 318 rwhp and 326 rwtq with a lid and an SLP Loudmouth cat-back
Then, I added the MACs with the off-road y-pipe to the Loudmouth and didn't dyno.
I hated the way it sounded, so I had a local muffler shop fabricate a 2.5" crush bent dual exhaust. They used a portion of the MAC y-pipe and fabricated their own x-pipe and dumps. They used 2.5" Dynomax Bullet mufflers. I have a video and a dyno sheet showing the run with those mods....308 rwhp.
Realizing that dual exhaust wasn't worth a crap, I ordered a 2.5" dual exhaust setup from Lane in Texas. He used Magnaflow mandrel bends, a Dr. Gas x-pipe, and 14" Magnaflow Magnapacks. I dynoed again to the tune of 340 rwhp and 340 rwtq...I have the video and dyno sheet for that run also.
All of the runs are on the stock PCM tune.
Go ahead and whine about differing weather conditions and all of that mess. Take it for what it's worth...I didn't respond to this thread to start a pissing contest. Those were my results, believe it, don't believe it, I don't give a crap. The locally fabricated exhaust was crappy...why is that so hard to believe?
I went from 308 rwhp with a press bent 2.5" dual exhaust to 340 rwhp with a mandrel bent 2.5" dual exhaust...both dumping at the rear axle, both with x-pipes, and both with bullet style mufflers.
so original u had 326rwhp, went to a shitty ture dual setup which lost hp, so in turn u really only gained the difference of (14hp) going from the 326 to the 340. thats not so hard to believe for gains of a true dual setup. (hope this doesnt sound to cinfusing lol)
Back on topic like said above "Press bends reduce the pipe diameter by about 25-30%."
On most cars they will dyno around the same numbers stock weither they have a twin 2 1/4" or twin 2 1/2" system and then people say "oh there no difference between mandrel and press as far as performance goes".
But a 2 1/4" mandrel system would probably flow the same as a 2 3/4" press bent system, with less drone/resonance.
Sort of like if you get custom mandrel bent headers 1 1/2" pipes would do the same as 1 3/4" off shelf press bent pipes that have some bad bends in them, but people like to claim bigger is better.
On most cars they will dyno around the same numbers stock weither they have a twin 2 1/4" or twin 2 1/2" system and then people say "oh there no difference between mandrel and press as far as performance goes".
But a 2 1/4" mandrel system would probably flow the same as a 2 3/4" press bent system, with less drone/resonance.
Sort of like if you get custom mandrel bent headers 1 1/2" pipes would do the same as 1 3/4" off shelf press bent pipes that have some bad bends in them, but people like to claim bigger is better.
Originally Posted by Black02SS
So what you are saying is you actually LOST power with the 2.5 Crush bent X. 326-308= LOSS of 18hp. Now with a better setup, you dyno 340. Which is a 14HP increase over your Macs. I can see that, but not anything more. Also, was the car tuned at any point?
Stock PCM tune for all the pulls.
Originally Posted by PewterNHRA2001
not to complicate things, but, what if he really did gain 32whp? wouldnt all of u want in on the secret? i bet he wouldnt give u the secret since u all doubted him at first...
So would it be better for me just to order the the pipes i need from slp and bolt it all up and have a shop well on the tips or what???
Muffler shop quoted around 250
SLP: intermediate pipe (60) and over the axle (80) + exiting pipes with tips
what would you do
Muffler shop quoted around 250
SLP: intermediate pipe (60) and over the axle (80) + exiting pipes with tips
what would you do