2.5 OD True Duals
08-05-2011, 05:53 PM
#1
2.5 OD True Duals Hi,
Just went with a new True Dual 2.5 OD exhaust setup. It has no H or X pipe but flows up and over the passenger side of the rear axle into a dual inlet/dual outlet magnaflow muffler and then out the back. The problem is: 1) The car sounds like a damn lawn mower at WOT about 3000 rpm 2) The car has so much back pressure that it feels as though it lost 40 or 50 rwhp. The car is a 396, cam specs are .600 intake, .580 exhaust, 248/254 duration @ .50. Head are 54 cc AFR 210s running about 13:1 static compression. I think what may be happening with this new setup is that the new muffler cannot keep up with the heads and cam at high rpm.
My old setup is as follows: 3 Inch true duals, X-pipe, and over the driver and passenger side of axle into 2 single 40 series flowmasters. This set up sounded great and performance was outstanding. The car dynoed at 464 rwhp with the 3inch setup. Best 1/4 run was 12.0 @119 w/ 2.1 ft 60 on nitto 555rs. I changed the setup because the driver side pipe going over the axle was nailing the rear end housing and creating a great deal of wear. I tried to fabricate it several different ways but 3" piping is a bit much going over that side of the axle.
Anyone have a solution? Would power sticks help? Anyone have this issue before with a high horsepower/Street application?
Just went with a new True Dual 2.5 OD exhaust setup. It has no H or X pipe but flows up and over the passenger side of the rear axle into a dual inlet/dual outlet magnaflow muffler and then out the back. The problem is: 1) The car sounds like a damn lawn mower at WOT about 3000 rpm 2) The car has so much back pressure that it feels as though it lost 40 or 50 rwhp. The car is a 396, cam specs are .600 intake, .580 exhaust, 248/254 duration @ .50. Head are 54 cc AFR 210s running about 13:1 static compression. I think what may be happening with this new setup is that the new muffler cannot keep up with the heads and cam at high rpm.
My old setup is as follows: 3 Inch true duals, X-pipe, and over the driver and passenger side of axle into 2 single 40 series flowmasters. This set up sounded great and performance was outstanding. The car dynoed at 464 rwhp with the 3inch setup. Best 1/4 run was 12.0 @119 w/ 2.1 ft 60 on nitto 555rs. I changed the setup because the driver side pipe going over the axle was nailing the rear end housing and creating a great deal of wear. I tried to fabricate it several different ways but 3" piping is a bit much going over that side of the axle.
Anyone have a solution? Would power sticks help? Anyone have this issue before with a high horsepower/Street application?
08-06-2011, 12:47 AM
#4
Staging Lane
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At first I read problem number two and became extremely skeptical, since a dual 2.5 inch system (even without a crossover) should be enough for 95% of the builds on this board...then I got to the next line where you described the build. I think you're in that 5% where you'll be better off with 3 inch. lol.
Honestly, I'd suggest going back to a 3 inch system. I know it sucks that you just got this new system on but realistically you're at a level where you actually do benefit from a larger exhaust. If you don't want to do that you could always stick a couple cutouts before your reducers (I'm assuming your collectors are 3 inch and are reduced to 2.5).
From there your best bet is probably additional mufflers (like people add in I-pipes on GMMG and Loudmouth setups, ya know?) or just replace the magnaflow entirely.
Honestly, I'd suggest going back to a 3 inch system. I know it sucks that you just got this new system on but realistically you're at a level where you actually do benefit from a larger exhaust. If you don't want to do that you could always stick a couple cutouts before your reducers (I'm assuming your collectors are 3 inch and are reduced to 2.5).
From there your best bet is probably additional mufflers (like people add in I-pipes on GMMG and Loudmouth setups, ya know?) or just replace the magnaflow entirely.
08-06-2011, 12:06 PM
#6
a x pipe should help with exhaust scavaging, how much is unknown to me.
I dont like the idea of true duals with no x pipe. Its alot of weight and i think true duals are purely a sound thing.
Could try a single 4" system?
I dont like the idea of true duals with no x pipe. Its alot of weight and i think true duals are purely a sound thing.
Could try a single 4" system?
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08-10-2011, 12:18 PM
#9
Does anyone want the magnaflow 2.5 dual in/dual out muffler? I bought brand new for 100.00 from summit, it has been on the car for 2 days brand new. I will sell for 90.00 shipped. Let me know.
email me at jgalipeau@worcester.edu if your interested.
email me at jgalipeau@worcester.edu if your interested.
