Gain with duals over catback..
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Gain with duals over catback..
I did a search and couldnt find the numbers that Chuck Riddeck got when he compared the mufflex and true duals....anyone have it?
Also anyone else with any evidence of a gain? Dyno, track, SOTP?
Also anyone else with any evidence of a gain? Dyno, track, SOTP?
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Joined: Aug 2001
Posts: 2,262
From: Nashville
Originally posted by 96z
Ive know kmook has posted the gain before...anyone else have a copy.
Ive know kmook has posted the gain before...anyone else have a copy.
Originally posted by Mr. Horsepower
Ok guys, as promised in the other thread I have the dyno results from the dual swap. First off, I'm not making any claims as to which exhaust you should run, just giving you the numbers.... so do with them as you see fit.
I would also prefer not getting into the combination as this is not my car. It belongs to a friend. I know a little about the setup but I don't want to turn this into a "What cam is he running" questionathon (my own word there ).
I will tell you this much... the heads are AFR 200's and I did about an hours worth of cleanup/blending on them last year. The cam is a custom ground Isky hydraulic roller and the other mods are as follows...
1.6:1 CC Magnum rockers, TPIS 1-3/4 headers, ported intake, K&N CAI, Granatelli MAF, AS&M 52mm TB, T56 w/LT4 clutch assembly. Oh yeah, it's a 383 running 11.3:1 compression. That's really about all I know other than the fact that I built the exhaust for it.
Ok, this car was running a 4" Mufflex catback and Rich replaced the Flowmaster with a Borla XR-1. Here are the dyno results from last weekend. I had to transfer these from the dyno graph so they aren't 100% accurate... good enough for this comparison though.
2000 rpm 139 rwhp/356 rwtq
2500 rpm 177/365
3000 rpm 226/395
3500 rpm 288/443
4000 rpm 341/459
4500 rpm 388/443
5000 rpm 408/428
5500 rpm 416/405
5600 rpm 418/396 (rwhp peak)
Tonight we tested the duals. This setup uses 3" to 2.5" transitions right off the collector. It then goes into the Dr. Gas x-pipe and then through a chambered muffler similiar to that used in the CMMG catback system. The system then exits at the side ahead of the rear wheel. It's a 2.5" system. There is a noticable tone difference with this setup. The x-pipe also creates a higher pitch exhaust note in comparison to the 'Y' or a straight dual setup.
Anyways, here are the results...
2000 rpm 150/370
2500 rpm 189/383
3000 rpm 236/416
3500 rpm 292/455
4000 rpm 339/458
4500 rpm 385/442
5000 rpm 413/430
5500 rpm 422/412
5600 rpm 426/401
Obviously the x-pipe is making some good torque over the Mufflex up til about 4000 rpm. From there til just past 4500 rpm the "Y" is winning, then the edge goes back to the x-pipe. This is usually typical of an x-pipe dual exhaust unless the situation is compensated for through valve timing. A little less exhaust duration would probably help gain back some of that torque loss in the 3500-4500 rpm range. AFR's generally have good exhaust ports so that only compounds the problem, which I'd conclude is a loss of volumetric efficiency in that rpm range. Maybe a swap to 1.5's on the exhaust would help. Either way, it warrants a little experimentation.
That's a wrap on the test so, considering this combination is pretty much inline with what most of you are doing, you can draw your own conclusions and go from there.
Any questions?
Take care,
Chuck Riddeck
Progressive Race Engine Development
Ok guys, as promised in the other thread I have the dyno results from the dual swap. First off, I'm not making any claims as to which exhaust you should run, just giving you the numbers.... so do with them as you see fit.
I would also prefer not getting into the combination as this is not my car. It belongs to a friend. I know a little about the setup but I don't want to turn this into a "What cam is he running" questionathon (my own word there ).
I will tell you this much... the heads are AFR 200's and I did about an hours worth of cleanup/blending on them last year. The cam is a custom ground Isky hydraulic roller and the other mods are as follows...
1.6:1 CC Magnum rockers, TPIS 1-3/4 headers, ported intake, K&N CAI, Granatelli MAF, AS&M 52mm TB, T56 w/LT4 clutch assembly. Oh yeah, it's a 383 running 11.3:1 compression. That's really about all I know other than the fact that I built the exhaust for it.
Ok, this car was running a 4" Mufflex catback and Rich replaced the Flowmaster with a Borla XR-1. Here are the dyno results from last weekend. I had to transfer these from the dyno graph so they aren't 100% accurate... good enough for this comparison though.
2000 rpm 139 rwhp/356 rwtq
2500 rpm 177/365
3000 rpm 226/395
3500 rpm 288/443
4000 rpm 341/459
4500 rpm 388/443
5000 rpm 408/428
5500 rpm 416/405
5600 rpm 418/396 (rwhp peak)
Tonight we tested the duals. This setup uses 3" to 2.5" transitions right off the collector. It then goes into the Dr. Gas x-pipe and then through a chambered muffler similiar to that used in the CMMG catback system. The system then exits at the side ahead of the rear wheel. It's a 2.5" system. There is a noticable tone difference with this setup. The x-pipe also creates a higher pitch exhaust note in comparison to the 'Y' or a straight dual setup.
Anyways, here are the results...
2000 rpm 150/370
2500 rpm 189/383
3000 rpm 236/416
3500 rpm 292/455
4000 rpm 339/458
4500 rpm 385/442
5000 rpm 413/430
5500 rpm 422/412
5600 rpm 426/401
Obviously the x-pipe is making some good torque over the Mufflex up til about 4000 rpm. From there til just past 4500 rpm the "Y" is winning, then the edge goes back to the x-pipe. This is usually typical of an x-pipe dual exhaust unless the situation is compensated for through valve timing. A little less exhaust duration would probably help gain back some of that torque loss in the 3500-4500 rpm range. AFR's generally have good exhaust ports so that only compounds the problem, which I'd conclude is a loss of volumetric efficiency in that rpm range. Maybe a swap to 1.5's on the exhaust would help. Either way, it warrants a little experimentation.
That's a wrap on the test so, considering this combination is pretty much inline with what most of you are doing, you can draw your own conclusions and go from there.
Any questions?
Take care,
Chuck Riddeck
Progressive Race Engine Development
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