3 inch true duals VS 4 inch mufflex with dual outlets
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Joined: Jan 2002
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From: Mobile, Ala..USA
3 inch true duals VS 4 inch mufflex with dual outlets
Which will provide the most performance? I will have 1 7/8 headers and a 383 shifting at 7000 RPM. I already have the mufflex. Mufflex has a dual exit Spintech muffler.
David
David
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Joined: Jan 1999
Posts: 989
From: Baton Rouge, la
I don't know they answer but I do know that when I droped the muffler at the track. I picked up .2 the rest of the day. I ran 3 before runs..then 3 after runs. Consistant results every time. So from what I see that spintech muffler isn't too good for high reving/flowing cars like mine and yours. I do run a 4" bullet in my intermediate pipe so what I had was a 3" mufflex y to a 4" collector to a 4" bullet and 4" pipe over the axle and a turn down where it would mormally enter the muffler. Hope this helps.
tim
tim
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Joined: Jan 2002
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From: Mobile, Ala..USA
Hey Tim, remember me? I ran you at Cruisin the Coast year before last? Black 6 speed Z28 from Mobile? I am building a new Combo, had a weird cam bearing failure in that last engine, going solid roller 383 this time. Think a Borla muffler on that Mufflex will do the trick? I dont want the hassles of true duals, but if I have to......
Big Dave
Big Dave
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Joined: Jan 1999
Posts: 989
From: Baton Rouge, la
yea..I remember you. Maybe a XR1 would help. But I had a borla on my car before I dumped it for the mufflex..there was an improvement to the mufflex so I don't know if the stock type borla would do the trick. Just do what I did. It took me about 10 min to dump the spintech and both tips before I went to the track. Put a 4" bullet in the intermediate pipe. I loved the sound of it. Im prolly gonna dump right after the bullet now and sell the whole mufflex. Plus you save a good bit of weight when you drop it.
This is that setup www.ipsb.net/herringt/spinning.wmv
This is that setup www.ipsb.net/herringt/spinning.wmv
Registered User
Joined: Nov 1998
Posts: 575
From: St Charles MO, USA
i had the single exit muffler with the flowmaster muffler.
first of all the 4 inch system weight a ton, i think the muffler weight more then my 3 inch duals.
i had two cut outs in my y-pipe when i was running the mufflex, and i would gain 22 hp opening them. with the duals i run a little hight mph then i did with the cut outs, so i figure i gained some.
i'll have it back on a dyno soon.
i hope that made sense
first of all the 4 inch system weight a ton, i think the muffler weight more then my 3 inch duals.
i had two cut outs in my y-pipe when i was running the mufflex, and i would gain 22 hp opening them. with the duals i run a little hight mph then i did with the cut outs, so i figure i gained some.
i'll have it back on a dyno soon.
i hope that made sense
Registered User
Joined: Oct 2002
Posts: 1,639
From: Toledo, OH
Why not a normal cat-back...and run two 3" cutouts directly after each header collector for the track, that will net you the most performance possible without open heads
, then you can keep it reasonably quiet on the street.
, then you can keep it reasonably quiet on the street.
Registered User
Joined: Nov 1998
Posts: 575
From: St Charles MO, USA
Originally posted by jonaddis84
Why not a normal cat-back...and run two 3" cutouts directly after each header collector for the track, that will net you the most performance possible without open heads , then you can keep it reasonably quiet on the street.
Why not a normal cat-back...and run two 3" cutouts directly after each header collector for the track, that will net you the most performance possible without open heads
, then you can keep it reasonably quiet on the street.
Advanced Tech Moderator
Joined: Aug 2001
Posts: 2,262
From: Nashville
I will give my infamous quote of Chuck that I always do when this question arises-
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
Last edited by kmook; Jan 10, 2004 at 02:01 AM.
Thread Starter
Banned
Joined: Jan 2002
Posts: 1,935
From: Mobile, Ala..USA
Looks like a Mufflex with a race type straight through muffler and a 4 inch turndown for me, this will be a true street car, the brain damage that true duals gives it not worth 6 hp and 6 lb ft of torque. Wonder what a 3 inch dual setup would net? Shows how good the Mufflex is , to me anyway.
Registered User
Joined: Oct 2002
Posts: 1,639
From: Toledo, OH
Id look at that dyno graph closer before you say 6hp/6lbft....thats everyones problem is they look at max hp/tq, max dont mean ****, you want to know what it is at different rpms. look right off the bat, 14 ft/lbs more torque and 11 more hp. and its at least that up to 4000 rpms then they are about equal, then the duals get a big advantage again. This probably just made the decision for me to go with duals, either that or a cutout after each collector....oh and how did ground clearance suck with cutouts after the collectors? they shouldnt be any lower than the pipe, unless you had the outlets pointing down, which isnt necessary
Registered User
Joined: Nov 1998
Posts: 575
From: St Charles MO, USA
Originally posted by jonaddis84
Id look at that dyno graph closer before you say 6hp/6lbft....thats everyones problem is they look at max hp/tq, max dont mean ****, you want to know what it is at different rpms. look right off the bat, 14 ft/lbs more torque and 11 more hp. and its at least that up to 4000 rpms then they are about equal, then the duals get a big advantage again. This probably just made the decision for me to go with duals, either that or a cutout after each collector....oh and how did ground clearance suck with cutouts after the collectors? they shouldnt be any lower than the pipe, unless you had the outlets pointing down, which isnt necessary
Id look at that dyno graph closer before you say 6hp/6lbft....thats everyones problem is they look at max hp/tq, max dont mean ****, you want to know what it is at different rpms. look right off the bat, 14 ft/lbs more torque and 11 more hp. and its at least that up to 4000 rpms then they are about equal, then the duals get a big advantage again. This probably just made the decision for me to go with duals, either that or a cutout after each collector....oh and how did ground clearance suck with cutouts after the collectors? they shouldnt be any lower than the pipe, unless you had the outlets pointing down, which isnt necessary
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