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Re: How much et loss with mufflers ?
[Re: hemi-itis]
#431434
08/09/09 08:50 PM
08/09/09 08:50 PM
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Joined: Jan 2003
Posts: 3,616
Riverside, Ca
G_bob
master
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master
Joined: Jan 2003
Posts: 3,616
Riverside, Ca
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I make no claims to having a great designed exhaust system. It's a three inch system with an H-pipe and spintech mufflers. Definitely not the best flowing when closed as the pipes off the headers are 3.5" that bend to the outside, and then the 3" pipes kind of T-off back to the H and mufflers. Sort of like the stock max wedge system. I'm sure there's got to be some turbulance in that design that hurts performance when the plates are on. To open them, it's as simple as three nuts off each side and take the plates off. I think the only savings I'd get from dropping the whole system is the 50 or so lb weight loss. As said before, with the old motor, on two different back-to-back tests, opening them was worth 3 tenths. Only back-to-back test with the new motor was 2 tenths.  
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Re: How much et loss with mufflers ?
[Re: BobR]
#431437
08/09/09 09:39 PM
08/09/09 09:39 PM
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Joined: Jan 2003
Posts: 5,894
Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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Quote:
Exactly, Mike. Kind of what I said. Some exhaust systems may bandaid a poorly designed/tuned exhaust(primary pipe too big/short-collector too big/short ect). Locomotion, I know you know what's what so I don't have an answer for you. I do know that for classes(non bracket) that don't require an exhaust very seldom is one ever used.
Just theorizing, but considering all the restrictions we have, including no porting, stock lift, compression & valve sizes, I am thinking that the X-pipe helps scavenging and increased the velocity through the entire engine. As mentioned, when I leaned the carb a bit, it ran better! (Stronger signal to the carb?) The 3" pipes and efficient, straight through mufflers are probably not a restriction for my engine size and rpms. So it helped my combo, in particular, to run better.
But over the years, I have heard of some pretty fast muffled cars. Although some did have what were arguably called "mufflers".
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Re: How much et loss with mufflers ?
[Re: Locomotion]
#431438
08/09/09 09:59 PM
08/09/09 09:59 PM
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Joined: Feb 2007
Posts: 6,295
U.S.
moparniac
master
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master
Joined: Feb 2007
Posts: 6,295
U.S.
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I took the whole exhaust sytem off my dart about a week ago! It exited behind the car also..., 63.2 lbs
Mopar Performance
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Re: How much et loss with mufflers ?
[Re: Locomotion]
#431439
08/09/09 10:57 PM
08/09/09 10:57 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
master
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master
Joined: Oct 2004
Posts: 8,165
Left Coast
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Quote:
Quote:
Exactly, Mike. Kind of what I said. Some exhaust systems may bandaid a poorly designed/tuned exhaust(primary pipe too big/short-collector too big/short ect). Locomotion, I know you know what's what so I don't have an answer for you. I do know that for classes(non bracket) that don't require an exhaust very seldom is one ever used.
Just theorizing, but considering all the restrictions we have, including no porting, stock lift, compression & valve sizes, I am thinking that the X-pipe helps scavenging and increased the velocity through the entire engine. As mentioned, when I leaned the carb a bit, it ran better! (Stronger signal to the carb?) The 3" pipes and efficient, straight through mufflers are probably not a restriction for my engine size and rpms. So it helped my combo, in particular, to run better.
But over the years, I have heard of some pretty fast muffled cars. Although some did have what were arguably called "mufflers".
Are you using step headers and a merge collector?
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Re: How much et loss with mufflers ?
[Re: ProSport]
#431440
08/09/09 11:03 PM
08/09/09 11:03 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
master
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master
Joined: Oct 2004
Posts: 8,165
Left Coast
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Quote:
Quote:
IMO this is about right for a full street exhaust of ANY BRAND. Anyone who does not pick up significantly is probably in need of collector extensions and/or jetting/timing changes or just isn't moving a lot of exhaust-aka not making a lot of power.
So you're telling me that a muffled street car should drop 2 tenths just by dropping the exhaust no matter what kind of exhaust system they run?
I tried 2 different lengths of collector extensions and tried re-jetting up and down and timing and could not get the car to run quicker with open headers, that made me very happy so the exhaust never had to be dropped again.
You might be right that the headers may not be perfect but who's gonna try a bunch of different headers to try and beat the times you turned with your exhaust system. And at 134-136 MPH I think that's decent power for a street car.
I think a good exhaust system will not slow a car down. 
Not trying to crap in anybodies Wheaties but I will maintain that for the vast majority of racers if an exhaust system makes better power than open headers you've got some more sorting out to do. I've raced everything from stock eliminator to Outlaw 10.5 and I've never had a car that went faster with tubes and muffs and have never known anyone else that did either. Locomotion's deal surprises me.
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Re: How much et loss with mufflers ?
[Re: BobR]
#431441
08/10/09 12:14 PM
08/10/09 12:14 PM
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Joined: Jan 2003
Posts: 5,894
Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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Quote:
[
Are you using step headers and a merge collector?
The headers are off-the-shelf TTI stepped headers - 1 5/8"-1 3/4", coated in and out. The collector is a standard style, non-removable and somewhat short that I ran with extensions.
* Perhaps the exhaust system overall helped torque because my minimum weight is 3,530 and I usually run 20-40 lbs over that? Heavier than most 340/360 Stockers.
* I don't know if the X-pipe without mufflers would help more. Doesn't Nascar use X-pipes? But I got the Dynomax Ultra-Flos because the are straight through and seemed to flow well based on published #'s. (I kinda like the quieter sound now!)
* I wish I had time to devote to specific testing. I'd have to fab new hangers if the mufflers were removed. But I ran the headers open for several years and tinkered with the jetting whenever time allowed. Then it ran a little better leaned out a few #'s after the exhaust system was put on. Maybe .05, but not more than .10.
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Re: How much et loss with mufflers ?
#431445
08/11/09 09:31 AM
08/11/09 09:31 AM
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Joined: Mar 2003
Posts: 15,489
the boonies
aarcuda
I Live Here
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I Live Here
Joined: Mar 2003
Posts: 15,489
the boonies
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Quote:
I have noticed little to no gain with my 3" exhaust uncapped or running it all the way out back..11.0's either way.. 
thats just because youre awesome
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Re: How much et loss with mufflers ?
[Re: Kindafast]
#431446
08/11/09 09:46 AM
08/11/09 09:46 AM
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Joined: Nov 2003
Posts: 2,273
Greenville, South Carolina
BBLM23
top fuel
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top fuel
Joined: Nov 2003
Posts: 2,273
Greenville, South Carolina
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When I first got the K I put the 451 in to slow the car into the 10's. The car came with 4 inch glasspacks, I had them on. When I needed to make 2 passes in the 9's I took off the mufflers and air cleaner. I had run 10.007 pulled off the mufflers and air filter and ran 10.007. I had to change the converter to get the 9 second runs a week later. Then it ran 9.87.
Walter
1969 Dart Swinger w/ARC Pump Gas 493 B1/BS 10.18 at 130mph
Racing Pro in street trim.
1981 Aries ARC 548 B1 8.88 at 147mph (footbraking)
1996 Ram 2500 V10 16.52 at 80mph
1981 Reliant 400
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Re: How much et loss with mufflers ?
[Re: aarcuda]
#431447
08/11/09 10:41 AM
08/11/09 10:41 AM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
Quote:
I have noticed little to no gain with my 3" exhaust uncapped or running it all the way out back..11.0's either way..
thats just because youre awesome
No,but my car is.. 
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Re: How much et loss with mufflers ?
[Re: jinxy]
#431448
08/11/09 11:59 AM
08/11/09 11:59 AM
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Joined: Jan 2003
Posts: 5,894
Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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Quote:
Myron,
Do you tune your stocker with an air/fuel ratio gauge? If so, what kind of ratio do you tune for at wot?
Jeff
Sorry, I haven't gotten that fancy yet! I just make a change and run it, making sure I do everything the same way, everything else is the same with the car and take into account any changes in the weather. Double-checked when possible. I keep track of as many details as I can.  Never had the engine or the car on a dyno either. Despite doing well, I don't have the time or budget to do as much as I'd like to. 
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