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Just curious, has anyone ever swapped mufflers and picked up E.T.? If so how much, what mufflers, what size exhaust and whats your approximate horsepower? I've seen dyno claims that say there is power to be gained by getting rid of my Flowmasters but I'm not sure I buy it, at least in my application. Thoughts?
I put a set of Dynomax Bullet 14x 3.5 race mufflers on the car later that same day after getting beat in the brackets and it slowed down right at .12 ET and 1.2 MPH My last street and strip car with a three inch system with a set of 14x7 oval x 3 inch in and out Magnaflows changed .04 ET and .2 MPH in the eight mile removing the complete exhaust system 
The muffs on that car where mounted behind the rear end at the rear bumper so the weight may have been the basic difference for the change and maybe not the back pressure 
Flow masters are not the best muffs out there 
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http://www.boyleworks.com/ta400/psp/exhaust.html
Although I really like the sound of the Flowmaster's it's to bad they perform so poorly in comparison to others. I wish they hadn't tested on a single exhaust application. Not really apples to apples, but still useful none the less.Quote:
Personally, I run electric cut-outs on all my cars. That way, I can have my quiet and my noise with no compromise on performance. And they are a blast at shows and cruises.
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my 605 hemi was almost a tenth faster through the muffs. 4 inch straight pipes into borla XR1, turned down in front of rear ladder bar crossmember.
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When you guys run open headers do you put collector extension on? Dulcich did an extensive header comparison awhile back on a hot 440 (Hooker super comp headers I think) and a proper length collector extension was worth a ridiculous amount of power over the factory collector length, something like 40-60 HP, but only in the lower to mid range level, it didn't seem to make a huge difference in the upper RPM's. I think the engine dyno'ed in the 600+HP range.
Quote:You probally did jet it up to much, go back and try it again with the same jetting with and without the exhaust system on it
i have a demon with a 440 . i run pro parts headers an H pipe and 3" flows dumped at the axle. my car has tons of torque and bottom end . i droped the exaust and jetted up 4 sizes went to the track didnt get to make any changes but the car lost all bottom end it was very lazy . im going to run exaust next time i go but the car felt slower to me maybe i jetted up to much i dont know?
Usually, when removing the back pressure of the exhaust, you jet the carb. down one or two jet sizes to make the car go faster 
BTW, by jetting the carb. up with the open exhaust you did prove your fuel system has enough volume to slow the car down, which is a good test It is far safer to jet the motor up to slow the car down first and then jet it down a little bit at a time(one jet size at a time, not four 
) until it starts to loose MPH in 1/4 Let us know your results
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I think 18" give or take not very much was the magic number depending on what was less than ideal in your combo.
Kevin
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When you guys run open headers do you put collector extension on? Dulcich did an extensive header comparison awhile back on a hot 440 (Hooker super comp headers I think) and a proper length collector extension was worth a ridiculous amount of power over the factory collector length, something like 40-60 HP, but only in the lower to mid range level, it didn't seem to make a huge difference in the upper RPM's. I think the engine dyno'ed in the 600+HP range.
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That's because the high velocity pulses of the tubes exiting into the collecter create a 'draw' (Bernoulli effect) behind them felt by the adjacent tubes. If there's not a sufficient amount of downstream volume the draw "scavenging" is minimized or negated.
flowmaster theory is also related to creating a low pressure area that draws (creates a negative pressure) on the upstream pipe, the CFM flow of pumping air through a muffler tells "A" story, but not the whole story....so just like flowing an intake port...take raw CFM data with a grain of salt.
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That's because the high velocity pulses of the tubes exiting into the collecter create a 'draw' (Bernoulli effect) behind them felt by the adjacent tubes. If there's not a sufficient amount of downstream volume the draw "scavenging" is minimized or negated.
flowmaster theory is also related to creating a low pressure area that draws (creates a negative pressure) on the upstream pipe, the CFM flow of pumping air through a muffler tells "A" story, but not the whole story....so just like flowing an intake port...take raw CFM data with a grain of salt.
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That's because the high velocity pulses of the tubes exiting into the collecter create a 'draw' (Bernoulli effect) behind them felt by the adjacent tubes. If there's not a sufficient amount of downstream volume the draw "scavenging" is minimized or negated.
flowmaster theory is also related to creating a low pressure area that draws (creates a negative pressure) on the upstream pipe, the CFM flow of pumping air through a muffler tells "A" story, but not the whole story....so just like flowing an intake port...take raw CFM data with a grain of salt.
Would it be logical to assume that a properly designed X-pipe creates the "Bernoulli effect" at the junction as well?
What is the theory behind "merge collector" styles manufactured by Lelchook, Burns, etc.?
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That's because the high velocity pulses of the tubes exiting into the collecter create a 'draw' (Bernoulli effect) behind them felt by the adjacent tubes. If there's not a sufficient amount of downstream volume the draw "scavenging" is minimized or negated.
flowmaster theory is also related to creating a low pressure area that draws (creates a negative pressure) on the upstream pipe, the CFM flow of pumping air through a muffler tells "A" story, but not the whole story....so just like flowing an intake port...take raw CFM data with a grain of salt.
Would it be logical to assume that a properly designed X-pipe creates the "Bernoulli effect" at the junction as well?
What is the theory behind "merge collector" styles manufactured by Lelchook, Burns, etc.?
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A number of experts all told me thoughout the years (and I've found it to be true) that the first 4-6 inches of pipe past the head flange are far more important than all that happens beyond it. In a production chassis the bends required in the initial primary tubes (off the flange) are almost always a compromise.
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A number of experts all told me thoughout the years (and I've found it to be true) that the first 4-6 inches of pipe past the head flange are far more important than all that happens beyond it. In a production chassis the bends required in the initial primary tubes (off the flange) are almost always a compromise.
This is interesting, that sounds like it would make the best option fenderwell headers, which they don't make for any of us other than big block A body guys now. But everyone ran them back in the day. It'd be interesting to see the dyno results of a fenderwell vs an underchassis header of the same size and tube length on the same engine.
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x2 Hey Ron what do you mean spaces the headers with washers over the flow masters?..............Yes please explain this?
Quote:Hmm.....learn something new every day,never herd this b4....Quote:
x2 Hey Ron what do you mean spaces the headers with washers over the flow masters?..............Yes please explain this?
Yes just as was said right where the 3 collector bolts bolt the collector to the header. Just take the bolts out and spread the header and collector apart and put the bolts back in with some washers in the gap on the bolts. Many guys around here did it years ago for the sound but I prefer a closed exh sound myself. But we did it with his car do see how much it slowed as we knew it had gone faster with open headers and it ran just as fast (11.40's) like this then it did with open headers. And this way you dont have to remove or hang the exh pipes out of the way. Ron