Dual exhaust with glasspacks
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#8
Why ISN'T a bigger pipe always better?
Got this off the Magnaflow site:
MagnaFlow's Frequently Asked Questions
Question: Why ISN'T a bigger pipe always better?
Answer: Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.
Not true. Due to a variety of factors, extensive testing is required. We've dyno'd extensively and our systems yield optimum power increases. Some manufacturers claim even higher horsepower numbers.
It is a fine line to reduce backpressure while maintaining good exhaust velocity. It is not about getting the biggest pipe, it is about getting a more efficient pipe diameter while maintaining exhaust velocity.
There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency.
Use the guide below when calculating pipe size for custom exhaust work. Keep in mind that the goal is to improve exhaust flow. In most cases, just changing the restrictive OEM muffler and replacing it with the same size straight-through, Wide Open Performance MagnaFlow muffler will do the job.
To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-bent tubing of the same size or one size up from the OEM. As a general rule, you can enlarge the pipe diameter of your OEM exhaust system by 1/4 to 1/2-inch to increase your horsepower. However, any additional increase in pipe diameter is likely to decrease your performance; specifically, low end torque.
MUFFLER INLET/OUTLET
ENGINE SIZE HORSEPOWER Single Exhaust Dual Exhaust
150-200 CID 100 to 150 2" to 2-1/4" 2"
200-250 CID 100 to 200 2-1/4" to 2-1/2" 2" to 2-1/4"
250-300 CID 150 to 250 2-1/2" to 3" 2" to 2-1/2"
300-350 CID 200 to 350 2-1/2" to 3" 2-1/4" to 2-1/2"
350-400 CID 250 to 550 3" to 4" 2-1/2" to 3"
Use as a general guide for engine size and performance
MagnaFlow's Frequently Asked Questions
Question: Why ISN'T a bigger pipe always better?
Answer: Don't be fooled! Bigger is not better! Many people think that having the biggest diameter pipe is the best way to make power.
Not true. Due to a variety of factors, extensive testing is required. We've dyno'd extensively and our systems yield optimum power increases. Some manufacturers claim even higher horsepower numbers.
It is a fine line to reduce backpressure while maintaining good exhaust velocity. It is not about getting the biggest pipe, it is about getting a more efficient pipe diameter while maintaining exhaust velocity.
There has to be a balanced design to enhance the maximum engine output, exhaust gas velocity, and sound. For example, imagine blowing air through a straw (comparing it to a smaller diameter pipe). This would take time to release all the air from your mouth, and you would feel pressure in your mouth while doing so. Now imagine blowing air through a paper towel roll (comparing it to a larger diameter pipe). You will relieve all your air much faster and feel little or no air pressure in your mouth because of the larger capacity of the tube. This is why it is important to get the correct size piping in order to relieve backpressure while maintaining thermal efficiency.
Use the guide below when calculating pipe size for custom exhaust work. Keep in mind that the goal is to improve exhaust flow. In most cases, just changing the restrictive OEM muffler and replacing it with the same size straight-through, Wide Open Performance MagnaFlow muffler will do the job.
To reduce additional backpressure, the OEM exhaust tubing can be replaced with mandrel-bent tubing of the same size or one size up from the OEM. As a general rule, you can enlarge the pipe diameter of your OEM exhaust system by 1/4 to 1/2-inch to increase your horsepower. However, any additional increase in pipe diameter is likely to decrease your performance; specifically, low end torque.
MUFFLER INLET/OUTLET
ENGINE SIZE HORSEPOWER Single Exhaust Dual Exhaust
150-200 CID 100 to 150 2" to 2-1/4" 2"
200-250 CID 100 to 200 2-1/4" to 2-1/2" 2" to 2-1/4"
250-300 CID 150 to 250 2-1/2" to 3" 2" to 2-1/2"
300-350 CID 200 to 350 2-1/2" to 3" 2-1/4" to 2-1/2"
350-400 CID 250 to 550 3" to 4" 2-1/2" to 3"
Use as a general guide for engine size and performance
#10
Glasspack
I just installed a Thrush Magnum Glasspack ($30 at O'Reily's) this weekend. It sounds awesome. Nice rumble, sounds like a muscle car with a lower tone. I have not complaints whatsoever. it's 28" long so you will need to buy at least 10" of extra piping to make the difference. let me know if you have any questions.
#12
ive got 18" glasspacks with 2 1/2" stock pipe out to 5" tips out under the corners and mine are pretty dang loud on a 4.6L.
https://www.f150online.com/galleries/mygallery.cfm?gnum=7113
https://www.f150online.com/galleries/mygallery.cfm?gnum=7113
#13
I like to run the 'packs with one size smaller pipe coming out then coming in, it's an old rodder trick. For instance, on my Bronco, I plan on running 2.25" in and 2" out. Gives it a hell of a rumble.
Another idea I like is simply to cut the muffler out and stick a set of Harley-Davidson baffles into the pipe. Heard this on an '31 Ford with an Olds straight 8 once, had 8 pipes coming straight out of the engine about 14". Sounded fantastic.
Another idea I like is simply to cut the muffler out and stick a set of Harley-Davidson baffles into the pipe. Heard this on an '31 Ford with an Olds straight 8 once, had 8 pipes coming straight out of the engine about 14". Sounded fantastic.
Last edited by jcp123; 01-21-2006 at 09:04 PM.
#15
Here is a link to a thread that has a video and sound clip of glass packs. Hope this helps.
https://www.f150online.com/forums/sh...d.php?t=210074
https://www.f150online.com/forums/sh...d.php?t=210074