Equal, Unequal headers...wtd?

Unit 5302 · 11-22-2001, 12:46 AM

Do I dare make another marathon post on this subject? Sure.

Equal Length Shorties: These headers rob low end torque, in a big way. They are not normally available in a size smaller than 1 5/8", which is too big for a stock engine anyway. Bigger is not always better. These headers offer a tuning effect which actually pulls the exhaust out of the head. The cost of that is lower cylinder pressure and less torque at lower rpms. Part of the reason this happens is the size. The factory exhaust ports on the E7's are very small. Since the header primary tube is larger, it has a tendancy to suck exhuast from the expansion. The other part is the way the exhaust pulses increase the exhaust velocity, or scavenging. The minor gain in horsepower over the unequal shorties are not worth it in my opinion. They are more difficult to install, they cost more, and as a general rule, they are more difficult to work around.

UnEqual Length Shorties: These headers allow for less restrictive exhuast flow, but do not tune the exhaust like the equal shorties. They are good for some horsepower over the restrictive factory headers, and if the 1 1/2" primary tube headers are purchased, they do not rob low end torque. 1 5/8" will rob torque because of the exhaust expansion noted above, but less drastically due to the lack of the additional scavenging effect. The 1 1/2" unequals could be good for mildly modded 5.0 without any cam swaps or anything drastic.

Long Tubes: Long tubes are the big daddies literally, and figuratively. They make more hp than the equal shorties due to a better scavenging effect, but they do not rob torque. The full sized and developed collector, along with the longer tubes acts much more like a tuned 2 cycle exhaust. It blocks the flow of the cylinders not on exhaust stroke, and tunes it for the ones that are. That creates a full tuned effect which is generally worth noteable gains in performance for even a stock car, along with excellent drivablilty.

The H pipe is the real bottleneck in the stock Mustang exhaust system, and it should be addressed first, or at the same time.

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11-22-2001, 12:46 AM	#12
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Do I dare make another marathon post on this subject? Sure. Equal Length Shorties: These headers rob low end torque, in a big way. They are not normally available in a size smaller than 1 5/8", which is too big for a stock engine anyway. Bigger is not always better. These headers offer a tuning effect which actually pulls the exhaust out of the head. The cost of that is lower cylinder pressure and less torque at lower rpms. Part of the reason this happens is the size. The factory exhaust ports on the E7's are very small. Since the header primary tube is larger, it has a tendancy to suck exhuast from the expansion. The other part is the way the exhaust pulses increase the exhaust velocity, or scavenging. The minor gain in horsepower over the unequal shorties are not worth it in my opinion. They are more difficult to install, they cost more, and as a general rule, they are more difficult to work around. UnEqual Length Shorties: These headers allow for less restrictive exhuast flow, but do not tune the exhaust like the equal shorties. They are good for some horsepower over the restrictive factory headers, and if the 1 1/2" primary tube headers are purchased, they do not rob low end torque. 1 5/8" will rob torque because of the exhaust expansion noted above, but less drastically due to the lack of the additional scavenging effect. The 1 1/2" unequals could be good for mildly modded 5.0 without any cam swaps or anything drastic. Long Tubes: Long tubes are the big daddies literally, and figuratively. They make more hp than the equal shorties due to a better scavenging effect, but they do not rob torque. The full sized and developed collector, along with the longer tubes acts much more like a tuned 2 cycle exhaust. It blocks the flow of the cylinders not on exhaust stroke, and tunes it for the ones that are. That creates a full tuned effect which is generally worth noteable gains in performance for even a stock car, along with excellent drivablilty. The H pipe is the real bottleneck in the stock Mustang exhaust system, and it should be addressed first, or at the same time.