Headers
#1
02-11-2015
Join Date: Feb 2015
Location: Norfolk, VA
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#2
02-11-2015
Join Date: Apr 2007
Location: Placentia, CA
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The JBA headers are the only ones I know of, but they are expensive and do not increase the performance the 4.0 by much. You are much better off getting a tuner for around the same price.
Why do you want to replace the headers? The stock ones flow pretty good and nobody makes long headers for a ranger.
Why do you want to replace the headers? The stock ones flow pretty good and nobody makes long headers for a ranger.
#3
02-11-2015
yes ^^^
Exhaust systems changes are pretty well documented in what they do and don't do.
30-40 years ago auto makers just slapped on an exhaust manifold with minimal design effort.
With the advent of emissions and higher fuel prices all exhaust systems are now tuned.
But generally for mid-ranger power.
What a tuned exhaust system does:
It uses the exhausts Velocity to lower the air pressure at the exhaust ports in the head.
When you put a fast moving gas in a small diameter pipe and then dump it into a larger diameter pipe you get a pressure drop, this is called scavenging the exhaust flow.
Now the tricky part of the design is to get the lowest pressure at a specific RPM.
Auto manufacturers aim for lowest pressure in the mid-range
Header makers will usually have 2 models, one that moves the low pressure down in the RPM range, and one that moves it up in the RPM range(race cars want high RPM power band)
These do not increase power, they just move the lowest pressure around, so you feel the power earlier or later in the RPM range.
The myth of "back pressure"
This comes from people designing their own exhaust systems.
No engine likes or needs back pressure(not counting two-stroke engines, they do need it, lol)
People would slap on 3" pipes at the heads for "a free flowing system", and lose power, WTF!!!
"Engine must need back pressure", wrong conclusion.
The larger pipes at the heads reduced the Velocity in the system so they lost any possible low pressure from the flow, so they lost the power they had from the original smaller pipe design.
Exhaust systems changes are pretty well documented in what they do and don't do.
30-40 years ago auto makers just slapped on an exhaust manifold with minimal design effort.
With the advent of emissions and higher fuel prices all exhaust systems are now tuned.
But generally for mid-ranger power.
What a tuned exhaust system does:
It uses the exhausts Velocity to lower the air pressure at the exhaust ports in the head.
When you put a fast moving gas in a small diameter pipe and then dump it into a larger diameter pipe you get a pressure drop, this is called scavenging the exhaust flow.
Now the tricky part of the design is to get the lowest pressure at a specific RPM.
Auto manufacturers aim for lowest pressure in the mid-range
Header makers will usually have 2 models, one that moves the low pressure down in the RPM range, and one that moves it up in the RPM range(race cars want high RPM power band)
These do not increase power, they just move the lowest pressure around, so you feel the power earlier or later in the RPM range.
The myth of "back pressure"
This comes from people designing their own exhaust systems.
No engine likes or needs back pressure(not counting two-stroke engines, they do need it, lol)
People would slap on 3" pipes at the heads for "a free flowing system", and lose power, WTF!!!
"Engine must need back pressure", wrong conclusion.
The larger pipes at the heads reduced the Velocity in the system so they lost any possible low pressure from the flow, so they lost the power they had from the original smaller pipe design.
#4
03-01-2017
Join Date: Mar 2017
Location: Wheaton, MD
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I had these JBA headers installed for me by a mechanic.
I got the 1 1/2” Titanium ceramic coated Stainless steel Cat4wardŽ Shorty, w/ Driver side EGR #1674S-1JT from jegs.com.
The mechanic ran into a problem, where I think, two of the mounting holes in the header had to be made slightly larger to fit over the studs.
Also, the stock EGR pipe was about 1" too short to attach to the new header, and the EGR valve. One good thing is that the EGR fitting did attach to the header bung OK.
I had to cut the EGR pipe close to the EGR valve, and I used high temperature hose, and metal tape to take up the gap.
I first tried the high temperature hose by itself, and it melted and leaked, and it triggered a computer code. I then had to put on the metal tape.
Not putting it on a dyno or anything, just an educated/seat of the pants feel:
I'd say these headers gave me about 5 horsepower.
I noticed the difference immediately.
I got the 1 1/2” Titanium ceramic coated Stainless steel Cat4wardŽ Shorty, w/ Driver side EGR #1674S-1JT from jegs.com.
The mechanic ran into a problem, where I think, two of the mounting holes in the header had to be made slightly larger to fit over the studs.
Also, the stock EGR pipe was about 1" too short to attach to the new header, and the EGR valve. One good thing is that the EGR fitting did attach to the header bung OK.
I had to cut the EGR pipe close to the EGR valve, and I used high temperature hose, and metal tape to take up the gap.
I first tried the high temperature hose by itself, and it melted and leaked, and it triggered a computer code. I then had to put on the metal tape.
Not putting it on a dyno or anything, just an educated/seat of the pants feel:
I'd say these headers gave me about 5 horsepower.
I noticed the difference immediately.
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