What advantage does a long tube header have over an equal lenth shorty? Is it worthwhile in terms of gains in a 331 stroker with HCI? Better with X or H pipe? better with Cats or without? thanks.
Long vs. Short! headers...that is
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LT's promote scavenging
The e pulse of one hole sucks the gas from another hole to help get rid
of the e gas
This is done in part because of the collector
You don't get this from shortys cause they have no collector
This promotes better low and mid range torque which is usually
more than just a subtle gain
PA
You got the pa cramming down the mix therefore the benefit of
scavenging is not as much of a deal breaker as with NA which
only has 1 atmosphere to work with
There ... I've already told you more than I know
Grady
LT's promote scavenging
The e pulse of one hole sucks the gas from another hole to help get rid
of the e gas
This is done in part because of the collector
You don't get this from shortys cause they have no collector
This promotes better low and mid range torque which is usually
more than just a subtle gain
PA
You got the pa cramming down the mix therefore the benefit of
scavenging is not as much of a deal breaker as with NA which
only has 1 atmosphere to work with
There ... I've already told you more than I know
Grady
WhiteCobra95
Mod Dude
- May 2, 2006
- 565
- 144
- 74
Like any car mod or engineering practice, there are many compromises. Here are some things to consider before you move forward.
SCIENCE:
Shorties offer a reduction in flow restriction compared to the stock headers. Less restriction = lower pumping losses and more potential peak flow. There are two types, unequal length and equal length primary tube shorty headers. This is a hot topic, but numerous tests have shown that there isn’t much advantage to equal length shorties due to the crazy pretzel routing that’s required to achieve their goal. The primary tubes of shorty headers are also too short to setup a scavenging resonance in the exhaust, so the equal length tubes doesn’t offer much advantage.
Long tubes offer the same flow restriction reduction with a tuning advantage as well. As mentioned above, the pulse of the exhaust gas from one cylinder creates a vacuum across the primary tube of another cylinder which can actually pull residual exhaust gas out of that cylinder and more fresh air charge in from the intake manifold. (The primary tubes on shorty headers are too short and the exhaust pulses are mistimed for our rpm range to create the scavenging effect.) This effect can be calculated using the dimensions of the long tube headers and the Helmholtz equation.
Power Production:
Long tubes will make more torque and power. Their effect will become more apparent the more radical the engine mods become.
Sound:
Long tubes just sound cooler. Both will probably make the car a bit louder than the stock headers, all else equal.
Installation:
Long tubes are a PITA to install. Most require unbolting the engine mounts and partially lifting the engine in order to clear the cross member. I think the passenger side header on SN95’s requires that the starter motor come out as well, but this is subject to the manufacturer’s routing. On our 5.0 SN95’s, most of the long tubes have dumped the EGR fitting so you will probably have to remove or plug your EGR valve.
Shorties are just like replacing the stock manifolds, which is much easier than long tubes.
Both header types will require special “header” bolts with smaller hex-heads to clear the larger-than-stock primary tubes. (Buy stainless!) The length of these bolts depends on the thickness of the header flange and if the bolt can even be fed through the flange next to a primary tube. (I think the standard thread length of the SBF header bolt is 0.75”. This is only gives a couple threads to grab on the head if you have a 3/8” header flanges. Not a big deal for iron heads, but cause for concern with aluminum heads since the threads in the head are much softer. In that case a 1” or longer header bolt would be ideal if it will fit.)
Post Installation:
Keep checking the header bolts for sings of them loosening up. The gaskets sometimes shrink with heat cycles, and this will require the bolts to be retorqued, multiple times. I find it works really well to give the botls a good twist with the egnine/exhaust hot - not noramlly a good practice, but it seems to work well for headers.
Materials:
Regardless of what brand and type you get, go ceramic coated. They look a whole lot better, keep the engine compartment cooler, and last a lot longer. Also, the thicker the header flange to the head is the better. Header flanges can warp. The thicker ones are less prone to this and have more meat to resurface if they do.
Price:
Long tubes are around 50% to 100% more expensive than Shorty headers. You can make up a fraction of this price difference since the H/X-pipes for long tube headers are a little bit cheaper than shorty H/X pipes. Long tubes also require extensions ($$) for the O2 sensor wires since they will have to be located at or behind the collector.
Equal length shorty headers are more expensive than unequal length shorty headers.
FIT:
Long tubes sometimes have ground clearance issues on lowered cars, depending on the header manufacturer and your suspension setup. Long tubes also have a tendency to burn clutch cables, rag joints, and interfear with your steering shaft. These issues could require either heat wrap, different clutch cable routing, or a solid steering shaft to resolve them.
Unequal length shorty headers usually fit in nearly the same place as the stock headers. Equal length shorty headers take up more space due to the convoluted routing and tend to rake havoc on spark plug wires, which might require the purchase of plug wire heat shields/temperature boots.
H/X pipes on long tubes are pretty straight forward. It’s usually best to go with the same manufacturers parts to insure a proper fit. It seems like it’s becoming harder to find long tube H/X pipes with cats, if that’s a concern.
H/X pipes with shorty header offer a bit more variety; you can use a stock H-pipe or aftermarket H/X-pipe. The main issues with the aftermarket pipes are fitment problems. These pipes have to include down-pipe section reaching up into the engine compartment and mage to the headers, usually in the stock locations. (More complex bends, more potential for error.)
All header types usually require some manipulation of the dip stick tube bracket for clearance of the larger primary tubes, but this is usually minor.
Conclusion:
Take all of these into consideration and weigh them carefully. Each approach has it’s own share of pros and cons / benefits and headaches.
Good Luck!
SCIENCE:
Shorties offer a reduction in flow restriction compared to the stock headers. Less restriction = lower pumping losses and more potential peak flow. There are two types, unequal length and equal length primary tube shorty headers. This is a hot topic, but numerous tests have shown that there isn’t much advantage to equal length shorties due to the crazy pretzel routing that’s required to achieve their goal. The primary tubes of shorty headers are also too short to setup a scavenging resonance in the exhaust, so the equal length tubes doesn’t offer much advantage.
Long tubes offer the same flow restriction reduction with a tuning advantage as well. As mentioned above, the pulse of the exhaust gas from one cylinder creates a vacuum across the primary tube of another cylinder which can actually pull residual exhaust gas out of that cylinder and more fresh air charge in from the intake manifold. (The primary tubes on shorty headers are too short and the exhaust pulses are mistimed for our rpm range to create the scavenging effect.) This effect can be calculated using the dimensions of the long tube headers and the Helmholtz equation.
Power Production:
Long tubes will make more torque and power. Their effect will become more apparent the more radical the engine mods become.
Sound:
Long tubes just sound cooler. Both will probably make the car a bit louder than the stock headers, all else equal.
Installation:
Long tubes are a PITA to install. Most require unbolting the engine mounts and partially lifting the engine in order to clear the cross member. I think the passenger side header on SN95’s requires that the starter motor come out as well, but this is subject to the manufacturer’s routing. On our 5.0 SN95’s, most of the long tubes have dumped the EGR fitting so you will probably have to remove or plug your EGR valve.
Shorties are just like replacing the stock manifolds, which is much easier than long tubes.
Both header types will require special “header” bolts with smaller hex-heads to clear the larger-than-stock primary tubes. (Buy stainless!) The length of these bolts depends on the thickness of the header flange and if the bolt can even be fed through the flange next to a primary tube. (I think the standard thread length of the SBF header bolt is 0.75”. This is only gives a couple threads to grab on the head if you have a 3/8” header flanges. Not a big deal for iron heads, but cause for concern with aluminum heads since the threads in the head are much softer. In that case a 1” or longer header bolt would be ideal if it will fit.)
Post Installation:
Keep checking the header bolts for sings of them loosening up. The gaskets sometimes shrink with heat cycles, and this will require the bolts to be retorqued, multiple times. I find it works really well to give the botls a good twist with the egnine/exhaust hot - not noramlly a good practice, but it seems to work well for headers.
Materials:
Regardless of what brand and type you get, go ceramic coated. They look a whole lot better, keep the engine compartment cooler, and last a lot longer. Also, the thicker the header flange to the head is the better. Header flanges can warp. The thicker ones are less prone to this and have more meat to resurface if they do.
Price:
Long tubes are around 50% to 100% more expensive than Shorty headers. You can make up a fraction of this price difference since the H/X-pipes for long tube headers are a little bit cheaper than shorty H/X pipes. Long tubes also require extensions ($$) for the O2 sensor wires since they will have to be located at or behind the collector.
Equal length shorty headers are more expensive than unequal length shorty headers.
FIT:
Long tubes sometimes have ground clearance issues on lowered cars, depending on the header manufacturer and your suspension setup. Long tubes also have a tendency to burn clutch cables, rag joints, and interfear with your steering shaft. These issues could require either heat wrap, different clutch cable routing, or a solid steering shaft to resolve them.
Unequal length shorty headers usually fit in nearly the same place as the stock headers. Equal length shorty headers take up more space due to the convoluted routing and tend to rake havoc on spark plug wires, which might require the purchase of plug wire heat shields/temperature boots.
H/X pipes on long tubes are pretty straight forward. It’s usually best to go with the same manufacturers parts to insure a proper fit. It seems like it’s becoming harder to find long tube H/X pipes with cats, if that’s a concern.
H/X pipes with shorty header offer a bit more variety; you can use a stock H-pipe or aftermarket H/X-pipe. The main issues with the aftermarket pipes are fitment problems. These pipes have to include down-pipe section reaching up into the engine compartment and mage to the headers, usually in the stock locations. (More complex bends, more potential for error.)
All header types usually require some manipulation of the dip stick tube bracket for clearance of the larger primary tubes, but this is usually minor.
Conclusion:
Take all of these into consideration and weigh them carefully. Each approach has it’s own share of pros and cons / benefits and headaches.
Good Luck!
White Cobra, excellent response, I have eq short length Mac's now and they have burnt a wire or 2, I have a used set of BBK 1519 long tubes with an egr outlet that I picked up cheap off CL because they were listed for a `95 GT or Cobra and I just never see them for my `94, and if I was ever going to do it, here;'s my chance. Unfortunately they are chrome and not ceramic so they may get wrapped if I decide to use them, also, they are heavy, well made for sure, flanges are thick and nicely constructed. If it's worth a mph at the track then it's worth it to me, thanks again
HCI 331 is going to need long tube headers. Shorties are going to choke that engine. I use BBK 1519s. Excellent fitting header with no ground clearance issues. I wouldn't worry about them being chrome. I've had mine for 10 years now. They were originally chrome. They look like crap now, but hey if you got a good deal on them, that's what counts.
Kurt
Kurt
earleys94gt
Active Member
Most of the headers for a 5.0, from someone like BBK, are usually 1 5/8 inches.
You want to research this first AND see if they even make some, but you want to look into 1 3/4 inch header. The measurement referers to the size of the individual runners on the header assembly.
The only downside, other than no headers being available, is the collector may require a 3 inch exhaust.
You want to research this first AND see if they even make some, but you want to look into 1 3/4 inch header. The measurement referers to the size of the individual runners on the header assembly.
The only downside, other than no headers being available, is the collector may require a 3 inch exhaust.
MysteryMachine
Active Member
I wouldn't wrap them either. You will sometimes read that wrapping them causes them to rust out faster
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