HP from long tube headers

Cavcloser29 · Jan 28, 2004

I have wondered this for a while and no one has come up with an answer for me. Why do long tude headers give you more Hp than shorty headers?

a_turbo_stang · Jan 28, 2004

Dunno good question. I head they were better and I am currenlty thinking bout getting a set myself.

hllon4whls · Jan 28, 2004

Dont mean to be an a$$, but for the same reason that water freezes at 32' c. Physics. The exhaust pulses like long tube headers. Michael Yount is one of the engineers on the site, maybe he can shed some specific exhaust velocity how tos and what ifs.

StangLou · Jan 28, 2004

I havent had a physics class in YEARS!!! Therefore my answer will stay away from physics talk . I think its something about how L/T's have a greater scavagging capacity. They can pull out more air, creating more backpressure, and thusly yeilding greater hp/torque figures
I dont know if this is remotely accurate, but it makes some sense .

MadMatt5oh · Jan 28, 2004

Long tubes are a PITA to install. I would hope for an added advantage over regular shorties. How much of a difference?

PURESTREET5006 · Jan 29, 2004

Your low,mid and top end will pick up alot if you have the right supportting parts...We use them on our class car with great results over the shorty style headers.Now all you need to know is what size tubing"diameter" You want to use...1 1/2-1 1/58-1 3/4 or bigger.

mike keirstead · Jan 29, 2004

MadMatt5oh said:
Long tubes are a PITA to install. I would hope for an added advantage over regular shorties. How much of a difference?

Longtubes are hard to install when people don't want to take their time and do it right. I had my shorties out and the MAC longtubes in and bolted up to my x-pipe in under 2 hours. It was easy. Jacked the motor up 4 inches and they slid in BUTTER. It was cake.

WEIGHT ADVANTAGE????

What would the difference be. 6-7 pounds. WOW.

TheRedBlur · Jan 29, 2004

I think that the longtubes are better because the collector is farther down, giving the gasses more time to straghten out before merging together, this will LOWER backpressure, and promote scavenging due to increased velocities at the collector.

90mustangGT · Jan 29, 2004

Well, it's harder to explain without going into a physics lesson. Lets put it this way, the longer runners increase scavaging lowering backpressure and increasing flow. Longtubes are harder to install and come down lower so they might be out of range for the average shade tree, and not a good idea for lowriders.

If you read the reviews section, look under the longtube reports and then the shortie reports. People who buy shorties usually report hardly any gains, those with equal length shories say they felt a little increase, but those with longtubes definatly felt something.

The sound of longtubes is different from shorties. Less drone and quieter at low rpm's but really loud ot higher rpms with the throttle down.

1984Convert · Feb 5, 2004

Longtubes

Do longtube headers get rid of that annoying resonation at 2000 rpm?

PURESTREET5006 · Feb 5, 2004

1984Convert said:
Do longtube headers get rid of that annoying resonation at 2000 rpm?

You Know what.i haven't even paid attention to that I have BBK 1 3/4 LT with Dr-gas X-pipe and DynoMax "BULLET" mufflers so i can't tell anyway plus my car isn't street driven alot.

willys1 · Feb 5, 2004

The longer the header the more power,up to a point! Why is a gun with a longer barrel more accurate and powerful?Im not sure I can explain it.Michael Yount can put it in words

90mustangGT · Feb 5, 2004

willys1 said:
The longer the header the more power,up to a point! Why is a gun with a longer barrel more accurate and powerful?Im not sure I can explain it.Michael Yount can put it in words

Actually, that's a good explanation if you think about it.

90mustangGT · Feb 5, 2004

mike keirstead said:
Longtubes are hard to install when people don't want to take their time and do it right. I had my shorties out and the MAC longtubes in and bolted up to my x-pipe in under 2 hours. It was easy. Jacked the motor up 4 inches and they slid in BUTTER. It was cake.

WEIGHT ADVANTAGE????

What would the difference be. 6-7 pounds. WOW.

....and this guy, he's stoned the whole time he's doing the install, so if you can't figure it out sober, close the hood.

LT's sound better also and cut down on drone.

willys1 · Feb 5, 2004

90mustangGT said:
....and this guy, he's stoned the whole time he's doing the install, so if you can't figure it out sober, close the hood.

LT's sound better also and cut down on drone.

He may be stoned all the time,but he forgot more about 5.0's then most people know!!!

Sunfire Power · Feb 7, 2004

what class car are you talking about?

Michael Yount · Feb 7, 2004

Headers? Isn't that when you score a goal in soccer by knocking it in the goal with your noggin'?

All I can add to this discussion is -- hllon4whls, water freezes at 32 F which is 0 C.

Y'all do a search on headers on the internet and read up. It'll be educational. But the basic theory is that when an exhaust pulse leaves the head and travels down the primary tube of the header, when it reaches the collector, it bounces a sonic wave back up the primary tube. If you can time that sonic wave such that it reaches the exhaust port and bounces back down the primary just when the next exhaust pulse is ready to leave, it will 'help' the next exhaust pulse leave the port -- which helps exhaust flow. That's how the scavenging you've been referring to works. The length of primary tube that's required depends on many things - the rpm range you're trying to optimize, the diameter of the primary, exhaust gas temperature, etc. But for most engines making peak power around 4500-7000 rpm, that calculation comes out somewhere in the 24"-36" range - which is why most long tubes are the length that they are. Equal length on the tubes assures that each cylinder is seeing the same conditions in the exhaust system - or as close to the same as you can make it.

hllon4whls · Feb 7, 2004

Michael Yount said:
All I can add to this discussion is -- hllon4whls, water freezes at 32 F which is 0 C.

OK, you got me on that one. But where is that on the kelvin scale mr smarty pants?

Michael Yount · Feb 8, 2004

If I remember correctly, Lord Kelvin thought it wise to have temperatures related directly to what folks called 'absolute zero' - the temperature at which molelcular action ceased as a practical matter. It was determined that this temperature on the Celcius scale was minus 273.16 degrees - so he set that point on his scale at zero. So, 0C = 273K. Water at standard pressure boils at 373K. So the popular 180F degree t'stat we use would be a 355K t'stat. By the way, Kelvin's name was really William Thomson. The British government bestowed upon him the title of "Baron Kelvin of the Largs" in 1892 - and he became known as Lord Kelvin formally thereafter. So, I guess you can wow your friends and call it the "Thomson" scale if you like. For grins I did a search - check out this site. Someone's got a surreal sense of humor. http://zapatopi.net/lordkelvin.html

Another by the way, if you want to better understand scavenging, do a bit of searching around about Helmholtz resonances and it'll give you some more background. It's all about the dynamics of a moving volume of air in a finite enclosure. Exactly the same theory used on the other end of the cylinder to design intake manifolds that are 'tuned' at a certain length.

hllon4whls · Feb 8, 2004

LOL!

Please freeze an item of your choice to zero kelvin so that we can prove that the molecules and atoms stop all motion. This will give us a valid reference point from which we can measure the centigrade temperature. In doing so, we can verify that water does indeed freeze at 273k.

The entropy on this board increases in direct proportion to the amount of sessile smegma at the standard input.

HP from long tube headers

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