Which Headers for towing?
06-20-2006, 08:44 PM
#11
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Listen dude.....I've been building motors for 20 years (started with my father...who used to race), I'd like you to ask ANYONE on here how much torque they LOST from installing a set of LT's...go on, I dare ya. On my 95 Silverado I picked up 21ftlbs of torque below 2000rpms when I put on the Hooker LT's, EVERYONE on here that has installed LT's has gained down low....please ask them. Torque loss does NOT occur from a loss of back pressure...it occurs from a loss of exhaust velocity which causes reversion of the spent fuel charge into the cylinders preventing a complete new air/fuel charge from entering, LT's keep exhaust velocity higher for longer due to their tube length and collector design which promotes better cylinder scavenging....therefor increasing torque
I DID agree that you can rev a motor past it useful RPM, but whether that will hurt it or not is a subject that is up to debate...you CAN damage a motor by reving it too high, but HOW HIGH that is exactly is also up for debate. Please define over-reving as the same displacement/component/design motor as mine is found in the new Corvette C6...and that revs to 6700rpm, it has THE SAME parts design as mine and I only rev to 6100, so in all reality I'm UNDER-REVING my motor according to GM.....
I DID agree that you can rev a motor past it useful RPM, but whether that will hurt it or not is a subject that is up to debate...you CAN damage a motor by reving it too high, but HOW HIGH that is exactly is also up for debate. Please define over-reving as the same displacement/component/design motor as mine is found in the new Corvette C6...and that revs to 6700rpm, it has THE SAME parts design as mine and I only rev to 6100, so in all reality I'm UNDER-REVING my motor according to GM.....
06-20-2006, 10:23 PM
#12
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it is a matter of were you make the torque, and lts do not make it down low,shortys with smaller primary tubes make the power down low.and that is what you want for towing.maybe you should call one of the main header companys and just ask them to explain it to you.
if you have been building motors 20 years, you started wene you were only 9 or 10 . you must be good buy now,maybe you should get this header thing strait before you go on .it is alright to be wrong every so often, you dont have to get all butt hurt. and then say something a little over rated.
if you have been building motors 20 years, you started wene you were only 9 or 10 . you must be good buy now,maybe you should get this header thing strait before you go on .it is alright to be wrong every so often, you dont have to get all butt hurt. and then say something a little over rated.
06-20-2006, 11:10 PM
#13
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LMAO at this guy ^^^^
You need to do some research on LT's before you post another reply bud. Go look at some REAL dyno graphs and do some research on this site, Bring us sources(links) to prove your "theory". Your pretty new to the site, this is not the way to earn the respect of other members.
You need to do some research on LT's before you post another reply bud. Go look at some REAL dyno graphs and do some research on this site, Bring us sources(links) to prove your "theory". Your pretty new to the site, this is not the way to earn the respect of other members.
06-20-2006, 11:21 PM
#14
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i would like to put my .02 cents in...... i just did my headers last week..... did i lose any low end tq? 
yeah right it feels like thier is twice as much low end tq..... dont listen to that guy..... the reason yelo said that the shorties dont do anything is cuz they flow almost exactly like the stockers... further more your final tq is judge by much more than just your headers man.... you have to have a good compleate exhaust to acomplish exactly where you want your tq range to be.... i think that you will be more than happy with the LT's....
Listen to YELO is advice should be taken.... his post's have helped me more then once i will tell you that
yeah right it feels like thier is twice as much low end tq..... dont listen to that guy..... the reason yelo said that the shorties dont do anything is cuz they flow almost exactly like the stockers... further more your final tq is judge by much more than just your headers man.... you have to have a good compleate exhaust to acomplish exactly where you want your tq range to be.... i think that you will be more than happy with the LT's....Listen to YELO is advice should be taken.... his post's have helped me more then once i will tell you that
06-20-2006, 11:47 PM
#15
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Originally Posted by shawn calvin
it is alright to be wrong every so often, you dont have to get all butt hurt. and then say something a little over rated.
* Long tubes make more power down low due to increased exhaust velocity and cylinder scavenging, an LT will lose it's benefits higher up compared to a shorty as explained below
* Shorties will make typically make more power above 6000rpms because the exhaust has a shorter path th travel before being scavenged by the other cylinders....this is important when valve event timing is dramatically increased like it is at very high rpms
Here's a dyno sheet to prove it. the red is stock manifolds, the blue is LG Motorsports Long Tube headers....everything else is stock, above 6k the shorties would have kept pulling where the LT's die off. you will notice down low that the LT's DO NOT make much more horsepower, but the do make ALOT more torque....and torque is what gets a truck and trailer moving...ignore the spike at the beginning, it's common to see that on dynos when they start logging the run, just carry an imaginary line down to idle to see the rest of the curve
I took hydro and thermodynamics in college, I used to build 10 and 11 second 1/4 mile cars, I PROMISE you I'm right, I've STUDIED this **** man. I DO NOT talk before I KNOW and UNDERSTAND a topic, you'll see me ask as many questions around here as I answer becaue I DON'T know it all...and I know it. I didn't get all butt hurt...nor do I ever and I didn't over-react...I showed you the facts.
I'm not looking for an enemy here man.....just trust me on this one and correct me the next time I'm REALLY wrong OK ??....Teach me something, I'm always looking for new knowledge
06-21-2006, 10:31 AM
#16
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i am not saying that lts are bad.i am also not saying that i know everything either because i dont. i am going by what i have been told from many header companys.all the ones that i talked to said that to go with the shorties if towing, and to go with the lts if you are racing.i dont have time to go look all over the web for dyno sheets and all that ****.and i dont think that you have to be a member of the site for a long time. to be the only way that you know anything. i am a member at some other sites and it seems to be that most of the members are young kids that dont know **** from shoe shine. i am not saying that is the case here, that is why i came to this site because i thought that there was more people that might have a clue, and not just a bunch of kids that like to talk ****. but i still stick to my claim on the headers.if you cant believe a company like hooker,who can you believe
06-21-2006, 11:15 AM
#17
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I'm gonna give you the benefit of the doubt here Shawn.....I'm gonna make a few calls and do some research on this, IF I'm wrong I'd like to know it and I'll be more than happy to admit if I'm wrong. give me until this afternoon to look into this and I'll get back to you with what I find out.
This could be interesting.....
This could be interesting.....
Last edited by Yelo; 06-21-2006 at 11:26 AM.
06-21-2006, 11:54 AM
#18
ive always understood it the way shawn explains it. "longtubes move the power higher in the rpm range" i dont have any dyno graphs but i know for a fact my brake stall dropped from 2500 to about 2200rpm after installing my longtubes.
torque converters use the engines torque to make higer stall so i chalked the loss of brake stall rpm's as a loss of torque down low. i think sticking with the stock manifolds is most cost efficient over shorty headers. most people claim little to no gains with shorty headers
torque converters use the engines torque to make higer stall so i chalked the loss of brake stall rpm's as a loss of torque down low. i think sticking with the stock manifolds is most cost efficient over shorty headers. most people claim little to no gains with shorty headers
06-21-2006, 12:15 PM
#19
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Here's what I've foud so far:
This is what AEM has to say about it:
I found this very interesting:
This is from Sanderson Headers, they build custom headers for all kinds of street rods and performance cars...this info really suprised me.
This is from LS1GTO.com, I know this isn't an "official" response but this guy really seems to know what he's talking about...he *may* be a member here as well
I've been unable to find a direct comparison between a shorty and an LT header on the same car but I'm still looking. I've called and left mesages with Dynatech and Hooker (Holley Performance) to have an R&D person call me (I DO NOT want a salesperson, they'll tell you anything you want to hear), as soon as I hear back I'll post up.
This is a start.....and I've actually learned quite a bit !!
This is what AEM has to say about it:
Originally Posted by AEM Brute Force website
Key Features:
• BRUTE FORCE long-tube designs increase power and torque over short versions
• Tuning of headers emphasizes low end torque and mid range horsepower for the best useable performance (towing and hauling)
• BRUTE FORCE long-tube designs increase power and torque over short versions
• Tuning of headers emphasizes low end torque and mid range horsepower for the best useable performance (towing and hauling)
Originally Posted by Mustang 5.0 Magazine
With these results in hand, the long-tube headers and H-pipe were removed, and the short-tube headers and H-pipe were installed. The results were interesting: the engine gained nearly 8 hp, and a little over 5 lb-ft of torque at 3,500 rpm over the long-tubes. However, the long-tube’s torque and horsepower curves lasted longer (see dyno charts), suggesting that these headers would indeed make even more power over short-tube headers if used on a more modified engine. This is due to the fact that a long tube header can make use of the engine’s exhaust pulses to “pull” exhaust gas from the cylinder, providing optimized scavenging. A short-tube header, with its much shorter primary tubes, simply does not have the same advantage.
Originally Posted by Sanderson Headers Website
Exhaust headers with equal length tubes have been shown to develop slightly more power in an open system, but not when hooked up to a street system with mufflers. Fact is, most street motors with shorty headers will produce the same power as they would with equal length headers.
Originally Posted by Hawkeye
The problem with short tube headers is that they won't scavenge at an rpm that you can use. Primary pipe i.d. and header tube length determine the rpm at which the motor will scavenge. Basically, the longer the tube or the smaller the i.d. the lower the rpm at which it will scavenge, and the opposite is true, the shorter the tube length or the larger the i.d. the higher the rpm at which scavenging takes place. Scavenging of the cylinder is where the out going gases create a vacuum, drawing in the incoming intake charge. Headers do more than just funnel spent gases out of the engine compartment less restrictively than manifolds; they draw spent gases from the combustion chamber by a process called scavenging.
If you look at the stock exhaust manifold you'll see it's very much like a shorty header. And it's only job is to direct exhaust gases, not tune anything. This is why you see such dismal results with shorty headers, they don't do anything the stock manifold doesn't already do. Tuning (scavenging) isn't something the factory manifolds are designed to do, and that's why LT's really wake up these engines.
If you look at the stock exhaust manifold you'll see it's very much like a shorty header. And it's only job is to direct exhaust gases, not tune anything. This is why you see such dismal results with shorty headers, they don't do anything the stock manifold doesn't already do. Tuning (scavenging) isn't something the factory manifolds are designed to do, and that's why LT's really wake up these engines.
This is a start.....and I've actually learned quite a bit !!
Last edited by Yelo; 06-21-2006 at 12:22 PM.
06-21-2006, 12:25 PM
#20
TECH Addict
Originally Posted by TXsilverado
ive always understood it the way shawn explains it. "longtubes move the power higher in the rpm range" i dont have any dyno graphs but i know for a fact my brake stall dropped from 2500 to about 2200rpm after installing my longtubes.
torque converters use the engines torque to make higer stall so i chalked the loss of brake stall rpm's as a loss of torque down low. i think sticking with the stock manifolds is most cost efficient over shorty headers. most people claim little to no gains with shorty headers
torque converters use the engines torque to make higer stall so i chalked the loss of brake stall rpm's as a loss of torque down low. i think sticking with the stock manifolds is most cost efficient over shorty headers. most people claim little to no gains with shorty headers
Here's a quote from Sanderson Headers that shows this:
Originally Posted by Sanderson Headers website
Smaller diameter pipes flow less volume than large ones, but the exhaust in the smaller pipe flows faster. Until you reach the RPM where the sheer volume of exhaust gases require bigger primaries, smaller tubes scavenge far more efficiently. If you're using the engine in the 1,500-3,500 RPM range, which is typical for a street driven car, you definitely want 1- 1/2" to 1-5/8" primary tubes for a small block and 1-3/4" to 1-7/8" for a big block. Any bigger and you'll lose plenty of low end torque. Beyond 3,500 RPM it's a question of where you want the power peaks. As you can see from the chart above, small tubes don't lose their edge in horsepower or torque until you get above 5,500 RPM.