What are the pros and cons of an equal length exhaust manifold?
ProjectGSX
Pros:
Equal legnth tubing puts exhaust pulse right inline, so that the exhaust doesn't collide with itself like in a manifold.
More efficient (see above)
Cons:
Expensive?
I can't think of too many cons. Hopefully somebody more knowledgable finds this thread worth noting in. That seems to be a problem on this board.
Equal legnth tubing puts exhaust pulse right inline, so that the exhaust doesn't collide with itself like in a manifold.
More efficient (see above)
Cons:
Expensive?
I can't think of too many cons. Hopefully somebody more knowledgable finds this thread worth noting in. That seems to be a problem on this board.
on a turbo car the gains from an equal legnth exhaust manifold are minimal... the exhaust pulses run into a huge wall (turbine wheel) anyway... so there's not really an advantage unless your at the point where you need to squeeze every last hp out of your car... the money, in most cases, is better spent elsewhere... the gains that you get from most aftermarket headers are from increased flow due to larger pipe diameter, smoother bends and full radius bends...
Cooter
http://www.sound-performance.com
Cooter
http://www.sound-performance.com
Actually to quote "Turbochargers" (see left column.. a long time bowl read of mine): "intake and exhaust tuning is just as important on a turbocharged engine as on a naturally aspirated one" this is a caption describing an equal length header going to a high output turbo application. Wait!! Theres more : "One of the biggest misconceptions is that ram tuning is not important on a turbocharged engine. Through extensive testing, I've found that a turbocharged engine responds to a tuned inlet and exhaust system and large-port cylinder heads as much as a naturally aspirated engine." They also highly recommend dual port turbos and manifolds as while they didn't increase power on a 640hp 2.0 liter BMW-Mclaren race engine they made lag "all but disappear". This same engine experience a 60hp gain from 540 when switching to equal length headers.
I think that is more of a custom made thing... I have never seen a tuned exhaust mani for eclipses
edit: and if anybody is gonna hang me on those numbers up there 540 + 60 =600... that additional 40 hp is from cam adjustment after the exhaust tuning was realized
[Edited by redgsturbo on 07-18-2001 at 08:20 PM]
edit: and if anybody is gonna hang me on those numbers up there 540 + 60 =600... that additional 40 hp is from cam adjustment after the exhaust tuning was realized
[Edited by redgsturbo on 07-18-2001 at 08:20 PM]
i'm sorry, i should have been more clear....
any improvements that are made to the effieciency of the intake and exhaust tract are beneficial... sure the manifold got 60 hp..... and i didn't see that article... but getting 60 more hp out of a 540hp motor isn't that hard.... relatively speaking...and 11% gain... something like a custom built header is not generally done because of the cost and the few ppl that actually mod their cars enough to get respectable gains from something that they have to invest that much money and time in.... hence 'the money is usually best spent elsewhere' an 11% gain one a typical bolt ons car will net you only 3.3hp... assuming your average bolt ons car makes 300hp... is it worth the $600 for the manifold? $600 can buy you more hp with different parts.. at that point... hence the 'unless your at the point where you need to squeeze every last hp out of your car' statement.. hope that clears things up...
Cooter
http://www.sound-performance.com
any improvements that are made to the effieciency of the intake and exhaust tract are beneficial... sure the manifold got 60 hp..... and i didn't see that article... but getting 60 more hp out of a 540hp motor isn't that hard.... relatively speaking...and 11% gain... something like a custom built header is not generally done because of the cost and the few ppl that actually mod their cars enough to get respectable gains from something that they have to invest that much money and time in.... hence 'the money is usually best spent elsewhere' an 11% gain one a typical bolt ons car will net you only 3.3hp... assuming your average bolt ons car makes 300hp... is it worth the $600 for the manifold? $600 can buy you more hp with different parts.. at that point... hence the 'unless your at the point where you need to squeeze every last hp out of your car' statement.. hope that clears things up...
Cooter
http://www.sound-performance.com
a local machine shops makes them
Max Rev:
dont know the price, but they do extremely good work. they are more of a custom shop, but i have seen there work up close and is second to none. they build monsters.
<<<you forgot one decimal place man... on a 300hp car 11% increase is 33 hp... worth $600 at that point.>>
you wont get the same % gain from tuned header as a 540 hp car does. ex flow is more important in a 540hp car than a 300 hp car.
quick example:
a 3inch turbo back could make over 100hp difference on a 500hp car(w/stock ex), but on your 250hp car is not going to give you 50hp. see what i'm saying?
Max Rev:
dont know the price, but they do extremely good work. they are more of a custom shop, but i have seen there work up close and is second to none. they build monsters.
<<<you forgot one decimal place man... on a 300hp car 11% increase is 33 hp... worth $600 at that point.>>
you wont get the same % gain from tuned header as a 540 hp car does. ex flow is more important in a 540hp car than a 300 hp car.
quick example:
a 3inch turbo back could make over 100hp difference on a 500hp car(w/stock ex), but on your 250hp car is not going to give you 50hp. see what i'm saying?
*feels stupid*
okay.. i'm sorry about that...thought that looked fishy but i was in a hurry.. blunttwister is right though, a 33hp increase is not realistic on a 300 hp motor..
Cooter
http://www.sound-performance.com
beware of white supras....
okay.. i'm sorry about that...thought that looked fishy but i was in a hurry.. blunttwister is right though, a 33hp increase is not realistic on a 300 hp motor..
Cooter
http://www.sound-performance.com
beware of white supras....
no its not.. and its not as cost efficient as a turbo upgrade, but how much are people *really* paying for 5 and 10hp chunks on cars.. realisticly i wouldn't be suprised if a tuned header system on a 300hp car netted 20hp or so. the "tuning" of the factory exhaust manifold is horrid. Some runners are almost twice as long as others. Keep in mind that the exhaust gas pulsastions would be more evenly distributed which would make a big difference in spoolup.. (think of the idea behind axially divided turbos. same principle is being applied here) so lets say you get no power gain.. but you spool 750rpm sooner? People pay so much and a lot more for porting. Anyways, I never meant to attempt to predict what a tuned header system's hp increase would amount to... I just meant to dispel the thought that tuned exhaust doesn't matter for turbo cars.
tuned headers
I remember the Archer brothers once provided a tuned stainless header system with a lifetime guarantee. They don't seem to provide that anymore.
Such custom headers are for dedicated track vehicles that only do a few hundred miles/year (in 1/4 mile increments.)
To put a tuned header on a street car and expect it to last for tens of thousands of miles is unrealistic.
Even the titanium custom made headers crack on street cars.
Maybe someday someone will make a CAST titanium equal-length, tuned header for us.... but generally we're a cheap bunch of hobbyists
so I would expect it.
Cheers,
Mark Miller
http://PhillyDSM.com
I remember the Archer brothers once provided a tuned stainless header system with a lifetime guarantee. They don't seem to provide that anymore.
Such custom headers are for dedicated track vehicles that only do a few hundred miles/year (in 1/4 mile increments.)
To put a tuned header on a street car and expect it to last for tens of thousands of miles is unrealistic.
Even the titanium custom made headers crack on street cars.
Maybe someday someone will make a CAST titanium equal-length, tuned header for us.... but generally we're a cheap bunch of hobbyists
so I would expect it. Cheers,
Mark Miller
http://PhillyDSM.com
Tuned and equal length...not the same thing...
Anyone with a tube bender can fab up a custom equal length turbo manifold...and it will improve HP. But you might as well get a tuned equal length for the same $$. Tuned pipes not only keep the exhaust pulses from colliding, they make maximum efficency of the collector (which is very important on a turbo car).
Example (the numbers represent a collector where the runners are meeting, the numbers correspond with the cylinder numbers):
12 14
34 23
Which one of the configurations is correct for maximum HP? The first one listed is...but why? Well cyl #1 and #4 fire together, so their exhaust puleses match. When they come together in the collector you want to have them caddy-corner from each other, not side by side. If they were side by side one half of the collector would have a high velocity moving exhaust flow with a dead spot on the other side of the collector. This situation would enable boyle's law and create a turbulant air mass that wouldn't flow well. But if you had them caddy-corner, you would split the flow equally across the collector and essencially eliminate this effect.
Anyone with a tube bender can fab up a custom equal length turbo manifold...and it will improve HP. But you might as well get a tuned equal length for the same $$. Tuned pipes not only keep the exhaust pulses from colliding, they make maximum efficency of the collector (which is very important on a turbo car).
Example (the numbers represent a collector where the runners are meeting, the numbers correspond with the cylinder numbers):
12 14
34 23
Which one of the configurations is correct for maximum HP? The first one listed is...but why? Well cyl #1 and #4 fire together, so their exhaust puleses match. When they come together in the collector you want to have them caddy-corner from each other, not side by side. If they were side by side one half of the collector would have a high velocity moving exhaust flow with a dead spot on the other side of the collector. This situation would enable boyle's law and create a turbulant air mass that wouldn't flow well. But if you had them caddy-corner, you would split the flow equally across the collector and essencially eliminate this effect.
Sport compact car did an article on the 600HP Bozz Lancer. Now I know there are a who slew of differences between the US DSMs and the Jap. Lancer, but it had equal length header from HKS. (Correct me if I'm wrong, I don't have the article right now) But among the other mods, a properly tuned header hsa got to be worth some level og significant power.
Archer did in fact make/sell the stainless headers, and yes they were very prone to cracking but they also used the wrong material to make them, 304L CRES. High temps, carbon, and 304 don't mix, it causes the material to leech out chromium and the net effect is the weld becomes brittle and cracks.
Titanium and 321 CRES are the materials of choice for a dedicated racer, but then again, they have budgets larger than the GDP of 3rd World Countries so they can use these materials. For us, the best alternative is to use a mild carbon steel (for economic value) and have the header Jet Hot coated. This coating is an organic/ceramic plating that will offer significant heat and corrosion protection. Plating the exterior is all that is required but plating the interior will keep heat rejection even lower (its a good thing). The coating needs to be reapplied at a certain service interval, something like 4-5 years, otherwise you lose that buffer of protection. Also, the mild steel welds will need to be touched up every few years.
One thing that will help your headers live a longer life is adequate bracketry and gussets. The less weight you are asking the tube welds to carry, the less force is on the weld, the longer the weld will last. Its an easy correlation.
Titanium and 321 CRES are the materials of choice for a dedicated racer, but then again, they have budgets larger than the GDP of 3rd World Countries so they can use these materials. For us, the best alternative is to use a mild carbon steel (for economic value) and have the header Jet Hot coated. This coating is an organic/ceramic plating that will offer significant heat and corrosion protection. Plating the exterior is all that is required but plating the interior will keep heat rejection even lower (its a good thing). The coating needs to be reapplied at a certain service interval, something like 4-5 years, otherwise you lose that buffer of protection. Also, the mild steel welds will need to be touched up every few years.
One thing that will help your headers live a longer life is adequate bracketry and gussets. The less weight you are asking the tube welds to carry, the less force is on the weld, the longer the weld will last. Its an easy correlation.
Re: Tuned and equal length...not the same thing...
But I do agree with you that equal-length isn't necessarily the same as tuned. I don't know how much HP you are going to gain from tuned headers but I'm sure the combination of improved spool-up and increased HP (however much it is) on a 400HP+ engine would make the tuned headers well worth it.
Umm...the only thing that fires together for cylinders #1 and #4 is the spark. But we have a waste spark system where coil 1 will fire when it's needed and coil 2 will fire when it's needed. This works out fine because when #1 is on it's compression stroke #4 is on it's exhaust stroke so firing the #4 spark at the same time won't do nothing. There's no gas to burn.dyezak said:
But I do agree with you that equal-length isn't necessarily the same as tuned. I don't know how much HP you are going to gain from tuned headers but I'm sure the combination of improved spool-up and increased HP (however much it is) on a 400HP+ engine would make the tuned headers well worth it.
I might need a custom manifold done for a turbo w/ a split housing. Which 2 runners should I combine for each collector to maximize turbo spool-up? I heard that 1&4 and 3&2 together should be used. Is that correct? It kind of disagrees w/ the previous post about what runners to mix.
one of my sponsors can make them, email me for that info. South florida performance makes them and from what i have seen they are decent. Wright touch also makes them to mount up the 25g but should be able to work on just about any turbo (just weld on a diff flange). When i called archer up to see if they would still make theirs they told me if i could get an order for 20 or more at 800 a pop, they don't want to make them mainly because they couldn't make any money off them (kept cracking and having to be replaced under warrenty) which i can totally understand. Mine i bought all the stainless for it and a sponsor is mocking it up to be shipped out and welded all total i spent about 300 in stainless pipe and flange material.
First off, Dyezak, I must say you know your shit. I am SO GLAD to see that there is someone who actually belongs on the ADVANCED technical section.
Bill, you are doing it again...
<<<Umm...the only thing that fires together for cylinders #1 and #4 is the spark. But we have a waste spark system where coil 1 will fire when it's needed and coil 2 will fire when it's needed. This works out fine because when #1 is on it's compression stroke #4 is on it's exhaust stroke so firing the #4 spark at the same time won't do nothing. There's no gas to burn.>>>
Let me ask you a simple question...have you ever had the head off the car? Which two pistons do you see at bottom dead center, and which two are at top dead center? Cylinders 1 and 4 are in time, and 2 and 3 are in time. What a WASTED spark ignition means, is that it will fire TWICE, once on the power stroke, once on the exhaust stroke. The "wasting" of the spark means that obviously, spark does nothing on the exhaust stroke. Cylinder's number 1 and 4 FIRE AT THE SAME TIME, and 2 and 3 FIRE AT THE SAME TIME (for nit-pickers, they are VERY slightly off, but so slightly it would be hard to measure with even measuring tools; it's determined by wire length, resistance, etc. but for arguments sake, they fire at the same time). That goes for exhaust, intake, etc etc. The theory Dyezak was talking about WORKS...and works for all 4 cylinder cars. You guys should pay more attention at least to him, if you won't listen to me. Tuned headers basically increase the scavenging affect from one cylinder to the next. As simply put as possible, how this theory works is when a cylinder fires, it sends an exhaust pulse into the exhaust (manifold/header) This exhaust pulse creates a vacuum, and basically you are going to try to team THIS exhaust tube with the NEXT exhaust pulse inline to fire. If this is done at the right distance (this distance is the actual part you would "tune" on a header), when the exhaust valve opens on the next cylinder, the vacuum caused by the exhaust pulse before it will help "scavange" all of the exhaust out of the combustion chamber. It gets more complicated than this, and actually incorporates variables such as how sound waves travel, but I don't want to confuse anyone. I hope this helps you understand the reason to run tuned headers. You are "tuning" to increase the scavenging affect. Bill...you are striking out dude. Do you really work on people's cars?
Bill, you are doing it again...
<<<Umm...the only thing that fires together for cylinders #1 and #4 is the spark. But we have a waste spark system where coil 1 will fire when it's needed and coil 2 will fire when it's needed. This works out fine because when #1 is on it's compression stroke #4 is on it's exhaust stroke so firing the #4 spark at the same time won't do nothing. There's no gas to burn.>>>
Let me ask you a simple question...have you ever had the head off the car? Which two pistons do you see at bottom dead center, and which two are at top dead center? Cylinders 1 and 4 are in time, and 2 and 3 are in time. What a WASTED spark ignition means, is that it will fire TWICE, once on the power stroke, once on the exhaust stroke. The "wasting" of the spark means that obviously, spark does nothing on the exhaust stroke. Cylinder's number 1 and 4 FIRE AT THE SAME TIME, and 2 and 3 FIRE AT THE SAME TIME (for nit-pickers, they are VERY slightly off, but so slightly it would be hard to measure with even measuring tools; it's determined by wire length, resistance, etc. but for arguments sake, they fire at the same time). That goes for exhaust, intake, etc etc. The theory Dyezak was talking about WORKS...and works for all 4 cylinder cars. You guys should pay more attention at least to him, if you won't listen to me. Tuned headers basically increase the scavenging affect from one cylinder to the next. As simply put as possible, how this theory works is when a cylinder fires, it sends an exhaust pulse into the exhaust (manifold/header) This exhaust pulse creates a vacuum, and basically you are going to try to team THIS exhaust tube with the NEXT exhaust pulse inline to fire. If this is done at the right distance (this distance is the actual part you would "tune" on a header), when the exhaust valve opens on the next cylinder, the vacuum caused by the exhaust pulse before it will help "scavange" all of the exhaust out of the combustion chamber. It gets more complicated than this, and actually incorporates variables such as how sound waves travel, but I don't want to confuse anyone. I hope this helps you understand the reason to run tuned headers. You are "tuning" to increase the scavenging affect. Bill...you are striking out dude. Do you really work on people's cars?
LOL! Umm, the pistons may be in time in your example but they most certainly DO NOT FIRE **on compression** AT THE SAME TIME, the valves have some say so there...ever look at your cams really close?!NosLaser said:
#1 is at TDC about to head down on power stroke. #4 just came up on exhaust stroke (dead spot) and will next head down on intake stroke, while #1 is on the power stroke down. When they come up together again, #4 is on compression stroke approaching TDC about to fire, while #1 comes up on the exhaust stroke.
AND, just for good measure #3 fired in between #1 and #4 cylinders just to keep things smooth. Anybody want to guess when #2 is gonna fire?
Because it sure ain't at the same time #3 fired. Basic automotive fundamentals of a four cylinder, four stroke engine...Now please withdraw foot from mouth... Wasted spark is not the same as tdc compression spark, 4G63Rydah had it right. They, #1 and #4, get spark pulse at the same time and one is a wasted spark, but NOT tdc compression spark.
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