What are the advantages to using an equal length?

[better_than_sx]

I know that equal length manifolds are better---but i just want to weigh a log mani--an a eq. length--to see if its worth it to spend all that extra money...gimme some feedback

[Naro182]

im not entirely sure but i think the advantages of an equal length compared to a log would be a smoother spool up and increased turbo life, i dunno...

[xxtrizz]

Well it would seem to me that the gases wuld get there evenly to the turbo. But I think that a log would have a quicker spool since the distance to the turbo is less. Honestly most of the gasses exitting the system are turbulant so getting a equl length or a log I dont think would matter.

Unless its proven somewhere by the dynos or something. But honestly i think a Log would be good enough for any application.

[better_than_sx]

i understand that each "puff" of gas from each cylinder flows smoother if thier put in line---an equal length puts the "puff" in its a logical order to one colection point---but i dont(in theory) see how it makes that much difference in a turbo manifold, bieng that the job of a equal length header is to reduce turbulence and reduce backpressure---a turbo creates turbulance and backpressure---so the gain (in my mind) isnt that much in my mind

if you dissagree--prove me wrong--i would like to know

[better_than_sx]

oh and as for longer turbo life---this is just a theory---most manufacturers use a log type manifold on stock turbo cars---why would they hinder their turbos performance and life by making a couple-hundred-dollar cheaper part, and sacifice all that "free" horsepower by a "smoother spool up"---just a thought

again if you dissagree--prove me wrong--this is just a theory--fact is always better:)

[xxtrizz]

Yeah I agree with both your statements but I was to lazy to type all of what you did hehe. I agree 100 percent

[better_than_sx]

yeah but thats only theory---anyone got a dyno comparison---or another plausable theory the contradicts mine--??

[:: orion ::]

Equal length will make more power at redicoulous power levels, like +400rwhp...I'd bet my RevHard makes similar power to a JGS, and they would both be close in power to a equal length...at 8-9psi.

I'd bet the differences would be more apparent as the boost was turned up...but for most of us, at the sub-300 power level, the extra price isn't worth it.

Equal lengthis REALLY important in high HP N/A application, as scavenging is needed to increase velocity and HP, but for turbo, just get the gasses out smoothly.

- Brian

[better_than_sx]

Thank you---i would still like other peoples opinions---and any proof you have

ps.---prove me wrong--if you think im full of it

[TrunkMonkey]

log style manifold vs. tubular.

-demetrius

[andrave]

so? that just proves that a ****ty log is worse than a good tubular. I have yet to see any evidence that proves that a tubular equal length is superior to a log.

[C-Kwik]

consider the way a log is designed. It's more or less a single pipe with 4 entries(on a I-4) and in exit. The air from the outer cylinders have to merge with the air from another cylinder before reaching the exit(if the exit is centered). And keep in mind how the air merges. It doesn't merge at a smooth collector. It merges at a 90 degree angle. Think about how a equal length mani's collectors are arranged. It's usually more of a gradual merge. And because the runners are equal in length, it will take each exhaust pulse the same amount of time to reach the collector. Since each cylinder fires at a different time, each pulse will reach the collector at at different times, so there will not be a clash of pulses trying to reach the same point simultaneously.

If you have a copy of Maximum Boost, Corky Bell touches on this some in there. Also find me a modern turbo race car motor with a log mani.

[better_than_sx]

im not looking to build a race car----im looking to build a relitively cheap ka-t running 6-7psi---i dont see the advantages of using a eq. length at such low boost

[Jeff240sx]

im not looking to build a race car----im looking to build a relitively cheap ka-t running 6-7psi---i dont see the advantages of using a eq. length at such low boost

Then don't. This is like the question - "Will coating a piston's sideskirts help me?" Yes, it will, but will only be noticeable at high power levels. So why spend the extra $$$ (and $200 for pistons) for a 1-2hp gain at nominal power levels? A race team has more money than problems to throw it at, and each 1/10th of a horsepower is cherished and extracted. On a street car, save the money, don't think about the additional 1-2hp you could have had, and get what you want and can afford.-Jeff

[C-Kwik]

And I'm not trying to influence you. Just stating the facts. You can decide for yourself what you want to do. You were asking for feedback were you not?

[SuperStyro]

I would have to say your goal with your setup would be the factor that determines which manifold/header to use.

If you are going with some decent power at a low cost and do not want to take the power WAY high then go with a log. If people are making ~350whp on a log manifold and that is what you want. Use the log.

If you want some serious power and like the looks of things and so forth; go with an equal length tubular header. If you think that you need to retain heat and want more 'bling bling', make it out of stainless steel. Like some have said before, equal length tubular headers are going to allow you to make more power at higher power levels. If this is what you are going for, use the ELTH (Equal length tubular header) Simple enough.

One more thing about turbo location. This link shows what proper turbo selection can do with a weird turbo location.

Eswift, from the link that demcj posted is stating that having the turbo closest to the exhaust ports is key to spool time, WRONG! Here is the evidence:

http://www.ststurbo.com/ls1_camaro_kits

[better_than_sx]

i thank you guys for all the feedback--i just wanted to know if i was aiming for 6-8lbs of boost would i need to spend $300 more and get an equal length manifold---thank you guys

[Nathan]

The new ETD mani's look like a good compromise between full equal length tubular and log style by being non-equal tubular. If was looking for a manifold and couldn't afford an eq. length, I'd probably go for that one...anything not to have a log

[better_than_sx]

edt?

[Nathan]

No, ETD...read the forum your in, there's at least 2 threads about it still up on the first page.

[better_than_sx]

oh ok--i know now---sorry:icesangel

they dont happen to make one for ka24e's do they?

[Def]

One more thing about turbo location. This link shows what proper turbo selection can do with a weird turbo location.

Eswift, from the link that demcj posted is stating that having the turbo closest to the exhaust ports is key to spool time, WRONG! Here is the evidence:

http://www.ststurbo.com/ls1_camaro_kits

As someone that loves efficiency and simplicity in mechanical system, the pictures on the site were perhaps one of the most disguisting car related experiences of my life...

I guess those guys had never heard of the term "dynamic response" with the couple of GALLONS of the NON-INTERCOOLED charge piping running the length of the car.

Nevermind the fact that the exhaust gas temps will be so low back AT THE BACK OF THE CAR! Maybe that's why at 5psi you could make more power with a few hundred bucks in bolt-ons on the same motor...

The reason why people say a "short" manifold will spool up a turbo better is that there is more energy available to drive the turbine in the form of exhaust gas energy. Thermodynamics will agree with this statement, since the power a turbine can theoretically produce is given by the change in enthalpy as the medium crosses the turbine. Enthalpy is a direct measure of the amount of heat energy a medium has, so it is analogous to the exhaust gas temperatures you'd see in a manifold. Obviously, the shorter the manifold, the less surface area to lose precious heat to.

BTW - if you can't tell, I think that Camaro sucks, and I normally LOVE anything that is turbocharged.

[C-Kwik]

Eswift, from the link that demcj posted is stating that having the turbo closest to the exhaust ports is key to spool time, WRONG! Here is the evidence:

http://www.ststurbo.com/ls1_camaro_kits

Actually, I think that proves the point that a turbo being closer makes for better spool. If the same turbo was used at the rear location, it will spool slower than the same turbo mounted closer to the motor. The FAQ's even describe this.

The FAQ's have a lot of good general turbo info, however, when they get to some of their numerical data, they really don't get into much detail. The part I am most skeptical of is their "piping intercooler efficiency". Pipes do not exactly make a very good heat transfer element. Even being under the car. While some heat will be radiated from the piping, you start getting to higher RPM's I'm sure the numbers they posted will likely be lower. They may have reached those numbers, but they do not tell you under what conditions. Particularly since they seem to also have to rely on a methanol/water injection system at what I consider to be relatively low boost. I'd love to see all their test data. I'd guess it may reveal many things on their site may be misleading...

[SuperStyro]

As someone that loves efficiency and simplicity in mechanical system, the pictures on the site were perhaps one of the most disguisting car related experiences of my life...

I guess those guys had never heard of the term "dynamic response" with the couple of GALLONS of the NON-INTERCOOLED charge piping running the length of the car.

Nevermind the fact that the exhaust gas temps will be so low back AT THE BACK OF THE CAR! Maybe that's why at 5psi you could make more power with a few hundred bucks in bolt-ons on the same motor...

The reason why people say a "short" manifold will spool up a turbo better is that there is more energy available to drive the turbine in the form of exhaust gas energy. Thermodynamics will agree with this statement, since the power a turbine can theoretically produce is given by the change in enthalpy as the medium crosses the turbine. Enthalpy is a direct measure of the amount of heat energy a medium has, so it is analogous to the exhaust gas temperatures you'd see in a manifold. Obviously, the shorter the manifold, the less surface area to lose precious heat to.

BTW - if you can't tell, I think that Camaro sucks, and I normally LOVE anything that is turbocharged.

Great explination, I am not trying to disprove the law of thermal physics here. lol I was just stating that spool times are not always the proper thing to concentrate on when selecting a turbo. Yes you could make way more power with it a lot closer yes, I do agree.

BTW- I do dislike camaro's also

[SuperStyro]

Actually, I think that proves the point that a turbo being closer makes for better spool. If the same turbo was used at the rear location, it will spool slower than the same turbo mounted closer to the motor. The FAQ's even describe this.

The FAQ's have a lot of good general turbo info, however, when they get to some of their numerical data, they really don't get into much detail. The part I am most skeptical of is their "piping intercooler efficiency". Pipes do not exactly make a very good heat transfer element. Even being under the car. While some heat will be radiated from the piping, you start getting to higher RPM's I'm sure the numbers they posted will likely be lower. They may have reached those numbers, but they do not tell you under what conditions. Particularly since they seem to also have to rely on a methanol/water injection system at what I consider to be relatively low boost. I'd love to see all their test data. I'd guess it may reveal many things on their site may be misleading...

Yes, the FAQ describe great things, but why would you use the wrong turbo for your application? Would you ever choose like a T88 for a Supra for a KA24e? I am not saying you are wrong in your statement, you are just taking it out of the context it is presented to show.

As for the piping, yea it will not even be as close as an intercooler. Why do you think that they added methanol/water injection? They do not have an actual intercooler. I know this is not the best thing to take place of an intercooler but it is something to suppress and detonation that may occur.

Also, I am not saying this LS1 turbo kit is the way to go. I just was showing it for the fact that the turbo spools around 3000RPM. I am not saying by any means that the turbo location is the best place either. Lol

[C-Kwik]

Yes, but again, they had to use a smaller turbine to achive the faster spool. They had to do that because the distance to the motor affects spool.

As far as my other comments about the FAQ, my point was that you should take everything you read with a grain of salt. I try not to believe everything I read. And I'd say the same of even what I post in here. Take the information, process it, if it doesn't make sense, do some research, question it, whatever, until it makes sense or until you prove it wrong.

[better_than_sx]

well put*golf clap*