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[Scott]

Explain the advantages of this mess to me please:

[Scott]

it is shown in context here:

There is no advantage. In fact, its built wrong. For optimum exhaust gas energy, the ports with matching firing sequences need to be routed together for pulsing.

[djsatan]

it's so it can look like a baby squid

[3s-a-Charm]

or Alien babies...watch out, it'll attach to yer face!

[Greg337]

can't tell but it would be best if all the tubes were the same length.

[MistressAnne]

I was thinking spider...

[greggearhead]

Old thread.  Yes, for every last ounce of horsepower, you should hand-make the runners to equal FLOW (not necessarily length) and rotational firing order.  

That said, show me one fucking CAST manifold that comes CLOSE to doing that, or close to flowing as well out of each port as that does and I will eat my shorts.  

Is it the best in terms of text-book building?  No.  Is it really good for his space and design constraints?  YES.  Is it better than any cast manifold I have seen locally?  Yes.

[punkrider99]

i'm not so sure that length (or maybe even flow) is really all that important with a turbocharged application.  if it were a n/a motor then yes length and flow characteristic s would really play an essential role in how the engine runs.  better scavaging and matching pulses would ultimately work the best.  but with a turbo it doesn't matter.  there isn't any scavaging going on because there is always positive pressure in the primaries.  and then it just dumps into the turbine housing.  you also have boost helping to evacuate the combustion chamber during the cam's overlap phase.  its looks like a decent setup to me.  but hey i'm no pro...

[greggearhead]

i'm not so sure that length (or maybe even flow) is really all that important with a turbocharged application.  if it were a n/a motor then yes length and flow characteristic s would really play an essential role in how the engine runs.  better scavaging and matching pulses would ultimately work the best.  but with a turbo it doesn't matter.  there isn't any scavaging going on because there is always positive pressure in the primaries.  and then it just dumps into the turbine housing.  you also have boost helping to evacuate the combustion chamber during the cam's overlap phase.  its looks like a decent setup to me.  but hey i'm no pro...

I hate reading this shit.  

Just because there is really just a higher pressure differental, people say physics don't apply.

Bull fucking shit.  Yes, you can turn up the boost 2psi and "make up" for the manifold deficiencies.  But what is the difference in a NA motor from sealevel to 6500ft altitude?   Pressure differential in the intake.  Hmm.  What if it was just a 2psi turbo?  Same physics.  

IMO, and it is just my opinion, all the same characteristic s and properties apply to a forced induction motor as a naturally aspirated one, it is just that some of the shortcomings are not as blatant.  Don't let that make you think they don't matter.  

How many different turbo manifolds have you experimented with?  The land speed Geo Metro (3 cyl 1.0) had manifolds made with 911 heater box primaries used for the cheap mandrel bends.  Yes, it makes a difference.

[punkrider99]

okay the pic naps posted is a tube style manifold that goes into a turbo.  a turbo is not a crank driven super charger.  a turbo creates a huge increase in exhaust pressure.  a crank driven super charger does not.  there is a huge difference between the two.  you can just throw out "forced induction" as a blanket term.  a turbo motor and a crank driven supercharged motor are two completely different animals.  

and yes greg there have been many studies and dyno test to show that on a turbo motor things like header/manifold design aren't as significant as on a n/a motor.

[SoFarKingFast]

Looks like a pretty good design to me.

Equal lenth runners are advantageous due to the fact that they support the "pulse system" concept.  As valves open and close pulses are sent down each runner, and hit the turbine at equal intervals, making it spool faster.  The energy tapped with this design is from the escaping exhaust gases after combustion.

A manifold design uses the force of the piston moving to the top of the cyclinder to support the "constant pressure" system.  A manifold is designed to eliminate the pulses and deliever a constant pressure (hence the name) to the turbine in order to spool.

Yes, this manifold doesn't appear to have equal length runners, but there is still a large advantage to having a pulse system that uses less energy from the pistons and instead uses the wasted energy of exhaust gases escaping under their own momentum.

Ryan

[yoogene]

[djsatan]

it's baby Yoogene drinking acoke  

and it will plant baby Elements if it attaches to your face  

[greggearhead]

but with a turbo motor it doesn't matter

and yes greg there have been many studies and dyno test to show that on a turbo motor things like header/manifold design aren't as significant as on a n/a motor.

So which is it - it doesn't matter or isn't as significant?  

Yes, like  I said, you can turn up the boost a bit and "erase" the difference a better manifold will make.  You can't do that on a NA motor, so it seemingly creates a bigger difference on a NA motor.

[greggearhead]

okay the pic naps posted is a tube style manifold that goes into a turbo.  a turbo is not a crank driven super charger.  a turbo creates a huge increase in exhaust pressure.  a crank driven super charger does not.  there is a huge difference between the two.  you can just throw out "forced induction" as a blanket term.  a turbo motor and a crank driven supercharged motor are two completely different animals.  
.

Boy, you think I would know that having done a bunch of the development work on the dyno for the supercharged Harley company.  Seriously, I just threw it out there because I was in a hurry.  Yes, there are big differences in exhaust requirements.  Cams, too.

[Scott]

I think Greg needs to get laid....

Yes, equal VOLUME runners are important, both on intake and exhaust (that's I and E for Sterling), AND for FI and NA.

The OPTIMUM design would have been equal runners with a 6-3-2 or a 6-2-3 design of collectors (depending on engine firing order) to maximize the pulsing effect (a derivative of the Helmholtz Theory).

Manifold design is extremely important in FI applications, both turbo and supercharged. They each require their own special designs, but they are still very important.  VERY.

And yes, space constraints are usually the driving factor in design.

END ARGUMENT or read "Maximum Boost". My office hours are 6:30am to 3:30 pm if you have any questions.

[punkrider99]

okay well i read you original posts right before i went to bed so i got to think about it all last night.  i figured that we both (or maybe just me) were misunderstandi ng each other.  i  know i'm not gunna say anything you don't already know but i just feel i need to clarify where i was coming from.  

it clicked in my head that you were talking about crank driven super chargers when you mentioned the hudson boy's metro (i happened to be safety tech who inspected their car the first year they came out).  last time i saw the car they still had a s/c on it and not a turbo.  

so as far as the exhaust side of things go, yes i agree that you still need to maintain an efficent design with a crank driven s/c motor.  obviously you can promoting scavaging through equal lengths and frequency tuning.  thats why you have 180 degree sbc headers, equal length headers, step headers, and triple y headers.  there are a hundred different ways to do it but its all about flow and minimizing back pressure.

now the intake side of things is a different story.  take a look at a 16v intake manifold and a 20v-t intake manifold.  there is a reason why the n/a motor has 18" long runners and the turbo motor has 3" long runners.  the n/a motor has to breathe in its own air.  longer, smaller tubes increase port velocity and help the engine to breathe better within its power band.  

the turbo motor doesn't need longer runners because its being force fed.  i think you were trying to say that supercharging will make up for shitty head flow specs and you're right.  you can take those specs, wad them up and throw them away.  ever notice that a blower manifold for a sbc or any other v-8 has like 2" long runners while the n/a intakes have long winding runners that share a common plenum?  

so like i said before i'm sure this is shit that you all already know, i'm just furthering what i was trying to say.  okay now lets look at the exhaust side of things for a turbo motor.  a turbo has the same effect as sticking a giant cork right up your exhaust.  if you're running 20 psi of boost, guess how much pressure you have on the hot side?  so things like equal length, firing sequences, and the like aren't as important to making a turbo motor run right.

now don't get me wrong.  of course it would be advantagous to try and utilize pulse tuning and equal length runners, but look who is doing that kind of thing....racer s.  they are in the job of squeezing every single last possible horsepower from their motors.  now consider a daily driver.  i'm sure driveability and reliability are a little more important than max power.  

so have the oe's been wrong for the past 20 years by making heavy ass, cast iron, short exhaust manifolds?  probably not.  they want to keep things as short as possible so that they minimize the volume.  and by keeping things short, they also minimize surface area.  more surface area dissapates more heat.  if you lose heat, you lose energy, and you lose potential boost.

[punkrider99]

okay the pic naps posted is a tube style manifold that goes into a turbo.  a turbo is not a crank driven super charger.  a turbo creates a huge increase in exhaust pressure.  a crank driven super charger does not.  there is a huge difference between the two.  you can just throw out "forced induction" as a blanket term.  a turbo motor and a crank driven supercharged motor are two completely different animals.  
.

Boy, you think I would know that having done a bunch of the development work on the dyno for the supercharged Harley company.  Seriously, I just threw it out there because I was in a hurry.  Yes, there are big differences in exhaust requirements.  Cams, too.

greg, you've never told me that you did that kind of work so how would i have known that?  i didn't mean to mean to get on your nuts.  i was just responding to what you posted.  

and by all means, i may be totally wrong.  i can only go off of what i've learned over the years.  no i'm not an engineer, and no i'm not a professional engine builder so i don't know all the theories and equations.  but i think that experience can go a long way.

[greggearhead]

OMG.  Read my posts and stop trying to read INTO my posts.  

The land-speed car I was referring to was NOT, repeat NOT the Hudson Boys Whipple-blown car, but a TURBO-CHARGED GEO METRO.  The owner of the Porsche shop I worked at built it and has run it with about 4 different motors, and has blown up 2 of them, and has used 3 different turbos, etc etc etc.  

The reason most manufacturers use cast iron and short runners for turbo (and NA) exhaust manifolds is not because it works better, but because it is a compromise of many objectives - space, durability, etc.  Same thing on the intake - manufacturers don't like to leave horsepower on the table, but they also have to package it and make it work with 1000 other constraints.  On a turbo motor, it is common to go with a short runner intake for a couple of reasons I am familiar with - to reduce plumbing difficulties, and to reduce the overall volume of the intake after the turbo to reduce the amount of time it takes for the turbo to build boost - reduce lag/response.

Saying an NA motor "has to breathe in its own air" is recockulous.  The atmospheric pressure is pushing it in.  Pressure goes from high to low, doesn't matter if it is being pushed by a turbo or the atmosphere - please understand that.  All the same physics apply to intake/resonance/inertia tuning, etc etc.

Supercharging will NOT, I repeat, NOT make up for shitty head flow specs.  This was bore out in SPADES with the Harley dynoing.  I was only there for about 100 pulls in the original development, about a week.  What we have found over the last couple years is that the heads are the bottleneck in the system and corking the horsepower.  Port the heads (or buy some aftermarket ones) and you can get huge increases in power, reduction in intake temps, etc etc.  This is more ignorance that is read and repeated all over the world because someone said it once.  

A supercharged or turbocharged engine doesn't have to have as good flowing ports as a naturally aspirated one to make "good" horsepower, but saying it doesn't matter is stupid.

How much heat is lost on a longer runner manifold?  I don't know.  Is it enough to loose how much energy?  Enough to reduce boost by .01psi?  More, less?  I don't know.  Saying thats why they do something without knowing it doesn't sit right with me though.

Scott- I agree equal volume is more important than length, but I still think that equal flow is more important than volume.  2 runners, equal volume, one flows 200 cfm@25" H2O, one flows 100cfm@25"H2O.

[MistressAnne]

If you guys don't simma down.....  :roll:

[punkrider99]

 The land-speed car I was referring to was NOT, repeat NOT the Hudson Boys Whipple-blown car, but a TURBO-CHARGED GEO METRO.  The owner of the Porsche shop I worked at built it and has run it with about 4 different motors, and has blown up 2 of them, and has used 3 different turbos, etc etc etc.  

Saying an NA motor "has to breathe in its own air" is recockulous.  The atmospheric pressure is pushing it in.  

Supercharging will NOT, I repeat, NOT make up for shitty head flow specs.  

A supercharged or turbocharged engine doesn't have to have as good flowing ports as a naturally aspirated one to make "good" horsepower, but saying it doesn't matter is stupid.

Scott- I agree equal volume is more important than length, but I still think that equal flow is more important than volume.  2 runners, equal volume, one flows 200 cfm@25" H2O, one flows 100cfm@25"H2O.

okay well unless you clarify then how the fuck would i know which metro you're talking about?  thats like saying "the land speed ford roadster."  theres like a thousand of those.  and i haven't been since '02 and i've only seen one metro.  excuse me for reading exactly what you wrote.

okay at first you say that supercharging will not make up for shitty flow specs and then you say a f/i motor doesn't have to have as good flowing ports.  so which is it?  last time i check boost will "mask" poor flowing heads because everything is working under pressure, not vacuum.  

obviously you need equal flow rates.  but why even mention that?  did you see something in that pic that made you thing they would flow differently?  all those tubes look the same diameter to me.  who would make an exhaust with different size primaries?

and yes engines "breathe".  ever stick you hand over a carb while an engine is running?  why do you think people put high flowing intakes and bored out tb's or high flow carbs on motors?

[Scott]

I think Greg needs to get laid....

[JettaGLXdriver]

WOW    :shock:

Greg, I'm so glad you're on these boards b/c you take much more time explaining shit than I do! :-) And you're 100% right...

I want to touch on one comment b/c it irked me so much that I couldn't continue reading...

The length of a runner DOES NOT effect flow velocity. A change in cross sectional area will. A runner that goes from big to small will increase velocity. Small to big will decrease it. The LENGTH of a runner affects the tuned RPM at which the resonance occurs (note: also a factor of volume and plenum shape and size). That's why variable intakes change the tract length... to create resonance (constructive interference) over a wide range of RPM's.

The physics here are staggering.

[greggearhead]

okay well unless you clarify then how the fuck would i know which metro you're talking about?  thats like saying "the land speed ford roadster."  theres like a thousand of those.  and i haven't been since '02 and i've only seen one metro.  excuse me for reading exactly what you wrote.

We were talking about turbos - I was using an example of a turbo car, I apologize for somehow leading you to believe it was a supercharged car.

okay at first you say that supercharging will not make up for shitty flow specs and then you say a f/i motor doesn't have to have as good flowing ports.  so which is it?  last time i check boost will "mask" poor flowing heads because everything is working under pressure, not vacuum.  

Head flow does make a difference.  That is what I said.  It does not make *AS MUCH* of a perceived difference because it cam be compensated for with boost, to a point.  

obviously you need equal flow rates.  but why even mention that?  did you see something in that pic that made you thing they would flow differently?  all those tubes look the same diameter to me.  who would make an exhaust with different size primaries?

As I indicated by starting my Statement with "Scott" the item was in regards to a comment he made that I thought I would clarify in my head and see what his input was.

and yes engines "breathe".  ever stick you hand over a carb while an engine is running?  why do you think people put high flowing intakes and bored out tb's or high flow carbs on motors?

OMG.  I fucking quit.  Think about what I said, about pressure - not about the physical act of breathing.  I am done looking at this fucking thread.  And I got laid the other day.

[The Asshole]

i love reading these techinogeek arguments....

my $.02
treat a FI car the same as a NA car, if it makes something more efficient, then do it.

inefficiency kills power.

THE WHOLE POINT OF TUNING AN ENGINE IS TO MAKE IT MORE EFFICIENT.
 
point bieng whether it is on a turbo'd car or not, anything done to improve efficiency is always the best route to go. PERIOD.

 you will never win a race by "turning up the boost" to negate the inefficiencies in your system.

[JettaGLXdriver]

Unless its agains a N/A VR6.  HEHEHE

[Jeff]

damn it, my computer breaks and i miss the only one worth while post here. scott and greg are dead on here in their posts, nice job guys. Where are you carlos, you still have my maximum boost book??

the main advantages of this particular manifold is its obviously alot better then the stock cast manifold. It allows him to put what ever flange he wants on it  so he can ditch the kkk stuff. with the bigger turbo there is no way it would fit in the stock location so he can move it where it will fit

[LOS]

Oh shit i forgot i still have it man... next time i see you remind me and I'll get it over to you

[punkrider99]

well from the way things looks, it sounds like we pretty much agree on what we're saying (except for the "breathing" thing).  

scott- i kinda fudged the length/diameter discussion a little bit too much.  isn't the normal practice to run longer runners for lower rpm and low range torque applications?  and then just the opposite for high rpm/high torque range.

in the end i think that hand made manifold is going to perform better than anything the oe's have to offer.