I understand the flow is wholly turbulent, I'm not debating that point. I was trying to figure out at what point the flow COULD become laminar.

My concern is this. With wholly turbulent flow, there are going to multitudes of various pressure points within the system which are not defined. You could have a pressure build up at the IC pipe at a certain speed which pulls the hose off. You could have intake dead zone where a there is a pressure point at a certain speed that could momentarily starve the engine for air. The intake manifold could feed one runner harder than another or even create a dead runner at certain pressure points.

But this still brings me back to my argument of data. There is no data for any of this stuff. It all has to be calculated on our end. Why can't the manufacturers who are building and testing these parts supply exactly what their parts are doing? This is not some sort of top secret information. With the right tools and the time any one of use can sit down and calculate exactly what each component does with proper baselining.

I'm seriously thinking about fabbing my own intake using Samco custom hoses, the stock maf, and a home grown airbox.

I am also going to wrap my IC pipe to prevent heat transfer. I will measure before and after temps while trying to eliminate as many variables as possible and see what difference it makes.

I have one issue though, what's the point of arguing about this? I'm just trying to figure out the best way to go about something in a logical manner. When I'm wrong... and I was... cool. It happens. I mean, every time I meet some one in real life driving and Evo I have a great conversation about their car and what they've done to it and how much they like it. Why come down on me like the village idiot using the wrong equations? I'm trying to better my understanding (and possibly others) not **** people off.

I still think I'm posing questions that need to be asked, my question was flawed, but I still believe in looking for information that should be available.

Aren't other people wondering the same thing???

This forum is an excellent repository of information, if we have to grow our own data then it seems like something we can take on as beneficial for the community as a whole.

 

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Speedlimit...

 

No, actually you don't understand my point at all. In fact, I think you should go read the definition of laminar and turbulent flow before making another reply to this thread. I would also suggest paying specific attention to the variables that make up the Reynold's number so you understand what size pipe would be necessary for this laminar flow that you so desire. Here, I will even help you out:

Start off using a kinematic viscosity value somewhere in the ballpark of 1.9X10^-4 ft^2/second, use the intercooler piping diameter as your charactaristic length, and post back when you have calculated your Re number.

Fundamentally you have no idea what you are talking about, actually, because a turbulent flow BY DEFINITION has a larger mass flow through the same diameter pipe as a laminar flow.

 

He is talking about inside the airbox. I think what he meant was which setup had a lower pressure drop since technically the box is under a vacuum and not boost so therefore can not have positive pressure.

I personally believe that the stock airbox creates lower IATs by sourcing outside of the engine bay.

It is also important to remember in all these discussions that pressure is not enough to characterize the intake air parameters, since mass flow (the measure that actually means something in terms of building horsepower in an internal combustion engine) is also dependant on the IATs.

 

I don't think RyanM claimed to "know what he was talking about" or tried to spread misinformation, he was just thinking out loud and looking for ideas. Why the harsh reception? There are more helpful let alone friendly ways to set someone straight.

 

I understand what your saying Fenris and I agree my terminology is flawed as well as my previous understanding. I've looked up laminar and turbulent flow several times today to try and make sure I am grasping the situation. What your saying is that no matter what, the type of air flow given the dimensions we have to work with, we are going to have turbulent flow and laminar flow equations do not really apply. I was thinking that there would be a way to smooth the air flow out in the system if pressure was increased. I did run the numbers and it looks like the intake tube would have to be 2meters in diameter in order to facilitate laminar flow! From reading the equations it looked like you could acheive laminar flow provided there was enough pressure and you had the right surface viscosity.

The reason I was thinking this would be possible or why I was even interested was that given these two types of air flow, laminar flow would result in the most consistent air flow characteristics but I definitely see what you are saying

But this brings me back to my initial problem set so I'm still looking for ideas/comments

Does my idea of having an IC tube without a 90 degree bend right before the throttlebody still make sense? There has to be a pressure increase at the bend and a corresponding drop afterwards. My concern is that this drop, if not calculated correctly can cause inconsistent or undesired performance anomolies.

For instance, lets say that at 120mph (seems like a good number) There is a spike because the air flowing through the IC pipe has that point where it is building too much pressure at the elbow. But then lets say the corresponding pressure drop across the TB might interfer with the butterfly valve or cause a dead spot in the surge tank starving a runner.

I'm just concerned that it seems like we can attack these issues with empirical data, ie, create larger surge tanks, that we're not getting at the root cause which in my hypothetical situation was an IC pipe bend pressure differential.

Also, it is my understanding that no matter what, it is always best to avoid 90 degree or greater bends in any flow because of the pressure difference it creates and the work that the corresponding pump has to do to overcome it (aka, lost turbo efficiency). (again, I may be wrong)

This one might be fairly easy to test, could probably do it with straws and water.

I'll try to come up with a model.

The golf ball through a garden hose analogy springs to mind. (I think I remember a fairly graphic example on Mr. Wizard as a kid with clear hoses, a 3 story building, a couple of kids and a 15 hp brigs and stratton pump)

Just trying to generate some ideas.

(listen to the following link on air pressure--yeah, not the REAL Mr. Wizard, but funny)
http://www.profzounds.com/wiz.html

 

I am actually talking about positive pressure in the airbox at high (120mph+ maybe higher for an EVO, I haven't tested it) speeds. It is very small, maybe less then .5 psi, but still it is something. Basically, the air entering the air box can cause a pressurization effect. That is why on hypersport motorcycles no one would ever think about removing the air box for an open filter. Of course, on a motorcycle, the pressurization will be alot better due to there ram air design.

IAT is extremely important. Open intakes just suck in hot air.

 

Again man, you are improving but still have a long ways to go. You do NOT want laminar flow. Laminar flow just means that the Re number is below approximately 30 and you need to take the pipe surface roughness into account. There is no such thing as laminar flow ANYWHERE in an engine as far as intake air is concerned. Turbulent flow is actually desired and can be accurately measured by a Karmen Vortex style MAF sensor.

Fluid engineers use a concept called "loss coefficients" to describe pressure drops due to lengths of pipe and various bends, transitions and junctions. Another method is to use equivalent lengths, ie at a given flowrate you could treat a 90* bend with a specific bend radius to pipe ID ratio as a length of straight pipe dictated by a chart of known values.

These values have already been calculated for the lancer and Buschur makes intercooler piping with shorter lengths and less bends which should in theory reduce the pressure drop across the piping and thus reduce the turbine speed necessary to maintain the desired boost level.

I hope this is starting to make sense. I need to go kill some brain cells and drink some beer, but I will check this thread tomorrow whenever I regain consciousness. Good night all

 

RyanM, as you go forward and become a design/fluid engineer you will learn that sometimes the best and most effective way just doesn't work in regard to the whole design. That is why good compromises have to be made i.e. 90 degree bend to the throttle body.

 

For the intake this is what I'm thinking...

Samco hose straight off the inlet to the MAF housing
Mount the MAF housing to a custom airbox directly (no extra hoses or junctions)
Filter element vertically mounted in custom box covering MAF junction
3" silicone hose run down to a duct in the bumper or a NACA duct in the tray (maybe both and install a Y junction)

NACA duct in fender might look kick *** if done correctly.

 

although i think your quest for knowledge is admirable, you are not going to get many concrete numbers relating to the characteristics of airflow in a car (turbocharged non-the-less). you best bet is to take the numbers that are known, such as the head loss differences between pipes with a 90* bend and pipes with no bends (or gradual curves). if there is a 90 degree bend you can reduce the pressure loss by eliminating this restriction. you could also increase efficiency by removing all pipes and making then polished smooth on the inside, as reduced friction at the walls will reduce head losses.

the reason you will never get solid numbers is because there are just to many variables at work on this one. not to mention how all of fluid dynamics is basically based off of experimental data and fitting curves to match the experiment. there are no simple equations like f=ma in fluids concerning turbulant flow. now take for example your turbo spinning at max boost, it depends on constant exhaust flow to spool at the correct RPM level to maintain a constant boost level (which we all now is hardly constant because of the properties of the exhaust, being a surge after every cylinder firing. which that is not very consistant either). so yeah, your not getting constant flow properties, which are turbulant, so your never going to get concrete numbers. the best bet is to take two parts, the part you don't like and the part you do like, and compare the two side by side. this will tell you if you are gaining anything valuable or not. there are some things that can be seen to make a difference just by looking at it, and a reasonable sense of mechanical properties will tell you such things.

i would be less concerned with the flow between the air filter and the turbo, and more concerned with other ways to improve the performance of your car. your idea about removing the 90* bend is a good one. now go fab up some aluminum tubing, in a mandrel bend, that is a gradual 90* bend. no welding pieces together because that will only increase the pressure loss. it needs to be one solid piece for max performance. maybe even coating the inside with teflon might decrease the friction on the tube walls.

also the idea about putting thermal wrap on the IC pipes is not a bad one. i would first look at the temps before the IC and after the IC and see if they are higher or lower then the ambient air inside the engine compartment moving at a speed of lets say 45 mph. i would imagine the temps are higher in the pipes then the air around it (and that is why they use intercoolers), and what this means is your not going to want to heat wrap the pipes, your going to want to increase the cooling effect by adding fins to the pipe (or whatever may work). heat wrapping them in the case that the intake air is hotter then the ambient air, is only going to keep the temps hot going into the engine. hot air = bad.


this is a very good thread thus far. maybe something good will come from this.

 

I'm lucky I live next to a race town, one of my friends from work is a machinst/sprint car driver/mechanic/psycho dirt track racer with a shop that can do the bend and has lots of test equipment. We're going to test the IC pipe theory.

 

Bravo! One of the best threads on EvoM! WORKS Engineers now realize there are EVO owners who appreciate real Mechanical Engineering. Now if we could only secure the budget and resources of Mitsubishi R&D.

BTW, WORKS has always offered a 5% discount on all non-sale items to SAE members. I'm sure we could also squeeze in the ASME members too!

 

Intake manifold concept question

I see many of the manifolds available have a squared surge tank. Wouldn't that create random turbulence at the end of the tank, opposite to the throttle body? If the end of the tank was curved on the inside of the tank was curved rather than angled would this create a more predictable swirl?

 

How about 10% to engineers that are members to both.