Intakes, I don't see how conical air flow is acheived at any point in the process. I'm not picking on any one vendor, I know that most are an improvement over stock but not sure if the air flow characteristics have been taken into account. The only one that really looks like it has been designed with wind tunnel testing to me is the APS, but I only have pictures to look at so not sure on that one.

What does this really mean? Obviously, once the air hits the turbo/intercooler its a whole other story anyway, but there has to be room for improvement pre-turbo here. If the air flow to the inlet is unstable, the turbine itself will lose operating efficiency. At any boost level, that flow to the impeller has an effect on the efficiency of the turbo to compress air. The higher the boost level the more impactful these airflow characteristics become, and this is not going to be a linear equation. At 30psi even micro nuances are going to have an effect. In a perfect world, I'd like to drop a nice conical air charge cenetered on the impeller shaft with laminar flow from intake straight onto the blades.

Moving on to the IC piping. My concern here, and with every IC pipe linking up to the TB, is the flow at the throttle body under WOT conditions. At moderate operating conditions it looks like the air flow would not be extremely turbulent but at WOT the angles involved do not work out for even air flow. I haven't started plugging and chugging the numbers (mainly because I don't have the drag coefficients for the materials and thats a weekend project) but it appears to be an opportunity for improvement--i.e. an IC pipe with an angle reduction at the mate point and limited material changes. I believe there would also be benefit in insulating the IC pipe to avoid heat transfer from the motor.

This brings up the manifold. I've been looking at the aftermarket options as well as the stock intake. Given the confined space with which to work here, this is always going to present a problem for even airflow. But there is one thing that would certainly make a difference--even length intake runners.

In every intake manifold I see, there is going to be a pressure differential from the point of entry to the motor. Equal length runners from the TB to each cylinder would be optimal--I'm not sure why this hasn't been taken into account outside of the space issue.

http://scienceworld.wolfram.com/phys...oullisLaw.html

http://scienceworld.wolfram.com/phys...minarFlow.html

 

Things to do...

Intake:
Chart flow rate of intake at varying boost levels/rpms
Determine optimum material characteristics (size, surface tension)

There is an optimum for what the length should be to ensure smooth airflow and pressure. I am going to modify my HKS racing suction to try to address these issues.


IC piping:
Determine air flow rate/temperature/pressure after the intercooler
Measure at IC outlet
Measure at TB after pipe
Create new IC pipe with less than 90 degree angle immediately before the TB (I believe a straighter shot into the TB will result in better air flow.)

Manifold:
Not sure on this one... Bueller... Bueller...
That will require some serious custom fabrication.

 

Any filter arrangement that causes turbulence through the MAS will upset the signal and compromise metering accuracy. The factory arrangement provides smooth airflow and plenty of filter surface area into a large capacity buffering box, and therefore does not disrupt the MAS signal. Furthermore, with cars making some 550+hp with the factory setup, any restriction (if any is evident at all) appears to be relatively insignificant. In my experience, attaching a cone filter directly to a MAS is the easiest means of creating turbulence, and I have noted instances whereby the physical orientation of the MAS/filter assembly itself inside the engine compartment affects the MAS signal.

Where intake manifolds are concerned, dyno tests have shown minimal advantage for aftermarket intakes with street applications where the EVO is concerned. Furthermore, the length from the TB to each intake valve is relatively unimportant, as the surge tank serves as a buffer from which each runner originates. The length of each individual runner, if not equal, would conceivably have some degree of impact on the synchronicity of mechanical tuning (e.g. intake and exhaust runner lengths), although again, testing has shown this to be of little significance with this particular application.

 

At what point would unequal pressure in the surge tank result in combustion variance?

 

Things to do:

Actually calculate the Reynold’s number for the problem at hand, realize that it is much greater than the critical Reynold’s number and is thus a wholly turbulent flow (ie has NOTHING to do with laminar flow characteristics)

 

Why couldn't that be compensated for with a pressure change?

(section 17 and lower of the following link)
http://scienceworld.wolfram.com/phys...minarFlow.html

 

It's difficult to answer that question (I have no empiricals). But as per my understanding, at least part of the purpose of the surge tank is to equalize and buffer pressure fluctuations. The volume of the surge tank must be sufficient to do this, and that volume likely takes into account both cylinder volume and runner volume for the cylinders it serves.

In 'V' engines (such as the SHO V6), there is a balance tube that connects the two surge tanks (one from each bank), which effectively doubles the size of each surge tank. If this tube is eliminated, the surge tank size is reduced, and engine loses a bit of torque. I believe for any specific application there is probably a minimum surge tank displacement, beneath which a loss of power will be observed, and above which there are diminishing returns.

 

what about using the conical oval filter from the 3000GT/eclipse K&N filters? K&N claimed long ago that round cone filters created turbulence and that the oval shaped filters provided straight flow to the MAS.

 

Why are you citing equations that do not even apply?

 

Basically, I'm looking at my mods, looking at what I'd like to do and I'm left wondering... who's doing the math??? I know this is many times more of an art than a science. I'm looking at the equation as a whole. As I increase output, I'm looking for the tangibles in what that means as a whole. As turbo pressure increases, what does my intercooler efficiency need to be? How much air does the intake need to breath in CFM for a given level of modification and how does that air need to be deliverd to the inlet? What is the heat transfer of the materials I'm using? I don't have any of this information. Its always pie in the sky, this mod does x. Why does this mod do x? What does x also effect? How do I know x won't cause y to explode???

Its all guess work.

The Evo (any car for that matter) is really a big equation. I don't think its balanced stock. I know there is a lot more capability to be had but I'm not getting a warm fuzzy looking at site after site, part after part. No data. How can I make a decision without data??? Right now I have compressor surge because my intake is running mass quantities of turbulent air to the turbo. I've read thats not a big deal, but it is a big deal. Its something that is not correct. I am probably going to go back to stock if I can't mod the Racing Suction in a way that eliminates this issue. I've read that the BOV can affect compressor surge but I recirc'd it with the same result.

So my immediate desire is to fix problem Y because of mod X. But I want to get on top of this so I don't wade knee deep into a black hole of mods and no math to stand on. As I do things, I want to know what I'm doing scientifically, not empirically.

Empirical
(a.) Pertaining to, or founded upon, experiment or experience; depending upon the observation of phenomena; versed in experiments.
(a.) Depending upon experience or observation alone, without due regard to science and theory; -- said especially of medical practice, remedies, etc.; wanting in science and deep insight; as, empiric skill, remedies

 

Unfortunately, you are set upon a course that leads to madness. It doesn't take long to realize that parts and power claims pertaining thereto abound, yet little real data is offered. When data is offered, it is usually insufficient to isolate the 'upgrade' itself as the sole source of the power increase. In short, makers and distributors of upgrades (especially those <$1000) need to offer little aside from 'bling' factor to sell them.

By no means am I demeaning many parts or the distributors thereof, but there must be a thousand ways to litter one's car with trinkets and gadgets that can only cause headaches and give little real value in return.

 

Why would that not be the correct equation? I'm trying to determine what the size of the intake tube should be (more specifically,what the pressure should be) to reduce or eliminate turbulence at the point of entry to the inlet of the Turbo.

My hypothesis is that there is a way to increase the pressure so that air flow into the Turbo could be laminar which would improve inlet efficiency.

 

IT IS NOT THE CORRECT EQUATION BECAUSE THE FLOW IS WHOLLY TURBULENT, NOT LAMINAR!

If you want to talk fluid dynamics, calculate an approximate Reynold's number and we will go from there. Otherwise you are just babbling on and citing equations you do not understand how to apply...

 

He speaks the truth. Time for you to open up that Fluid dynamics book to the turbulent flow section. Once you have calculated the apporximate Re number then you can begin to figure out the rest.

Here is something else for you to think about. With the stock airbox, how much positive pressure is made at 120mph? How much with an aftermarket intake?

 

Well, I have never been afraid to ask a dumb a question. Positive pressure where?

Speedlimit..