Hello,

I've been reading about how it's good to reduce turbulence in the air intake tubing, MAF sensor, etc. to increase airspeed into an engine. I was wondering if there is a way to estimate how much improvement (smoothing of the airflow) I can expect if I do something to smooth out the "ribbed" portions of the intake tubing between my air filter and the throttle body. I'm wondering if this is worth doing. Any thoughts on this?

 

It wouldn't hurt as long as you're not spending a lot of time and money doing it. At least that's how I define "worth doing".

You can see and hear turbulant areas. As far as improvement just from that? It's probably all going to show up in the 8000rpm and up range and our engines can't rev that high.

 

I agree, it doesn't seem *worth* it. Its possible that there are gains, but they'll be in area's you wont see.

You're better to port your maf, plenum, stuff of that nature if you want a project.

 

Well, I like to make improvements where I can but I'm not really into doing a lot of work (don't have the tools, etc.) so I keep things as simple as possible. I have an open air filter and an airfoil between the butterfly valves on the throttlebody, both homemade, and smoothing out the ribs was the next thing I could do in the airstream. I figured I could probably do it for about $3 in 1 hour.

 

Fluid Dynamics is one of the scarier and more complex sciences. Unless you have some grad work under your belt in the field, i'd suggest you leave modeling turbulence alone, lol. There is just no way a laymen could try to understand it (i have an engineering degree and probably know all the relevant math and i still wouldn;t go near fluid dynamic with a 10 foot pole)

If you want to quanitfy improvments in airflow, why not do it the good old fashioned way. Before and after drag strip (or dyno) testing. You can do math until your eyes fall out, and it will still never replace actual physical measurements of the system in operation.

But honestly, smoothing out every little wrinkle in the intake tract is probably not worthwhile. Air flowing near the surface of the tube moves much slower than the air in the center.

 

Good point which only brings up another...


Its possible that the actual airflow isn't hurt by the "ripples". The first bump of that series would setup the "laminar" (sp?) flow at that spot where the flow now is moving slower than the rest acting as a surface for the main flow to "glide" across, thus creating kinda a "Flow void" if you will in the first indent (right behind the first bump) and this pattern would continue all the way across the ripples to the end, so unless you could do something to increase the diameter of the first bump to a larger size I doubt smoothing would have any quantifiable improvements.

 

That's the same reason the space shuttle has a blunt nose instead of a sharp pointy one. Just a thought..

 

Yeah, you guys are all correct. I guess I was hoping someone knew of some simple equations that would help me visualize the amount of turbulence near the walls. I picture lines of vortices (sp?, plural for vortex) forming behind all those ribs. I just don't know how far they extend into the airflow. Thanks for the input.

 

Well if you wanted to "see" what the turbulent areas looked like you could build a crude air flow bench and just put your intake tract on it and blow some air through it while injecting smoke into the airstream. If you don't use a lot of smoke you should be able to see any of the major air flow disturbances and how they form and react to the surrounding areas. This would give you an idea of how to go about eliminating whatever is inducing the turbulence.
This would be a lot of work with very little reward, other than the fact that you can say that you have done all the porting yourself.

 

^Is that what "porting" means? Actually, by "see" I meant in my minds eye. If it was important enough to build a flow bench I might as well duplicate the tubing in clear plastic so I could see everything inside and use multi-colored smoke to watch the turbulent mixing. I'm nowhere near that ambitious, even if I was, I don't know enough about working on cars in general to do half the things I see people write about on this forum. It's just not my field. That's why I keep my mods super-simple. I have a nephew who's going to auto mechanic school now and I'm blown away at all the things he tears into on his car.

 

It comes with time and exposure. Expose yourself to as much as you can, and spend the time and effort and you'll be right up there next to the pro's.

If you have the desire that is.

 

Intake ducting is Free HP.
For every 1% reduction in airflow gets you an increase of 2% HP.

It takes a huge air cleaner to be really low resistrictive.

Then there are the trade offs, ie short and pick up some radiator air, or long ducting to get cooler air. You'll only find the truth by doing some experimentation. You also have to treat the air colum as a single mass, ie, air really doesn't like to bend around much. Large diameters, and large radiuses.

http://www.gnttype.org/techarea/engine/mafrelocate.html

While the above is specific to a GN, it's obvious what I've done. Phase one starts with 3" ducting, and III ends up with using 4".

To maintain the same AFR I had to add fuel. If you make a mod and you have to add say 2% more fuel, your making 4% more power (in rough terms).

Again, talking about street cars, when you get to really fast stuff harmonics, acoustics, and trans sonic considerations are needed, but you can make gains, with clever ducting.

 

:hail:

I personally love it when grumpy shows up on the TPI board, I dont care what the rest of ya'll say

 

Wow! I'm gonna go cap off my intake tract right now! That'll reduce my airflow by 100% and increase my HP by 200%!

As for turbulence in the intake bellows and calculating that, youre wasting your time. Like Ed said, its a surface condition and in essence (or simple terms) what it does is reduce the diameter of the tube. The intake bellows is large enough that theres little issue for most of us that the surface isnt a concern. More of a concern is the shape of the air duct, changes from one shape to another, bends, that kinda thing. Both the Camaro and Firebird TPI have their own problems in that respect. As for air filters, the panel filters on the Camaro are really too small, the early TA setup is some sort of sick GM joke, about 3.5" of the filter is effective, the rest is useless no matter what you do. The later TA setup is better but still youre not using anywhere as much of the filter element as you should unless you modify the housing and then youre sucking in hot air. There's probably 10HP tied up in the intake forward of the TB easy, and I'd say almost none is caused by the ribs on the bellows. I guess the general idea you should follow is to address the major concerns first and if you have a 500hp motor and are trying to squeak out another 1hp you can spend the time making calculations on how much affect the ribs have. Probably simpler to just change it rather than spending time crunching numbers.

 

lol.. you beat me to it..

...

Yup, sometimes I wonder about some people.. Spend gross amounts of time figuring out what something will do on paper when it'll take all of 1 minute to do it on the car. Ah well, it all goes to the same place...

 

Thanks for setting me straight guys, I appreciate the help.

Jim.

 

This should read, For every 1% reduction in airflow resistance, gets you an increase of 2% in HP.

Since we were talking about turbulence and airflow I thought it was rather self explainatory, obviously not for everyone. Anyway, apologies for those that were so completely confused and bewildered.

And it's easy to sit back and talk in theory rather then turn a wrench and see what actually happens.

 

This is your problem, you are using English units. The metric system was made for simplifying the dimensional math in complicated fields like thermal and fluids.

Now where is that "slug".......:lala: