Modding the stock intake manifold (Upper not lower)

[sen2two]

After looking at the stock UIM, I really dislike the design. Air go's in and hit a flat wall for the primary runners. And there are hard abrupt corners everywhere in the primary and secondary areas. So i cut it open, sandblasted everything, and ground out most of the bumps, corners, and round edges. I then added JB Weld to help smooth the air flow.

Before i go ahead and weld it back up, anyone have any good ideas to further improve upon this "experiment".


Here's what I came up with:
*These pics are before the sanding, polishing, and finishing.


Stock:

[sen2two]

And the work in progress:

[vex]

Turbulent flow=good
Laminar flow=bad

Edit: Let me clarify it a little bit: Rough up the surface of the intake runners. The rougher the better. If you smooth out the surface of the runners you create a laminar flow which slows down the flow going to the intake ports. As such you will reduce the airspeed velocity which results in a lower torque curve.

[infernosg]

Originally Posted by vex

Turbulent flow=good
Laminar flow=bad

Yes, but this

Originally Posted by vex

Edit: Let me clarify it a little bit: Rough up the surface of the intake runners. The rougher the better. If you smooth out the surface of the runners you create a laminar flow which slows down the flow going to the intake ports. As such you will reduce the airspeed velocity which results in a lower torque curve.

is not correct. Turbulent flow != higher velocity but rather, more energy. Laminar flow is typically considered to be uniaxial whereas turbulent is not, so in the direction of your flowlines laminar flows will always have the greater velocity. Due to its higher energy a turbulent boundary layer is smaller and more stable than a laminar boundary layer so it will adhere to the surface better (think golf balls).

To the OP, smoothing out the transitions is good, but for finish you don't want a mirror finish, nor do you want something resembling sandpaper in there. Too smooth and your flow area will actually decrease (due to large laminar boundary layers) and hurt flow into the engine. Conversely, too coarse will result in excessive friction, which will slow down flow significantly despite utilizing the entire flow area.

[vex]

Originally Posted by infernosg

Yes, but this

is not correct. Turbulent flow != higher velocity but rather, more energy. Laminar flow is typically considered to be uniaxial whereas turbulent is not, so in the direction of your flowlines laminar flows will always have the greater velocity. Due to its higher energy a turbulent boundary layer is smaller and more stable than a laminar boundary layer so it will adhere to the surface better (think golf balls).

To the OP, smoothing out the transitions is good, but for finish you don't want a mirror finish, nor do you want something resembling sandpaper in there. Too smooth and your flow area will actually decrease (due to large laminar boundary layers) and hurt flow into the engine. Conversely, too coarse will result in excessive friction, which will slow down flow significantly despite utilizing the entire flow area.

I should have paid more attention in Aero/Hydro.

I thought the purpose of the rougher surface (and similarly vorticity generators) was to trip the boundary layer inducing a turbulent flow? Maybe I'm confusing terms/physics here? Clarify?

Oh wait, I see my mistake. LOL, what a stupid thing to say!

[Rotary#10]

wow kinda crazy! but that makes sense to me at least. smooth out the air flow in the upper intakes.

[Rotary#10]

make another smooth mold
copy
?
profit !

[sen2two]

I never mirror finish my intakes or ports. I rough them out with 320 grit sand paper for a smooth, yet rough finish. I'll be welding it up tomorrow. Hopefully i'll make some decent gains. Only cost me 10 bucks to do (two JB Weld sticks). So even no HP gain is fine as long as my power band improves some...

[sen2two]

All done now... just gotta put in on the car. I'll be butt dyno'ing only. So i will not know for sure if it made a difference. But in theory, it should definitly help.

[TitaniumTT]

Theory is about as usefull as ass dyno's. I like the effort, but make it worthwhile and send it out to have the CFM tested or dyno a before and after then we'll decide. Until then all we have are pretty pics and proof that you can weld.

How many millions of dollars did Mazda spend to design these intakes to optimize the powerband? I don't think a little JB and welding will do anything worthwhile to improve it but untill it's properly tested, no one knows.

Oh, JB weld sucks.

[sen2two]

Originally Posted by TitaniumTT

Theory is about as usefull as ass dyno's. I like the effort, but make it worthwhile and send it out to have the CFM tested or dyno a before and after then we'll decide. Until then all we have are pretty pics and proof that you can weld.

How many millions of dollars did Mazda spend to design these intakes to optimize the powerband? I don't think a little JB and welding will do anything worthwhile to improve it but untill it's properly tested, no one knows.

Oh, JB weld sucks.

"We" don't have to decide. Since the manifold is on MY car. I'm not trying to prove anything, just posting pics to give people ideas on doing some low buck improvements. I'm not going to spend money on dyno's every time i post pics of work i have done to prove its worth. I feel the difference in my car, and see the difference at the track. Thats good enough for ME.

And btw, top race teams use JB Weld at the track to enhance the manifolds lap after lap for test and tuning. I don't know why you would think JB Weld sucks. I love it...

[TitaniumTT]

Originally Posted by sen2two

"We" don't have to decide. Since the manifold is on MY car. I'm not trying to prove anything, just posting pics to give people ideas on doing some low buck improvements.

You don't know if it's an improvement or not yet, don't get ahead of yourself there kitten

Originally Posted by sen2two

I'm not going to spend money on dyno's every time i post pics of work i have done to prove its worth.

In this instance you should. "Hey everyone, look what I did, it should make an improvement."

Go read about Paul Yaw's experience port-matching a 12A intake mani then we'll talk.

I'll save you the time and give you the cliffs notes. Paul flow tested a 12A intake mani. Then he port matched it. Then he flow tested it. He found that he actually LOST CFM. So he tossed the mani off to the side and ran a stocker.

Assumption is the mother of all fuck ups

I spent close to $500 on an ignition system over the winter. you can bet your ass I'm going to test them against the $260 system I have sitting in my basement. If you're not testing, you're guessing. Ass dyno's don't count. How many times have we heard, oh snap, I put this CDI box on and my car pulls great and idles awesome.

Fine, what they fail to mention is they also added new plugs, wires, reset the TPS, new air filter etc etc etc. Back to back testing or I don't care. No one else should either.

Like I said, I like the idea, but you never know unless you get good numbers. What does a few pulls on the dyno cost? Pocket change for definitive answers.

Originally Posted by sen2two

I feel the difference in my car, and see the difference at the track. Thats good enough for ME.

Soooooo if you're car feels faster even if it's actually slower you're happy with that?

Originally Posted by sen2two

And btw, top race teams use JB Weld at the track to enhance the manifolds lap after lap for test and tuning. I don't know why you would think JB Weld sucks. I love it...

At the track for emergencies sure. I've never heard of a pro team building an intake mani with JB weld.

[sen2two]

I pretty much agree with everything you said. But this is a hobby for me. I drive this car daily. It's not going to set any records or win any competitions. Now if i was doing this to my race car, there would be some sort of testing being done...

Im not looking for more cfm or even more power from this. Im more concerned with having a smoother flow for (hopefully) a better power band throughout the rpm's. For instance, porting the TB dosnt really add much HP, but you get much more power lower in the rpm's without losing any power up top. And that has been tested and proven.

A lower HP car can be faster than a higher HP car. A nice powerband with a stong *average HP beats out peak power.

[TitaniumTT]

Originally Posted by sen2two

I pretty much agree with everything you said. But this is a hobby for me. I drive this car daily. It's not going to set any records or win any competitions. Now if i was doing this to my race car, there would be some sort of testing being done...

Yeah I know, and it's turning out to be more than a hobby for me now which is really cool.

Originally Posted by sen2two

Im not looking for more cfm or even more power from this. Im more concerned with having a smoother flow for (hopefully) a better power band throughout the rpm's. For instance, porting the TB dosnt really add much HP, but you get much more power lower in the rpm's without losing any power up top. And that has been tested and proven.

True true, but I still wanna see some before and after numbers.

Originally Posted by sen2two

A lower HP car can be faster than a higher HP car. A nice powerband with a stong *average HP beats out peak power.

You my friend should understandf quite well (along with maybe only 4 other people) why I worked so hard getting these twins fuctioning properly. I'll take these over a 400 rwhp GT35R any day of the week and twice on trackdays