[Get Rad]

I know that it has been accepted within the community that the stock uicp expands. But I wonder if that's just hearsay that's been passed down without question. I know the pipe will collapse when squeezed inward, but there is a material wrapped around the rubber pipe that, for lack of a better example, is sort of like seatbelt fabric. So unless someone has actual evidence, I believe there is no way that the fiberous material will allow the pipe to expand outward. I think aftermarket UICPs are just engine compartment bling. I will have no problem retracting my previous statement if someone can provide proof that expansion occurs.

Think of it like this, you stretch a rubber band from post to post. Now you try running through that rubber band with all your power. As you run towards it that rubber band pushes back on you which slows you and and makes you work harder. This is what is happening with the stock IC piping. The clothe and rubber pipe around them has a much lower tensile strength compared to that of a metal pipe. We can also talk about the expansion of the pipe which creates a larger cross sectional area and we all know that as area increase pressure decreases. Pressure=Force/Area based on the science of that alone it is quite obvious. So in today's lesson we have learned that the hard pipe is better and not just for bling. I don't need data to prove this cause it can be proved theoretically using good old fashion math and having an understanding of material and fluid properties.

This is coming from a mechanical engineer.

 

[Get Rad]

Doesn't take a mechanical engineer to understand what's going on here. This is coming from a nuclear engineer

What he's asking has nothing to do with the theory behind why it would mean less power, what he's asking is "people claim it expands, but does it really?"

I don't want to put my stock UICP back on otherwise I'd take a video of the rubber section to see if it really does expand.

It has to expand its rubber and mesh clothe. You would have to disregard all material properties of the pipe. Just reading that made me want to face palm through my skull. Not to mention the affect of heat from the motor on the piping which would allow for the material to expand easier than when its cold.

I completely understand that you don't need to be an engineer to understand this which is why my mind if blown lol

 

[Get Rad]

This is getting a little beyond the scope, but you do not know the tensile strength of this woven fiber. Get a sheet of 2x2 weave carbon fiber and tug on the ends, measure how much it expands. Get a soft, fluffy cotton blanket and do the same thing. I guarantee the blanket is going to expand a whole lot more. This is an extreme example but I'm trying to clarify why it's not as simple as you're trying to make it out to be. You have no idea how much this material resists expansion and neither do I. None of us do.

The argument he made about the woven material... I'll also put that into perspective... inflate a balloon half way and pinch the opening. Tie a string around the middle of the balloon somewhat snug, then continue blowing up the balloon. Will the expandable balloon widen where the string is tied? Or will the string keep the same circumference? My money is on the string keeping the same circumference.

Now try the same experiment except with a thousand strings all tied in criss-crossing pattern. Are you going to have the lung capacity to blow the balloon up any further? Probably not. Will the turbo be able to expand the rubber section of the "pipe" any further? Maaaaybe not!

Now I feel like I have to face palm for describing why it's possible that a completely metal UICP might not even be beneficial at all.

No need to explain I do understand the properties of having a woven material being much stronger but unlike carbon fiber there isn't a polymer binding that material together to help maintain its rigidity. Also that string and material does not want to hold it shape it wants to return its natural form which is a floppy string. The more you boost the more that rubber tube with woven mesh will want to resist that expansion, hard pipe there is no resistance or deformation of the material and if anything what deformation there is its negligible. Which would you find it easier to maintain a constant flow, a tube that maintains its shape or one that's shape is in a constant struggle of expansion and contraction?

 

[Get Rad]

Never tried it, but I doubt it would expand much. Revving it up in neutral wouldn't build any boost pressure for any significant expansion. Does this sound right?


Sent from my Autoguide iPhone app

That's correct you would want to have this done on a dyno. Or take the piping off and cap off both ends and just pressurize it with air.

 

[Get Rad]

Woven carbon fiber starts out with no epoxy, it's just fibers. They are strong and tightly woven, they don't stretch very easily. I think you're missing the point. Nobody knows if the stock tubing expands. You're speculating that 25psi is blowing this tube up like a balloon when it's very possible that it holds 25 lbs like a champ and doesn't expand more than .01mm in diameter, aka negligible. In that event, replacing with a hard pipe will have negligible benefit besides looking purdy.

I think your missing the point. It still wants to return to its original shape no matter how you try to spin it. It's rubber under pressure it's goin to want to expand and contract and that's where the loss is.

 

[Get Rad]

Here is a LINK to Thermal expansion coefficients for some common materials. The higher the number the more prone the material is to thermal expansion. Take a look at both the Poly Carbonate and Rubbers coefficients of thermal expansion compared to that of aluminum. I feel confident in assuming that the material wrapping the rubber braided piping is produced of a polymer base. Since we know that the material wrapping those piping isn't reinforced, when you look at even the lowest coefficients of thermal expansion for the polymers based material its about it's a little greater than 50 m/mk compared to that of aluminum which is is 22.2 m/mk.

The seat belt example is a good one. What if that fiber wrapped around the rubber is made from the same stuff a seat belt is made of? Seat belts don't give. You can tug on them like a mofo and they're not going to stretch. If the nylon or whatever is in seat belts is the same stuff that's tightly woven around the UICP, why would it expand?

I get what you are saying completely and in theory this sounds like a good idea but the truth of the matter is that this has nothing to do with the fluid properties of the flow with in the pipe. You are also ignoring that mentioned that the hard pipe is more resistant to deformation than the stock piping. Should we also start talking about how the rubber hose is more prone to turbulent flow to do a the rubber being a less dense material that that of a hard pipe?

Why would that rubber section expand? It's not 100% rubber. It's braided nylon shit. You keep avoiding that and saying "it's rubber, it'll expand."

This is just common sense to anyone who knows anything about cars. To further bring home what I am saying Here is an in depth explanation about the friction losses of air through out a rubber hose. as well as an excert from the Doctors conversation. Even though it's for a different application they modeled the experiment using fluid properties of air.

"In lean phase the pressure losses in rubber are higher due to a number of reasons.
1. The wall friction between particle and rubbers hose is very high as compared to steel. This causes increased losses.
2. Due to the soft nature of rubber hose when the particle impacts the hose the rebound energy is less then steel pipe.
That explains the 50% higher pressure drops in lean phase as stated above. In dense phase the most materials will have very high wall friction with rubber hose and it will not move on the hose wall and instead will have an outside stationary layer and the plug will slide on this stationary layer. If you want to quantify this the increase in pressure drop will be the difference between the wall friction of the material with steel pipe and internal friction of the material. Which when correlated to pressure drop will be in agreement with Dr Mills observations."

I have also included a graph of the Moody diagram which is a graph in non-dimensional form that relates the Darcy friction factor, Reynolds number and relative roughness for fully developed flow in a circular pipe. It can be used for working out pressure drop or flow rate down such a pipe.

So what we have learned to day is that the softness of the rubber increase the friction factor which has an impact of the flow of fluid, in our case its air and we experience what they call in the industry a "pipe loss". So like I said the hardness and higher density material is more resistance to deformation which allows for a less turbulent flow to develop with in the pipe and overall increase performance.

I really didn't want to get into the affects on laminar flow and friction loss in a rubber hose but you left me no choice. The studies have been done and are proven and I don't need to watch the pipe expand or do a dyno pull to understand this. So to sum everything up on the debate of Stock UICP vs. after market hard pipe hard pipe, after market hard pipe hard pipe is better than the OEM UICP. the Now close this thread lol


Quod Erat Demonstratum

 

[Get Rad]

My head exploded after reading all these responses, but thanks for the input guys. I think I might end up just sticking with the stock pipe as the amount of modding I'm doing to the car might not get adversely affected by the soft stock pipe, whether it affects air flow or not. The main point of the original question was whether I would get adversely affected if I just planned on getting a cat back, drop in filter, fmic, and tune.

You will be fine with the OEM pipes. Just keep searching the market section and pick up a used one when the price is right.