L31 Extreme Budget Build

[L31MaxExpress]

I wonder how much the tube will cut down on the flow. There will be some resistance there.

I agree, however there will be 2 scoops and hoses when it is said and done. Those high velocity fans only move air at about 20-25 mph as well. At 70-75 mph there should be a good bit more energy in the wind to overcome the hoses resistance as well. If I remember correctly, wind energy increases with the cube of its velocity. That means if you double the wind speed, it would have 8x the energy atleast in theory. Triple the speed and it has 27x the energy. Increase to 4x the speed and it has 64x the energy. If that scoop is facing 80-100 mph wind, the energy should be increased ~64x.

 

[BeXtreme]

I agree, however there will be 2 scoops and hoses when it is said and done. Those high velocity fans only move air at about 20-25 mph as well. At 70-75 mph there should be a good bit more energy in the wind to overcome the hoses resistance as well. If I remember correctly, wind energy increases with the cube of its velocity. That means if you double the wind speed, it would have 8x the energy atleast in theory. Triple the speed and it has 27x the energy. Increase to 4x the speed and it has 64x the energy. If that scoop is facing 80-100 mph wind, the energy should be increased ~64x.

Close, it is the velocity squared... not cubed. Basically air can be considered an incompressible fluid at lower velocities(below the speed of sound) and can therefore be evaluated using Bernoulli's principles of fluid flow. A big part of that is the kinetic energy of the fluid, which can be expressed as 1/2 MV^2. So the energy of the fluid only goes up by half of the mass increase, but it is squared by the velocity.

https://www.grc.nasa.gov/www/k-12/airplane/bern.html

 

[Scooterwrench]

Close, it is the velocity squared... not cubed. Basically air can be considered an incompressible fluid at lower velocities(below the speed of sound) and can therefore be evaluated using Bernoulli's principles of fluid flow. A big part of that is the kinetic energy of the fluid, which can be expressed as 1/2 MV^2. So the energy of the fluid only goes up by half of the mass increase, but it is squared by the velocity.

https://www.grc.nasa.gov/www/k-12/airplane/bern.html

Too much math man. What is known is he is going to get some forced induction. The faster he goes,the better it gets.
I like it!
I've got the same idea for Smoky when I get the 355 dropped in but figured I'd have to add another snorkel to my existing breather housing and make my own inlets out of sheet aluminum.

 

[L31MaxExpress]

Close, it is the velocity squared... not cubed. Basically air can be considered an incompressible fluid at lower velocities(below the speed of sound) and can therefore be evaluated using Bernoulli's principles of fluid flow. A big part of that is the kinetic energy of the fluid, which can be expressed as 1/2 MV^2. So the energy of the fluid only goes up by half of the mass increase, but it is squared by the velocity.

https://www.grc.nasa.gov/www/k-12/airplane/bern.html

Last I was in a math class, that would be an increase by the factor of 8 if velocity is doubled. You are forgetting that you have 2 times the mass of air if you double its velocity. You would be correct if the airflow mass was constant, but if you double the velocity, the air volume thus mass doubles as well.

 

[BeXtreme]

Last I was in a math class, that would be an increase by the factor of 8 if velocity is doubled. You are forgetting that you have 2 times the mass of air if you double its velocity. You would be correct if the airflow mass was constant, but if you double the velocity, the air volume thus mass doubles as well.

Mass is not increased by velocity... that is not how that works. The air is incompressible, so a set volume of air is always the same amount of mass no matter how fast it is going. You can calculate how much mass flow you have with a set volumetric cross section and velocity, but that does not change the MASS of the air in the cross section. Mass in this equation would only be changed based on the atomic composition of the material that would affect it's density and temperature. In most airflow calculations they just simplify to say that mass is unchanging since the air composition is always the same and it isn't doing any work, so temperature stays the same. The NASA link I gave you doesn't even have the mass portions in it, because it is unchanging in these cases.

The MASS in the equation is basically saying that if you threw a ball of wood(1lb) and a ball of lead(2lb) at the exact same speed, the ball of lead would only have .5lb more energy in it. If you throw that lead ball twice as fast, it now has 4lbs more energy in it(very simplified).

 

[L31MaxExpress]

Mass is not increased by velocity... that is not how that works. The air is incompressible, so a set volume of air is always the same amount of mass no matter how fast it is going. You can calculate how much mass flow you have with a set volumetric cross section and velocity, but that does not change the MASS of the air in the cross section. Mass in this equation would only be changed based on the atomic composition of the material that would affect it's density and temperature. In most airflow calculations they just simplify to say that mass is unchanging since the air composition is always the same and it isn't doing any work, so temperature stays the same. The NASA link I gave you doesn't even have the mass portions in it, because it is unchanging in these cases.

The MASS in the equation is basically saying that if you threw a ball of wood(1lb) and a ball of lead(2lb) at the exact same speed, the ball of lead would only have .5lb more energy in it. If you throw that lead ball twice as fast, it now has 4lbs more energy in it(very simplified).

I am basing my calculations off what real world engineers use for power calculations on wind turbines. Power of a Wind turbine is off the cube of the wind speed. Double the winds velocity, you get 8x the energy from the same swept area of turbine. Triple its speed and you get 27x the energy.

http://homework.uoregon.edu/pub/class/es202/wind.html

You must be registered for see images attach

 

[BeXtreme]

I am basing my calculations off what real world engineers use for power calculations on wind turbines. Power of a Wind turbine is off the cube of the wind speed. Double the winds velocity, you get 8x the energy from the same swept area of turbine. Triple its speed and you get 27x the energy.

http://homework.uoregon.edu/pub/class/es202/wind.html

You must be registered for see images attach

That's not what is happening there. That is a half-baked homework assignment that is being used to allow engineering students to try to understand how to do energy conversions with the kinetic energy of the air being extracted over time. The document even says that it is not actually used in practice. Also, none of that applies to what you are talking about happening with your air intake. If you are going to try and do any calculations related to airflow, mass flows, and the amount of air you can expect to be going into those inlets at highway speed, you should be using the bernoulli equations in the NASA link. Windmill stuff of converting kinetic energy of air to work over time is not applicable.

 

[L31MaxExpress]

I also saw this math which is interesting in itself. Using that math with the size of the dual scoops, the air box should be at atmospheric pressure under 20 mph. Above 20 mph it will have a slight increase in pressurization exponentially building with vehicle speed. That is of course negating resistance in the intake tubing and the effect of having the scoops behind the grille and filter. Assuming 700 cfm of peak airflow through the induction system and the scoops being ~80 sq/in.

700 x 1.64 / 80 = 14.35 mph.

Calculating Critical Air Scoop Speed With A Forward Facing Air Inlet

For a motorsports race car or boat, a forward-facing air inlet creates ram air above certain speeds. Find the critical air scoop speed for your engine.

www.enginelabs.com

 

[Scooterwrench]

Hmm,
Pi r round,cornbread r square.

 

[L31MaxExpress]

I added the ducts to the system when they arrived and retested. Seems like it will work great. May even have to bring out my GPS 0-60 and test with and without the ducting connected. Maybe drive it around for 10-15 minutes, let it get heat soaked and compare. With cooler air feeding the air box, I bet there is some real acceleration gain.

xc_hide_links_from_guests_guests_error_hide_media