Free or cheap "mods", with dyno results

[1997k1500Calvin]

I'm pretty sure the TB hat and MAF are 4"

Thanks I've been doing other mods too the truck haven't had timer for this one yet

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[TerryD]

-Descreened MAF. I've seen arguments both ways on descreening the MAF, I have had no issues. The screen simply pops out. I used emory cloth and sensor cleaner on the inner surface to clean the housing up a bit (take it apart and remove the sensor itself first), it was pretty nasty. And then I painted it red. Because I can.

I've been stewing this over some and have a preliminary theory for you. For credibility proposes, I'm an instrument technician in a large paper mill and deal with air and other liquid flows quite often.

Let's first consider why the screen is in there. In the factory configuration, the MAF meter is mounted right after a sharp 90° bend in the intake tube. This causes the air to stagnate near the center of the bend and more air to rush around the outside of it. Since this creates turbulence in the tubing, the screen was put in to help evenly distribute the air across the wires to improve the accuracy of the meter. While your airflow readings may increase, it could just be due to the fact that the spiraling fast air stream in the pipe is crossing center at that point and causing a false high reading.

One type of flow meter we use regularly here, although using a different method of measuring, requires 5 pipe diameters up steam and two pipe diameters down stream of the meter to create a smooth uniform flow in the pipe. If the MAF meter is 4", then you would need 20" (4"x5 diameters) of straight pipe before the meter and 8" (4"x2 diameters) after. I believe that the factory MAF screen is to correct for this turbulence since space is at a premium under a truck hood.

If you have a straight pvc pipe in there, you might swap places with the MAF meter and the tube, putting the MAF meter closer to the intake and giving the air flow time to smooth out inside the tube before being read by the meter. You might also do a pull measuring air flow then rotate the meter 90° in the line and see if your flow changes. Remember though, the higher numbers may be false highs caused by turbulence in the tubing. If the measurements didn't change, then you could be reasonably sure the meter is measuring accurately and that you improved the air flow.

I will think on this more and may even try it on my truck once I start the mods on it.

This is just a theory based on my experiences at work with flow.

 

[96Z71ECSB]

Makes sense. I've actually been debating the same theory for the past few weeks.
I knew the 90+ degree bend is a problem for air flow characteristics but I was debating how to remedy the problem on the cheap.
A Volant intake would be the answer but at a $200+ price tag.
I did buy an intake similar to what VorTecxas has, or had, on his truck.

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Mine came with a different shaped filter and the instructions said to mount the MAF at the engine side of the tube.
I mounted mine as Vortecxas did but I eventually went back to stock because of the noise.
I should mount the MAF as per the instructions (at the engine) and give it a go.

Thanks for the info.

 

[rcman989]

I've been stewing this over some and have a preliminary theory for you. For credibility proposes, I'm an instrument technician in a large paper mill and deal with air and other liquid flows quite often.

Let's first consider why the screen is in there. In the factory configuration, the MAF meter is mounted right after a sharp 90° bend in the intake tube. This causes the air to stagnate near the center of the bend and more air to rush around the outside of it. Since this creates turbulence in the tubing, the screen was put in to help evenly distribute the air across the wires to improve the accuracy of the meter. While your airflow readings may increase, it could just be due to the fact that the spiraling fast air stream in the pipe is crossing center at that point and causing a false high reading.

One type of flow meter we use regularly here, although using a different method of measuring, requires 5 pipe diameters up steam and two pipe diameters down stream of the meter to create a smooth uniform flow in the pipe. If the MAF meter is 4", then you would need 20" (4"x5 diameters) of straight pipe before the meter and 8" (4"x2 diameters) after. I believe that the factory MAF screen is to correct for this turbulence since space is at a premium under a truck hood.

If you have a straight pvc pipe in there, you might swap places with the MAF meter and the tube, putting the MAF meter closer to the intake and giving the air flow time to smooth out inside the tube before being read by the meter. You might also do a pull measuring air flow then rotate the meter 90° in the line and see if your flow changes. Remember though, the higher numbers may be false highs caused by turbulence in the tubing. If the measurements didn't change, then you could be reasonably sure the meter is measuring accurately and that you improved the air flow.

I will think on this more and may even try it on my truck once I start the mods on it.

This is just a theory based on my experiences at work with flow.

I have taken fluid dynamics classes and I would have to agree with this. When designing engineers did the research as to why this part is in the intake. It is not to filter out large particles because that is what your air filter is for and if you are using the screen to filter large particles, then you have problems. I would agree it is to get the air to laminar flow for an accurate reading. Turbulent flow will have pockets of higher flow and lower flow if you slice a section out of the air intake. This leads to as TerryD described above. Laminar flow will have the same flow rate across the entire section of the air intake, providing a more accurate reading.

You can actually calculate if you have turbulent flow throughout your intake by using Reynold's number with is based upon interial and viscous forces of the air. (Reynolds Number = Velocity * Diameter of Geometry * Density / Dynamic Viscosity) As TerryD described above as a longer length tube will changing the velocity of the and in some cases density (compressible flow). This will result in a lower Reynolds number so when you use a Moody Diagram as you move towards the left you can achieve laminar flow resulting in a the same velocty across a section of the air intake, resulting in a more accurate reading from you MAF.

 

[1997k1500Calvin]

I have taken fluid dynamics classes and I would have to agree with this. When designing engineers did the research as to why this part is in the intake. It is not to filter out large particles because that is what your air filter is for and if you are using the screen to filter large particles, then you have problems. I would agree it is to get the air to laminar flow for an accurate reading. Turbulent flow will have pockets of higher flow and lower flow if you slice a section out of the air intake. This leads to as TerryD described above. Laminar flow will have the same flow rate across the entire section of the air intake, providing a more accurate reading.

You can actually calculate if you have turbulent flow throughout your intake by using Reynold's number with is based upon interial and viscous forces of the air. (Reynolds Number = Velocity * Diameter of Geometry * Density / Dynamic Viscosity) As TerryD described above as a longer length tube will changing the velocity of the and in some cases density (compressible flow). This will result in a lower Reynolds number so when you use a Moody Diagram as you move towards the left you can achieve laminar flow resulting in a the same velocty across a section of the air intake, resulting in a more accurate reading from you MAF.

So what is the best cai in your opinion

Tapatapatalk

 

[TerryD]

So what is the best cai in your opinion

Tapatapatalk

I'm not sure this was directed at me or not, but I'll bite. I'm looking at a Volant cai for my truck. It utilizes the factory fender air intake and a sealed air box to prevent it from pulling in hot under hood air. It also makes it a straight shot from the fender to the TB hat and eliminating the sharp bends and corrugated tube that cause the turbulence. Summit also sells it cheaper than the K&N FIPK. VNT-15957 is their part #.

 

[1997k1500Calvin]

Yea it was and thanks...I'm thinking about making my own though..wife thinks I'm spending too much on the truck

Tapatapatalk

 

[TerryD]

The wife is your problem, but you need to make sure you seal the air filter to the air inlet on the fender. Last week, we went to my parents house for the weekend. We drove my K2500 down and Dad and I wound up taking it to town one evening.

Out side temperatures were in the high 60s as we came home. IAT was running around 70.5°F on the highway doing about 60mph. Just for kicks, I pulled over and popped the top on my filter box of and threw it in the back seat. After about a mile, the IAT had risen to around 85°F with no change in driving style or speed. When I stopped and let it idle before putting the top back on, the IAT quickly rose to over 90°F! Imagine what stop light to stop light driving would get you for IATs.

The general equation is a 1% loss in hp per ~8°F rise in IAT. so I lost nearly 2% of my already suffering 270k mile 5.7L's power just by popping off the air filter box lid.

 

[1997k1500Calvin]

The wife is your problem, but you need to make sure you seal the air filter to the air inlet on the fender. Last week, we went to my parents house for the weekend. We drove my K2500 down and Dad and I wound up taking it to town one evening.

Out side temperatures were in the high 60s as we came home. IAT was running around 70.5°F on the highway doing about 60mph. Just for kicks, I pulled over and popped the top on my filter box of and threw it in the back seat. After about a mile, the IAT had risen to around 85°F with no change in driving style or speed. When I stopped and let it idle before putting the top back on, the IAT quickly rose to over 90°F! Imagine what stop light to stop light driving would get you for IATs.

The general equation is a 1% loss in hp per ~8°F rise in IAT. so I lost nearly 2% of my already suffering 270k mile 5.7L's power just by popping off the air filter box lid.

Yea I know about the sealing of the box...I just want to get rid of the acordian tubing..

Tapatapatalk

 

[glfirefighter144]

This is why I like my aFe intake, it creates a seal with the hood, and while not being sealed from the engine, it still draws the majority of its air from the fender piping, once I put on the cowl hood, temps shouldn't be much of an issue I wouldn't think

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