Reducing restriction on the cold side of the compressor, will benefit spoolup time in a big way. QUOTE]
This I agree with you 110%!!!
It will be interesting to see some final results.
However, I think ALL the models of our engines need a complete makeover in the breathing and (farting)?? departments.
But baby steps right!!!
Thanks for the great info guys and keep it coming!!
Compressor Efficiency Problem
- Thread starter Killerbee
- Start date
Reducing restriction on the cold side of the compressor, will benefit spoolup time in a big way. QUOTE]
This I agree with you 110%!!!
It will be interesting to see some final results.
However, I think ALL the models of our engines need a complete makeover in the breathing and (farting)?? departments.
But baby steps right!!!
Thanks for the great info guys and keep it coming!!
:rofl::rofl: never heard it put this way
Are you sure about that? Or just can't remember?
I hope you dont plan on starting this week off picking on me :blowme:
A ton of good info in this thread, hopefully we can come up with something COOL
pun intended
Larry just say the word and:army: Mike should know to:admin2:
pun intended
Larry just say the word and:army: Mike should know to:admin2:
I am a tiny bit surprised that nobody has questioned the smallish aspect of the total idle resistance numbers, something along the lines of "why do we need to worry about 1 iwc?" ...which is also the pressure you feel when you lightly blow on your hand.
I am a tiny bit surprised that nobody has questioned the smallish aspect of the total idle resistance numbers, something along the lines of "why do we need to worry about 1 iwc?" ...which is also the pressure you feel when you lightly blow on your hand.
Why do we need to worry about it? Hopefully you tell us.
And by the way, thank you for being 90% of the reason Larry is finally doing something about his truck concerning this topic. Michael I am a little confused, maybe it's because I just woke up, but can you explain what exactly the above statement means?
Is it good?
Is it bad?
What is Total Idle Resistance exactly??
Thanks
as in 1" of water colum as in like a 0.5 PSi?
Im wondering also what this would matter,But thinking if you brought it up it, Im gonna listen
Im wondering also what this would matter,But thinking if you brought it up it, Im gonna listen
I'll try to help here.
At idle the compressor mouthpiece makes up for 2/3 of the total intake restriction, when the engine is moving the LEAST amount of air through the track.
How do you think that will change when you step up the CFM requirements?
My truck moves 5 lbs/min of air at idle. At WFO it is more than 12 times that.
Before there was modern measuring equipment, water in a tube was used to measure small pressure changes, I think it was called a manometer. The force that it takes to move water against gravity by 1" is an "iwc" of pressure. Turns out that a colum of water 28 inches high is equal to 1 psi, and there is 400 iwc in 1 atm. Example: If you have a straw in your cup of water that is 14 inches tall above the surface of the water, your mouth will have to come up with 1/2 psi of suction to quench your thirst.
The pie chart is saying that 66% of 1.07 iwc is the restiction in the mouthpiece.
1.07 iwc is not a lot of pressure, barely enough to make us blink. But the laws of fluid flow follow that if you double flow, you will see a 4 fold increase in resistance. Its an exponential relationship, resistance goes up by the square of flow rate. If you want to predict what will happen at 65 lb/min, you just do the ratio thing, 65^2/5^2=X/1.07, and solve for X. Then you would then just apply the pie proportions to X.
This is only an approximation, but experimentally, the numbers at full flow are staggering (do the math). Also interesting is that as flow rate increases, the flow characteristics in each piece of the pie are changing. The element falls to 2-3% of the total, while the mouthpiece goes from 66% to 84% of the total.
The pie chart is saying that 66% of 1.07 iwc is the restiction in the mouthpiece.
1.07 iwc is not a lot of pressure, barely enough to make us blink. But the laws of fluid flow follow that if you double flow, you will see a 4 fold increase in resistance. Its an exponential relationship, resistance goes up by the square of flow rate. If you want to predict what will happen at 65 lb/min, you just do the ratio thing, 65^2/5^2=X/1.07, and solve for X. Then you would then just apply the pie proportions to X.
This is only an approximation, but experimentally, the numbers at full flow are staggering (do the math). Also interesting is that as flow rate increases, the flow characteristics in each piece of the pie are changing. The element falls to 2-3% of the total, while the mouthpiece goes from 66% to 84% of the total.
Ok thanks!! I get it now!! I was reading into it too much.
That being said, and looking at your numbers, there is a benefit to running the track with no air filter then-contamination concerns set aside of course!!
Another question, if we did remove the air filter, would it affect the final numbers? If it's 21% now, and we take it off the chart, what happens to the rest of the chart? Would the percentages change??
That being said, and looking at your numbers, there is a benefit to running the track with no air filter then-contamination concerns set aside of course!!
Another question, if we did remove the air filter, would it affect the final numbers? If it's 21% now, and we take it off the chart, what happens to the rest of the chart? Would the percentages change??
That was 21% at idle.
At full flow, it falls to only 2-3% of the total restriction. IMO, this happens because at idle, air flow through the element is governed by what is known as "laminar" viscous forces. The stock element has something like 20 sq feet of surface, and average velocity is across the element at idle is something under .1 mph. Other parts of the intake are already at turbulent flow. Anyway, i don't pretent to thoroughly understand why< but the fraction of loss to the element goes from 21% at idle to only 3% at full flow. (incidentally, I put a KN drop-in in for testing, that number went to 2%-obviously a waste of money).
So this should explain Pat's comment about why removing the element does nothing for you on the dyno or track.
At full flow, it falls to only 2-3% of the total restriction. IMO, this happens because at idle, air flow through the element is governed by what is known as "laminar" viscous forces. The stock element has something like 20 sq feet of surface, and average velocity is across the element at idle is something under .1 mph. Other parts of the intake are already at turbulent flow. Anyway, i don't pretent to thoroughly understand why< but the fraction of loss to the element goes from 21% at idle to only 3% at full flow. (incidentally, I put a KN drop-in in for testing, that number went to 2%-obviously a waste of money).
So this should explain Pat's comment about why removing the element does nothing for you on the dyno or track.
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Oh I see Michael!! Did I miss that earlier??
That was an LLY with the flat filter right??
I would like to see that test with the LBZ set-up. That stock filter looks restrictive.
The only advantage I see, is that a stock filter costs close to the same as a reusable K&N. If it is the same restriction and not alot worse. I'm sold!!
That was an LLY with the flat filter right??
I would like to see that test with the LBZ set-up. That stock filter looks restrictive.
The only advantage I see, is that a stock filter costs close to the same as a reusable K&N. If it is the same restriction and not alot worse. I'm sold!!
The Meat and Potatoes
I went and found a better compressor map, that I think will better approximate the VGT map. These both have 88 mm compressors, though the A/R is not the same, ours has A/R of .58.
I entered the map with stock air flow of 50 lb/min, and with a 5 psi cold side loss, the CIP is 9 psi. I know from past measurements that COP is about 36 (38 if IAT gets away from me), So PR=36/9=4.0. Off map operating point
If 3 psi of that restriction can be removed, or PR=36/12=3.0 (the PR decrease is the intended topic of this thread)
We get the same airflow with 20,000 less rpm, and some really big drive pressure benefits. Efficiency increases in a big way also, so the charge temp will be lower.
On the quick runs you guys do, you don't see much benefit of the heat reduction, mainly because the CAC acts to absorb short thermal spikes, as a heat sink. But the tow guys...they run for minutes at a time. Can anybody else appreciate that? The extra heat being shipped to the CAC is coming from all this extra plumbing resistance that is killing efficiency.
You should still see a fairly large performance benefit as parasitic drag is eliminated. If you run added boost (everybody here:rofl then the operating point is off the page altogether. If run augmented boost at 6000 ft (12 psi atm) the op point is out of the park, a 5 or even 6 PR
I am setting up the shop to tool several new mouthpieces. If anyone would like to donate their old LLY compressor mouthpiece to this effort, I would be eternally grateful. If I end up with one that is significantly better and can be marketed, I will return the favor by sending you one.
I went and found a better compressor map, that I think will better approximate the VGT map. These both have 88 mm compressors, though the A/R is not the same, ours has A/R of .58.
I entered the map with stock air flow of 50 lb/min, and with a 5 psi cold side loss, the CIP is 9 psi. I know from past measurements that COP is about 36 (38 if IAT gets away from me), So PR=36/9=4.0. Off map operating point
If 3 psi of that restriction can be removed, or PR=36/12=3.0 (the PR decrease is the intended topic of this thread)
We get the same airflow with 20,000 less rpm, and some really big drive pressure benefits. Efficiency increases in a big way also, so the charge temp will be lower.
On the quick runs you guys do, you don't see much benefit of the heat reduction, mainly because the CAC acts to absorb short thermal spikes, as a heat sink. But the tow guys...they run for minutes at a time. Can anybody else appreciate that? The extra heat being shipped to the CAC is coming from all this extra plumbing resistance that is killing efficiency.
You should still see a fairly large performance benefit as parasitic drag is eliminated. If you run added boost (everybody here:rofl
then the operating point is off the page altogether. If run augmented boost at 6000 ft (12 psi atm) the op point is out of the park, a 5 or even 6 PRI am setting up the shop to tool several new mouthpieces. If anyone would like to donate their old LLY compressor mouthpiece to this effort, I would be eternally grateful. If I end up with one that is significantly better and can be marketed, I will return the favor by sending you one.
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