Why do pop-chargers HURT low end on autos? ASKED A DOZEN TIMES, Never answered...
Why do pop-chargers HURT low end on autos? ASKED A DOZEN TIMES, Never answered...
Given the discussion in this thread here, I got to thinking about popchargers and their supposedly detrimental effect on low end in autos. I know that the question has been asked a hundred times. When I was shopping for an intake (which I bought, then promptly got rid of), I searched hundreds of posts. I knew he standard explainations of benifits and detriments for CAIs (PR, WS, Injen, Cattman), Hybrids (homemade, Frankencar, Fastlane, RVM), Pops (homemade, JWT, Stillen), and everything in between.
I could understand how the restrictions on airflow in a CAI might hurt high end and how the length of the airflow might cause problems in the lower piping.
I could see why hybrids might not benefit from cooler air due to their locations and how shorter intake lengths might help them develop power.
I could understand how the removal of the restrictive airbox (and everythign before it) could help with a popcharger intake.
What I could not (and still cannot) understand is WHY A POPHARGER HURTS LOW-END IN AUTOS. How does removing restriction from the airflow hurt low end? By this logic, sealing the whole system up would give us the greatest power. Are we getting TOO MUCH air? Is it screwing w/ the MAF? WTF makes an auto lose power w/ a popcharger?
I got rid of my hybrid (and my CAI) because the sound annoyed me (and my wife). I would like to have better power, but popchargers can be loud as well. I am not in the market for an intake. I am just baffled by the inability for anyone to come up with a logical (or mechanical) explaination for the low-end loss. Not that I can either, but it seems that someone knows the answer to practically everything on here.
I could understand how the restrictions on airflow in a CAI might hurt high end and how the length of the airflow might cause problems in the lower piping.
I could see why hybrids might not benefit from cooler air due to their locations and how shorter intake lengths might help them develop power.
I could understand how the removal of the restrictive airbox (and everythign before it) could help with a popcharger intake.
What I could not (and still cannot) understand is WHY A POPHARGER HURTS LOW-END IN AUTOS. How does removing restriction from the airflow hurt low end? By this logic, sealing the whole system up would give us the greatest power. Are we getting TOO MUCH air? Is it screwing w/ the MAF? WTF makes an auto lose power w/ a popcharger?
I got rid of my hybrid (and my CAI) because the sound annoyed me (and my wife). I would like to have better power, but popchargers can be loud as well. I am not in the market for an intake. I am just baffled by the inability for anyone to come up with a logical (or mechanical) explaination for the low-end loss. Not that I can either, but it seems that someone knows the answer to practically everything on here.
Dyno plot says I have the most area under the Administrator curve
Joined: Jul 2001
Posts: 7,064
From the other thread...
Originally posted by SteVTEC
I forget the exact equations, but a longer tube will be more restrictive than a shorter tube. I know that much. This is why you gain more top-end with a POP, and it's also why all the new VQ engines with VIM's open up a secondary shorter runner at high-RPM's. Because it's less restrictive than the longer runners. So why not use a short runner all the time? I don't know exactly (forget the equations), but probably to promote smoother running and cleaner (less turbulent) intake air for better overall flow than a short runner. If the air flowing into the intake manifold isn't very smooth, then it'll mess up your low end power and decrease the efficiency of the intake manifold, and in turn give you less power.
So now apply this to intakes...
<< Clip CAI >>
<< Clip Hybrid >>
A JWT POP charger intake (short tube, filter almost directly on throttle body) will promote the best top-end power (almost no tube to act as a restrictor), but because the intake charge flowing into the manifold won't be as smooth, perhaps this is why people with these intakes report lost low-end. The pop charger decreases the overall efficiency of the intake manifold at the low-end, but because there's almost no tubing, you get the best gains at the top-end.
I forget the exact equations, but a longer tube will be more restrictive than a shorter tube. I know that much. This is why you gain more top-end with a POP, and it's also why all the new VQ engines with VIM's open up a secondary shorter runner at high-RPM's. Because it's less restrictive than the longer runners. So why not use a short runner all the time? I don't know exactly (forget the equations), but probably to promote smoother running and cleaner (less turbulent) intake air for better overall flow than a short runner. If the air flowing into the intake manifold isn't very smooth, then it'll mess up your low end power and decrease the efficiency of the intake manifold, and in turn give you less power.
So now apply this to intakes...
<< Clip CAI >>
<< Clip Hybrid >>
A JWT POP charger intake (short tube, filter almost directly on throttle body) will promote the best top-end power (almost no tube to act as a restrictor), but because the intake charge flowing into the manifold won't be as smooth, perhaps this is why people with these intakes report lost low-end. The pop charger decreases the overall efficiency of the intake manifold at the low-end, but because there's almost no tubing, you get the best gains at the top-end.
Originally posted by SteVTEC
From the other thread...
From the other thread...
And if so, we can assume that the velocity stack (i.e. Stillen) is not long enough to smooth things out. So how long would it need to be? Could you do a stillen Pop w/ velocity stack and a short (3-5") or 3" pipe to lengthen the intake to give the air more distance to stabilize itself?
i have never experienced a low end loss with my intake setup, but i have noticed hesistations when its warm or hot outside. i attributed this to the warm air and to my automatic. i cant get in the power band or rpm that id like as easy as someone with a manual can. the lag is what i thought most people were referring to when they say low end power loss. with the berk intake and franken midpipe, i feel (with no dyno to back up) that i have not lost any low end, most likely just kept what i had or maybe a little more. however, i do experience lag from time to time depending on the weather.
Dyno plot says I have the most area under the Administrator curve
Joined: Jul 2001
Posts: 7,064
Hmm...I'll try to explain this another way.
When the impedance (resistance) of your source (the intake) and the load (the intake manifold) are "matched" (meaning equal impedance), the maximum power will be delivered from the source to the load.
Intake Manifold @ Low RPM: High Impedance
Intake Manifold @ Mid RPM: Medium Impedance
Intake Manifold @ High RPM: Low Impedance
Now look at the various intake setups...
CAI Intake: High Impedance
Hybrid Intake: Medium Impedance
POP Intake: Low Impedance
So in order to get the maximum performance *WHERE YOU WANT IT*, you need to select an intake system that is "matched" to the rest of the engine at those points.
If your main goal is low-end, then a POP would be a BAD choice since it has a very low impedance which does not work with the engine very well at that point.
If your main goal is top-end, then a POP *would* be a GOOD choice since that's where its low impedance works best with the rest of the engine. But because the intake is matched "poorly" at the low end (low impedance vs high impedance), it will not work very efficiently at all at the low-end.
So there are always tradeoffs
In the end, you just want to match up an intake system that works best for whatever type of performance that you're looking for.
IM @ Low RPM: High Impedance - CAI Intake: High Impedance
IM @ Mid RPM: Medium Impedance - Hybrid Intake: Medium Impedance
IM @ High RPM: Low Impedance - POP Intake: Low Impedance
Note that pretty much *EVERY* factory intake setup you'll see is more of a hybrid length from the filter to the throttle body. This has a medium impedance, which is the best overall setup for stock cars since it works well at all RPM ranges that the powertrain needs to cover.
This answer probably isn't 100% technically accurate, but it is definitely on the right track. I'm an Electrical Engineer, so I'm relating my knowledge from this area to mechinical. It might not translate perfectly, but there are nevertheless many parallelisms between the work that I do matching electronic circuits and the work that an engine designer does matching different components of the engine together for optimal flow.
When the impedance (resistance) of your source (the intake) and the load (the intake manifold) are "matched" (meaning equal impedance), the maximum power will be delivered from the source to the load.
Intake Manifold @ Low RPM: High Impedance
Intake Manifold @ Mid RPM: Medium Impedance
Intake Manifold @ High RPM: Low Impedance
Now look at the various intake setups...
CAI Intake: High Impedance
Hybrid Intake: Medium Impedance
POP Intake: Low Impedance
So in order to get the maximum performance *WHERE YOU WANT IT*, you need to select an intake system that is "matched" to the rest of the engine at those points.
If your main goal is low-end, then a POP would be a BAD choice since it has a very low impedance which does not work with the engine very well at that point.
If your main goal is top-end, then a POP *would* be a GOOD choice since that's where its low impedance works best with the rest of the engine. But because the intake is matched "poorly" at the low end (low impedance vs high impedance), it will not work very efficiently at all at the low-end.
So there are always tradeoffs
In the end, you just want to match up an intake system that works best for whatever type of performance that you're looking for.
IM @ Low RPM: High Impedance - CAI Intake: High Impedance
IM @ Mid RPM: Medium Impedance - Hybrid Intake: Medium Impedance
IM @ High RPM: Low Impedance - POP Intake: Low Impedance
Note that pretty much *EVERY* factory intake setup you'll see is more of a hybrid length from the filter to the throttle body. This has a medium impedance, which is the best overall setup for stock cars since it works well at all RPM ranges that the powertrain needs to cover.
This answer probably isn't 100% technically accurate, but it is definitely on the right track. I'm an Electrical Engineer, so I'm relating my knowledge from this area to mechinical. It might not translate perfectly, but there are nevertheless many parallelisms between the work that I do matching electronic circuits and the work that an engine designer does matching different components of the engine together for optimal flow.
Not DAVEB the parts guy
Joined: Aug 2000
Posts: 8,549
I think this "lowend loss" with the POP is probably felt in autos mostly from idle to about 2000rpms. Correct? I think what is happening is that initial intake charge at the low rpms (idle to 2000rpms) results in turbulent airflow therefore the car feels a little "soft" when just starting out. In a 5 speed it isn't quite as noticeable, but I can feel it. The stock intake and even the PR CAI have a good bit more tubing for which the air velocity can build up and smooth out the air flow therefore giving the car a more powerful feeling on initial takeoff. The soft spot won't be seen on a dyno either because dyno runs are typically started from 2000-2500rpms. When I had my Poorman's CAI, my seemed to roll off the line much easier in around town driving. In an auto, I'd imagine things would feel even better.
phenryiv1-
If you want pretty solid gains in power for cheap, all the while keeping the intake quiet, build the Poorman's CAI. Buy a midpipe to get ride of the upper factory resonator. Get a K&N filter panel for the stock airbox and pull the lower resonator elbow that goes into the factory intake snorkel. The elbow is located below the snorkel, just behind the radiator fan. By some 2.5" shopvac hose and pop it into the former location of the elbow on the intake snorkel. Run the vac hose somewhere that gets a decent shot of cooler air. This setup produced exactly the same amount of power as my HKS POP from 2200-5500rpms on the dyno. Only after 5500rpms (after peak power) did the HKS make power over the Poorman's CAI. If this setup is still too quiet, then consider cutting a 2.5" hole on the driver's side of the lower airbox and running another section of shop vac hose from the airbox to behind the headlight. I never dynoed with that setup, but it sounded really good.
Dave
phenryiv1-
If you want pretty solid gains in power for cheap, all the while keeping the intake quiet, build the Poorman's CAI. Buy a midpipe to get ride of the upper factory resonator. Get a K&N filter panel for the stock airbox and pull the lower resonator elbow that goes into the factory intake snorkel. The elbow is located below the snorkel, just behind the radiator fan. By some 2.5" shopvac hose and pop it into the former location of the elbow on the intake snorkel. Run the vac hose somewhere that gets a decent shot of cooler air. This setup produced exactly the same amount of power as my HKS POP from 2200-5500rpms on the dyno. Only after 5500rpms (after peak power) did the HKS make power over the Poorman's CAI. If this setup is still too quiet, then consider cutting a 2.5" hole on the driver's side of the lower airbox and running another section of shop vac hose from the airbox to behind the headlight. I never dynoed with that setup, but it sounded really good.
Dave
Pusssseeeehhhh
Joined: Dec 2000
Posts: 2,001
Heat plays a role as well. When your sitting at a stoplight and you are running a Pop charger, your cars first breath of air is just the hot air sitting under the hood. Your low end suffers as your car sucks only the hot air available under the hood. Not until the car starts moving at speed does "fresh" air rush in. A CAI on the other hand is ready to go anytime and that first breath of air will be much cooler(denser) then any Air under the hood. Of course this will most certainly be challanged by others but I stand by the CAI and its real world gains. 
Thread
Thread Starter
Forum
Replies
Last Post
MaximaDrvr
7th Generation Maxima (2009-2015)
16
Aug 19, 2015 08:20 PM