Quick update:
I removed my quick warm air intake mod and put everything back to normal, to compare. Having done that I'm not convinced the gains were anything worthwhile. Although it did warm the air about 20-30 degrees F above normal, I can't say for sure whether it increased lean burn (frequency or duration). Plus, I'm pretty sure it made the car run rougher and weaker at low rpms, like between 1000-1700; stock it feels noticeably smoother and more powerful... Also, earlier I had said that the air/fuel ratio seemed to be higher, by about a point or 2, but that doesn't appear to be the case, at least, not due to the warm air mod....
Eq1,
I think the hot air mod takes a specialized setup to really work properly.
Theory:
The hot air mod is designed to thin the air enough to cause the throttle plate to open further for a given speed and thus reduce the engine pumping losses.
Application - Slow Driving:
The hot air mod should work great for this application, as it should do exactly what theory says that it should.
Application - Acceleration:
Here is the part of driving where having a hot air mod is counter productive. It thins the intake air and actually reduces horsepower to allow good acceleration.
Proper Design:
The hot air mod is something that should detect the intent of the driver and either thin the air when straight-line cruising, or deactivate when accelerating and allow more horsepower from the engine.
A fixed hot air setup only meets half of the requirement for daily driving.
My theory:
It' mainly about LOAD and TEMPERATURE of the intake air.
Which would equal thinner air.
(Remember the hot air balloons?)
I've see lean burn as high as 80 mph if all the circumstances are there during some experimenting, mainly temp and load.........But not for long.
HTH
Willie
__________________
01 MT "Little Red Rocket"
The first "TURBOCHARGED" Hybrid, Insight G1- (01/2003)
MaxIMA Battery (Serial #2), on 8/25/12 @ 301,520 miles
Use: 321,000 mi. @ 57.8 LMPG
...Application - Acceleration:
Here is the part of driving where having a hot air mod is counter productive. It thins the intake air and actually reduces horsepower to allow good acceleration...
I think this is a big part of why my mod was suffering - lower power due to both no resonance chamber and warmer air. I can't remember the exact numbers, but I recall there being particular figures associated with horsepower INCREASES with respect to LOWERING intake air temperature, as most people do. At least there were figures for the Miata... Can't find them. It was like, x% increase for such and such increment decrease in intake temp... Though it wasn't huge, it wasn't trivial...
Do you know how LOAD is measured? What goes into the car's calculation of 'load'?...
I can attest from the obdiic&c gauge that LB definitely ends out at anything greater than 85% LOD.
i.e. 86% LOD then immediately no more LB seen while running more or less steady TPS into a strong gusting wind cruising at about 100kph.
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Haven't gotten to details within the repair manual stuff etc specifically for the first gen car, but if the Insight's are like other vehicles there may be two modes of calculation for load LOD:
a.) MAF & RPM
First, on idle closed loop engine load is often calculated using just the air flow sensor values and engine speed., and
MAF RPM IAT & BAR
b.) For driving along in open loop operation, i.e. accel/decel etc, the air flow sensor, engine speed and intake air temperature plus barometric pressure are used for the %LOD calc.
There may be other variables at work such as rate of change etc.
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d-i-y ers: There are likely some vehicles to be found in the wreckers yards, [auto recyclers] that may have a winter warm up system to be cannibalized for valves etc. I recall seeing winter valve setting close to an airbox for intake air regulated to 86F/30C. Check VW 2L engines iirc. nb <110F/43C max rec. temp according to IC posts.
From everything I've ever read here, it seems we don't have a MAF and this would have to be calculated with MAP.
I see lean-burn higher in the 80's than 85 but it definitely needs less load if I'm cranking the RPMs needed for anything over 65mph. Since load likes to float even with the same TPS indication, I usually aim for a LOD value of 80.
When I check an OBDII guide I see this under ODBII mode 1 PID values:
Pid 04, 1 byte Value=Calculated engine load value 0-100% Byte decryption A*100/255
Description - Calculated utilized torque percentage of peak available torque based on determined airflow utilization.
Calculation method - Current airflow divided by peak airflow at zero altitude. Linear calculation by engine vacuum.
Troubleshooting notes - Vacuum leaks may cause this erroneous values to be displayed.
....Calculated engine load value 0-100%....
Calculation method - Current airflow divided by peak airflow at zero altitude. Linear calculation by engine vacuum....
If LOD value in part impacts lean burn, and LOD is calculated from air flow, I wonder what impact changes to the air intake make, such as removing the resonator, and thus how it might impact lean burn... Does anyone know what "peak airflow" refers to? Where's the peak? Is it a static measure, such as determined by the engineers, or is it something that changes?
Besides enabling the insertion of an air cleaner element/box, why do cars need any kind of tube to draw in air? Why can't it just pull air straight into the throttle body, or can it? What about the tubes, if anything, makes the air flow more efficient? Is it simply a matter of being able to locate the inlet in a better place? Does the air travel faster, is there more air, with different shapes and lengths?
My own take is that, besides being able to pick better locations for the inlet (such as a cooler or more consistent temp location) and allowing the insertion of an air cleaner, the shape and length tune the air flow in such a way that you get more air, a ram effect, faster flow, much like hod rodders buy expensive, tuned exhaust headers to increase exhaust flow...
If this is the case, what impact does the resonance chamber have? You add a passage with a box on the end. It increases the volume of the tube. At low rpm, the engine sucks less air in, there's less vacuum(?)... Maybe it has to do with pressure differentials? Something about the longer intake track, extra passage/box, added volume, perhaps increase the pressure differential so that, at low rpms, when there's the least vacuum, you still get a good amount of air flow?
Besides enabling the insertion of an air cleaner element/box, why do cars need any kind of tube to draw in air? Why can't it just pull air straight into the throttle body, or can it? What about the tubes, if anything, makes the air flow more efficient? Is it simply a matter of being able to locate the inlet in a better place? Does the air travel faster, is there more air, with different shapes and lengths?
You note one of the important drivers of intake engineering, a convenient location of the mandatory air cleaner, but it is a lot more complicated. The entire intake and exhaust systems are largely acoustical devices. The length and configuration of tubes are tuned to accomplish specific goals. In the case of the resonator on the Insight, it is designed to improve charge "stuffing" at a specific RPM range, as are all resonators. 3wheeler has made the argument that the resonator works in the 1500-1800 range and I can't disagree. The overall length of the intake runners is important both before and after the air cleaner, for acoustical tuning reasons, but the filter dampens considerably the effect of any tuning before the filter. Tuning between the filter and the intake valve is quite effective.
I think engine designs in their native form exhibit various peaks and troughs in torque. Early on, the designer will start optimizing the intake system and the exhaust system to try to level out the torque curve to a more "normal" smooth curve.
Because the Insight engine designer made the decision to fully "contain" the exhaust manifold within the cylinder head, to retain engine heat, exhaust tuning was largely off limits. Normally the most effective exhaust tuning is in the selection of tube lengths and the way in which they are combined - given a particular performance objective. But, I think Honda was much more interested in thermodynamic efficiency than they were in smoothness and power, and I for one agree with them. they produce and engine that is virtually without peer when considered on an efficiency basis. We get 60-90 MPG from the Insight, while the much less sophisticated 1 liter Metro got 35-55 MPG or so
I haven't seen published fine grain data on torque from the Insight engine, but there does seem to be some dips in the torque curve. I have noticed a nice peak in torque at around 2200 RPM, but the zone between 1800-2000 RPM seem to me to be particularly dead, so it is far from perfectly smooth.
If LOD value in part impacts lean burn, and LOD is calculated from air flow, I wonder what impact changes to the air intake make, such as removing the resonator, and thus how it might impact lean burn
Whoa! Lot's of questions here. I will try to answer the one's that I know something about.
Several years ago when I performed that resonator experiment, I wanted to know what affect it had on the intake performance, and thus the "hill test" to determine that.
The resonator, "stuffs" as JimE put it, more air into the intake tract just before the intake valves close and thus giving a slight rise in power at 1300 and around 2100 rpm.
However there IS a drawback to using this device as well, but I will touch on that later.
Quote:
Originally Posted by eq1
Besides enabling the insertion of an air cleaner element/box, why do cars need any kind of tube to draw in air?
On the Insight I believe that the long snorkel running parallel to the radiator is there strictly to reduce intake pulsation noise. That's all. Notice that the snorkel is smaller at the inlet and then gets larger. This shape provides no energy boost to the intake system. If the intake were shaped like a megaphone, then it would be another matter entirely.
Quote:
Originally Posted by eq1
If this is the case, what impact does the resonance chamber have? You add a passage with a box on the end. It increases the volume of the tube...
A resonator acts like a Helmholtz resonator. Loudspeaker designers sometimes use this effect to boost bass performance at lower frequencies. It essentially makes the speaker cabinet act as if it has more internal volume.
For a loudspeaker with a frequency cutoff of let's say 40 Hz, changing the closed cabinet (infinite baffle) to a tuned system, lowers the cutoff to 30 Hz. The drawback is a null in output at 50 Hz. Always a compromise.
In the case of the Insight, the resonator impacts the efficiency of the intake system only at the resonance points in which the resonator effect works, i.e. at 1300 and 2100 rpm.
1300 rpm is equivalent to the primary resonant frequency, and 2100 is the secondary "harmonic", which is normally how resonators work.
Drawback:
Any time a resonator is used in a "tuned" system, there are side effects which also show up. In this case the resonator has an anti-node at 1700 rpm. Most people who drive the Insight work through this range and it does not bother them. I am not one of these people!
The resonator in my case affects my drive out of corners enough, since I drive at low rpm all the time, to the point that I have disabled the resonator completely, and so far like the results.
Yes, there is more intake noise emanating from the engine compartment, but it is not enough to concern me, and the power output seems more "linear" to me with it disabled.
Yes, the engine output at 1300 rpm is reduced, but the power through this range is "flatter" and less peaky.
Another benefit is a slightly wider throttle setting at this rpm, which should in theory reduce pumping losses in the engine.
Correct JIM, the resonator is there solely for the "intake noise". It's a sound thing.
Do you have an OBDIIC7C installed?
If so, look at the timing you are running at 1300 rpm., with a wider throttle opening. I assume you mean large with assist?
Scary to me.
Willie
__________________
01 MT "Little Red Rocket"
The first "TURBOCHARGED" Hybrid, Insight G1- (01/2003)
MaxIMA Battery (Serial #2), on 8/25/12 @ 301,520 miles
Use: 321,000 mi. @ 57.8 LMPG
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