Air Pod filters will work, you just have to be smart about it!

I'm pretty novice, as well. I'm well aware of the engine mods to produce torque, but we're talking about the carbs here. I'm confident enough in my knowledge that the motor's fuel/air mixture has an affect on torque, as well. That's what I'm referring to. Torque curve and horsepower are directly related. As I understand it, torque flattens out as you go up in the rpm's. So if any carb modification reduces a motor's ability to produce torque at the low rpm, I personally am not interested.
 
deviant said:
Personally, I'm more interested in torque. Where's the torque?
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If you mean you'd like to see the torque figures for the BHP test I posted, you can do the math and get the figures and even draw the curves if you want.
T= (5252 x HP)/ rpm

I just did some of the math and comparing the stock set up to test 5, which is the pods on stock carbs, you find that the peak torque rpm of 6500 did not change but you gained .4 lbs/ft of torque with the pods. At 5k and under there is a loss of torque, .3 lbs/ft at 5k, 2 lbs/ft at 4k, and I did not do the math below those rpms because if your riding a GS1000 at those revs your a wussy.
From 6k up to 9k it's all gravy, as torque and HP were increased by the use of the pods on the stock carbs.
This most certainly indicates a restriction caused by the stock airbox and a useful gain from it's loss.
 
deviant said:
As I understand it, torque flattens out as you go up in the rpm's. So if any carb modification reduces a motor's ability to produce torque at the low rpm, I personally am not interested.
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Correct. Torque curves head downwards as HP curves head upwards. The wider the spread between the two peaks the easier the motor is to ride and the greater the perceived "torque" as many people call it. The more dependent a design is on revs to make peak power the less low to mid rpm pull you'll have. Look at a typical Harley for an example of a motor that makes a wide spread of power by keeping revs low in comparison to most 4 cylinder or high revving twins. Contrast that with a highly tuned two stroke that can have a 500 rpm spread between the two peaks.
But in regards to your carb question, any changes that result in a loss of airflow velocity through the carb will upset the metering, improper jetting can result in a loss as well because a rich or lean mixture results in less than maximum power output. The two are tied together as well. Big carbs work better at higher rpms, smaller carbs at lower rpms.
An engine is simply an air pump. And it needs approximately 12.5 parts of air mixed with 1 part fuel by mass to work at maximum efficiency in the case of a gasoline engine. This holds true throughout the entire rpm range. So if a carb mod upsets that ratio at any given rpm, power will fall. Correct it and power will return to the maximum allowed by the engines design. Then you get into flame speed, airflow through ports and valve seats.... but that's enough for now. Long answer to a simple question, I tend to roll that way, sorry.
 
I think maybe 2 people here have drag bikes and they dont need an explanation to how this works. And no, it doesn't. off-idle torque is desireble in every application, regardless of whether or not it is achievable.

Theres nothing to argue here.
 
That's a blanket statement and it can be argued but I'd rather not since that's not my idea of fun. But I will make one example for you. My main background is building and tuning 2 stroke roadracers based on street bikes. Off idle torque is nonexistent. And we don't need it. If I had to trade 3hp at 9.5K for 5 lbs/ft of torque at 1600 rpms I'd say forget it. You have a clutch and 5 or 6 gears to keep the revs in the powerband, and the only time the bike idles is on the stand during warm up. Once it's rolling it never see's idle again. I have boxes full of trophies that were won without the need for off idle torque. I also have a great many street bike customers using cylinders modified by me that I'm quite sure feel the same way.
 
bamajoe said:
You, sir, should be permanently banned from all 2 wheeled forums for such a statement.


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Shoeman said:
I'll stand by my statement that back in the day swapping the airbox for individual filters could often provide a useful power gain. Old airbox designs were for the most part designed with only a secure position for the filter in mind, and ease of access to the filter as well. The typical liter bike of the late '70's fed it's 1000+/- cc engine through a hole up under the seat about 2" in diameter.
Here's a shot of a page out of Bell's 4 stroke tuning book that shows, in his usual careful manner, a series of dyno tests that do in fact show some good hp gains from removing the airbox and using individual filters.
I'm not arguing your dyno results, DOHC, but I'd then wonder that if restricting airflow more than stock in some cases yields an increase, might that indicate a lean condition that was partially corrected by the reduction in airflow? Would rejetting those carbs and using the stock airbox possibly yield a gain?
One could argue that the power curve suffers in some way often by mods such as these, and that is true. The results in the picture illustrate that. Gain some at 8K, lose some at 4k. If that is acceptable really depends on the characteristics of the curve you are after. Modern high performance bikes take full advantage of airbox design, but that's tough to implement on the old dogs most of us are fooling around with here, some part of the frame is always in the way it seems.
It's been a long week at work and it's Friday night. Time for a beer!
Click to expand...

I do not consider K&N when most people talk about pods. If you look at the chart, the 26mm carbs made less power across the board when the airbox/filter was removed and made just slightly more power above 6500rpm with K&N filters.
The bigger 29mm carbs only gained 1hp on the top end above 7500rpm over the 26mm.
I'd like to read more of what was cut off the bottom of that page. Looks like it starts to say "Superbike owners are not the only ones being fooled into believing their bikes run better on pods" And goes on to talk about how many speed parts are made that are worthless.
I'd argue "useable horsepower gain, we're talking maybe 3hp max at 7500rpm, hardly what I would consider a useable gain.
 
Tests 1 and 4 are stock carbs with airbox versus stock carbs with no airbox. That is not a net loss across the board. There are gains from 7k up. The cut off remainder of the page goes on to show a similar test on an sr500 and details some airbox mods that are beneficial. whether or not an extra 4 or 5hp in the upper rpms is helpful or not is up to the rider and was not my point. These are actual test results, not gut feeling or intuition or bs repeated often enough it becomes a supposed fact. They are proof that in at least this case the stock airbox could be called restrictive. If the resulting power curve is a good thing is an individual preference. Same as varying cam timing or paint colors.
 
Research intake runner length. I think you will find shorter wider runners are good for a few hp while longer narrow runners will provide more torque.
 
Shoeman said:
Tests 1 and 4 are stock carbs with airbox versus stock carbs with no airbox. That is not a net loss across the board. There are gains from 7k up. The cut off remainder of the page goes on to show a similar test on an sr500 and details some airbox mods that are beneficial. whether or not an extra 4 or 5hp in the upper rpms is helpful or not is up to the rider and was not my point. These are actual test results, not gut feeling or intuition or bs repeated often enough it becomes a supposed fact. They are proof that in at least this case the stock airbox could be called restrictive. If the resulting power curve is a good thing is an individual preference. Same as varying cam timing or paint colors.
Click to expand...
Your previous point was how individual filters could make more power. I don't argue that the airbox may be restrictive in some instances, your chart shows nothing to back up more power from individual filters.
 
I've learned it really makes a difference which carbs you are talking about whether pods are easy or not. It really varies so much by setup that you just can't say they always work or that they can't work.
 
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