Pods or Airbox--an Anthology

[T99Ford]

Since there is so much discussion about these two, I decided to lay out the crazed reasoning of my own mind. Some of the information is my own, and some is what I have seen here:

Displacement:
A naturally aspirated engine, moving at any RPM, and given any cylinder/piston condition, can only displace a certain amount of air. For instance, a theoretical 1100 cc motor at 1000 rpm will displace 1,100,000 cc's of air in one minute (not accounting for mechanical innefficiencies or engine wear). The actual number would be less, but it will always be constant. And, if the rpm were to increase the displacment would increase accordingly, but in a linear manner, not exponentially (ie 2000 rpm would produce a displacement of twice 1000 rpm) So we will call this linear displacement "X".

So given that our engine moves X displacement, in order to achieve optimal naturally aspirated results, we would want to provide an air inlet to the engine that provides X airflow. Any less would limit our motor, and any more would be a waste and unncessary.

Optimal:
No air cleaner at all. While not practical, this produces the least amount of restriction. This was seen on many XS period race and sport bikes.

Other Option "A": Pods.
Also provides minimal restriction, though more than no air cleaner. Our engine still will only draw X (actually X-minimal restriction). The engine will draw no more air. Fuel mixing and atomization is taking place behind the slide, well away from mysterious "side drafts". However, many tuners recommend jetting up when installing pods after a stock airbox. If this is indeed a requirement, then the following logic applies: Jetting up adds fuel to the fuel/ air mixture. This means that by adding pod filters, more air is being injested, requiring more fuel to accomodate the delicate F/A mixture. SO, it follows that more F/A mixture is being drawn into the motor. If this is being burned, then we must assume that pods will increase HP, since more fuel is being turned into combustion engery. BUT...
This is only if the jetting is truly required. Remember that our engine only draws X displacement. So for what is said of pods to be true, it would have to be proven that there is less restriction in pods than in the

Airbox.
Designed at factory production prior to the advent of intake tuning. The airbox provides a place to store the air filter, and draws its air from the top of the engine under the gas tank. Since it is only a "box" and not a tuned chamber, no power benefit is provided by the box (though only on this era bike. Later bikes made large power gains by tuning the airbox in much the same way that an exhaust is tuned). I suspect that this box was brought into existence mainly to quiet throttle body noise and fill the gap ahead of the battery (my own opinion, though). I suppose it could be argued that the stock box is more restrictive than pod filters, given the size of the snorkel opening. I can not prove this, however without flow testing both. Many have agreed with me, though, and have cut large holes in the airbox. As none have reported power loss from this, it would be safe to assume that the integrity of the airbox is a marginal player to performance. These modified airboxes, have become, in essence, pods with a shroud. It makes the bike look original, and gives the (remember arguably) less resistance of the pods. However, since the bike only draws X displacement, still only X is going in, and therefore, there is no power increase over pods. The pod filter and cartridge air filter must flow a similar amount of air when fully exposed. If this is true, then they are second in flow rate only to No Air Filter! Additional arguments for the shrouded air box filter maintains that furtive cross drafts are avoided, making the bike more tuner and rider friendly. However, the logic of this argument seems slightly uninformed when the following is considered: any moving air at the filter is still at atmospheric pressure, and more than the pressure of the float bowl. At the carburetor bell, the air is still moving slowly and is not accelerated until it enters the venturi. Note that the venturi is varied by the slide. The purpose of the venturi is to move air faster. If the surrounding air movements actually played a large factor, all intakes would be placed in the front of a vehicle to take advantage of ram air, rather than hidden under the gas tank. And, it is hard to argue with the 20-30 years of race technology that ran without filters.

Conclusion:
It would appear from the logic above, that the unless a tuned intake was put into use, the promoters of pods and airboxes are fighting the same battle. The one to win the battle would remove his air cleaner, but would...only ...win for a short time! Otherwise, we are all as close to drawing X as we can be, and must content ourselves with that (unless, of course, you would like to force the air issue with a turbo). And if we have a completely stock box, our ears thanks us as well, though we might not quite be drawing X My logic may be flawed; Please feel free to correct major flaws with solid, hard, printable, and documented evidence. My logic is not interested in the seat of your pants, or how it SEEMS to you, no hard feelings.

About the author:
The author has been using pods the entire time he has owned this bike. He lists two main reasons:"The airbox was broken when I got it, and I like how pods looked". Did he re-jet with pods,"No", he tells us. Did he with his other pipe and tuning mods? "Yes, but only after careful dyno testing".

[mro]

It's the carbs

Increase restriction on the intake side of a vacuum increases "water lift" (don't know what term used for carbs).
These are CV carbs and the way the fuel flows thru them is affected by air flow/suction.


mro
Well .... at least sounds plausible

[tw1980]

I like your thesis.I also use pods.I'm going to award you an honorary PHD.You are now Doctor of Podalogy.

[CatatonicBug]

Very nice! So, as long as the pod users are installing their pods in the correct, least-restrictive manner, and the stock airbox folks are using the least restrictive stock-shaped air filter, both are essentially the same. The rest is a matter of taste. Or, in the case of pods, the desire to make removal of the carbs (arguably) easier.

[DGXSER]

I've taken the liberty of quoting you without the quote tool applied so I can add my thoughts and facts in red. I had fun thinking through the physics of it all though.

Displacement:
A naturally aspirated engine, moving at any RPM, and given any cylinder/piston condition, can only displace a certain amount of air. For instance, a theoretical 1100 cc motor at 1000 rpm will displace 1,100,000 cc's of air air fuel mixture, the air quantity is determined by the carburetor, more on that laterin one minute (not accounting for mechanical innefficiencies or engine wear). The actual number would be less, but it will always be constant. And, if the rpm were to increase the displacment would increase accordingly, but in a linear manner, not exponentially (ie 2000 rpm would produce a displacement of twice 1000 rpm) So we will call this linear displacement "X". Or simplify to every one revolution, each cylinder displaces roughly 275 CC's of fuel air mixture which = X displacement which is again 275 CCs per cylinder

So given that our engine moves X displacement, in order to achieve optimal naturally aspirated results, we would want to provide an air inlet to the engine that provides X airflow. Any less would limit our motor, and any more would be a waste and unncessary. Actually to get technical about it, the engine will pull this volume from where ever it can so all your controlling is how hard it has to work to get it, therefore absorbing some of the HP you developed in the combustion of the gases.

Optimal:
No air cleaner at all. While not practical, this produces the least amount of restriction. This was seen on many XS period race and sport bikes. Only optimal if the carbs are tuned to produce the required fuel air ratio for proper combustion at the compression the engine develops. Else you run rich or lean and develop less HP from the same displacement and less HP

Other Option "A": Pods.
Also provides minimal restriction, though more than no air cleaner. Our engine still will only draw X (actually X-minimal restriction). Actually, the engine will still draw X, it has to, it will just use slightly more of the developed HP to do so.The engine will draw no more air. Fuel mixing and atomization is taking place behind the slide, well away from mysterious "side drafts". However, many tuners recommend jetting up when installing pods after a stock airbox. If this is indeed a requirement, then the following logic applies: Jetting up adds fuel to the fuel/ air mixture. This means that by adding pod filters, more air is being injested, requiring more fuel to accomodate the delicate F/A mixture. SO, it follows that more F/A mixture is being drawn into the motor. If this is being burned, then we must assume that pods will increase HP, since more fuel is being turned into combustion engery.Actually, what happens is by creating a less restictive path for the air fuel mixture to get through, the engine creates less vacuum to pull it, therefore it is pulling less fuel through the same size opening or jets in the carburetor. So a bigger opening/jet is required to get the same fuel through at the lower vacuum. By having to create less vacuum, it uses less of the developed HP. Now, here is where the carbs come back in. The carbs on these bikes were selected to operate with the air box designed for them. Therefore the designed jetting and intake lengths, were all laid out based upon the vacuum created under the stock setup. By adding pods, your changing the vacuum being created. so again, the jetting needs to be worked out. From what I have seen here on XS11, many Pod filter owners struggle to get the jetting corrected, especially when combined wiht exhaust mods, which again play with restriction and therefore pressures which effect vacuum. BUT...
This is only if the jetting is truly required. Remember that our engine only draws X displacement. So for what is said of pods to be true, it would have to be proven that there is less restriction in pods than in the

Airbox.
Designed at factory production prior to the advent of intake tuning. The airbox provides a place to store the air filter, and draws its air from the top of the engine under the gas tank. Since it is only a "box" and not a tuned chamberThis is where I have to suggest that this is pure conjecture on your part, for all we know the engineers at Yamaha were ahead of the game and did "tune" the shape, no power benefit is provided by the box (though only on this era bike. Later bikes made large power gains by tuning the airbox in much the same way that an exhaust is tuned). I suspect that this box was brought into existence mainly to quiet throttle body noise and fill the gap ahead of the battery (my own opinion, though). I suppose it could be argued that the stock box is more restrictive than pod filters, given the size of the snorkel opening. I can not prove this, however without flow testing both. Many have agreed with me, though, and have cut large holes in the airbox. As none have reported power loss from this, it would be safe to assume that the integrity of the airbox is a marginal player to performance. These modified airboxes, have become, in essence, pods with a shroud. Actually, they still offer more restriction than the pods, this is a guestimate, but from someone who calculates pressure drops for air devices practically daily.It makes the bike look original, and gives the (remember arguably) less resistance of the pods. However, since the bike only draws X displacement, still only X is going in, and therefore, there is no power increase over pods. The pod filter and cartridge air filter must flow a similar amount of air when fully exposed. If this is true, then they are second in flow rate only to No Air Filter! Additional arguments for the shrouded air box filter maintains that furtive cross drafts are avoided, making the bike more tuner and rider friendly. However, the logic of this argument seems slightly uninformed when the following is considered: any moving air at the filter is still at atmospheric pressure, and more than the pressure of the float bowl. At the carburetor bell, the air is still moving slowly and is not accelerated until it enters the venturi. Note that the venturi is varied by the slide. The purpose of the venturi is to move air faster.Actually it is to move it at the rate designed so it creates the proper fuel air mixture, no faster, no slower, or rejettign is required, and the more laminar a flow is, the less restriction on the flow it creates requiring less vacuum to achieve the same flow. thus the straight length of piping designed into the air intake system from the airbox to the inlet of the carbs and sized to meet just so to the intake bell of the carb. If the surrounding air movements actually played a large factor, all intakes would be placed in the front of a vehicle to take advantage of ram air, rather than hidden under the gas tank. And, it is hard to argue with the 20-30 years of race technology that ran without filters. Again it is all about pressure drops and vacuum required

Conclusion:
It would appear from the logic above, that the unless a tuned intake was put into use, the promoters of pods and airboxes are fighting the same battle. The one to win the battle would remove his air cleaner, but would...only ...win for a short time! Otherwise, we are all as close to drawing X as we can be, and must content ourselves with that (unless, of course, you would like to force the air issue with a turbo). And if we have a completely stock box, our ears thanks us as well, though we might not quite be drawing X My logic may be flawed; Please feel free to correct major flaws with solid, hard, printable, and documented evidence. My logic is not interested in the seat of your pants, or how it SEEMS to you, no hard feelings. The real factor is HP developed and where it gets used, combined with tunability of the fuel air mixture. Less restriction uses less HP to create vacuum required to pull the air fuel mixture into the cylinder. The bike as a whole was designed to work best with these carbs and tune properly with the air box setup, going to POD filters, you are searching to find the right combination that works best. Not that it can't be done, but it takes alot more effort and knowledge to get it right. All information provided can be backed with physics and documented pump laws as required.

About the author:
The author has been using pods the entire time he has owned this bike. He lists two main reasons:"The airbox was broken when I got it, and I like how pods looked". Did he re-jet with pods,"No", he tells us. Did he with his other pipe and tuning mods? "Yes, but only after careful dyno testing".I have used the factory air box as came wiht my bike, never had it on a dyno, and it runs like a scalded dog. I am sure it could be tuned better, but I also doubt the street use it gets would ever unveil the difference in performance that could be achieved, same could be said for the pod filters vs air box argument.

[T99Ford]

*quote*Actually, what happens is by creating a less restictive path for the air fuel mixture to get through, the engine creates less vacuum to pull it, therefore it is pulling less fuel through the same size opening or jets in the carburetor.

I thought the fuel was added after the air filter, and the venturi. Only the air is less restricted.

quote:This is where I have to suggest that this is pure conjecture on your part, for all we know the engineers at Yamaha were ahead of the game and did "tune" the shape

Proof? They were just starting to understand intake technology. On a tuned intake bike, you will lose significant power every time by taking the intake off, and you will not make it back.

quote:same could be said for the pod filters vs air box argument.

This is my point! There is virtually no difference in what air filter you use, if you can tune it. I commend you on pointing out some very key points about intake flow, too. The main reason behind this thread was to point out that there is not reason to argue over this issue, since both means will reach the SAME end! I believe that your additions and changes serve to effectively enforce this point. Thank You!

[mro]

This is my point! There is virtually no difference in what air filter you use, if you can tune it.

Seems to be a difference, slightly noticeable at the "top end"


mro

[T99Ford]

Some additional thoughts...

Also provides minimal restriction, though more than no air cleaner. Our engine still will only draw X (actually X-minimal restriction). *quote* Actually, the engine will still draw X, it has to, it will just use slightly more of the developed HP to do so.

More thinking has led me to believe that the original statement was true before the correction. Here is why: since atmospheric presure and cylinder vacuum are remaining the same, and just the restriction (airbox, pods) is increasing, X will diminish, since time (RPM) is a factor. Volume (air flow) is reduced at the restriction. Above a certain engine speed (not sure what) the restricted engine will not have time to pull in the same volume of A/F as the non-restricted engine before the intake valve closes. What remains is less A/F volume in the cylinder, though the theoretical displacement is the same. DG is correct that more HP will also be used in drawing this reduced volume. Therefore, the higher the restriction, the more likely it is that the engine has an increased parasitic load, and a reduced cylinder inlet volume, since valve duration, atmospheric pressure, and cylinder vacuum all remain the same. This would tend to give the less restricting intake an edge over the restricting intake. The lost fuel due to reduced intake vacuum of the less restrictive intake can be replaced by jetting up, making the A/F ratio of both intakes even. However, the parasitic HP consumption of the restrictive intake would give the edge to the non-restrictive intake, however small it might actually be. The restricted intake loses power in the areas of parasitic load and reduced intake volume.

quote: Actually it is to move it at the rate designed so it creates the proper fuel air mixture, no faster, no slower

This is to the letter correct! However, my statement was more a generalization of the venturi and Bernoulli's principles, that the air will increase speed at the venturi, and drop pressure on the back side of it. Obviously this rate is calibrated for a certain return, based on venturi and slide shape. The air filter restriction will regulate the cylinder vacuum.

Quote:From what I have seen here on XS11, many Pod filter owners struggle to get the jetting corrected,especially when combined wiht exhaust mods, which again play with restriction and therefore pressures which effect vacuum.

It is true that many struggle with this issue, but it does not discredit the fact that the proper jetting can be achieved to achieve optimal results. Also, Exhaust mods, while ultimately dealing with pressures, play less with the idea of restriction per se, and more with the idea of reducing the parasitic load from the engine to the exhaust flow. The tuned exhaust idea simply put is to create a vacuum (low pressure) condition in the cylinder that the cylinder does work to create. This is done by controlling exhaust frequency, and is controlled more by pipe shape and length rather than restriction.

I am not trying to stir the pot, just looking to put all the facts on the table, so that we can understand this huge divide more intelligently. The info provided by DG is extemely helpful to this. More information and insite please!

[trbig]

You have assumed through this whole last post that there will be less volume in the cylinders as the RPM rises. Your cylinders, as stated, will draw in 275.25cc of air/fuel mix, no matter what RPM. It will fill this volume at each downstroke from wherever it can. If the rings are bad, it will use a small amount from the crankcase.

The intake design of the carbs works best when they are getting air straight into the bell, not swirling around like they get from just pod filters. Sidewinds, speed and other variables will change this. That's why many people fix performance problems by using the velocity stacks.. much like the stock airbox used. I haven't noticed any problems on mine with just pods, but I've never run the stacks to have anything to compare to. I finally, just this weekend, got to look at what rpm I normally shift at when racing. I never watched the actual rpm.. I just shifted at when I feel the motor's power starts to drop off. For my bike with the pods, it's at @ 9500 rpm. No telling what rpm the motor hits when I occasionally miss a shift. It's always pulled strong to this point, so I never worried about what the actual numbers said.

You assume a filter is causing the airflow to be restricted to a point that at high rpm, at the bottom of the piston's stroke when the valve closes, there is still a vacuum in the cylinder, equating to a loss in volume. These heads, valves, carbs,and even a fairly plugged up air filter will move more air/fuel volume than the motor could ever use, even when bored to the 1196cc.


Tod

[DGXSER]

I thought the fuel was added after the air filter, and the venturi. Only the air is less restricted.

Yes, fuel is added after the air filter, however, its all in the vacuum, which is Bernoulis principal. Same thing that makes an airplane fly. The air velocity moving across the venturi creates a vacuum that then pulls the fuel out of the bowl through the appropriate jets. Not going to dig to deep into the carb functions here, mostly because it would be a short conversation on my end. I am a student and learning alot. Anyway, as the less air restriction decreases the amount of vacuum created and therefor less fuel is sucked up based upon the restriction on the fuel from the size of the jet. So to get the same amount of fuel to mix with the air you need larger jets for less restriction on the fuel flow.

quote:This is where I have to suggest that this is pure conjecture on your part, for all we know the engineers at Yamaha were ahead of the game and did "tune" the shape

Proof? They were just starting to understand intake technology. On a tuned intake bike, you will lose significant power every time by taking the intake off, and you will not make it back.

I would suggest you offer PROOF of your statement. For allwe know these Yamaha guys working on the XS1100 project were the ones that DID understand the intake technology and applied it to the intake of the bike. Id o not care how you "Tune" an intake, the physics already outlined WILL apply. Taking the "tuned" intake off will ahve the same overall effect as a non tuned intake. All this tells us is that the overall intake system was more closely selected to match components to the intake design including the carbs and or injectors.

[DGXSER]

Also provides minimal restriction, though more than no air cleaner. Our engine still will only draw X (actually X-minimal restriction). *quote* Actually, the engine will still draw X, it has to, it will just use slightly more of the developed HP to do so.

More thinking has led me to believe that the original statement was true before the correction. Here is why: since atmospheric presure and cylinder vacuum are remaining the same, and just the restriction (airbox, pods) is increasing, X will diminish, since time (RPM) is a factor. Volume (air flow) is reduced at the restriction. Above a certain engine speed (not sure what) the restricted engine will not have time to pull in the same volume of A/F as the non-restricted engine before the intake valve closes. What remains is less A/F volume in the cylinder, though the theoretical displacement is the same. DG is correct that more HP will also be used in drawing this reduced volume. Therefore, the higher the restriction, the more likely it is that the engine has an increased parasitic load, and a reduced cylinder inlet volume, since valve duration, atmospheric pressure, and cylinder vacuum all remain the same. This would tend to give the less restricting intake an edge over the restricting intake. The lost fuel due to reduced intake vacuum of the less restrictive intake can be replaced by jetting up, making the A/F ratio of both intakes even. However, the parasitic HP consumption of the restrictive intake would give the edge to the non-restrictive intake, however small it might actually be. The restricted intake loses power in the areas of parasitic load and reduced intake volume.

If the piston moves down, as TRbig stated, it will create an opening that MUST be filled with something. It WILL fill it with something so X stays X. Now if you seal the opening so it has NO source, it will then draw a vacuum. But in this case, there is an opening and it will draw to fill it, it is just a matter of how much HP it consumes to do it. And it will draw it from the carbs. If RPM has any effect it will onyl be to ever so slightly increase the volume of X as the components such as rods and crank stretch ( if they do) from the higher forces being applied to them

It is true that many struggle with this issue, but it does not discredit the fact that the proper jetting can be achieved to achieve optimal results. Also, Exhaust mods, while ultimately dealing with pressures, play less with the idea of restriction per se, and more with the idea of reducing the parasitic load from the engine to the exhaust flow. The tuned exhaust idea simply put is to create a vacuum (low pressure) condition in the cylinder that the cylinder does work to create. This is done by controlling exhaust frequency, and is controlled more by pipe shape and length rather than restriction.

But the part that is missing here is that the shape and length have a direct correlation to the restriction, they are what cause the restriction. The exhaust restriction is just the another aspect of HP consumption. We could write an entire book on here going to that depth on engine function, but there are already books on it by much smarter folks than me.[/QUOTE]

[T99Ford]

quote: You assume a filter is causing the airflow to be restricted to a point that at high rpm, at the bottom of the piston's stroke when the valve closes, there is still a vacuum in the cylinder, equating to a loss in volume. These heads, valves, carbs,and even a fairly plugged up air filter will move more air/fuel volume than the motor could ever use, even when bored to the 1196cc

Tod--you are probably correct here, though I would guess that it becomes a much closer reality than we realize at high R's. I also think that the resistance between filters is not enough to quibble over since the engine is actually a victim of its own design at these high rpms. I think other forces are affecting high speed power loss rather than the filters. I made that argument for the sake of the theory; I think all of that exists on our bikes, but at levels too small to detect!

quote: If the piston moves down, as TRbig stated, it will create an opening that MUST be filled with something. It WILL fill it with something so X stays X. Now if you seal the opening so it has NO source, it will then draw a vacuum. But in this case, there is an opening and it will draw to fill it, it is just a matter of how much HP it consumes to do it.

No. Just as Tod stated, it will be replaced by vacuum, unless it can come through the rings or other leak. Because time is a factor. The cylinder will not necessarily fill enough to replace the vacuum already present at a given RPM. If this were water, and the restriction reduced a gallon per minute (to represent atmospheric pressure) to one drop per minute (extreme), and you had a displacement of one gallon, you would not fill the restricted cylinder as fast in RPM of one per minute as you would the cylinder with no restriction getting the full one gallon per minute. A tight cylinder would fill with mostly vacuum. It would not fill with its displacment in water, not matter how much horsepower was involved, since it can only go one RPM, and in that time it only gets one drop, not one gallon. This is because you cannot increase atmospheric pressure or vacuum! HOWEVER, the amount of the air filter/pod restriction difference is small enough that I would doubt it would come into play at anything but high R's, if at all. This is purely theoretical, and any difference would be difficult to test/ detect.

quote: I would suggest you offer PROOF of your statement. For allwe know these Yamaha guys working on the XS1100 project were the ones that DID understand the intake technology and applied it to the intake of the bike. Id o not care how you "Tune" an intake, the physics already outlined WILL apply. Taking the "tuned" intake off will ahve the same overall effect as a non tuned intake. All this tells us is that the overall intake system was more closely selected to match components to the intake design including the carbs and or injectors.

Clearly you do not understand tuned intake theory. This is not something that is done by an operator, such as jetting. A tuned intake works in much the same way on the intake side as the pipe does on the exhaust side. In fact, the tuned intake can utilize exhaust frequencies. A tuned intake will be a specified length, complete with expansion and compression chambers, used to alleviate parasitic HP loss on the cylinder. None of these components exist on stock XS. Further, the technology was not implemented until the middle 1980's, after the XS was discontinued. That is pretty clearly documented in any history of sport bike development. The early airboxes were a place to store the filter, and were primarily introduced to reduce noise pollution. Taking a tuned intake off a bike will reduce midrange power, as it increases parasitic HP loss on the cylinder. While the physics still apply, they are much exaggerated when exhaust and intake tuning are applied to simple intake theory. The reason for this is that both the pipe and the tuned intake reduce (sometimes greatly) the amount of parasitic loss on the engine. The naturally occuring intake and exhaust frequencies are utilized to do this. I believe that the XS operates under simple intake, with the only benefits coming from the exhaust; that is, unless someone has undertaken to develop a tuned intake for this bike (haven't seen one).

I think in the end we are all arriving at the same conclusion, that the difference between the two is so minimal (maybe even undetectable) that further argument is unnecessary. If pods or filters made any significant change, we would all move to the one that did. Since there are devout followers of both, I still maintain that neither can outdo the other on a stock bike. I hope no one is getting mad here, since I am only trying to review closely the actual effects of running either.

[Larrym]

Gag Reflex

Finally! We get to one of the performance limiting factors of any internal combustion engine:

"Volumetric Efficiency"

http://en.wikipedia.org/wiki/Volumetric_efficiency

Pods or most any aftermarket intake system aim to increase the VE by increasing the air flow on the intake side.

Imagine using a larger straw in your soft drink. Works "better" but unless you're prepared for it you might just choke on the unexpected rush of fluid. We can drink the entire beverage in a shorter time by being able to fill our "intake chamber" more quickly versus the smaller straw.

Pods will increase total overall HP at max rpms due to better VE. Just like running open headers with no mufflers would be better for lowering your ET's at the drag strip.

Low Idle, midrange, and main circuits all expect that smaller straw to be in place. Can you remember the last time you drank something and it went down the wrong pipe?

[T99Ford]

quote: Low Idle, midrange, and main circuits all expect that smaller straw to be in place. Can you remember the last time you drank something and it went down the wrong pipe?

But if you jet to account for the larger straw...

Thanks for adding the VE idea! Keep the fresh ideas coming!

[Larrym]

Shrivel Factor

Right! Planned compensation for the "delta"(Change in conditions) is almost mandatory. Then the engine is happily devouring fuel at WOT or idle. Looks like the Dyno-Jet kits are the RX for those who want a perfect match between the Pods and the aftermarket exhausts.

I'm one of those guys who has taken the top of the air cleaner (on my car...) and flipped it upside down for the weekend: Lots of sound and fury for the cruise up and down main street. But I always put it back for the Mon-Fri work week. One thing the air cleaner/box does that pods does not do is pre-warm the air a little bit. Not like we've got that extra hose which runs down to the headers in order to assist cold weather running. Temperature of the intake air does affect "combustability" of the mixture.

Once the engine is up to operating temp then the pods would keep the incoming air cooler than normal. Great for the desert heat but maybe not so fun for the commuters in Minnesota.