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Gas Saving Gizmos & Gadgets

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Comments

  • bumpybumpy Posts: 4,435
    Naah, just put a nice CAI on it. :P

    My favorite gas-saving gadget is a rock glued to the back of the pedal. ;)
  • Last weekend I had a K & N ram air system installed on my 2007 Honda Civic EX. I'm not a teenager but I am open minded and just want to see the effect on mpg for myself. What I have noticed so far is that there is a noticable power increase. K & N claims almost a 6 hp increase at the driving wheels. I find it much easier to merge into traffic and that I use a lot less throttle at 55 mph. I haven't gassed up so can't report any effect on mpg but should be able to do that in a week or so. I'm already satisfied with just the increase in power as the civic has so little to begin with.
  • shiposhipo Posts: 9,148
    While I buy the slight increase in power at WOT, using "a lot less throttle at 55 mph" makes absolutely no sense. Why? The engines' demands upon the filter element at that speed are extremely meager, as in less than 10% of WOT. To the best of my knowledge, there is no OEM air filter on the market today that offers any significant restriction at sedate freeway speeds.

    Regarding your experiment with this filter, please keep in mind that UOAs from K&N equipped cars over on the BITOG web consistently show higher silica (sand) readings than cars fitted with the OEM filter. That and the hot wire used for measuring intake air density is often damaged by the oil used in the K&N filter element.

    Good luck with your test, keep us posted.

    Best Regards,
    Shipo
  • zaken1zaken1 Posts: 556
    Your comment implies that, when adding a ram air system, the amount of restriction in the air filter at normal operating speeds is the main factor which affects engine efficiency. This is not true. It WOULD be true only if the new filter was the identical size and shape, and in the same location as the stock one; and it drew its air supply through the stock intake ducting; but that's not how ram air systems work. Ram air systems change the length and shape of the intake tract, along with reducing the temperature of the incoming air. These parameters have far more effect on engine efficiency and fuel economy than does any change in the restriction of the filter. I've read a number of similar comments, which all fail to consider the difference between just adding a low restriction filter; or adding an engineered system which changes the resonant length of the intake tract, and in addition reduces intake air temperature, plus also using a low restriction filter.

    Changing the shape and resonant length of the intake tract will cause substantial changes to the engine's torque curve. This has been documented repeatedly in dynamometer tests. If you have a manifold vacuum gauge on a car, you can quickly see how much difference changing intake length makes. And this is why motorcycles, race cars and hot rods have those long intake extensions on their engines. Stock air intake systems are usually designed primarily to reduce sound levels, which often creates a system that is a very poor match for the performance characteristics of the engine. There is a 'small' company in Southern California called Edelbrock, which has become famous by designing performance boosting replacement intake manifolds for popular engines, which change the shape and length of the intake passages to tune them to match the engine's breathing characteristics. And there are now a half dozen other companies which also make such parts.

    Now that awareness of the importance of intake tuning has become widespread, filter manufacturers like K & N have gotten into the act, by applying the same engineering principles to air filter assemblies. And even the after-market exhaust manufacturers are finally becoming aware of the scientific principles of controlling pulse reversion, which they've long overlooked. So we're all getting wiser; and as a result, engines now run better.

    But you are right; just adding a low restriction filter in the stock location won't do much of anything. It's those long pipes and the cold air that make all the difference.

    I'd also like to mention that the increase in sand getting into the engine which you mentioned, is probably more related to fact that ram air systems move their air pickup point away from the relatively quiet and protected under-hood environment, and place it right out in the wind and dust that bombards the front of the vehicle, than it is to any lower filtering efficiency (unless the filter is not oiled, which is lately becoming a common practice). Unfortunately, all too many people either don't oil their K & N filters at all; or else over-oil those filters when they service them. And both of those practices cause different sorts of problems.

    So, as far as I'm concerned, if you're not wiling to learn and practice properly maintaining a K & N filter, then you'd be better off with a ram air system that uses a paper filter.
  • shiposhipo Posts: 9,148
    And your point is?

    For the record, my argument is that a K&N modification to the intake system of virtually any recent vintage of car will cause the engine yield a bit more power at wide open throttle (WOT), both due to the lower restriction of the filter element and the new plumbing, and any theoretical differences in induction resonance. That said, I'd wager that a K&N system doesn't do squat for the induction resonance.

    Further, it is my argument that the addition of a K&N system cannot and will not improve fuel economy, as the system does nothing to the fuel injection system, a system that weighs the intake charge and dispenses the exact amount of fuel necessary. If (and I say "if" only for the sake of argument) the K&N system allowed in more air during a steady state cruise, then the fuel injection system will simply supply more fuel keeping the air to fuel ratio exactly the way the designers of the engine specified. Net result, the fuel economy doesn't change one wit.

    Best Regards,
    Shipo
  • zaken1zaken1 Posts: 556
    Over the last few years, I've spent more hours than I'd care to remember, along with driving thousands of miles, to test and refine a custom ram tuned intake system I designed and built for my 3 cylinder Geo Metro. The final result is a car that has a lot more torque than the stock engine, at both light and heavy throttle openings. The increased power of the ram tuned Metro makes it much more enjoyable to drive than it was before I added the ram tuned intake.

    My work with the Metro builds on years of previous experience with tuned intake and exhaust systems on both motorcycle and car engines.

    My point is that I know from hands on, direct experience that ram tuning DOES A WHOLE LOT for the induction resonance. So your theoretical arguments to the contrary just don't move me.

    I do concur that changing the volumetric efficiency in a modern fuel injected engine will not alter the air/fuel ratio. I'm glad that is the case, because these engines fuel mixtures are already set for best economy.

    The increased economy from a ram tuned intake does not come from leaning out the mixture. It comes from the increased torque, which enables the engine to operate at a smaller throttle opening while cruising at speeds that previously required more throttle. A smaller throttle opening means less air will be drawn in, which in turn means less fuel will be injected. And that creates better economy.
  • shiposhipo Posts: 9,148
    "The increased economy from a ram tuned intake does not come from leaning out the mixture. It comes from the increased torque, which enables the engine to operate at a smaller throttle opening while cruising at speeds that previously required more throttle. A smaller throttle opening means less air will be drawn in, which in turn means less fuel will be injected. And that creates better economy."

    To say that I'm skeptical is an extremely gross understatement. In my experience, changes upstream of the throttle body don't amount to anything at a steady state cruise. Statements such as yours regarding the throttle setting and less air simply makes no sense from an engineering perspective. Volumetric efficiency is simply a measure of how much air and fuel can be crammed into a combustion chamber. Pack less air and fuel into the chamber and you'll get less power out of the engine.

    Said another way, until you've convinced the auto industry at large of your miracle skills at induction plumbing, I'm not buying.

    Best Regards,
    Shipo
  • texasestexases Posts: 8,887
    Maybe it would help if you describe the various modifications you've made.
  • zaken1zaken1 Posts: 556
    I doubt that I could do more than I already have to explain or validate my position. So I'll simply close by recommending that you Google 'intake tuning' or 'velocity stacks' or 'resonant intake lengths' or 'airbox design', and see what recognized industry experts have written about the importance of events outside of the throttle body.

    Thanks for your interest!

    Joel
  • shiposhipo Posts: 9,148
    I'm very well acquainted with resonant factors relative to intake plenums, exhaust chambers, porting, volumetric efficiency and such, in fact I currently have a patent pending in this area of art. Even still, I did as you suggest and found nothing that would indicate that changing the airbox and plumbing upstream of the throttle body will do anything at all relative to fuel economy at a steady state cruise in a car with a modern fuel injected four stroke engine. Assuming that you are a member of the SAE, providing references to published articles within the SAE archives would go a long way toward supporting your claims.

    Failing the above, you can argue all you want, until you come up with more specifics about how you managed to coax more power out of any given unit of intake charge simply by changing the plumbing upstream of the throttle body, I'll remain extremely skeptical. Keep in mind, as a general rule folks who offer only oblique references and illogical arguments have typically been found to have the same credibility as your run of the mill snake oil salesman. Your existing arguments seem to bordering on that realm.

    Best Regards,
    Shipo
  • zaken1zaken1 Posts: 556
    If you're ever in Northern California, contact me, and I'll be happy to show you what I've done. But, for reasons I'm sure you understand, I'm unwilling to publish the details here.

    Joel
  • drftrdrftr Posts: 3
    Joel,
    I am looking into buying a 96 Geo Metro and was wondering what kind of improvements you've had with your ram air system.
  • zaken1zaken1 Posts: 556
    It makes the car able to climb hills at higher speeds, while using a substantially smaller throttle opening. It also produces much crisper throttle response under both light and heavy acceleration.

    But bear in mind that my 1990 has the 3 cylinder engine, while some of the newer ones used 4 cyl engines. The system would also be adaptable to the 4 cyl, but it would probably require some retuning.

    If you want to discuss this in more detail, we'll need to work out a way to communicate more directly and privately.
  • drftrdrftr Posts: 3
    My e-mail address is my login name at where the mail is hot. I would be interested in checking out the ram air system you installed. I am a recent Mechanical Engineering graduate and in my Thermodynamics & Energy systems classes we did problems involving the Otto cycle and indeed the lower your ambient temperature(air temperature) is, the more efficient your system will be.

    The Geo I am planning on buying is a 3 cylinder, I think that was the last year they build the 3 cylinder.

    THANKS!
  • shiposhipo Posts: 9,148
    "I am a recent Mechanical Engineering graduate and in my Thermodynamics & Energy systems classes we did problems involving the Otto cycle and indeed the lower your ambient temperature(air temperature) is, the more efficient your system will be."

    Hmmm, apparently the real world that isn't always correct. In aviation circles it has been long known (as in many decades) that by heating the intake charge to at least 40 degrees Fahrenheit, the engine will propel the plane further per pound of fuel consumed.

    Best Regards,
    Shipo
  • drftrdrftr Posts: 3
    40°F to an engine is considered cold compared to the temperature inside an engine compartment. Most of us that live and drive in California rarely experience temperatures colder than 40°F inside the engine compartment of our cars.
  • zaken1zaken1 Posts: 556
    Dear Shipo,

    In this case, it seems that each of you is referring to a different truth: Heating the intake charge will insure optimal atomization of the fuel, which can raise economy. There were several famous add on devices that heated or totally vaporized fuel; which were claimed to dramatically increase fuel economy. The most well known of these was developed by a Canadian inventor named Charles Winton Pogue. He built an elaborate fuel vaporizing device, which he installed on a Ford V-8. Newspaper accounts reported it got over 200MPG. More recently, a Texan named Ray Covey redesigned this device, and sold kits to convert your car to vapor fuel. He also claimed economy of 50 to 150MPG on big sedans and vans. But carrying a tank of vaporized fuel under the hood involves a great risk of explosion.

    The other side of this coin is that, when you heat the intake air/fuel, the charge density is reduced; which leads to a lowering of the maximum power potential. That is why professional drag racers use refrigeration cans to cool the fuel before it reaches the engine. This is also why high performance turbocharging systems use intercoolers to cool the intake air that has been compressed by the turbo. And this is why ram air systems pick up their incoming air from a point that is not in the warm underhood atmosphere.

    The legendary engine tuner Smokey Unick built an experimantal car that integrated these two opposite principles. He took a 4 cylinder Pontiac and installed a heat exchanger to vaporize the intake charge. He then ran the vaporized mixture through a turbocharger (or supercharger-I don't remember which it was). The result was a car that got 40-50 miles per gallon, and was much more powerful than the original.

    So, like in so many issues, there is more than one truth to consider.

    Joel
  • shiposhipo Posts: 9,148
    "40°F to an engine is considered cold compared to the temperature inside an engine compartment. Most of us that live and drive in California rarely experience temperatures colder than 40°F inside the engine compartment of our cars."

    The problem is that you didn't qualify your earlier statement, you simply said, "...the lower your ambient temperature(air temperature) is, the more efficient your system will be.", and to that I completely disagree.

    Now, if you're talking about "volumetric efficiency" then yes, I agree with your statement. The colder the intake charge, the heavier the charge; the heavier the charge, the greater the power output from any given combustion event (assuming the mixture is rich enough).

    The above said, combustion efficiency suffers when the charge gets too cold.

    Best Regards,
    Shipo
  • shiposhipo Posts: 9,148
    "The legendary engine tuner Smokey Unick built an experimantal car that integrated these two opposite principles. He took a 4 cylinder Pontiac and installed a heat exchanger to vaporize the intake charge. He then ran the vaporized mixture through a turbocharger (or supercharger-I don't remember which it was)."

    Nothing really new there. Pratt & Whitney ran very similar studies back in the 1930s on their "legendary" radial engines and produced very similar results.

    "So, like in so many issues, there is more than one truth to consider."

    Quite true.

    Best Regards,
    Shipo
  • texasestexases Posts: 8,887
    Thanks for summarizing the three best known crackpot schemes out there. There is no realistic way to get 50-150-200 mpg out of an existing design just by vaporizing fuel. Pure nonsense.
  • shiposhipo Posts: 9,148
    Oddly enough I need to side with zaken1 on this one. While the extreme mileage that you quoted is questionable, there is little doubt that proper vaporization of fuel leads to better fuel distribution within the combustion chamber, and as such you can run the mixture a little leaner and still get the same power and economy. That's the theory anyway.

    In the 1930s P&W pioneered a methodology of fuel injection that was downstream of one supercharger (or turbocharger) of any design and immediately upstream of a second low ratio centrifugal supercharger. The resultant atomization of the fuel made a huge difference in the smoothness and power of those large radials (imagine trying to get even fuel distribution to a 2,800 cubic inch, 18 cylinder engine). In fact, even though those engines were developed some seventy years ago, they are still among the most efficient intermittent combustion gasoline engines ever built (as measured by the BSFC).

    Best Regards,
    Shipo
  • texasestexases Posts: 8,887
    I'm sure there's some incremental benefit in a car, but not 2X-10X increase in efficiency. Maybe 10%? And yes, getting even fuel distribution in an 18-cylinder, 2-row radial at altitude is difficult!
  • shiposhipo Posts: 9,148
    "I'm sure there's some incremental benefit in a car, but not 2X-10X increase in efficiency. Maybe 10%?"

    Agreed. I might even buy a tad more than that. :blush:

    "And yes, getting even fuel distribution in an 18-cylinder, 2-row radial at altitude is difficult!"

    And they figgered all that stuff out on slide-rules and SOTP testing. I read one account of an engine balance test (the R-2800 I think) with a full size propellor where the prop broke off the engine and went through a multi layer cinderblock and brick wall. Yikes!

    Best Regards,
    Shipo
  • texasestexases Posts: 8,887
    Oddly, the best stories I've read on aviation engine development is the tech guy's columns in Cycle World magazine (Kevin Cameron, I think). They would build a 1-cylinder part of an engine, run it till it broke, improve that part, go back and do it all over. Who needs a pc when you've got real live shrapnel!!
  • shiposhipo Posts: 9,148
    You betcha. I want to be reincarnated as one of the forensic engineers that P&W used to use after "it blowed up". Apparently they had one team of engineers that designed and built the original running prototypes, and a second set that ran them until destruction, figured out what went wrong, attempted a fix and then ran the new version until destruction once again, over and over and over until it would hold together for a certain minimum of time and/or power output.

    Ohhhh, would I love a job like that. ;-)

    Best Regards,
    Shipo
  • zaken1zaken1 Posts: 556
    Shipo,
    That same type of "seat of the pants" R&D still takes place today. A few years ago, Harley Davidson wanted to build an EPA legal version of the engine in their VR1000 racebike. They tried, but were unable to solve the engineering challenges of integrating sound control, performance, and durability. So they farmed the project out to Porsche. Porsche built a whole series of V-twin test engines, and ran them on the autobahn until they either broke, or didn't perform as desired. They then disassembled those engines, analyzed the parts for signs of wear, and redesigned them. They eventually came up with a design that met their specifications. And that engine is now used in the Harley Davidson V-Rod.
  • 0patience0patience Oregon CoastPosts: 1,712
    I'm enjoying this topic very much.

    Some things to consider.
    As was stated, the less air you pack into the cylinder, the less efficient it will be, the less power it will make. That's physics.

    Also, if your fuel and air is not balanced to what the computer wants, fuel economy suffers.
    Guys adding cold air intakes, re-usable filters designed to "create more airflow" and other bolt on addons aren't going to gain much without re-programming the computer to the changes that those add ons make.

    As for the heat exchanger for the turbos.
    Diesels have had them for years. Diesels call them prechargers. They are designed to cool the air before it gets to the turbo. Smokey wasn't the first person to test the theory.

    Here is an article on fuel economy and add-ons which hits the mark nicely.
    http://www.batauto.com/Forums/index.php?topic=3.0

    As for intake after the throttle body. A statemtent was made once that smoothing out the intake gives better air flow. It may, but it also causes problems with fuel atomization. You see the fuel needs the turbulents to help keep the fuel atomized or cause it to further atomize.
    Correct placement of where the turbulents are, is also very important.

    Ok, I'll go back to my corner now. :P
  • shiposhipo Posts: 9,148
    "As was stated, the less air you pack into the cylinder, the less efficient it will be, the less power it will make. That's physics."

    Here again you need to define "efficient". If you're saying the amount of power generated for any given amount of air and fuel in the proper ratio will suffer, I absolutely disagree. If you are saying the maximum amount of power from the engine at WOT, then we are in complete agreement.

    Best Regards,
    Shipo
  • 0patience0patience Oregon CoastPosts: 1,712
    If you are saying the maximum amount of power from the engine at WOT, then we are in complete agreement.
    Sorry about that, to clarify.....
    Most instances, my mindset is always at peak horsepower.
    So, yes.

    But, at any rpm, the air fuel ratio must have the optimum balance or efficiency and power suffer.
    You can have too much air, too little air or too much fuel or too little fuel. At rpms above off idle to before WOT, this is especially critical.
  • zaken1zaken1 Posts: 556
    Thanks for your comments! I agree with most of the points you made. The one about smoothing out the intake causing potential problems with fuel atomization is a significant issue that many people overlook.

    But I want to address several misconceptions. One of them came from the article you referenced, where the author claimed that the 6mpg loss from installing a free flowing exhaust system on a vehicle was due to the increase in the volume of air that was pulled through the engine, and the corresponding increase in fuel which the computer had to add in order to correct the air/fuel ratio.

    First of all, potential changes in the volume of intake air required to compensate for a free flowing exhaust are not great enough to cause a loss of 6 miles per gallon IF THE AIR/FUEL RATIO IS KEPT AT THE MANUFACTURER'S RECOMMENDED SPECIFICATION. As long as the mixture is correct, you can vary the total volume within that kind of range and not see much change in economy. Increasing the total mixture volume while holding the air/fuel ratio constant will just result in needing to use a smaller throttle opening at a given speed. The reason free flowing exhaust systems (and radical camshafts) sometimes ruin mileage is because the changes they create exceed the compensating capabilities of the fuel injection computer. When that happens, the air fuel ratio does not remain constant; it becomes way too rich. That's why the exhaust from modified engines often smells so bad.

    Another issue which sometimes happens is that when someone installs a free flowing exhaust system, they also remove the oxygen sensor. And this disables the fuel injection system's ability to monitor and correct the mixture.

    Fuel injection computers are designed with a limited capability to adjust the mixture. They work fine, as long as the engine is kept stock. But some modifications, particularly to the exhaust and camshaft, create changes which are too much for the computer to handle. And that's why the EPA and CARB approve mild performance add ons, but outlaw radical modifications.

    The other point I need to make is that the heat exchanger in Smokey Unick's Pontiac was used to heat the mixture until it was well vaporized. The diesel heat exchangers you spoke of do the opposite; they cool the air to make it more dense.

    I'm glad you enjoy this discussion.

    Joel
This discussion has been closed.