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Car Forum / Ford / Ford Explorer / February 200497 EB: How can I improve gas mileage a little bit?
I just got a 97 Explorer Eddie Bauer with the 4L V6 and AWD. The weather is pretty cold and I drive mostly in the city. The mileage is at 13mpg. I just bought the vehicle and would like to know if there is a way to increase the fuel efficiency. I realize it is an SUV and I don't expect much... Thanks Matt a clean air filter and tire pressure at 32psi wth > I just got a 97 Explorer Eddie Bauer with the 4L V6 and AWD. The weather is > pretty cold and I drive mostly in the city. The mileage is at 13mpg. I [quoted text clipped - 3 lines] > Thanks > Matt Take the element out, and get the lid out of the way. Find an angle drill and a 3-1/4" hole saw. (If memory serves me right, that's the diameter of the rubber intake hose) From the inside, carefully position the holesaw over the snorkel sticking out the front of the box. Cut it out and put the air filter assembly back together again. You have now removed a major restriction in the intake air, the snorkel that is less than half the diameter of the rest of the intake system. Forget K&N, and just replace the stock element regularly. >>a clean air filter and tire pressure at 32psi >>wth [quoted text clipped - 8 lines] >>> Thanks >>> Matt I have a 95 w/ 4.0 also. I added a K&N air filter it helps little on fuel mileage and well as a small increase in power. HD > I just got a 97 Explorer Eddie Bauer with the 4L V6 and AWD. The weather is > pretty cold and I drive mostly in the city. The mileage is at 13mpg. I [quoted text clipped - 3 lines] > Thanks > Matt or you could put your tires up to 150 PSI... >I have a 95 w/ 4.0 also. I added a K&N air filter it helps little on >fuel mileage and well as a small increase in power. [quoted text clipped - 8 lines] >> Thanks >> Matt Or always drive downhill, never uphill. > or you could put your tires up to 150 PSI... > [quoted text clipped - 10 lines] > >> Thanks > >> Matt Ah... when all else fails we can go with the good old K&N engine duster..... I'm constantly amused by these kinds of tricks...... how a different style of air filter can affect computer controlled fuel mixtures is still a mystery.... to me, it's alot like sex without a partner. K&Ns own stance is that their filters are more "efficient" at filtering dirt when they are close to plugged... and that means they are getting almost as good as the old cheap paper filter at keeping contaminants out of our motors. Jim Warman mechanic@telusplanet.net > I have a 95 w/ 4.0 also. I added a K&N air filter it helps little on > fuel mileage and well as a small increase in power. [quoted text clipped - 8 lines] > > Thanks > > Matt >Ah... when all else fails we can go with the good old K&N engine duster..... >I'm constantly amused by these kinds of tricks...... how a different style [quoted text clipped - 7 lines] > >Jim Warman I've explained that several times. With a carb, K&N filters may provide a little more fuel economy or more power, but with our modern feedback controlled electronic fuel injection, it's well nigh impossible. Plus, as you say, K&N's own advertising will tell you that they flow more dirt than the stock paper filters. For racing, K&N may be reasonable. For our EFI vehicles, they are not anywhere as good as they pretend to be. Cow magnets, OTOH...  SignatureBill Funk replace "g" with "a" Jeez, Bill.... if my wife ever sees your "cow magnets" comment...... we're already at the point where the fridge door is getting ready to part company with the rest of the fridge from the shear weight these power inducing devices... Jim Warman mechanic@telusplanet.net > On Thu, 05 Feb 2004 08:50:52 GMT, "Jim Warman" > [quoted text clipped - 9 lines] > > Cow magnets, OTOH... >Jeez, Bill.... if my wife ever sees your "cow magnets" comment...... we're >already at the point where the fridge door is getting ready to part company >with the rest of the fridge from the shear weight these power inducing >devices... > >Jim Warman Every once in a while, I remove about 5 or 6 pounds of stuff from our fridge door. My wife never misses it! SignatureBill Funk replace "g" with "a" You know one of the main reasons the diesel engine get better fuel economy than the gasoline?...because the diesel engine doesn't have a throttle plate restricting the intake air. The technical terminology is "a reduction in pumping losses". The diesel engine doesn't have to fight the throttle plate to take in the air it needs to combust. Now, some same that a dirty air filter will improve fuel economy since the throttle plate must be opened wider to get the same amount of air flow as compared to a clean filter. This would mean that the K&N filter, which reduces intake air restrictions, would produce lower fuel economy numbers. The problem with this reasoning is that it ignores the pressure drop increase accross the dirty air filter when capitalizing on the benefit of a more open throttle plate. Hence, the only sure-fire way I found to improve fuel economy numbers was to buy a small, 4-cyl, economy car. Yeah, the tire pressure thing is good too; also, drive a little less aggressive. Tom > Ah... when all else fails we can go with the good old K&N engine duster..... > I'm constantly amused by these kinds of tricks...... how a different style [quoted text clipped - 25 lines] > > > Thanks > > > Matt I thought the main reasons were the higher compression ratio (longer piston stroke that extracted more of the energy from each detonation) and that diesel has more energy per unit volume than gasoline. http://www.dieselrvshopper.com/rv_chassis/spartan_chassis.htm http://www.edmunds.com/advice/specialreports/articles/93338/article.html Ben >You know one of the main reasons the diesel engine get better fuel >economy than the gasoline?...because the diesel engine doesn't have a [quoted text clipped - 45 lines] >> > > Thanks >> > > Matt Right Ben...so I guess if want to increase fuel econ numbers and don't want to reduce intake air restrictions you could stroke your engine and run higher compression ratios...much more economical. Tom > I thought the main reasons were the higher compression ratio (longer piston > stroke that extracted more of the energy from each detonation) and that diesel [quoted text clipped - 55 lines] > >> > > Thanks > >> > > Matt Tom, this was entirely about correcting an erroneous statement regarding diesel engines, nothing else. Ben >Right Ben...so I guess if want to increase fuel econ numbers and don't >want to reduce intake air restrictions you could stroke your engine [quoted text clipped - 61 lines] >> >> > > Thanks >> >> > > Matt One of the major reasons the diesel fuel economy is better is the lack of a throttle plate....... Tom was right about "pumping losses".... an idling gasoline engine has intake manifold vacuum resisting the downward motion of the piston on intake.... the diesel has no such restriction. Looking closely, let's compare a (for the sake of argument) 20 cubic inch single cylinder gas engine to a 20 cubic inch single cylinder diesel engine. At idle, the closed throttle plate on our fictitious gas motor restricts the flow of air into the cylinder.... the nest result is that our 20 cubic inch cylinder has much less than 20 cubic inches (compared to barometric) of working fluid in it when the intake closes and compression begins (please, let's not get into a discussion on compression ratio/static compression/dynamic compression). OTOH, our normally aspirated (trying for as close to an 'apple to apple' comparison as possible) 20 cubic inch diesel will pretty much have 20 cubic inches of air in the cylinder when the intake valve closes. Yes... diesel contains more BTUs per pound.... yet diesels idle cold because of the massive airflow through the cylinder. The higher compression numbers exist only because this is a "compression ignition" engine...... 17ish to one is the low side and can range even over 21.5 to one. There are racing teams running 17 to one for gasoline, but this technology comes at a price... both in development and maintenance. While the diesel is a wise choice economywise, it pays a hefty price in convenience.... noise, smell, the exacting requirements of the fuel system (even a small amount of moisture can kill an eight hundred dollar injector), cold weather performance, starting technique..... and that ghastly oil change that promises to alter your bathing habits and a good portion of your wardrobe (providing you loving bride will even consider putting "that shirt" through her washing machine). The long stroke is not a necessity for diesels but it is part of the secret behind some of the torque monsters...... the idea is to have maximum cylinder pressure occur as the crankpin crosses 90? to the bore centerline giving the maximum leverage....the longer the stroke, the longer the 'lever'.... Back to Toms statement.... it is tough to assign much in the way of affects of a pressure drop across a properly maintained air filter in a gasoline engine when there is such a tremendous pressure drop across the throttle blades at anything other than WOT. Certainly a plugged air filter is bad..... increasing the flow through the filter can only 'help' at high throttle angles. Unfortunately, this leaves "big hole" air filters siting in some tenuous neverland that has us allowing more and bigger dirt into places where more and bigger dirt are not welcome.... For the K&N afficianados.... if having something under your hood that requires you to nearly make love to it several times per year is up your alley, go with the K&N.... if your time has some meaning in your life, perhaps the time spent (must be all of three of four minutes) to change a paper air filter may be your cup of tea. Me???? I think.... washing filter and drying filter and oiling filter an greasing filter equals a lot of time NOT spent sitting across the new scooter (or the "ol' lady" as the case may be). YMMV > I thought the main reasons were the higher compression ratio (longer piston > stroke that extracted more of the energy from each detonation) and that diesel [quoted text clipped - 55 lines] > >> > > Thanks > >> > > Matt More so than the compression ratio and higher energy content of the fuel? If so, do you have a reference for this? Thanks Ben >One of the major reasons the diesel fuel economy is better is the lack of a >throttle plate....... Tom was right about "pumping losses".... an idling [quoted text clipped - 120 lines] >> >> > > Thanks >> >> > > Matt I'm not sure I understand the question...... a diesel wouldn't diesel without the high compression pressures (anything less than 350 - 325 psi isn't going to run very good if at all)..... the high energy content is in the realm of petrochemical engineers but seems to be a fact of nature...... gasoline fires are relatively cool - diesel much hotter and crude oil is a sumb*tch to put out - roughly put.... heavy oil burns hot and the lighter "ends" burn cooler as we go up the scale. I can only suggest that you research all the variations and permutations of the Otto cycle motor (we're not gonna get into liquid piston technology, are we 8^) If you can rephrase the question and add some context, I'm sure I can offer suitable documantation... Jim Warman mechanic@telusplanet.net > More so than the compression ratio and higher energy content of the fuel? > If so, do you have a reference for this? The following statement was made earlier. (names are omitted to protect the innocent). >You know one of the main reasons the diesel engine get better fuel >economy than the gasoline?...because the diesel engine doesn't have a >throttle plate restricting the intake air.... Do you believe this statement to be correct or would you say that there are more significant reasons why diesels get better mileage? Ben >I'm not sure I understand the question...... a diesel wouldn't diesel >without the high compression pressures (anything less than 350 - 325 psi [quoted text clipped - 16 lines] >> More so than the compression ratio and higher energy content of the fuel? >> If so, do you have a reference for this? I did make the statement so I would say that I must believe that it is correct..... at idle and/or low throttle settings, the intake manifold of a gasoline engine is at a much lower pressure than atmospheric while in a naturally aspirated diesel, the intake manifold is AT atmospheric pressure. Ergo, the gas motor has to work harder to simply move the piston down the bore on the intake stroke. The fact, in itself, strikes me as significant. No less significant is the fact that one pouind of diesel fuel contains more heat energy than one pound of gasoline - since the Otto cycle engine is basically a heat pump...... Another significant factoid would deal with injection pressures.... modern gasoline engines operate with about a 30 to 50 psi pressure drop across the tip of the fuel injector while the diesel can exceed 2000 psi across the injector tip resulting in much better fuel atomization. Since the diesel engine is a "package" that must possess high compression pressures, high injection pressures, fuel injected directly into the combustion chambers, fuel with a high flash point that just happens to have high energy content (and doesn't require a throttle blade), it's impossible to give one feature more credence than another. If we remove any one of these, it will stop running or run very poorly. Remember, I said "ONE OF the main reasons...." Jim Warman mechanic@telusplanet.net > The following statement was made earlier. (names are omitted to protect the > innocent). [quoted text clipped - 5 lines] > Do you believe this statement to be correct or would you say that there are more > significant reasons why diesels get better mileage? At idle or low throttle setting? So if we are doing normal city or highway speed driving does it stop being one of the major reasons? Ben >I did make the statement so I would say that I must believe that it is >correct..... at idle and/or low throttle settings, the intake manifold of a [quoted text clipped - 35 lines] >are more >> significant reasons why diesels get better mileage? Sorry for the delay, Ben..... been at school again and polishing, polishing, polishing.... scooter weather is coming... With the gas motor, once we are up to our cruise speed, we only need deliver enough throttle opening to sustain the RPM...... manifold vacuum usually returns to a fairly high (though not generally as high as idle or coastdown) value..... we are still "throttling" the intake air the cylinder cannot completely fill and our cam design cannot scavenge the cylinder well...... Our 20 cubic inch diesel will still have pretty close to 20 cubic inches of atmospheric air in it while our 20 cubic inch gas motor will likely have significantly less atmospheric air as well as a small amount of spent exhaust gasses. Throttling the intake is required for gas engines but is inefficient because of it's nature...... when the intake opens, the piston moves down against the intake vacuum on the gas motor whilst the psiton moves down against atmospheric in the diesel (normally aspirated, remember?) - we're not dealing with that Gawd-awful trap door in the intake stream... Diesel engines never have "manifold vacuum" whilst gas motors almost always have some amount of manifold vacuum. HTH Jim Warman mechanic@telusplanet.net > At idle or low throttle setting? So if we are doing normal city or highway > speed driving does it stop being one of the major reasons? Just curious Jim, on the diesel, how do they take care of all the things that use vacuum for operation (power brakes, etc.)? >Sorry for the delay, Ben..... been at school again and polishing, polishing, >polishing.... scooter weather is coming... [quoted text clipped - 26 lines] >highway >> speed driving does it stop being one of the major reasons? Vacuum pump..... the older ones used an engine driven pump while the new ones use an electric pump. Many used a "HydroBoost" type brake booster but most of these pumps produce enough to even run the brake booster. Jim Warman mechanic@telusplanet.net > Just curious Jim, on the diesel, how do they take care of all the > things that use vacuum for operation (power brakes, etc.)? >Vacuum pump..... the older ones used an engine driven pump while the new >ones use an electric pump. Many used a "HydroBoost" type brake booster but >most of these pumps produce enough to even run the brake booster. > >Jim Warman >mechanic@telusplanet.net Back in the 70's, several GMC/Chevy models used the power steering pump to provide power for the brakes. >> Just curious Jim, on the diesel, how do they take care of all the >> things that use vacuum for operation (power brakes, etc.)? SignatureBill Funk replace "g" with "a" Yep.... After looking at my message I see oldtimers disease... the "HydroBoost" was the oldframe maounted vacuum booster we used to see on larger trucks with hydraulic brakes. IIRC, GM called their hydraulic booster a "Hydraboost" which does use power steering pressure for the unit. Both Ford and Dodge have used this setup.... " Jim, While a gasoline engine may have to expend a tiny bit more energy to pull air/fuel into it's cylinder than a diesel on the intake stroke, the diesel has to work a tiny bit harder forcefully injecting a fuel/air mixture into the cylinder that has already been fully compressed so maybe the two items balances each other out? Ben >Sorry for the delay, Ben..... been at school again and polishing, polishing, >polishing.... scooter weather is coming... [quoted text clipped - 26 lines] >highway >> speed driving does it stop being one of the major reasons? Actually, the pumping losses experienced any time manifold vacuum is high are much more than negligible. Vacuum is a very powerful force in nature and it can be quite easily misunderstood as to how powerful it really is (remember that 'absolute' vacuum is on the order of 30"of mercury at sea level.... memory don't fail me now...) and here we are driving a piston down 'against' 1/3 to 1/2 that. The effort expended in injecting fuel into a diesel cylinder (static compression is 300 to 400 or so psi compared to 130 to 160 for gasoline) even at pressures like 3000 psi is nowhere comparable to wasted energy in a gas motor. Many of todays diesels feature HEUI injectors (hydraulicly <controlled> electronically <actuated> unit injector) and are probably one of the wonders of the modern world in light of the fuel control they offer. The high pressure oil pump that feeds these injectors offers up a much smaller parasitic loss under most operating conditions than the older high pressure fuel pumps. Let's not forget that we can also keep adding fuel as the piston travel down on power stroke..... in the gas motor, what the cylinder got squirted at the back of the intake valve is all the cylinder is gong to get. Once we get our vehicle up to speed, it will likely only require 20 hp (and I'm using hp quite loosley here since it is indeed torque that is the measure of work)or so to maintain that speed on level gtound, yet we are spinning our motor merrily at an rpm where it produces 5 or even 10 times that amount of power. Todays technology allows the vehicle to lean the mixture out (limiting torque), but it can only go so far before we run into serious engine damage and/or increased tailpipe emissions. The diesel doesn't have that limitation..... unthrottled, we control torque output by varying the amount of fuel added to the cylinder - at cruise, we only add enough fuel to remain at cruise without incurring any lean mixture woes. In spite of it's poor extreme cold weather starting characteristics, noise, smell and weight..... the diesel remains to be a more efficient use of the Otto-cycle principal than it's gasoline fueled cousin. Regards Jim Warman mehanic@telusplanet.net > Jim, > [quoted text clipped - 5 lines] > > Ben >Once we get our vehicle up to speed, it will likely only require 20 hp (and >I'm using hp quite loosley here since it is indeed torque that is the >measure of work)or so to maintain that speed on level gtound, I think you've got this backwards. Torque is a measure of twisting force, while work is the transfer of energy. Torque applied to an axle that doesn't turn is still applied, even though it does no work. http://www.renthal.com/site/resources/guide.htm SignatureBill Funk replace "g" with "a" I still have trouble with the concept some days..... yes - torque is the force and hp is the "rate of doing work".... scratch out my parenthesis and my statement reads better (two or eight beverages can do that to a man). > >Once we get our vehicle up to speed, it will likely only require 20 hp (and > >I'm using hp quite loosley here since it is indeed torque that is the [quoted text clipped - 9 lines] > > http://www.renthal.com/site/resources/guide.htm Where did the diesel reference come from........ when we're talking 7.3, where I live a K&N can have you spending $22,000 CA a lot sooner than you need to - I don't even want to think what the retail on a 6.0 is going to be. To reduce the pressure drop across the filter medium, we can do one of two things..... we can increase the surface area of the medium or we can make the "holes" bigger..... IIRC 5 microns would denote a decent paper filter.... as the filter dusts off, we expect the flow rate to decrease as the micron number decreases. I have yet to see a finite micron number from K&N yet, with LESS filter area, they offer more air flow - I can only read this as "bigger holes" meaning more dirt and bigger dirt can make it through. Even after we spray the "magic oil" on the filter, we have BIG holes. I have yet to see anyone quoted as saying "a plugged air filter is good for fuel economy" but it is pretty obvious that a prematurely worn engne is bad for both fuel economy AND your cheque-book...... oh, I can relate to those telling me the K&N delivers more power...... way back when, it was popular to turn the lid on the air cleaner upside down (those not familiar with carbs wont understand) ... naturally, the increase in noise was equated to some magical increase in horsepower. The only sure fire way to improve fuel economy is to never start the beast...... otherwise we can only accept the fact that our autos will burn gasoline and conduct ourselves in such a manner as to avoid driving conditions and techniques that will increase fuel consumption..... Read that last statement as "I drive the vehicles I want to drive..... I pull up to the gas pump and pay what the pump reads..... I like to drive what I drive and will pay the price..... if I don't like the price, I can always drive something I DON'T want to drive"..... anything else is a lot like having your wife look for a shoe that's size 10 on the inside and size 6 on the outside.... Jim Warman mechanic@telusplanet.net > You know one of the main reasons the diesel engine get better fuel > economy than the gasoline?...because the diesel engine doesn't have a [quoted text clipped - 45 lines] > > > > Thanks > > > > Matt |
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