cover a %age of the radiator grille in winter, depending on how cold it is, to improve highway mpg by reducing wind resistance
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Quest for Better MPG
- Thread starter Winston
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Winston
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Thanks Gary for letting me know how my new O2 sensor might be getting me better mpg, even in the "Open Loop" mode.
The aerodynamics on this car are so bad, I dont think covering the radiator would make much difference, but I might try it anyway.
I don't have much of an option to "Pulse and Glide". Pretty heavy traffic on both ends of my commute. All four lanes full of cars.
The aerodynamics on this car are so bad, I dont think covering the radiator would make much difference, but I might try it anyway.
I don't have much of an option to "Pulse and Glide". Pretty heavy traffic on both ends of my commute. All four lanes full of cars.
Someone here mentioned synthetic fluid in the manual transmission. This is not the first time I've seen this in threads on BITOG. What makes this interesting is that I have a hard time understanding this one... many people see measureable improvement, but I'm wondering... how?
That is, including the transmission and the differential, rotational torque goes into these components and some comes out to drive the wheels. If it doesn't come out, it must be lost in friction (and heat). Is there really that much to be gained by going synthetic?
Again, I'm not trying to dispute anything, just trying to understand. If this is real, it seems like a cheap and effective way to get better fuel economy while making your components last longer at the same time. (A win-win, I like those.........)
That is, including the transmission and the differential, rotational torque goes into these components and some comes out to drive the wheels. If it doesn't come out, it must be lost in friction (and heat). Is there really that much to be gained by going synthetic?
Again, I'm not trying to dispute anything, just trying to understand. If this is real, it seems like a cheap and effective way to get better fuel economy while making your components last longer at the same time. (A win-win, I like those.........)
Winston:
Well, yep, that would make P&G a little difficult to pull off. Keep in mind that though I live in Pensacola, I spend M-F in New Orleans where I’m stationed. It’s pure, hard-core big-city commuting driving most of the way for me too, most of the time, I just blend the technique in where I can, decelerating in a dead-band glide if I can, and so forth. I do, however, have two separate stretches of a tad over a mile each on my ten mile, one-way commute on which I can pull off a good run of P&G. Works really nicely for me. Just a thought – would have been interesting to see if it could have helped you.
Brian:
Sorry it took so long to get back. You posted:
As to the first, yes, sort of. Keep in mind that in an HSD system car (originally just Prius, but now Camry, Highlander, Lexus RX and GX too), regeneration also happens when you’re coasting too, not just when you brake. As you push the brake pedal, you get progressively stronger and stronger regeneration. Incidentally, the only time the pads actually touch the rotors is below 7 mph (every stop) or if the car senses a “panic stop” (any speed).
The idea is that the very most efficient way for an HSD car to move from Pt A to B is “gliding”, where it’s neither using energy to push, nor is it experiencing the drag losses associated with regeneration (and regen braking too, of course).
So when you “glide”, yes the actual throttle plate is closed (by action of the ECU), and in fact, the entire ICE (internal combustion engine) is off and not turning at all. You are not, however, off of the gas pedal. You gently modulate it to keep the car right in between accelerating and “coasting” where the regen would kick in.
Your second question is a trickier one, and leads right to some of the Prius’ unique characteristics. The “transmission” in a Prius is really unique and simple. Click here for a great animated and text explanation of the HSD transmission. . Be sure to scroll down to the interactive part where you can make the parts move as you wish. As you can see, it looks more like an old fashioned differential than a modern, complicated automatic transmission. An astonishingly simple solution, esp compared to some of the six and seven speed autos out there today.
As useful as the diagram is, here are a couple clarifications. First, the outer ring is MG2, the big motor, the center “core” is the smaller MG1, the inner ring, which carries the planet gears (and which you can hardly see because of the color) is linked to the ICE (gas engine). The rotation of the outer ring is what is transmitted directly to the driveshafts.
So consider this, especially in light of your question: you can be driving down the road at any speed up to 42 mph, AND the ICE will be directly connected to the driveline, AND it will be perfectly stationary (that is, 0 rpm)! This is pretty well at odds with how most of us are used to thinking about automobile power trains, but it’s 100% true. Play around with the sliders on the animated diagram, and you’ll get a feel for it. I’m awful at spatial perception problems, so it took me a while to figure it out – should be quicker for most other folks. As you can see, the engine never disengages from the wheels, and at the same time, it can be very much shut off.
I suppose in a conventional car, there’d be two ways to approximate gliding. First, you could put the car in Neutral, but as you correctly suggest, that is illegal in most places. My thought was that the other way would be to edge the throttle open just far enough that the engine is neither pulling nor engine braking. In that condition, one could “glide” with very little resistance, and very low fuel flow while the car “naturally” allows its existing momentum to carry it as far as in can (or until the driver aborts the procedure).
As to the sync stoplights, as I said, one must adjust to the conditons. If there’s little traffic, I’d still P&G since at least in an HSD car, P&G is even better than steady state cruising. You just have to be willing to work at it and tolerate doing so.
Well, yep, that would make P&G a little difficult to pull off. Keep in mind that though I live in Pensacola, I spend M-F in New Orleans where I’m stationed. It’s pure, hard-core big-city commuting driving most of the way for me too, most of the time, I just blend the technique in where I can, decelerating in a dead-band glide if I can, and so forth. I do, however, have two separate stretches of a tad over a mile each on my ten mile, one-way commute on which I can pull off a good run of P&G. Works really nicely for me. Just a thought – would have been interesting to see if it could have helped you.
Brian:
Sorry it took so long to get back. You posted:
Quote:
On the Prius, is that "neutral point" when the throttle is closed but the regenerative braking has not turned on?
In a regular car, that point would be..with your foot off the gas pedal. (In top gear). The difference is that in a regular car the engine will slow down the car..but the fuel injectors are completely turned off. In a Prius I would expect the engine to be disengaged from the wheels and shut off. You can't do that legally in a regular car...
If the road you're on has traffic lights, consider not doing this--they might be coordinated for traffic operating at the speed limit.
As to the first, yes, sort of. Keep in mind that in an HSD system car (originally just Prius, but now Camry, Highlander, Lexus RX and GX too), regeneration also happens when you’re coasting too, not just when you brake. As you push the brake pedal, you get progressively stronger and stronger regeneration. Incidentally, the only time the pads actually touch the rotors is below 7 mph (every stop) or if the car senses a “panic stop” (any speed).
The idea is that the very most efficient way for an HSD car to move from Pt A to B is “gliding”, where it’s neither using energy to push, nor is it experiencing the drag losses associated with regeneration (and regen braking too, of course).
So when you “glide”, yes the actual throttle plate is closed (by action of the ECU), and in fact, the entire ICE (internal combustion engine) is off and not turning at all. You are not, however, off of the gas pedal. You gently modulate it to keep the car right in between accelerating and “coasting” where the regen would kick in.
Your second question is a trickier one, and leads right to some of the Prius’ unique characteristics. The “transmission” in a Prius is really unique and simple. Click here for a great animated and text explanation of the HSD transmission. . Be sure to scroll down to the interactive part where you can make the parts move as you wish. As you can see, it looks more like an old fashioned differential than a modern, complicated automatic transmission. An astonishingly simple solution, esp compared to some of the six and seven speed autos out there today.
As useful as the diagram is, here are a couple clarifications. First, the outer ring is MG2, the big motor, the center “core” is the smaller MG1, the inner ring, which carries the planet gears (and which you can hardly see because of the color) is linked to the ICE (gas engine). The rotation of the outer ring is what is transmitted directly to the driveshafts.
So consider this, especially in light of your question: you can be driving down the road at any speed up to 42 mph, AND the ICE will be directly connected to the driveline, AND it will be perfectly stationary (that is, 0 rpm)! This is pretty well at odds with how most of us are used to thinking about automobile power trains, but it’s 100% true. Play around with the sliders on the animated diagram, and you’ll get a feel for it. I’m awful at spatial perception problems, so it took me a while to figure it out – should be quicker for most other folks. As you can see, the engine never disengages from the wheels, and at the same time, it can be very much shut off.
I suppose in a conventional car, there’d be two ways to approximate gliding. First, you could put the car in Neutral, but as you correctly suggest, that is illegal in most places. My thought was that the other way would be to edge the throttle open just far enough that the engine is neither pulling nor engine braking. In that condition, one could “glide” with very little resistance, and very low fuel flow while the car “naturally” allows its existing momentum to carry it as far as in can (or until the driver aborts the procedure).
As to the sync stoplights, as I said, one must adjust to the conditons. If there’s little traffic, I’d still P&G since at least in an HSD car, P&G is even better than steady state cruising. You just have to be willing to work at it and tolerate doing so.
I don't believe that, with a regular engine, you can achieve a state where the engine is engaged to the drive wheels (in other words, not in neutral) and neither pulling nor engine braking. You either feed the engine the air and fuel it needs to keep the car at the current speed, or you feed it more and the car accelerates, or you feed it less and the car decelerates (engine braking).
One could wire a switch in series with the common 12V feed to the the fuel injectors, turn them off, and then push the gas pedal to the floor to minimize engine braking (without any fuel flow a car has much less engine braking with the throttle pushed to the floor!).
Come to think of it, electronic throttle control could make this happen automatically with the right programming. If the electronic pedal position sensor detects that the driver's foot is off of the pedal, and the car is moving above a certain speed, the fuel injectors are already cut off, so the electronic throttle control need only go to full throttle to minimize engine braking. (It could close the throttle when the brakes are applied for normal additional engine braking)
But what happens if the driver steps on the clutch in such a state? The engine will stall, unless the control system is fast enough to restore fuel and close the throttle before the engine stalls.
Now I'm wondering--my Saab 93 has electronic throttle control. And the engine braking on it seemed to be less than what I would have expected. I really wonder if the throttle is closed on that car during deceleration.
One could wire a switch in series with the common 12V feed to the the fuel injectors, turn them off, and then push the gas pedal to the floor to minimize engine braking (without any fuel flow a car has much less engine braking with the throttle pushed to the floor!).
Come to think of it, electronic throttle control could make this happen automatically with the right programming. If the electronic pedal position sensor detects that the driver's foot is off of the pedal, and the car is moving above a certain speed, the fuel injectors are already cut off, so the electronic throttle control need only go to full throttle to minimize engine braking. (It could close the throttle when the brakes are applied for normal additional engine braking)
But what happens if the driver steps on the clutch in such a state? The engine will stall, unless the control system is fast enough to restore fuel and close the throttle before the engine stalls.
Now I'm wondering--my Saab 93 has electronic throttle control. And the engine braking on it seemed to be less than what I would have expected. I really wonder if the throttle is closed on that car during deceleration.
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Winston, I hope that you gapped the new plugs. And, if you understand them, maybe you can index them. If you have long spark plug wire runs, you might benefit from better wires. Don't forget the cap and rotor if equipped. And, their are possibly improved ignitions, coils, current and voltage increasing devices.
If timing is adjustable and if preignition/detonation is nil, advance it a little.
I find that old wiring harnesses and normal corrosion can prevent improvements. Clean all chasis grounds and battery/alternator/distribution power cables and connections. Caig deoxit or Stabilant should also be considered at all wiring harness connections. Upgraded power/ground or additional ground wires might also help.
Synthetics everywhere. Even though the synthetics are the same weight(at temp), their superior cold flow is where you'll get the MPG improvement. PSF, ATF, MTF, front/rearends, Xcase, motor oil, u-joints, wheel bearings,...are all the places to use it.
Tire pressure should improve MPG. But, MPG increase might not be enough that is easily measured. Tire selection is also important. When it is time to buy new tires, do not buy mud terrain or all terrain tires. They are useless on the street. Get a good all season street tire and make sure alignment is perfect.
Worn suspension joints will also reduce MPG. Inspect replace anything worn in the suspension and steering.
Run an UCL. Dose some Marvel, Lubrigas, Lucas, FuelPower, GTA, Trublu, Neutra, SoyUltra, BioValve....or a little 2-stroke oil at each fill up.
Run an FI cleaner prior to every OCI. Regane, Redline, VentilSauber, Seafoam, Amsoil, Techron,.....are some to alternate among. With high mileage, I'd consider pulling all injectors and sending them out for cleaning and flowing.
Engine tune is important.
Your cooling system should be checked out. Make sure rad cap and thermostat are working perfectly or just replace them. Use new antifreeze and possible an additive to keep everything clean.
Other engine sensors should be tested. Engine temp coolant sensors, MAP, MAF, position sensors,.....should be tested for function and/or replaced.
Inspect, trim, or replace any and all vacuum lines.
Replace the PCV, air filter, fuel filter, and other tuneup items for that vehicle.
Adjust driving style. This isn't a Prius hybrid thread. Mildly accellerate, limit top speed, and practice coasting, will do wonders for MPG. I always wonder why the typical driver races to every stop sign or red light. Makes no sense. Anticipate red lights, stop signs, traffic, and coast away.
Consult the aftermarket. There might be some MPG improving mods, like free flowing intake/exhausts/catalytics, A/F tuning like fuel PSI reducing regulators and splice in fuel computers, underdrive or lighter pulleys, E-fan conversions, weight reducing components(CF or fiberglass hoods, fenders, smaller battery, no spare tire), a good vacuuming to remove the 20lbs of dirt in the carpets, lighter rims......
And, above all, wash/wax your vehicle. Break out the carnauba or polymer waxes to reduce air drag.
If timing is adjustable and if preignition/detonation is nil, advance it a little.
I find that old wiring harnesses and normal corrosion can prevent improvements. Clean all chasis grounds and battery/alternator/distribution power cables and connections. Caig deoxit or Stabilant should also be considered at all wiring harness connections. Upgraded power/ground or additional ground wires might also help.
Synthetics everywhere. Even though the synthetics are the same weight(at temp), their superior cold flow is where you'll get the MPG improvement. PSF, ATF, MTF, front/rearends, Xcase, motor oil, u-joints, wheel bearings,...are all the places to use it.
Tire pressure should improve MPG. But, MPG increase might not be enough that is easily measured. Tire selection is also important. When it is time to buy new tires, do not buy mud terrain or all terrain tires. They are useless on the street. Get a good all season street tire and make sure alignment is perfect.
Worn suspension joints will also reduce MPG. Inspect replace anything worn in the suspension and steering.
Run an UCL. Dose some Marvel, Lubrigas, Lucas, FuelPower, GTA, Trublu, Neutra, SoyUltra, BioValve....or a little 2-stroke oil at each fill up.
Run an FI cleaner prior to every OCI. Regane, Redline, VentilSauber, Seafoam, Amsoil, Techron,.....are some to alternate among. With high mileage, I'd consider pulling all injectors and sending them out for cleaning and flowing.
Engine tune is important.
Your cooling system should be checked out. Make sure rad cap and thermostat are working perfectly or just replace them. Use new antifreeze and possible an additive to keep everything clean.
Other engine sensors should be tested. Engine temp coolant sensors, MAP, MAF, position sensors,.....should be tested for function and/or replaced.
Inspect, trim, or replace any and all vacuum lines.
Replace the PCV, air filter, fuel filter, and other tuneup items for that vehicle.
Adjust driving style. This isn't a Prius hybrid thread. Mildly accellerate, limit top speed, and practice coasting, will do wonders for MPG. I always wonder why the typical driver races to every stop sign or red light. Makes no sense. Anticipate red lights, stop signs, traffic, and coast away.
Consult the aftermarket. There might be some MPG improving mods, like free flowing intake/exhausts/catalytics, A/F tuning like fuel PSI reducing regulators and splice in fuel computers, underdrive or lighter pulleys, E-fan conversions, weight reducing components(CF or fiberglass hoods, fenders, smaller battery, no spare tire), a good vacuuming to remove the 20lbs of dirt in the carpets, lighter rims......
And, above all, wash/wax your vehicle. Break out the carnauba or polymer waxes to reduce air drag.
Quote:
(...snip...)Adjust driving style. This isn't a Prius hybrid thread. Mildly accellerate, limit top speed, and practice coasting, will do wonders for MPG. I always wonder why the typical driver races to every stop sign or red light. Makes no sense. Anticipate red lights, stop signs, traffic, and coast away.
Consult the aftermarket. (...snip...)
Of course it isn't a Prius thread. But believe it or not, Prius drivers tend to focus, to a much greater degree, on fuel economy improvements. P&G is one of the techniques that is not dependent upon having a hybrid. That's why I brought it up. I remember a friend of mine using a variant of the technique when we were back in high school. When he knew he was about to run out, he'd actually turn the car off and glide in neutral for as far as he could, start, accel, repeat. Legality was not a big concern at that point. I always wonder why some discussion group members obsess so much over other people's posts when they could simply not bother reading them if they didn't want to. . . If you don't want to read it -- skip it.
The most expensive thing in driving is the brake pedal. Driving habits are kind of important and show the greatest improvement for the least amount of investment.
Quote:
The most expensive thing in driving is the brake pedal. Driving habits are kind of important and show the greatest improvement for the least amount of investment.
Yup. I hate coming to a complete stop. The light up ahead is red? Time to coast and watch other drivers race up to the light and then sit and idle. Never understood that.
As far as improving mpg on a 1995 Montero, well, my heart goes out to you. You can only do so much with a heavy vehicle with the aerodynamics of a brick. At least you got some preventive maintenance done!
I recently improved my milage greatly by running larger tires. They weigh the same as the smaller size but the car runs at lower rpms for the same speed. You have to adjust for speedometer error and odeometer error but after adjustments with my miata it is giving close to 35mpg and the best I could get before was 31-32. A bottle of techron seems to keep it at its best milage so I give it one every six months or so.
Quote:
Slightly off topic, but along the same lines. A professional MX racer once said that he observed a lot of amature racers spending gigantic sums of money for go fast goodies like pipes, titanium fasteners, cylinder mods, etc., and seeing little, if any, improvement. He said the best mod he ever made to his bike was getting in the gym, and losing 15 pounds. Moral of the story is, look close to home for improvements before spending big bucks for a mile or two better MPG.
I take that as the best way to be faster is lose weight.
IF you can't do it with the car, start with the driver.
Which in theory should improve fuel econ.
A neighbor has noted a 1mpg increase when he left off the front skidplate on an 03 v8 4Runner from 23 mpg to 24, all long trips on the freeway with very little city driving. If it's all city, he gets 18mpg, either way, plate or no plate.
Quote:
I drive a fairly innefficient 95 Mitsu Montero for my 25 mile commute to work. I carpool so I only drive two days a week. Through the past year I have been trying to maximize my mpg.
IMHO one of the better forums for fuel economy discussion is: http://www.gassavers.org
They don't have anywhere near as many active users as this forum, but their numbers are growing. And like this forum, they put a lot of effort into separating the things that actually help, from the things that don't do much good (or worse yet, even hurt FE). I suggest you check them out, if fuel economy is of interest to you.
I know I've already learned a number of things from that forum. And some of the things that help, are pretty surprising, and non-obvious. As just one example, putting a (partial) block of your car's grill (corrugated plastic seems to be the material of choice for this, as it's lightweight, easy to work with, and waterproof), can be surprisingly effective at lowering aerodynamic drag (and thereby improving fuel economy). Now, you do have to balance this against cooling needs (as the grill is there to help engine cooling). But in many cases, you can still block part of the grill, and not worry about overheating. In fact, in the winter you can usually block the entire grill (for maximum aerodynamic benefit), and still get enough cooling from the cold air entering from below the car!
I use corrugated plastic and masking tape on my car.
I took the roof rack off my wagon. Never use it anyway.
Highway mileage improved significantly.
Highway mileage improved significantly.
Clean MAF sensor, de-carbonize combustion chambers, and clean TB.
If it is too reliable why not trading some for the economy or pep. I occasionally use oil additives with friction reducers. Doors are sagging, blower chirping, left signal cancelling has cancelled and 22 y/o engine is purring like just broken in... it doesn't need to overlast the car I guess.
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