Insanely Good Gas Mileage Out Of N/A Modded tC
09-26-2006, 06:45 PM
#42
Senior Member
SL Member
Join Date: Jul 2006
Posts: 2,320
What is everyone saying here? Going downhill in a modern fuel-injected engine, you should never put it in neutral. Not only is it dangerous, but it also wastes gas.
If you are in gear, then the wheels turn the engine. When your RPMs dip below a certain amount, the fuel injectors will turn on to keep the engine running - this is what happens in neutral, and why the engine doesn't just quit in neutral.
Not to mention the fact that it is just flat out dangerous (and of questionable intellgence) to go coasting down hills in neutral.
If you are in gear, then the wheels turn the engine. When your RPMs dip below a certain amount, the fuel injectors will turn on to keep the engine running - this is what happens in neutral, and why the engine doesn't just quit in neutral.
Not to mention the fact that it is just flat out dangerous (and of questionable intellgence) to go coasting down hills in neutral.
09-26-2006, 06:49 PM
#43
Originally Posted by paul34
If you are in gear, then the wheels turn the engine. When your RPMs dip below a certain amount, the fuel injectors will turn on to keep the engine running - this is what happens in neutral, and why the engine doesn't just quit in neutral.
09-26-2006, 06:54 PM
#44
Senior Member
SL Member
Join Date: Jul 2006
Posts: 2,320
Some questions for you, good sir:
Do you know how a bump start works?
Why you can overrev into redline when doing an incorrect downshift?
Why the car will stop moving if the engine is off, and handbrake is down, and you left the car in gear?
Why an engine stalls when the wheels stop moving?
Do you know how a bump start works?
Why you can overrev into redline when doing an incorrect downshift?
Why the car will stop moving if the engine is off, and handbrake is down, and you left the car in gear?
Why an engine stalls when the wheels stop moving?
09-26-2006, 06:56 PM
#45
Originally Posted by dziuniek
ooh yeah great idea. let's all turn our car off in 5th gear while rolling down a hill...
BUAHGAHAHAHAHAHAHAHAHAHAHA ;p;p;p;p;p;p
neutral only please.
BUAHGAHAHAHAHAHAHAHAHAHAHA ;p;p;p;p;p;p
neutral only please.
your momentum turns the wheels which turns the crank/engine when you're not on the gas. no gas necessary. hence engine braking, because of the resistance created without the gas. it is not free energy, as none is created. it's exploiting momentum while the car is on.
09-26-2006, 07:09 PM
#46
Originally Posted by paul34
Some questions for you, good sir:
Do you know how a bump start works?
Why you can overrev into redline when doing an incorrect downshift?
Why the car will stop moving if the engine is off, and handbrake is down, and you left the car in gear?
Why an engine stalls when the wheels stop moving?
Do you know how a bump start works?
Why you can overrev into redline when doing an incorrect downshift?
Why the car will stop moving if the engine is off, and handbrake is down, and you left the car in gear?
Why an engine stalls when the wheels stop moving?
A car traveling downhill in neutral has to overcome 2 basic forces: air resistance, and friction between the tires and the road.
A car traveling downhill in gear has to overcome: air resistance, friction between tires and the ground, rotating mass, and the engine's own compression.
The wheels are not moving the pistons. The wheels are spinning at a rate greater than the engine is supporting; their rotational rate is increase by the action of the car's inability to fight gravity: it rolls downhill. This is why the fuel mileage going downhill is better than going uphill. Less load, so the car uses less fuel to move. But it's still using fuel at a rate greater than idle. And to think otherwise is ridiculous.
So no matter how you slice it, you will use less fuel coasting downhill than rolling in gear-- because you've effectively removed the engine from the equation. It is neither trying to speed the car up or slow it down. It's dead weight, consuming only what fuel it needs to run it's own life-support systems (charging and cooling).
09-26-2006, 07:15 PM
#47
i realized i totally forgot to say something. unless this was just going without saying it: naturally you're oging to further in neutral than with the engine in gear. but if you're coming to a stop, coasting in gear saves more fuel than neutral. thats my whole argument.
09-26-2006, 07:32 PM
#48
Senior Member
Scikotics
SL Member
Team ScioNRG
Join Date: Jul 2006
Location: Peru, NY
Posts: 135
"in a manual car, for the electronic control unit (ECU) to impose deceleration fuel cut-off (DFCO), a fuel-saving mode whereby the fuel injectors are turned off if the throttle is closed (foot off the accelerator pedal) and the engine is being driven by the momentum of the vehicle."
i always thought that neutral was better then i did a bit of reasearch, thats waht i found out.
coasting downhill in gear is better than neutral!
09-26-2006, 07:44 PM
#49
Originally Posted by Jayjr
"in a manual car, for the electronic control unit (ECU) to impose deceleration fuel cut-off (DFCO), a fuel-saving mode whereby the fuel injectors are turned off if the throttle is closed (foot off the accelerator pedal) and the engine is being driven by the momentum of the vehicle."
i always thought that neutral was better then i did a bit of reasearch, thats waht i found out.
coasting downhill in gear is better than neutral!
Quoting from the Wiki is tantamount to quoting quantum physics via Paris Hilton. But I've only been driving MT cars for 18 years now-- so this mythical DFCO may indeed exist in practice, somewhere. I've not seen in in effect, though. Sure, GM got a patent on it in 1992... so it must be working. Most of their cars get terrible fuel economy, and they've re-released Fuel Crisis-era variable displacement in an attempt to avoid another hundred million in CAFE fines.
I can't stay out of the right pedal anyway. I average 25.4mpg. But hey, I've an open mind. I'll coast in gear for the next 4 tanks. If my mileage goes up, I'll go out and buy a hat. And eat it.
09-26-2006, 08:00 PM
#51
Senior Member
SL Member
Join Date: Aug 2006
Location: Pittsburgh, PA
Posts: 1,520
Does it really matter either way? You might save 1-2 mpg if it matters at all, not much point in arguing. I personally ride the gear just to save brakes, and the fact that coasting in neutral is dangerous and technically illegal, but basically impossible to prosecute against. And to mtopper518, a professional wouldn't matter, can't you tell everyone here already is a "professional" lol.
09-26-2006, 08:01 PM
#52
Junior Member
Join Date: Aug 2006
Posts: 21
Dr. Isotope... I just want to say that while Wikipedia may not be the official authority on anything it's a compilation of many people's input and is actually subject to revision if something false is discovered. I'm not trying to say the Wiki is right but I don't think comparing it to Paris Hilton/String Theory is fair.
If it's wrong.. it should be corrected. You all make valid points... I think...
If it's wrong.. it should be corrected. You all make valid points... I think...
09-26-2006, 08:02 PM
#53
Junior Member
Join Date: Aug 2006
Posts: 21
Originally Posted by tCizzler
Does it really matter either way? You might save 1-2 mpg if it matters at all, not much point in arguing. I personally ride the gear just to save brakes, and the fact that coasting in neutral is dangerous and technically illegal, but basically impossible to prosecute against. And to mtopper518, a professional wouldn't matter, can't you tell everyone here already is a "professional" lol.
09-26-2006, 08:12 PM
#55
Senior Member
SL Member
Join Date: Jul 2006
Location: Central Maryland
Posts: 2,338
To get back on topic, I get great gas mileage with my mods. I'm at around 360-380 with close to 1.5 gallons to go. About 75% highway driving at 70-75.
I can't remember the formula, but in highschool (back in the day), we did this formula that ended up making the optimal speed for a vehicle to burn fuel at its most efficient level is 66 mph. It was an Algebra class and we were learning how to calculate distance (in time) from one object to another via speed.
I can't remember the formula, but in highschool (back in the day), we did this formula that ended up making the optimal speed for a vehicle to burn fuel at its most efficient level is 66 mph. It was an Algebra class and we were learning how to calculate distance (in time) from one object to another via speed.
09-26-2006, 08:16 PM
#56
Senior Member
SL Member
Join Date: Aug 2006
Location: Pittsburgh, PA
Posts: 1,520
Actually mine are kinda cheezy,i used window tint and stretched it around and had to cut a line at the top. they look great when its clean, but crappy when they're dirty cuz the line collects dirt. But i will get back to you in a pm cuz when i was looking for them myself, i found them for like 50 bucks, but i cant remember where. Ill look in my HISTORY and get back. But thanks anyway.
I wish i could say the same about yours but you don't have any pics up that i saw. Oh well its a tC, so i'm sure its SEXY as hell anyway.
I wish i could say the same about yours but you don't have any pics up that i saw. Oh well its a tC, so i'm sure its SEXY as hell anyway.
09-26-2006, 08:28 PM
#57
Senior Member
SL Member
Join Date: Jul 2006
Location: Dallas, TX
Posts: 486
The most fuel effecient speed is the lowest possible speed (without lugging) that you can travel at, in your highest gear. For the tC that's going to be about 45. This formula translates to the fastest speed while maintaining the lowest RPMS. I travel at 45 in my 350Z in 6th gear at about 1,600 RPM and the computer says I'm getting like 43MPG, the only thing is stopping at traffics lights, and acceleration drop the average back down to about 27. IT's absoulely insane to think that engine braking is more effecient than neutral coasting. The tC idles a 800 RPM after finishing it's warm up dance( correct me if i'm wrong on the idle, it's been a while since I drove a tC). So if you're traveling down a hill at 45 MPH, the tC will be running at about 2K RPM, which is 1200RPM more than Idle , which means the engine is demanding that much more fuel to keep going. IF youre theory of the fuel cut off and the wheel powering the engine is correct, go drive down a hill, leave the car in gear, and turn off the car. You're driving wheels will lock up so fast and send you all over the road... why, becuz the engine stops spinning, so the wheels stop spinning. If you don't believe me, go try it, and then tell me how you screwed up your car in the process, cuz it will. Engine braking is hard on the engine and causes excess wear and tear on it. The use of engine braking was introduced when cars still had drumb breaks which quickly overheated and fade out, so the drivers would downshift to slow down the car, to aviod overheating the breaks and crashing into the bushes when the faded. Todays modern cars have advanced disc brakes with vented rotors, Brake force distribution, ABS, and high heat capacity calipers, with pads that are designed to wear out and be replaced. Please, PEOPLE,just use your brakes. It's better for you milage and your engine. To say that you want to save your breaks and use engine breaking is like saying you want to power shift so you don't wear out your clutch...
09-26-2006, 08:34 PM
#59
Senior Member
SL Member
Join Date: Jul 2006
Location: Central Maryland
Posts: 2,338
Originally Posted by flintgauge86
The most fuel effecient speed is the lowest possible speed (without lugging) that you can travel at, in your highest gear. For the tC that's going to be about 45. This formula translates to the fastest speed while maintaining the lowest RPMS. I travel at 45 in my 350Z in 6th gear at about 1,600 RPM and the computer says I'm getting like 43MPG, the only thing is stopping at traffics lights, and acceleration drop the average back down to about 27. IT's absoulely insane to think that engine braking is more effecient than neutral coasting. The tC idles a 800 RPM after finishing it's warm up dance( correct me if i'm wrong on the idle, it's been a while since I drove a tC). So if you're traveling down a hill at 45 MPH, the tC will be running at about 2K RPM, which is 1200RPM more than Idle , which means the engine is demanding that much more fuel to keep going. IF youre theory of the fuel cut off and the wheel powering the engine is correct, go drive down a hill, leave the car in gear, and turn off the car. You're driving wheels will lock up so fast and send you all over the road... why, becuz the engine stops spinning, so the wheels stop spinning. If you don't believe me, go try it, and then tell me how you screwed up your car in the process, cuz it will. Engine braking is hard on the engine and causes excess wear and tear on it. The use of engine braking was introduced when cars still had drumb breaks which quickly overheated and fade out, so the drivers would downshift to slow down the car, to aviod overheating the breaks and crashing into the bushes when the faded. Todays modern cars have advanced disc brakes with vented rotors, Brake force distribution, ABS, and high heat capacity calipers, with pads that are designed to wear out and be replaced. Please, PEOPLE,just use your brakes. It's better for you milage and your engine. To say that you want to save your breaks and use engine breaking is like saying you want to power shift so you don't wear out your clutch...
Awesome, so now we all know
. I thought engine braking wasn't that bad if done at proper RPMs. Of course not going from 80 mph in 5th to 3rd and 45 mph, but coasting down from 5th and around 55 going into 4th or something. But yes, I do see how this wears more on the motor and yes, the brakes are much cheaper to replace than the clutch or other engine parts.
