Downshifting bad for MPG?
#31
12-02-2005, 02:21 PM
Originally Posted by Hotrod
You really didn't say that diesles run lower compression than N/A gas motors did you??
#32
12-02-2005, 02:40 PM
#33
12-02-2005, 03:02 PM
I believe if you read the car manual, it tells you to downshift for engine braking.
Originally Posted by htownboy
Brilliant!
Automatics downshift so why should you not downshift with your standard? You should always downshift but easily, it uses no extra fuel and is not at all bad for your engine... Been doing it since 1978 and still do everyday... getting 25+MPG's with my 04 6MT coup.
Also, my last Supra was given to my little brother at gradualtion and it had 240K miles on only it's 3rd. clutch, 2nd, head gasket, and 4th. full brake service. Very good for 240,000 miles. Always downshifted it since day one!
Had an Isuzu truck with over 200K that I downshifted from day one... Was on 3rd brake job and no engine work besides normal tunes and maintenance.
So downshift your 6MT's, it burns no more fuel and is the proper way to drive a manual.
Automatics downshift so why should you not downshift with your standard? You should always downshift but easily, it uses no extra fuel and is not at all bad for your engine... Been doing it since 1978 and still do everyday... getting 25+MPG's with my 04 6MT coup.
Also, my last Supra was given to my little brother at gradualtion and it had 240K miles on only it's 3rd. clutch, 2nd, head gasket, and 4th. full brake service. Very good for 240,000 miles. Always downshifted it since day one!
Had an Isuzu truck with over 200K that I downshifted from day one... Was on 3rd brake job and no engine work besides normal tunes and maintenance.
So downshift your 6MT's, it burns no more fuel and is the proper way to drive a manual.
#34
12-02-2005, 03:08 PM
#35
12-02-2005, 03:27 PM
I'll downshift for more power or sometimes for braking. On the braking side Iwill usually only do that on a downhill or in a traffic situation where I will need to cruise along at a lower speed or be ready to accellerate again. Most times I just throw it into neutral coming to a stop without downshifting.
#36
12-02-2005, 03:33 PM
First, why would anyone put it in neutral and glide while depressing the brakes? - you're killing your pads as the car has more "mass" going down heel in neutral than if it was in gear. If anything, I would leave it in gear and brake. That way, the load is evenly divided between the engine braking and the brakes.
As to downshifting...
I usually downshift if I need to slow down fast from a high speed to a low one, like going downhill on a highway and my exist is coming up, I would rev-match and go down the gears 6-5-4 and if needed, into 3rd. I rarely go to second as there is no need, unless I'm crawling into a turn and need a quick exit.
As to downshifting...
I usually downshift if I need to slow down fast from a high speed to a low one, like going downhill on a highway and my exist is coming up, I would rev-match and go down the gears 6-5-4 and if needed, into 3rd. I rarely go to second as there is no need, unless I'm crawling into a turn and need a quick exit.
#37
12-02-2005, 03:36 PM
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Wow... interesting responses.
Fuel delivery in most modern cars are dependent on the throttle position. When we downshift the throttle is nearly closed and the fuel delivery should be close to idle state. So theoretically it should not affect fuel mileage as long as we don't blip the throttle to rev match.
As to whether downshifting is good for the engine... It's not. Higher rpm's means higher wear on the engine. It doesn't matter whether you use it to accelerate or decelerate. Simple as that.
Trucker's downshift because diesel motors are built to handle the wear and it's high compression is a very affective non-emergency brake. It also keeps the real brakes from overheating. The motors are usually well looked after and are rebuilt whenever its required.
Racers downshift to stay in the power band after slowing down for a corner. Real race cars are also well looked after and the motors are rebuilt for every race if not new.
Us drivers downshift for fun and to show off! And unless you downshift at redline everyday you wouldn't notice the wear.
Fuel delivery in most modern cars are dependent on the throttle position. When we downshift the throttle is nearly closed and the fuel delivery should be close to idle state. So theoretically it should not affect fuel mileage as long as we don't blip the throttle to rev match.
As to whether downshifting is good for the engine... It's not. Higher rpm's means higher wear on the engine. It doesn't matter whether you use it to accelerate or decelerate. Simple as that.
Trucker's downshift because diesel motors are built to handle the wear and it's high compression is a very affective non-emergency brake. It also keeps the real brakes from overheating. The motors are usually well looked after and are rebuilt whenever its required.
Racers downshift to stay in the power band after slowing down for a corner. Real race cars are also well looked after and the motors are rebuilt for every race if not new.
Us drivers downshift for fun and to show off! And unless you downshift at redline everyday you wouldn't notice the wear.
#38
12-02-2005, 03:36 PM
Originally Posted by Speedoholic
First, why would anyone put it in neutral and glide while depressing the brakes? - you're killing your pads as the car has more "mass" going down heel in neutral than if it was in gear. If anything, I would leave it in gear and brake. That way, the load is evenly divided between the engine braking and the brakes.
As to downshifting...
I usually downshift if I need to slow down fast from a high speed to a low one, like going downhill on a highway and my exist is coming up, I would rev-match and go down the gears 6-5-4 and if needed, into 3rd. I rarely go to second as there is no need, unless I'm crawling into a turn and need a quick exit.
As to downshifting...
I usually downshift if I need to slow down fast from a high speed to a low one, like going downhill on a highway and my exist is coming up, I would rev-match and go down the gears 6-5-4 and if needed, into 3rd. I rarely go to second as there is no need, unless I'm crawling into a turn and need a quick exit.
#39
12-02-2005, 03:43 PM
As to the original question (Gas consumption): If you leave your car in gear and let it glide (foot OFF the gas pedal), there is ZERO gas consumption. The ECU shuts the injectors down. There is no need to inject gas, as at that state, the engine is being ran by the wheels. Therefore, leaving the car in neutral and letting it glide, would consume MORE gas than if you would to leave it in gear. The RPM level makes no difference - as long as your foot is off the gas pedal. As soon as you step on it, the ECU will turn the injectors back on, at which point - yes, there will be more gas consumption as you are running the car at higher RPMs while stepping on the gas. However, again, if you downshift and let off the gas you will save more gas. You can even see that if you have a NAVI. Put it on the fuel consumption screen and watch how the MPG jump up as soon as you let off the gas. The RPMs could be higher, but that's only because the wheels are running the engine at a lower gear. On the other hand, if you downshift, and step back on the gas then the engine will consume more, as now it's being ran not only by the wheels at lower gear, but also by the excessive gas injection.
Last edited by Speedoholic; 12-02-2005 at 03:50 PM.
#40
12-02-2005, 03:49 PM
#41
12-02-2005, 03:53 PM
Originally Posted by madchef
Yes, technically it would lower your MPG. Downshifting obviously is raising the RPM's to a higher level, so yeah more gas is used (barely).
The only way the engine would consume more gas, would be if you rev-match before downshifting. That would mean you blip the throttle for a second or so, and raise the gas levels in the cylinders. As soon you let off the gas and let the engine-braking do its job, there is no gas consumption whatsoever.
#42
12-02-2005, 03:59 PM
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#43
12-02-2005, 04:17 PM
Originally Posted by jayelleseven
man u guys are much less informed than the guys at 6mt.net First off, DONT engine brake too much, in the long run it messes with ur transmission and dont make me explain it cuz i cant word it right, jus know that ur are forcing revs and makin the transm. work harder
Been driving MT's since 1978 and it hurts nothing at all as long as your not dropping several gears at once without knowing what the hell your doing... All automatics downshift; so are you saying that they are hurting themselves and their engines? Do you relly think manuafacturers would engineer something like this if it burned more gas or wore things out prematurelely, heck no!
Also, you can test for yourselves, there will be no noticable change in fuel consumption whether you downshift or not but you can save many brake jobs which do add up to cost as much or more than a cluch replacement especially if you don't catch it and do it in time, it could actually cost more, add up rotors, calipers, pads, labor... add up parts for replacing your Brembo's or Stoptechs and see if the numbers don't add up to making you wish you had downshifted.
Last edited by htownboy; 12-02-2005 at 04:24 PM.
#44
12-02-2005, 04:18 PM
[QUOTE=Speedoholic]First, why would anyone put it in neutral and glide while depressing the brakes? - you're killing your pads as the car has more "mass" going down heel in neutral than if it was in gear. If anything, I would leave it in gear and brake. That way, the load is evenly divided between the engine braking and the brakes.
That's an easy one to answer. If I am granny driving along in say 6th gear at a very leisurely 70km (42mph) and I see a stop light ahead i will frequently leave the car in gear for a moment and then flick the shifter into neutral so that the car will not stall as I slow down. I see two alternatives. One is to downshift through the gears wearing the clutch and engine using it to unnecessarily brake the car. The other is to leave the car in top gear and stall the engine since the rpms are already very low. In this case I prefer to use my brakes alone most times to slow the car.
For the rest of my driving at different speeds my downshifting style is pretty much how you described yours.
That's an easy one to answer. If I am granny driving along in say 6th gear at a very leisurely 70km (42mph) and I see a stop light ahead i will frequently leave the car in gear for a moment and then flick the shifter into neutral so that the car will not stall as I slow down. I see two alternatives. One is to downshift through the gears wearing the clutch and engine using it to unnecessarily brake the car. The other is to leave the car in top gear and stall the engine since the rpms are already very low. In this case I prefer to use my brakes alone most times to slow the car.
For the rest of my driving at different speeds my downshifting style is pretty much how you described yours.
#45
12-02-2005, 04:20 PM
Originally Posted by Speedoholic
^ WRONG. Read my response above.
The only way the engine would consume more gas, would be if you rev-match before downshifting. That would mean you blip the throttle for a second or so, and raise the gas levels in the cylinders. As soon you let off the gas and let the engine-braking do its job, there is no gas consumption whatsoever.
The only way the engine would consume more gas, would be if you rev-match before downshifting. That would mean you blip the throttle for a second or so, and raise the gas levels in the cylinders. As soon you let off the gas and let the engine-braking do its job, there is no gas consumption whatsoever.
I think you mean little gas consumotion as opposed to "no" or "zero" gas consumption. The engine is still running so there is fuel being used just as there is when it is at idle when stopped.