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?Riddle me this?

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micahdj

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Discussion starter · #1 ·
Assuming your foot does not touch the accelerator. Do our engines burn more fuel when you coast down a hill with the car in neutral or with the car in gear?
Just curious what everybody thinks. I was surprised when I found out the answer but it does make sense. I am sure a lot you know this already but thought it might make a good discussion.
 
#3 ·
Re: ?Riddle me this? (Bolsen)

WHen your in gear and not apply your foot on the gas there is no fuel being injected....If your in N then theres fuel being injected to keep the car running...

Reason why manuals are cheaper on gas...Down shifting...also acounts for better on breaks http://****************.com/smile/emthup.gif

If im wrong someone make fun of me......Iv been drinking
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#7 ·
Re: ?Riddle me this? (SpooledAWP)

Quote, originally posted by SpooledAWP »
you are correct...it is better to be in gear then in neutral...even at a red light

But you have to hold the clutch in so how would that be different from just being in neutral?
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#8 ·
Re: ?Riddle me this? (01 Wolfsburg)

Quote, originally posted by 01 Wolfsburg »

But you have to hold the clutch in so how would that be different from just being in neutral?
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heh... I couldn't help but laugh at this and read your signature too. lol
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#10 ·
Re: ?Riddle me this? (RQtechVR6)

When you are stopped at a light either in gear with your foot on the clutch OR in neutral with your foot off the clutch, you are still burning fuel. The car isn't moving, if you weren't injecting fuel, the engine would stop
When you downshift and coast down a hill, the transmission is actually spinning the engine, no fuel or spark is required to keep everything going until you stop. ALTHOUGH, while it isn't required I really don't know weather or not it actually stops injecting fuel.
This only works in manual transmissions because there is a true mechanical connection between the engine and trans. Auto's use a torque converter which is a fluid connection, where the transmission spinning the engine is not possible.


Modified by jschweg at 11:39 AM 4-21-2004
 
#11 ·
Re: ?Riddle me this? (DimceMKIV)

Quote, originally posted by DimceMKIV »
WHen your in gear and not apply your foot on the gas there is no fuel being injected....If your in N then theres fuel being injected to keep the car running...

So when you're going down a hill in gear there is no fuel being injected? I could understand very little fuel being injected (less than is needed for the engine to keep the rpms up in neutral) but is there really no fuel being injected? it seems like there would need to be at least some to keep the engine running.
 
#12 ·
Re: ?Riddle me this? (BIGwayner)

Quote, originally posted by BIGwayner »

So when you're going down a hill in gear there is no fuel being injected? I could understand very little fuel being injected (less than is needed for the engine to keep the rpms up in neutral) but is there really no fuel being injected? it seems like there would need to be at least some to keep the engine running.

When you are going down a hill in a lower gear, the transmission is spinning the engine, keeping it going.
 
#13 ·
Re: ?Riddle me this? (BIGwayner)

If you guys dont believe that fuel is not being injected, log injector duty cycle and be surprised. I forget which block it is, but log it. http://****************.com/smile/emthup.gif
 
#14 ·
Re: ?Riddle me this? (new 337)

Quote, originally posted by new 337 »
If you guys dont believe that fuel is not being injected, log injector duty cycle and be surprised. I forget which block it is, but log it. http://****************.com/smile/emthup.gif

I totally believe you, just didn't know that, very cool tidbit of information.
 
#16 ·
Re: ?Riddle me this? (BoostedGolf02)

With gas prices reacing 2.50 a gallon in Cali i could care less about tranny wear from downshifting. My car will be long gone before the warranty is up or the tranny blows.
engine breaking and using breaks 50/50 is the most efficient i have found. anticipation stops is also good.
The Toyota hypbrid only uses gas when it is needed so slowing down stopped or cruising the gas is off.
 
#17 ·
Re: ?Riddle me this? (BoostedGolf02)

Quote, originally posted by BoostedGolf02 »
Wouldnt it be better for you to burn some fuel and SAVE your tranny. Aslo downshifting is bad for the motor mounts and bad for the tranny

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Maybe the clutch is worn a little more... but not the tranny.
How on earth does this hurt the mounts?
 
#18 ·
Re: ?Riddle me this? (BoostedGolf02)

Quote, originally posted by BoostedGolf02 »
Wouldnt it be better for you to burn some fuel and SAVE your tranny. Aslo downshifting is bad for the motor mounts and bad for the tranny
that's funny.... bad for motor mounts??????

you're probably one of those guys that sits at lights in 1st holding the clutch in....
 
#19 ·
Re: ?Riddle me this? (SnowGTI2003)

I'm a downshifter. If you do it right, it wont be harmful in any way. In georgia, it's the law, you can't coast in neutral. You also must leave the car in gear with the clutch depressed when stopped, this is for safety reasons. this doesn't really wear the clutch, slipping hurts clutches.
EDIT: most manual cars manuals state that when going down steep grades, put the car in a lower gear to reserve your brakes for when they are needed. Auto's suck in the mountains


Modified by TurboZen at 10:20 AM 4-21-2004
 
#20 ·
Re: ?Riddle me this? (TurboZen)

Quote, originally posted by TurboZen »
I'm a downshifter. If you do it right, it wont be harmful in any way. In georgia, it's the law, you can't coast in neutral. You also must leave the car in gear with the clutch depressed when stopped, this is for safety reasons. this doesn't really wear the clutch, slipping hurts clutches.

This guy is absolutely 100% correct. I don't know what idiot started spreading the rumor that sitting at a red-light in 1st with the clutch depressed wears something out. That is absolutely WRONG. It will not wear out the clutch and it WILL NOT wear out the throw-out bearing any faster than popping the car in neutral.
Sitting at a red-light with your car in neutral and your clutch out is both dangerous and wears on your synros more, how you ask?
1) Because when you let the clutch out you spool up your primary input shaft and when you go to put the car back in first to take off you have to stop that shaft again.
2) Its dangerous because you are left without one of your primary controls at the ready and that's the ability to get moving in a hurry if needed.
Before anyone jumps in there with their BS about how sitting with the clutch depressed wears a clutch out keep this in mind,
1) I am still running on the stock clutch on my 1.8t after 50,000 miles and its not slipping! Hell the last 10,000 miles has been with 300+ WHP and 280+ torque.
2) I have been driving for 26 years and have NEVER smoked a clutch or broken the internal parts of ANY transmission.



Modified by MRP2001GTi at 10:30 AM 4-21-2004
 
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