03 CL 6-speeds ( and 6spd TLs )
10-30-2005, 01:17 AM
#41
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Originally Posted by goredcar
To be be fair, I notice that when coasting in neutral, it takes a hell of a lot longer to slow down than coasting in neutral... of course requiring more brake pedal.
10-31-2005, 02:52 PM
#42
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Okay allow me to put this issue to bed.
Coasting downhill in neutral DOES use more fuel than coasting in gear at 0 throttle input. I swear I've settled this debate before but here goes... Obviously fuel has to be injected to keep the engine idling (neutral) to overcome the negative pumping loop which is a characteristic of a throttled gasoline engine. However when going downhill (or coasting to a stop on a flat for that matter) NO FUEL needs to be injected to keep the engine running because it is being propelled by its mechanical linkage to the drivetrain and the momentum of the vehicle. There is a transition point at which the engine decides it needs to start injecting fuel again to keep the engine running which, for Honda engines, is ~1200rpm. It will then start to inject fuel again which is why you can 'drive' around in gear without pressing the throttle. You can test this (most easily with a manual transmission) by leaving the car in gear (try 2nd/3rd/4th) and letting off the gas... the car will decelerate evenly but at the 1200rpm point you will feel it lunge a little... that is fuel being injected again. If you have a loud fuel pump like I do, you can also hear this transition. Is everybody happy with this explanation? I don't know if all cars do this, but my two Hondas definitely do.
On a side note, diesel engines (since they don't have a throttle) have hardly any negative pump loop to overcome thus use almost no fuel at idle. This is why you see them idling a lot. It costs them little fuel but they can have all their accesories running. However the downside is there is no 'compression' (negative pumping) to overcome when coasting downhill so they have to rely almost 100% on their brakes... that's why you see them overheating a lot (besides the fact that they weigh so much). Anyways I personally never coast in neutral because cars get out of control really fast and brakes heat up quickly. Yes and it saves fuel.
Coasting downhill in neutral DOES use more fuel than coasting in gear at 0 throttle input. I swear I've settled this debate before but here goes... Obviously fuel has to be injected to keep the engine idling (neutral) to overcome the negative pumping loop which is a characteristic of a throttled gasoline engine. However when going downhill (or coasting to a stop on a flat for that matter) NO FUEL needs to be injected to keep the engine running because it is being propelled by its mechanical linkage to the drivetrain and the momentum of the vehicle. There is a transition point at which the engine decides it needs to start injecting fuel again to keep the engine running which, for Honda engines, is ~1200rpm. It will then start to inject fuel again which is why you can 'drive' around in gear without pressing the throttle. You can test this (most easily with a manual transmission) by leaving the car in gear (try 2nd/3rd/4th) and letting off the gas... the car will decelerate evenly but at the 1200rpm point you will feel it lunge a little... that is fuel being injected again. If you have a loud fuel pump like I do, you can also hear this transition. Is everybody happy with this explanation? I don't know if all cars do this, but my two Hondas definitely do.
On a side note, diesel engines (since they don't have a throttle) have hardly any negative pump loop to overcome thus use almost no fuel at idle. This is why you see them idling a lot. It costs them little fuel but they can have all their accesories running. However the downside is there is no 'compression' (negative pumping) to overcome when coasting downhill so they have to rely almost 100% on their brakes... that's why you see them overheating a lot (besides the fact that they weigh so much). Anyways I personally never coast in neutral because cars get out of control really fast and brakes heat up quickly. Yes and it saves fuel.
10-31-2005, 03:42 PM
#43
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54,000 on the clutch and no problems. I changed brakes to power slot rotorswpro ceramic pads. much improved stopping. No mechanical issues. I have comptech h/e/sways/springs:AEM
CAI/pulleys:UR Crank pully NOoo problems. I am however going to revert back to the stock pully w its harmonic balancer to prevent Crank Bearing issues in th future.
This car runs great. Anthracite grey w/Motegi Litesand goodrich KDWs.
CAI/pulleys:UR Crank pully NOoo problems. I am however going to revert back to the stock pully w its harmonic balancer to prevent Crank Bearing issues in th future.
This car runs great. Anthracite grey w/Motegi Litesand goodrich KDWs.
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