Engine braking - not a good thing?
01-05-2001, 01:11 PM
#22
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You kidding. Of course if you press the gas pedal.( cont.)
We are talking about braking so you are NOT pressing the gas pedal. In this situation although you are downshifting no gas spends except idle run.Now, at 60 mph, downshift w/o pressing the gas pedal, please look through the ins.gasoline mpg. display.I am sure you will see 0.0 mpg. Please you let me know.
BesTT to you.
BesTT to you.
01-05-2001, 01:13 PM
#23
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Re: Engine braking never uses gas as far as I know.
If the engine is running faster (higher revs) then it must be using more gas, all else being equal.
Remember, the choice here is either (1) braking with the car in neutral (at idle, foot off gas) or (2) downshifting and lifting off the gas (which raises the revs) and possibly braking too. All else is equal...option (2) simply must use more gas.
Am i missing something here?
Remember, the choice here is either (1) braking with the car in neutral (at idle, foot off gas) or (2) downshifting and lifting off the gas (which raises the revs) and possibly braking too. All else is equal...option (2) simply must use more gas.
Am i missing something here?
01-05-2001, 01:16 PM
#25
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18 wheelers ok; passenger cars (even TTs) in normal road driving...unnecessary.
At the risk of irritating many...
As someone said, we have 180 or 225 hp engines and about 1000 hp brakes. (A TT can stop in 165 ft from 70 mph, but takes lots more distance to accelerate 0-70.)
An engine which has max full-throttle torque at 2000 rpm and revs to 6500, has a usable 5th gear (180) speed range from about 45-135+. If you need more acceleration than top gear gives right after hard braking to stay with traffic flow, you are in a somewhat competitive environment.
If you are not at full throttle, you are wasting your engine, gas, etc. cruising/accelerating at rpm much above 2000 (180) in any of the lower gears. (Open can of worms here.) Part throttle acceleration at 3000-6000 which gives same performance as full (or close to full) throttle in higher gear at 2000-4000 is also a waste.
If you are driving a Honda S2000, this doesn't apply, because it has virtually no low end torque. I'm talking about TT.
Anyone agree? I don't have to ask about those who disagree.
Just my $.02
As someone said, we have 180 or 225 hp engines and about 1000 hp brakes. (A TT can stop in 165 ft from 70 mph, but takes lots more distance to accelerate 0-70.)
An engine which has max full-throttle torque at 2000 rpm and revs to 6500, has a usable 5th gear (180) speed range from about 45-135+. If you need more acceleration than top gear gives right after hard braking to stay with traffic flow, you are in a somewhat competitive environment.
If you are not at full throttle, you are wasting your engine, gas, etc. cruising/accelerating at rpm much above 2000 (180) in any of the lower gears. (Open can of worms here.) Part throttle acceleration at 3000-6000 which gives same performance as full (or close to full) throttle in higher gear at 2000-4000 is also a waste.
If you are driving a Honda S2000, this doesn't apply, because it has virtually no low end torque. I'm talking about TT.
Anyone agree? I don't have to ask about those who disagree.
Just my $.02
01-05-2001, 01:25 PM
#27
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Not kidding at all. I've tried it in other vehicles too. I'll stay with my claim.
BTW: Idle fuel flow assumes idle rpm. If you used idle fuel flow at high rpm engine would run very lean, or not at all.
