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Old 06-06-2011, 12:08 AM   #1 (permalink)
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Some Hypermiling questions

I recently purchased a manual transmission car, and have a few questions on how to increase its fuel efficiency even greater. This is my first time driving stick shift (aside from a motorcycle), so I was wondering what would be the best time to shift gears (in rpm's) in order to keep efficiency up. Its a '93 Civic Dx if that helps. One more question. Lets say I'm coasting in neutral at 30 mph, and need to accelerate because the streetlight turned green. Would I shift to the appropriate gear for that speed? And would going from neutral to 3rd, for example, damage the transmission? Any answers would be greatly appreciated, since I'm only a beginner! I've been hypermiling in automatic cars though, and have seen some impressive gains, like 20% mpg, so I'm optimistic! Thanks again

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Old 06-06-2011, 12:23 AM   #2 (permalink)
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couldn't tell you the RPM's to shift at, the last time i owned a honda it was turbocharged and i made good use of it. as far as the shift from neutral to 3rd (or whatever gear you're going to) make sure you "blip" the throttle to raise engine RPM prior to engaging the clutch (a process called "rev matching") it could take some time to figure out exactly how high you want to rev your engine prior to engaging the clutch, it's all practice.
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Old 06-06-2011, 01:16 AM   #3 (permalink)
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I would start by reading the owners manuel, if you didn't get one with the car find one and read it.
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Old 06-06-2011, 05:11 AM   #4 (permalink)
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Quote:
Originally Posted by JohnnyRun View Post
I was wondering what would be the best time to shift gears (in rpm's) in order to keep efficiency up. Its a '93 Civic Dx if that helps.
Traditionally, Belgian beginners were told to shift up at 20, 40, 60 and 80-90 kph.
That's 12.5 , 25, 37.5 and 50-56 mph.
Because the gearing is normally adjusted to the engine's power, this works pretty well for just about every manual car regardless of displacement or fuel type.
That's the traditional way, but it'll get you started fine.

The more ecological way is to shift earlier and accelerate at lower rpm and higher engine loading (which gives better specific fuel consumption).
Beginners are now taught to short-shift up around 2500rpm in gasoline cars - and 2000rpm on diesels.

There's plenty of hypermilers with Civics of that generation.
They'll be short-shifting as well

You'll hear and feel it when you're lugging the engine, so do some experimenting on quiet roads to see at what speeds / rpm it happens in the different gears, then avoid going that low in the rpm range when the engine has to work.


1st gear is there to get you going and for very slow speed manoeuvring only.
1st is a wildly inefficient gear.
In slow moving traffic that's too slow for steadily using 2nd, don't change down into 1st, but briefly pulse in 2nd and then push in the clutch again to glide. Try to keep it rolling, and repeat when required.


Shift into 2nd right after getting going.
I shift into 2nd within about 2 car lengths from a stop.
Some people skip 1st altogether, and start going in 2nd.

Try to always be in the highest gear the engine will cope with, for the speed you're driving.

Coming down from higher speed to a lower constant speed, or on slight downhills, try to stay in a higher gear than you normally would. You can often get away with it without lugging the engine, when you're just rolling along and the engine is very lightly loaded.
It'll work well for FE - until you need to accelerate again or have to deal with a slight incline, and the higher gear can't pull off the low rpm anymore so you'll need to change down 1 or even 2 gears.


Quote:
Lets say I'm coasting in neutral at 30 mph, and need to accelerate because the streetlight turned green. Would I shift to the appropriate gear for that speed?
Shift into the appropriate gear for the speed you're doing.

If the speed is near the upper end of the speed range for a gear, switch to the higher gear right away - it'll be a lot smoother without feathering out the clutch for a long time.

Help the engine to get up to speed by rev-matching it with a bit of throttle while you're re-engaging the clutch.

Quote:
And would going from neutral to 3rd, for example, damage the transmission?
It won't if you disengage the clutch fully - so make sure to push it in all the way, then shift into gear and smoothly re-engage the clutch.

At 30mph, you're probably OK to shift into 4th already.


A note on using the clutch :

Beginning stick-shifters have a tendency to use the clutch to control speed.
This is only done when manoeuvring at very low speeds in 1st and reverse, when a fully engaged clutch would give excessive speeds.

Other than that, the clutch is only briefly and smoothly used to get rolling, and to shift gears.

However, some hypermilers will use the clutch to bump-start their engine after coasting with the engine shut off . That's pretty advanced hypermiling.

Other than these conditions, the clutch should be either fully engaged, or fully disengaged. Clutch slippage = wear, and should be reduced to a minimum.


On a manual tranny, there's no slush box to compensate anything, and no slippage unless you use the clutch, so you have to be smooth with the expensive foot.

Train yourself to use the accelerator smoothly, so you can smoothly accelerate away from idle to higher rpm, then slow down smoothly to rolling in idle again without any jerking or bucking - all while staying in the same gear and without using the clutch.
Only when you can do that in 1st, are you really controlling your right foot
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Old 06-06-2011, 07:51 AM   #5 (permalink)
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Wow, that is a lot of info to process! I'm gonna start learning to drive on Thursday so I'll post up how it goes, thanks for the tips
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Old 06-06-2011, 09:28 AM   #6 (permalink)
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Quote:
Originally Posted by Joenavy85 View Post
as far as the shift from neutral to 3rd (or whatever gear you're going to) make sure you "blip" the throttle to raise engine RPM prior to engaging the clutch (a process called "rev matching")...
I never rev matched on any car I drove, gasoline or diesel, and never heard about it before reading hypermiling forums.

Is it how old cars (older than late 70's) had to be driven or is it an hypermiling trick ?

May be when decelerating as the rev after the down shift is higher than before; noticeably when racing as the rev will be as high as possible to have more engine brake.

In fact the single time I hear about rev matching is when you want to drive a manual and the clutch doesn't work anymore...

TIA,

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Old 06-06-2011, 12:28 PM   #7 (permalink)
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Quote:
Originally Posted by JohnnyRun View Post
Wow, that is a lot of info to process! I'm gonna start learning to drive on Thursday so I'll post up how it goes, thanks for the tips
Just take it easy in the beginning.

Sit in the car, handbrake on, and do some dry shifts with the engine off.
That way, you'll get an idea of where the stick is relative to the gear you're in, without looking, just by feel.

When driving, if anything goes not as you'd want it to - lurching, bucking, slowing down too fast - push in the clutch, and check the gear you're in

Never push or pull hard on the stick.
If the gearbox and clutch are OK, it'll shift smoothly and won't require force.
If it won't go into gear, put it in neutral, release the clutch, push it back in, and try that gear again.

Shifting into reverse : only when fully stopped.
Downshifting into first : only at very low speeds , say < 6mph
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Old 06-06-2011, 12:35 PM   #8 (permalink)
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Quote:
Originally Posted by groar View Post
I never rev matched on any car I drove, gasoline or diesel, and never heard about it before reading hypermiling forums.
I've been doing that since I learned to drive in the late 1980s.

You're doing it when shifting up, but probably don't realize it

Quote:
Is it how old cars (older than late 70's) had to be driven or is it an hypermiling trick ?
It uses gas, so it's not really a hypermiling trick.
It keeps you from slowing down much though, if you just want to get into a lower gear.
It also reduces wear on the clutch plates, as you reduce their relative speeds when coupling them.
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Old 06-06-2011, 02:32 PM   #9 (permalink)
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It is not much different from riding you motorcycle you are just using your feet when letting out the clutch in first on a bike you get that sweet spot ... same thing on a car car is easier than a bike in my opinion. Don't stress it, drive proper before trying to hypermill, there is no one set rpm to shift at each engine has its own area of power I can short shift a chevy v8 at 2000 rpm and get to speed steady or bring it to 3,000 for a much faster run but it all depends if I am driving a 3spd 4spd 5spd or a 6spd transmission and what the gearing is.

A new clutch pressure plate and throw out bearing costs a whole heck more than a tank of gas.
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Old 06-07-2011, 10:43 AM   #10 (permalink)
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I'll weigh in this. My next-gen DX should be similar in gear ratios and engine power to yours.

Here's how I handle my shifts. You can shift even sooner but these are close enough and easy to remember.

1st: just enough to get rolling for a few seconds. This gear gobbles gas so get out of it.
2nd: up to 20 mph
3rd: up to 30 mph
4th: up to 40 mph
5th: anything above that

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