Shifting Question

[actionstan]

Hello All,

I have a 99 saturn sl1, 5sp manual transmission.

I was just curious if when you fellas are cruising along on the interstate, or any road for that matter in a stick shift, When you come to a hill, Do you give it more gas? or downshift to maintain speed? I notice automatics I drive typically downshift.

What is more efficient? Seems like even if downshift is more efficient the cost could be offset by more wear from downshifting? Currently I just give it a little bit more throttle as long as I am in a good RPM range not lugging the engine.


Let me know your thoughts.

 

[GutsyGecko]

Stay in top gear and throttle away. Much more efficient.

 

[JHZR2]

Originally Posted By: GutsyGecko
Stay in top gear and throttle away. Much more efficient.


+1

I cant think of any interstate hills this side of the Mississippi, besides a couple in WV, where one would even need to think about downshifting with any normal modern car.

 

[dparm]

Keep doing what you're doing.

No need to put more wear and tear on the clutch and trans by downshifting unnecessarily.

 

[surfstar]

Downshift when necessary if you'll loose speed (and care), other wise top gear no problem.

 

[KenO]

Yes to all of above. The engine is an air pump. The pumping losses of higher rpm operation outweigh any losses of more throttle input.


Shifting doesn't have to wear the clutch, if you know what you're doing

 

[eljefino]

My SOHC saturns have occasionally had to drop a gear fully loaded on interstates.

"Lugging" is when you open the throttle more but get no more power because the car can't breathe. If this happens, downshift.

In normal driving I acellerate at 1/3 to 1/2 throttle. If I want to acellerate slowly I upshift early. If I need more pep I hold my gears longer but still keep the pedal in the same spot. It takes off when it gets up to 3000 RPMs.

 

[MolaKule]

Quote:
"Lugging" is when you open the throttle more but get no more power because the car can't breathe. If this happens, downshift.



Lugging can overheat the engine.

Clutches and MTL's are less expensive than engines.

 

[KenO]

They say it can also excessively wear bearings, in a similar fashion that detonation does. Although, I know somebody in particular who has a habit of lugging their engine, and at ~300k when it was torn down, the bearings still looked fine. It was torn down because of blowbye mostly, not a hard part failure.

 

[rationull]

Originally Posted By: JHZR2
Originally Posted By: GutsyGecko
Stay in top gear and throttle away. Much more efficient.


+1

I cant think of any interstate hills this side of the Mississippi, besides a couple in WV, where one would even need to think about downshifting with any normal modern car.


There are plenty of long, steep freeway grades around here that pretty much require a downshift in some cars (I have 3 miles or so of 7% grade on my commute). In my Civic I had to downshift to 4th. My wife's Mazda3 can do it in 5th (top gear) but you have to be floored or nearly so for part of it. Anything with more power is fine in top gear though, which to be fair is probably most new cars sold these days.

Still, +1 for me too. I always stay in top gear unless I specifically need/want to accelerate up at a good clip.

 

[nleksan]

Lugging an engine can very quickly press the ejector seat button for a piston or two courtesy of the immensely higher wear put on the journal rod bearings.

My rule is, if I'm not driving, err, enthusiastically (which isn't on highways anyway), and going up a hill my TPS is between 66-75pct or so with little to no actual acceleration, I immediately downshift. Of course, the roads are all imprinted on me anymore, so I just automatically blip the throttle and drop a gear at the same point every time.


It amazes me how many people, not necessarily here but in general, think that the lower the engine speed, the better, under any and all circumstances with absolutely no exceptions.... Ugh

 

[CBR.worm]

But what some people here are describing is not lugging, just not having enough power (possibly at 3,000rpm) to maintain speed.

If it is truly lugging, say less than 900 rpm (I use about 1,200 as a min) downshift. If you are approaching idle speed with your foot on the floor, downshift multiple gears. If it starts shaking due to low engine speed, push in the clutch and think about what you are doing.