Highway cruising gear

[Pegasus]

Hmmmm, okay lets just say 6th is overdrive. True I have no idea how the ratios work. But I'll take your word for it. But I previously have seen a thread on fuel economy. Some guy was saying he shifts at 2-2.3K rpm. So I suppose if he shifts that low he would be running it at low 1K's at the beginning of the next gear. He was getting something crazy like 36mpg. So I am kinda trying his method. I'm going to reset my average mpg gauge and see what I get. If I'm getting bad mpg I try your method ( which is shifting at 4Kish? ). If I get 36 or something around there I'm probably going to keep shifting wrong because I can't think of a reason not too. Maybe it's cause I'm at sea level but it still goes pretty decent at 6th & 35mph. Last I checked, with it floored in 6th its getting 11mpg. But that's only for 5sec, then im at 60.

[Darkrune]

I am going to say thos again. Never floor your car in final gear ever. Bad ending.

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[woode]

Originally Posted by Akari

Ah, I daily get stuck on 6-10 mile long roads going 45mph behind traffic that keeps at a constant speed. Must just be differences in traffic!

Same here. 90% of my morning commute is 45-50mph.

[SirBrass]

Originally Posted by Darkrune

I am going to say thos again. Never floor your car in final gear ever. Bad ending.

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Unless you can't downshift to another gear without braking.... granted, for that to happen, you've got to be going pretty fast (like, above 100), b/c that long 6th gives you a wide speed band over which 6th operates well.

Basically, don't floor the throttle in ANY gear below about 3-4krpms... more ideally, not below 5k.

[anthros]

Originally Posted by SirBrass

Basically, don't floor the throttle in ANY gear below about 3-4krpms... more ideally, not below 5k.

Why on earth not? What do you think might happen if you do?

[Jyn]

FRS is my first manual car, so pardon any "off" questions, but I often find myself entering on-ramps at about 60 mph in 6th with enough room to hit merge speeds (70 mph) by the time the ramp ends. I'm not really laying into the accelerator pad, but are y'all recommending to just use 5th (or even 4th from some peoples' ranges) to get up to 70, then shift into 6th?

[subiestyle]

coasting in 6th at 45mph with no throttle is fine, but if you are actually giving some throttle to keep speed constant, you are lugging the engine.

[SirBrass]

Originally Posted by anthros

Why on earth not? What do you think might happen if you do?

Lugging the engine, mainly. You won't severely lug it, if you go full pedal down above 2k, but doing so regularly isn't good for long term engine health. It puts a strain on engine parts that don't really need to be strained like that.... b/c flooring it at that low an RPM isn't going to do much for acceleration. Better to downshift and then roll onto the throttle all the way.

[Akari]

Originally Posted by subiestyle

coasting in 6th at 45mph with no throttle is fine, but if you are actually giving some throttle to keep speed constant, you are lugging the engine.

Not true at all. Coasting in 6th gear will shut off your injectors and cause your speed and RPMs to drop to the point where your IAC takes over(Which will cause a very, very inefficient AFR as your car struggles to keep itself running).

Staying on throttle, below about 10% throttle is quite efficient.

[anthros]

You say that flooring the gas at, say 3000 RPM "won't severely lug" the engine; I'd say it's not lugging the engine at all. And because these are gasoline engines, the throttle valve restricts flow and increases pumping losses unless it is fully open. These pumping losses increase with the square of engine speed.

So if it's acceleration you're after, downshift by all means. But you won't hurt your engine if you go WOT at 2500 RPM. In fact, you'll save a little gas (at the expense of acceleration) compared to downshifting.

Here's a helpful column on the subject...it may clear some things up for the newer drivers on the board:

http://www.caranddriver.com/columns/...-lug-and-coast

[Darkrune]

Originally Posted by anthros

You say that flooring the gas at, say 3000 RPM "won't severely lug" the engine; I'd say it's not lugging the engine at all. And because these are gasoline engines, the throttle valve restricts flow and increases pumping losses unless it is fully open. These pumping losses increase with the square of engine speed.

So if it's acceleration you're after, downshift by all means. But you won't hurt your engine if you go WOT at 2500 RPM. In fact, you'll save a little gas (at the expense of acceleration) compared to downshifting.

Here's a helpful column on the subject...it may clear some things up for the newer drivers on the board:

http://www.caranddriver.com/columns/...-lug-and-coast

A lot of people don't take into consideration engine load vs. gear ratio and engine tolerances. Going WOT in 6th gear makes your load tables very high, which put stress on connecting parts in the engine. Save your rods and don't go WOT in 6th gear unless you are at a rpm appropriate level. This is especially true for people who are boosted.

[ntron1]

6th gear is for 100 mph+.....

[DrDuquette]

What's your need to that rpm? 6th gear. Use it. Your just going down the highway not racing down it. Think of it like your heart rate. It's okay to be fast, but not when your relaxing and taking a stroll.


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[subiestyle]

Originally Posted by Akari

Not true at all. Coasting in 6th gear will shut off your injectors and cause your speed and RPMs to drop to the point where your IAC takes over(Which will cause a very, very inefficient AFR as your car struggles to keep itself running).

Staying on throttle, below about 10% throttle is quite efficient.

hmmm. can you explain this further? first time i've heard this.

I've always heard that when you coast to a stop in gear, the transmission is turning the engine, so the engine is not struggling to keep itself running until you get really slow and the rpms drop below 1500. but at that point, I just disengage the clutch and stop, which turns on the injectors to keep the engine idle.