At what speed is it ok to drop into 6th gear without lugging or doing harm to the components? I so want to drive efficiently, but it is always so tempting to put my foot into it. So I want to do the best when I am able to behave. Is the OBC instant MPG the best gauge of this? I will admit I haven't tackled the Manual yet, and figure you folks have more real-world info anyway. Thanks

Chris Kueny
05 MCS
02 Outback (hers)
95 Silverado
85 Mercedes 300TD-T

 

More applicable than a speed reference is RPM as this applies to all gears. I try to keep the revs above 2,000 and I don't hit the throttle heavy until it's >2,500.

 

That's not what I have been doing. Glad I asked.

 

Speed is irrelevant to a manual tranny. RPM's are everything.

I usually shift up at 5k, and shift down at 2k.

 

I use 6th gear travelling at 45 mph w/ revs just under 2K. Helps mpgs. If I want to get up and go, I simply downshift.

 

That's about what I have been doing. Thanks.

 

I try really hard not to shift into first over 2 mph regardless of rpms

 

I do about the same. I find myself using 1 - 2 - 4 - 6 around town. Unless you're accelerating to highway speed, 3 and 5 don't seem necessary...

Anybody else?

 

I like to keep the engine above 3,000 rpm, the highest gear I use in town is 4th, I don't even use 6th on the highway.

 

Lugging the engine can actually lower your gas milage (And damage the engine). Under 2k RPM's in 6th gear is DEFINITELY going to lug the engine.

Load has a lot more to do with fuel consumption than RPM's. You will use less fuel in a lower gear, say, at 6k RPM's (cruising under light throttle) than you will in 6th gear. At 2k RPM's, you will have to load the engine up to 85-90% to maintain speed. The engine has to work against its gearing to hold your speed, rather than having the ability to freely rev.

Another example, at redline coasting in vacuum (No throttle) you're actually using NO fuel, the injectors are completely shut off. In this case, even though you're at 6500+ RPM's you're not burning any fuel. Compare this to 2k RPM's, trying to hold 40 MPH in 6th gear.

IMO you shouldn't be in 6th gear unless you're on the freeway (60+ mph). I alternate between 4th and 5th on city streets, depending on traffic flow.

 

Rusty makes a good point. There really isnt a reason to use 6th under speeds of sixty miles an hour. Even if you run it up to 4500 RPM, if you arent going crazy on the throttle you MPG wont suffer that much. That said I still find myself shift at around 3500 around town and using 2000 as the low limit.

You also have to consider how you car will react when you get on the throttle, if your in sixth at say 1800-2200 RPM when you hit the gas not much will happen (tall gear, low on the torque curve). Naturally in a lower gear higher rev situation you will get moving faster. To some extent you can look at this as a safety thing almost.

 

Exactly! Best way to get good mpg's. Those that wait to 5K rpm before upshifting explains the bag mpg posts.

 

1100 in first is like 10mph !

 

Lol i did that once when i was running out of gas! the OBC showed 49mpg!

 

For stoplight to stoplight driving I usually manage to stay between 2k-3k rpms. For regular around the town "some stops" driving I maybe go up 3.5k, for when I want to accelerate hard around town I usually give full throttle up to about 5k. (Obviously for really getting on it I'll go to redline).

I've hit 6th gear at 40mph before, usually not that low, though. Rustyboy's post gave me some insight into shifting. I'll try to run the engine out a little more for city driving see how things turn out on the MPG report.

 

i shift 1st to 3rd at 2k then 3rd to 5th at 2k then to 6th whenever i feel like it after that. i try to save as much gas as possible. unless im on an onramp. then i go 1st to 2nd to 3rd to 6th haha ; )

 

I don't know if it's the best for gas, but I usually shift at ~3k during city driving, and keep the revs above 2k. Sometimes I'll push it to 3.5k. But like others said, don't lug the engine, and if you feel/hear it, downshift! It will kill your mileage. If you have a boost gauge, you can tell when your in vacuum or boost.

-Cody

 

1st - 10mph, 2nd - 20mph, 3rd - 30mph, 4th - 40mph, 5th - 50mph, 6th - 60mph. I typically try and keep a minumum of 2250 to 2500 rpms. I don't like the way it feels at or under 2000 rpms.

I have tried the 3000+ rpms at steady state and you still get pretty good mpg but not as good as 2250 - 2500. If driving in hilly areas the 3000 rpms does work well because lugging up a hill at 2000 - 2250 definitely uses more fuel.

I drive by rpms mostly - Obeying the speed limits at all times of course!

 

Can I have dibs on your 2nd gear/synchros and 4th gear/synchros; perhaps your 1-2 shift fork plus 1-2 hub and 3-4 shift fork plus hub Dustinhxc.

Way to maintain part of your gearbox for a rainy day!

For all the luggers out there: Don't overdo detonation please.

Jeremy

 

Shifting at 2K is way to low.

"Lugging an engine means putting the engine under an extremely stressful load. A common way to lug an engine is to operate it at an extremely low rpm while the transmission is in a higher gear (for instance, leaving the transmission in fourth gear when it should be in second or third where engine speed is better matched to transmission speed). Lugging causes extreme stress between the rear thrust faces of each piston and the cylinder walls. Small bits of piston skirt can break away causing the rear surface to scuff. The best prevention for lugging an engine (either old or new) is to downshift to a lower gear where the engine runs more freely, and the transmission assists the engine in delivering peak power to the rear wheel."

 

whaaat!?!?! i thought i was saving gas not hurting my car wtf..
so your saying i should wait till 2200? or 2500?

 

When to shift is about the RPMs you are dropping to and the load you are putting on the engine. If you are lightly feathering the gas, maybe you can drop to 1750 rpms when you start the next gear (and I mean lightly feathering, almost no load), if you're into the throttle I would advise not dropping below 2K when you hit the next gear (which I believe means to shift at 3K+).

 

I wait until at least 4k to shift. Gas milage is a function of injector cycle, not RPM's. You could be at 7k RPM's and be getting better gas milage than at 2k RPM's. RPM's has NOTHING to do with gas milage. As I stated before, take your car and stick it in 6th at 25 MPH, then push the pedal to the floor. Watch your gas milage plunge down into the single digits.

But but but, the rpm's are low! Doesn't matter! Engine load determines how much fuel your injectors squirt. If your engine is loaded to 95% at 1800 RPM's in 6th cause you're not in the right gear, you're using MORE fuel than you would be at 3400 RPM's in 4th or 5th.

As others have said, you're hurting the engine by lugging it. Even if you were getting better gas milage, .97 cents a tank in gas is cheaper over the long run than rebuilding your engine because you lugged the it so much it damaged it...

Just drive the car normally, shift where you need power, keep the RPM's at a point where you can accelerate in the gear you're in. There's no reason to drive at 2k rpm's in any gear unless it's 1st.

 

how about 2nd gear?
downshifting to 1 is hella lame

 

2k is probably boarderline in 2nd. Uphill I'd shift to 1st on a stock MCS if it was much lower than that. If you make enough torque to get going in 2nd then it's not going to hurt anything.