[Z06] Best cruising RPM?
11-30-2013, 04:30 AM
#1
Instructor
Thread Starter
Best cruising RPM?
So if I'm cruising at 70 or so, is it better to shift into 6th or is it ok to cruise in 5th for long distances at a higher RPM? The revs just seem so low in 6th at this speed, and it is not as responsive as in 5th. Any danger of under-revving? Is 6th there just to increase gas mileage?
11-30-2013, 05:35 AM
#3
Melting Slicks
Your fine to use 6th..... Of coarse the car is not as responsive as 5th/ and 5th is not as responsive as 4th. and so on.
hell cruse around in 3rd. it will do over a 100 so you should be fine......
But for real, its fine you can bog the motor and it will pull the car along and get some mileage too. even lower then where you are at. I never understood people hating on the 6th gears, its too low....WTH? that's the point of a double over drive, to lower the rpms...
NOW there is a difference in LUGGING a motor. The term "lugging a motor" came from the fact that if you LUG one all the time it i will slowly wear on the cylinder walls. because of the extra pressure the gasses are putting on the rings, with out the extra oil from a normal rev, and they scrape the walls. slowly making them bigger. its also harder on the bearings and can be easy for detination at this point.
BUT Lugging a motor is not what your talking about. an example would be 6th gear, 1200 rpms and you floor it, and just hold it. the motor with try its damdest to rev and it will slowly but thats a LUG. bogging one at 1200 rpms on a road at 55 in 6th gear just easing along at part throttle is fine
bogging the motor in a gear at part throttle is not a problem at all.
hell cruse around in 3rd. it will do over a 100 so you should be fine......
But for real, its fine you can bog the motor and it will pull the car along and get some mileage too. even lower then where you are at. I never understood people hating on the 6th gears, its too low....WTH? that's the point of a double over drive, to lower the rpms...
NOW there is a difference in LUGGING a motor. The term "lugging a motor" came from the fact that if you LUG one all the time it i will slowly wear on the cylinder walls. because of the extra pressure the gasses are putting on the rings, with out the extra oil from a normal rev, and they scrape the walls. slowly making them bigger. its also harder on the bearings and can be easy for detination at this point.
BUT Lugging a motor is not what your talking about. an example would be 6th gear, 1200 rpms and you floor it, and just hold it. the motor with try its damdest to rev and it will slowly but thats a LUG. bogging one at 1200 rpms on a road at 55 in 6th gear just easing along at part throttle is fine
bogging the motor in a gear at part throttle is not a problem at all.
Last edited by mittens; 11-30-2013 at 05:43 AM.
11-30-2013, 12:48 PM
#5
So if I'm cruising at 70 or so, is it better to shift into 6th or is it ok to cruise in 5th for long distances at a higher RPM? The revs just seem so low in 6th at this speed, and it is not as responsive as in 5th. Any danger of under-revving? Is 6th there just to increase gas mileage?
I would recommend against cruising under 2000 RPM. Has to do with valve rotation in the cylinder head, which is not a simple issue, and might even not apply to the LS engine.
Also, significant throttle opening at low RPM in high gears (say, passing or going up hill) loads the engine which can lead to an increase in cylinder pressures and temps, as well as the chance of detonation (knock). Unfortunately there is not much technical discussion on the issue and it is far from obvious to the driver when the engine has a boatload of reserve power/torque on tap (such as an LS7... try pulling out to pass in 6th gear at 1400 RPM in a 4 cylinder econobox and you probably won't be going anywhere anytime soon).
11-30-2013, 01:06 PM
#6
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Somewhere around 5,000 RPM in 5th is a nice cruising speed. 
11-30-2013, 01:20 PM
#8
Burning Brakes
11-30-2013, 01:36 PM
#9
70 MPH, typical speed limit in most states, in 6th would be 1508 RPM. I would recommend 5th instead (2232 RPM).
2800 RPM in 5th would not particularly concern me... after all, the engine is rather expensively designed for 7000 RPM.
Edit: the only real need I ever found for 6th gear was at a sustained 160 MPH in a C4 ZR-1 (Nevada Open Road stuff)... it would bring the engine and trans oil temps down a bit due to the reduced RPM, but it wouldn't accelerate very well (if at all; been a long time)... for that you had to drop it back down into 5th (~5100 RPM) where, other than temps creeping up, the engine seemed quite happy to run.
Last edited by Mark2009; 11-30-2013 at 01:47 PM.
11-30-2013, 01:45 PM
#10
Instructor
Thread Starter
Yes.
I would recommend against cruising under 2000 RPM. Has to do with valve rotation in the cylinder head, which is not a simple issue, and might even not apply to the LS engine.
Also, significant throttle opening at low RPM in high gears (say, passing or going up hill) loads the engine which can lead to an increase in cylinder pressures and temps, as well as the chance of detonation (knock). Unfortunately there is not much technical discussion on the issue and it is far from obvious to the driver when the engine has a boatload of reserve power/torque on tap (such as an LS7... try pulling out to pass in 6th gear at 1400 RPM in a 4 cylinder econobox and you probably won't be going anywhere anytime soon).
I would recommend against cruising under 2000 RPM. Has to do with valve rotation in the cylinder head, which is not a simple issue, and might even not apply to the LS engine.
Also, significant throttle opening at low RPM in high gears (say, passing or going up hill) loads the engine which can lead to an increase in cylinder pressures and temps, as well as the chance of detonation (knock). Unfortunately there is not much technical discussion on the issue and it is far from obvious to the driver when the engine has a boatload of reserve power/torque on tap (such as an LS7... try pulling out to pass in 6th gear at 1400 RPM in a 4 cylinder econobox and you probably won't be going anywhere anytime soon).
11-30-2013, 02:04 PM
#12
It's there to satisfy Corporate Average Fuel Economy (CAFE) requirements mandated by the gov't.
Car won't run 190 in 6th... you'll have to downshift to 5th. I doubt it would run over about 160 in 6th.
11-30-2013, 03:02 PM
#13
Wil Cooksey #256
On the highway I shift into 6th at anything over 57 MPH On a 55 MPH road I use 5th. I've driven cross country many times and this works for me...
11-30-2013, 03:39 PM
#14
Le Mans Master
11-30-2013, 03:53 PM
#15
Pro
Also worked for me on my '98 C5 (same gearing) with over 98,000 miles on it when I traded it in. Under 2,000 might be bad for a Honda Civic, but for our LSA's LS7's, and LS9's with great low rpm torque, we're just fine as long as the engine is not lugged.
11-30-2013, 10:08 PM
#17
Melting Slicks
Yes.
I would recommend against cruising under 2000 RPM. Has to do with valve rotation in the cylinder head, which is not a simple issue, and might even not apply to the LS engine.
Also, significant throttle opening at low RPM in high gears (say, passing or going up hill) loads the engine which can lead to an increase in cylinder pressures and temps, as well as the chance of detonation (knock). Unfortunately there is not much technical discussion on the issue and it is far from obvious to the driver when the engine has a boatload of reserve power/torque on tap (such as an LS7... try pulling out to pass in 6th gear at 1400 RPM in a 4 cylinder econobox and you probably won't be going anywhere anytime soon).
I would recommend against cruising under 2000 RPM. Has to do with valve rotation in the cylinder head, which is not a simple issue, and might even not apply to the LS engine.
Also, significant throttle opening at low RPM in high gears (say, passing or going up hill) loads the engine which can lead to an increase in cylinder pressures and temps, as well as the chance of detonation (knock). Unfortunately there is not much technical discussion on the issue and it is far from obvious to the driver when the engine has a boatload of reserve power/torque on tap (such as an LS7... try pulling out to pass in 6th gear at 1400 RPM in a 4 cylinder econobox and you probably won't be going anywhere anytime soon).
12-01-2013, 12:32 AM
#18
Instructor
Thread Starter
12-01-2013, 12:43 AM
#19
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I use 6th from at any speed from 45 or 46 on up. At 70 or 80 in 6th the car is more responsive than most other cars on the road. Finished a trip south about two months ago on I81. In West Virginia and particularly Virginia the road has a large share of left lane bandits riding along at about 65 mph in a 70 mph zone. In the summer my 4 cylinder Malibu didn't have the oomph to pull right as I passed a truck and squirt past a few cars on the left to get to the next hole in the line. When I made the trip in the Vette I could pull right see another spot in traffic 5 or 6 cars ahead and squirt into it well before getting to the next truck in the right lane. Never shifted out of 6th. Just pushed to the floor, the car launched and I swung into place, jabbed the brakes to match speed with the car ahead. Repeated that process for several hours while working my way down the highway. Even got great gas mileage while doing it.
By the way GM recommends not driving the car at less than 900 rpm. So if you are ticking along at 1000 in 6th that is fine. Using cruise is usually best as it will compensate for any slight hills you hit. Of course on steep hills the car will let you know you have to down shift, however, I went all the way through the mountains on I81 and never had to downshift except when making a pitstop.
Bill
By the way GM recommends not driving the car at less than 900 rpm. So if you are ticking along at 1000 in 6th that is fine. Using cruise is usually best as it will compensate for any slight hills you hit. Of course on steep hills the car will let you know you have to down shift, however, I went all the way through the mountains on I81 and never had to downshift except when making a pitstop.
Bill
12-01-2013, 01:57 AM
#20
Instructor
Thread Starter
I use 6th from at any speed from 45 or 46 on up. At 70 or 80 in 6th the car is more responsive than most other cars on the road. Finished a trip south about two months ago on I81. In West Virginia and particularly Virginia the road has a large share of left lane bandits riding along at about 65 mph in a 70 mph zone. In the summer my 4 cylinder Malibu didn't have the oomph to pull right as I passed a truck and squirt past a few cars on the left to get to the next hole in the line. When I made the trip in the Vette I could pull right see another spot in traffic 5 or 6 cars ahead and squirt into it well before getting to the next truck in the right lane. Never shifted out of 6th. Just pushed to the floor, the car launched and I swung into place, jabbed the brakes to match speed with the car ahead. Repeated that process for several hours while working my way down the highway. Even got great gas mileage while doing it.
By the way GM recommends not driving the car at less than 900 rpm. So if you are ticking along at 1000 in 6th that is fine. Using cruise is usually best as it will compensate for any slight hills you hit. Of course on steep hills the car will let you know you have to down shift, however, I went all the way through the mountains on I81 and never had to downshift except when making a pitstop.
Bill
By the way GM recommends not driving the car at less than 900 rpm. So if you are ticking along at 1000 in 6th that is fine. Using cruise is usually best as it will compensate for any slight hills you hit. Of course on steep hills the car will let you know you have to down shift, however, I went all the way through the mountains on I81 and never had to downshift except when making a pitstop.
Bill