08msmZ06

When I'm just cruising around I always seem to find myself running in second gear at 40 mph or fourth gear at 70 mph, which is 3000 rpms. Is it hard on the LS7 to run a lot at 3000? I like how the car feels at 3000 and the sound. I'm not concerned about fuel economy, but I am concerned about maybe working the motor a little harder than I should be. I know we put these motors through a lot with quick, high-revving launches, etc., but I also know these motors are built to handle higher stress loads. I'm just not sure how much stress, if any, the motor has to endure with a lot of DD duty in the 3000 RPM range. Thanks for the help.

BSSN

Sustained "high" rpm for "load" (i.e. driving at 3K rpm and 40mph with no acceleration) can lead to ring-flutter in some engines and excessive oil consumption. I do not know if the LS7 has ring-flutter or not to any degree. The LS1 and LS6 did.

An engine turning at 3,000rpm is experiencing exponentially more internal force than one at 1500. Inertia is not linear but exponential.

All this being said, yes, you are wearing it out faster, but it's your money, drive it how you want. I don't think it will blow up tomorrow, or the next day, but you may get 175K miles instead of 225K miles out of it, or whatever.

overst33r

You're probably putting LESS load on the engine at 4th at 3000rpm than in 6th at 1500rpm, due to the tall gear ratio.

These engines are stress tested for 24+ hrs at WOT in top gear. You will be fine.

Two of my other cars turn nearly 5000RPM at 80mph. They are known to go 200k+ Neither of them are world class sports cars like the Z06 is.

bigterpsfan

[QUOTE=overst33r;1575330840]You're probably putting LESS load on the engine at 4th at 3000rpm than in 6th at 1500rpm, due to the tall gear ratio.

These engines are stress tested for 24+ hrs at WOT in top gear. You will be fine.

Is this true??

JoesC5

It won't hurt it. My Mercedes turns 3,000 RPM at 80 MPH in fifth gear OD, cruising all day long on a trip on I-35/I-44.

Landru

Don't think running at 3K will hurt an LS-7, obviously gas consumption bill will be significantly higher than going to 4th at the same speed, also.

I choose 3rd gear for normal city driving, around 2.5K.
OTOH if/when I want to be noticed, it's usually a matter of shifting down one gear.

The sound of a LS-7 at 3.5K+ RPM gets attention, real fast; but, also begins the process of emptying my gas tank, too.

RFZ

my normal cruise rpm is 800 to 1200.....it puts way less wear than running 2500 to 3500....short of the normal wear that takes place from the simple fact of way more total engine revolutions, you can pretty much drive these at what ever rpm you desire without doing harm....on the street i am all about mpg....on track its a whole different story...

loflite

I don't use 6th gear unless I'm 70+MPH. That means in 5th at normal highway speed I am turning between 2-2.5kRPM. Driving in 6th gear at 60 MPH concerns me because going up the slightest incline could mean you engine is "lugging".

Hatdude

3k RPM is nothing. You'll be FINE.

Think of it this way.. cars in the 70's and older didn't even have an overdrive and would turn over 3K on the highway *all the time*. Many of those engines weren't even good for over 5k redline. Again, 3,000 RPM is nothing. If you can live with the decreased mileage enjoy it.

Bill Dearborn

The LS1 and early LS6 suffered oil consumption from owners who buzzed their engines above 3500 rpm at low or no load. Running in second at 40 mph in traffic is basically a low load situation. I would avoid it. Why beat up on the engine when you don't have to. At 40 mph I am on the verge of shifting into 6th gear when driving around town. Most of our in town speed limits are 30 and I use 5th for most of that. I shift into 6th once I can do so without rpms falling below 900. 70 mph at 3K rpm isn't that bad as the load increases as speed increases.

Bill

160KTS

The LS2 was the worst of the bunch for coil consumption. My GTO didn't eat oil, but my buddies would be putting in a quart or more between oil changes!

FrankTank

Man, I don't mean to sound like a jerk, but I just don't understand this. I guess to each his own...you are going to be sucking some serious fuel sustaining that RPM all the time.. you really like it at 3k all the time? I've just never heard of this before so I am scratching my head trying to figure out why you like it (other than sound). Do you have headers or something, or just stock manifolds and exauhst?

Landru

While I recall the issue of ring flutter resulting in abnormal oil etc?
My '06 C6 never drank a drop. Lucky, I guess.

Bill Dearborn

As with the previous engines the difference could be buzzing the engine and not buzzing it. The 01 C5s had a issue with one of the rings on the pistons and the fix was to replace just that one ring. Even then people who didn't buzz their engine didn't seem to have the oil consumption problem as often as people who did.

Bill

DaOtherOne

What does "buzzing the engine" mean?

RFZ

you have to be kidding... i use 6th at 35.....800 rpm...thats one of the reasons i haven't put a cam in.....the ls7 stock runs from about 700 rpm to 7000 with no issues what so ever

Landru

Bet you're correct, Bill.
My driving style doesn't favor running at prolonged high RPMs.

As I'd stated I clearly recall the issue, manifested with oily rear ends.
Still I've owned LT-1s, LS-1 & 2 and now a LS-7 -- never experienced anything of the sort with any of 'em. Which is why I tend to conclude the issue's very likely related to how an engine's driven.

C5 Frank

The way I look at it is this.... the engine will only rev so many times before it expires. Why not save the high revs for the times you need them.... ie at the track or when you are getting on it.
I usually cruise under 2k once my desired speed is reached.

goatts

Same here. I'm in 5th gear at 40 and 6th at 60. These engines have huge torque. 3000 rpm cruising is nuts.

To the OP, is this your first manual tranny car?

JGarland

I routinely cruise in the 2.5-3k range. Have done so for 25 years. It just my driving style. Sometimes I will back it down to 2k but rarely.

I don't think I have ever put my it in 5th or 6th before. I suppose I would if I was on a road trip or something.

Yeah, I am burning more gas but I am not trying to save the planet.