z06scentair

Wow mine will not do this, the LS6 will but not the LT5.

dtana

I'm sorry but considering that 6th gear is a double overdrive (for lack of a better expression) , I'm not sure how what that example is supposed to suggest..............nor do I see when that particular action could ever be interpreted to be a "good" idea.

glass slipper

Your C5 Z06 doesn't have the same 6th gear as the C4 ZR-1...drop the speed down to get the LS6 down close to 500 RPM and it won't do it. If your LT5 won't do it, there is something wrong with it.

glass slipper

Gears are typically used to multiply engine torque but as you pointed out, 6th gear is a double overdrive which means it divides engine torque to the rear wheels, in half to be exact. That's a perfect example of how the LT5 makes very good torque at low RPM.

The speed limit in my old neighborhood was 25 MPH and strictly enforced. Since I had about 2 miles of that, I would put it in 6th and cruise. I don't understand why you can't see it as the "best" idea...why would you ever consider it to be a bad idea?

dtana

Because no high performance car is designed with even the remotest thought that someone is going to be "cruising" at 25mph in top overdrive gear. I'm guessing that 25mph is so much slower than the minimum recommended speed for your car in that gear, that it's not even funny. I understand that you're saying that the car can do this.............but I'm surprised that you actually & voluntarily subject your car to this sort of experience. You have now set a new standard for the commonly (& admittedly misunderstood) expression.........lugging the engine.............regardless of whether you're actually lugging it or not.

z06scentair

Negative. We will agree to disagree here!

USAZR1

I agree with Brad and dtana. I would never abuse my ZR-1 that way,either. Just because you can do something,doesn't mean you should.

Tom400CFI

That thinking is wrong.

The title, "high performance sports car" (A title that you created there) doesn't change what the car can and can not do. Most Corvettes have what is basically a truck engine, in them. That "title" doesn't change anything either. The engines (all engines) in C4's are perfectly happy/willing/able to loaf along at very low RPM in a high gear w/no ill effects. As long as the motor is running high enough to make enough oil pressure, where is the harm? There is none.



The term "Lugging" IS misunderstood, and like many "old skool" practices, it's been rendered obsolete. Lugging could be detrimental to a motor...30 years ago, in the absence of combustion control (advanced electronic controls w/ feedback). Engines are so highly controlled now, lugging will not result in pinging, A/F ratio issues, bucking, etc.

Second, GS didn't say he was at WOT @ 25mph in 6th. I run my C4 through my neighbor hood in 6th too....25 mph speed limit. I'm not touching the throttle. Engine is basically idling, only it's doing so, in gear. Wife's CTS-V (LS6) will do it too. Heck...even my factory carb'ed '83 Trans Am would go down to 28 mph/900 RPM, locked up in O/D -Even up hills! Sold that car w/245k on it, so...

As long as there is sufficient oil pressure, the engine won't "care" what RPM it's turning. the "problem" of "lugging" in this day and age, is not a mechanical problem....it's a psychological one.


.

z06scentair

If my LT5 is in 6th gear at 25 MPH, it would be bucking HARD. This type of bucking will result in pre-mature failure of driveline mechanical component's.

And I guarantee nothing is mechanically wrong with the car!

Tom400CFI

For the sake of accuracy, According to GM docs, the LT1 makes more TQ @1000 RPM (and anything below~2500) than the "Tork monster" L98....though the LT1 will NOT make 300 lbs @1k, like the LT5 will....At 1k, LT1 is "only" doing about 290 lbs.

Tom400CFI

I would agree w/ GS that something is not right w/you're car.

z06scentair

I would be willing to bet either one of you my car is perfecto!

The car will be at the 2015 Denver NCRS National Convention for either of you to observe and critique.

USAZR1

You can talk all you want,Tom,but we will just have to agree to disagree about this topic. I don't really give a damn what anyone else thinks because I'm not going to try to drive my car at 25mph,in 6th gear.

Also,the LT5 was never designed for a truck application.

Tom400CFI

Disagree all you want but my "talk all I want" isn't rhetoric. It's fact and experience in this field. I'm not trying to convince anyone that they should drive their car a certain way. Absolutely not. Like you, "I really don't give a damn"...drive your car around at 6k in 2nd gear for all I care. MY point, was to correct the "lore" that "lugging = motor destruction" -which is dead wrong.



Right. You'll note that what I said was;
"Most Corvettes have what is basically a truck engine"

See the "most" part? Doesn't really matter though b/c again, we're using "titles" which I attempted to dismiss. Fundamentally, the LT5 operates the same as the L98 or any any other GM V8 except that it's even more robust and better controlled than it's contemporary peers.

Enlighten yourself. There is good technically correct info being given here. Drive your car the way you want to, but you can learn something in the process.

Tom400CFI

So how does GS's car drive at low RPM then? How does my ratty, low-tech, pushrod LT1 manage to do it? Surely, the LT1 is not more refined than an LT5...

I'm sure your car is spectacular. But it should be able to run smooth down that low.

FASTAZU

Just got back from a long drive in the 93, 3.45 gears, I tried as slow as I could get comfortably in 6th was around 35mph. I would never do this on a regular bases as it felt like I was lugging it very hard, now 5th was fine at low speeds. I like to stay in 3rd for 30+mph, 4th 40+mph etc.

z06scentair

I'm not sure about GS's car...will not speak for him.

Just as Clint said I would not recommend doing this in an LT5. I have done this by accident only.

Steve just verified for you, and I promise that 93 car does not have any problem's.

Tom400CFI

What RPM do you consider to be "OK with the engine", to go to WOT?

Below which, there would be engine damage?

Tom400CFI

All Steve verified for me, was HIS "comfort level" for his operating RPM. I "verified" mine above too. Like I said; it's psychological, more than mechanical.

FASTAZU

I could have gone down to 25 just did not want to (this was on a flat road would not have wanted to start up a hill) also had very little acceleration or throttle response from that range. no ping or bucking. would the LT5 run at this low of an RPM and speed Yes that is all I proved!
I would go WOT from idle 775 in 1st of coarse but would just get a lot of wheel spin.

Next I will try it with the 91 500hp and 3.73 gears