htownboy

One word "DUH"
I must apologize in advance nut you put yourself out there for that.
Of course you need to downshift before accelerating!

MSCA

iTrader: (3)

Negative. First of all, the ECU has no say in the matter. We're not talking about an AT car here, we are talking about MT cars. The driver has the ability lug the engine. The driver also has the ability to overrev the engine. If you disagree, I can tell you how to do it. But think about it and you'll figure it out for yourself.

And as far as only lugging under idle RPM....have you ever wondered why you can be in 1st gear at idle RPM and accelerate quickly from the moment your foot presses down on the accelerator, but the same thing isn't true in higher gears? Try that in 6th gear and let me know what happens...

Mike

iTrader: (1)

Uh, you accelerate faster in 1st gear because you have mechanical torque multiplication.

Do you understand the concept of load? Load at 600 RPM in 1st gear is not the same a load at 600 RPM in 6th gear. Here's an example. Bike up a hill in a low gear. Now bike up in a high gear. Feel that extra pressure on your shins and knees? That's load. The ECU will prevent a higher load by reducing engine output. Take a look at the stock fuel and timing maps. Nuff said. I challenge you to make me a video when you get your car of the engine lugging without undue load. No stupid crap like going uphill at 20 mph in 6th.

AT/MT makes no difference in engine lugging. If you lug an engine, you lug an engine.


Your observations are based on the perceived lack of acceleration at low speeds in high gear. My observations are based on hard evidence and physics.

MSCA

iTrader: (3)

Hmmm...you and I have remarkably similar backgrounds. I was also an ASE Master Tech (and worked for Toyota) before I got into engineering. I usually don't like to tell people that on a message forum for fear of being labeled as a "know-it-all", but I guess that doesn't really matter. Even though I'm out of the business now, I still keep current and I wrench on cars as a hobby & for fun because I still love doing it....

There absolutely is a "booooooooog like you're driving a tractor trailer" if you try to accelerate from such a low speed in 6th gear. I experienced it myself. It probably has more to do with the unique exhaust system/mufflers on these cars because it's more of a resonance sound than an engine sound, but still the car doesn't sound like it's too happy trying to accelerate from 33 MPH in 6th gear.


I don't think anyone here is saying (or has said) that a consistent 33 MPH on a flat road is a bad thing....we're talking about accelerating from that speed and lugging the engine. As a former ASE Master Tech, I can only assume that you understand how the stresses associated with lugging an engine will affect not only piston & cylinder walls, but also promote rod bearing & crankshaft wear. The fact of the matter is that gasoline internal combustion engines were not designed to operate under that kind of unneccesary loads.

At the end of the day, we can all drive our cars however we want...and being MT drivers gives us even more freedom to control our cars. But I still think it is especially important for MT drivers to understand that they do have the ability to cause damage to their engines much more so than AT drivers. That said, it is important to understand what's going on inside your engine & transmission and the effects your driving style may or may not have on them.

Mike

iTrader: (1)

That "booooooog like youre driving a tractor trailer" is exhaust drone. It's very evident around 900-1100 RPM. You don't hear it in typical daily driving because you're not typically at that RPM for any extended period of time or not flooring it at that RPM.

MSCA

iTrader: (3)

Hmmm.. don't know where to start on this one. Okay, first of all, I don't appreciate your attitude. You really shouldn't tell me to educate myself when you have no idea who I am or what I know. You actually made my point for me and regurgitated the example I gave earlier about riding a bike. Can you not understand that? Do you not understand how torque multiplication (or lack thereof) is related to having the ability to lug an engine? Do you understand that the load on an engine is greater at low rpm and wide throttle openings compared to higher rpm and narrower throttle openings?

Here's a newsbreak for you....you can't lug an engine in an AT G37. Can't be done....and of course you can lug an engine in an MT car. Another newsflash.....you can't overrev the engine in the AT either, but you can in the MT.

If you think the ECU on a MT G37 will do anything to prevent high loads by reducing power output, then it is you who needs to educate yourself. Just how do you think this is possible? Does the engine cut fuel? Perhaps shorten the fuel pulse? And what mechanism do you think it uses to measure load? I look forward to your response....maybe you know something about the G37 engine that I do not. The funny thing here is that I've actually lugged the engine of a G37, so none of this ECU magic you speak of seems to exist. If it did, then I wouldn't have been able to lug the engine in the first place.

MSCA

iTrader: (3)

Didn't I just say that? Scroll up and read ^^^^^^

BTW, "drone" and "resonance" are interchangeable terms with the same meaning. It's funny how the AT guys don't get the same sounds. Ever wonder why? Yes...because the AT will downshift when the RPMs drop too low.

Mike

iTrader: (1)

It uses a preset table.

At a low RPM, engine output is restricted via less air and fuel. I suggest you do some research on VVEL, and take a look at the low rpm fuel maps.

Torque multiplication itself has no bearing on lugging an engine. Lugging is a function of load, which torque multiplication can affect.

News break. You CAN lug an AT, just how you can perform a mechanical overrev with a MT. Is it typical? no. Can it be done? yes. Lock the torque converter, force the trans into a higher gear. It's about as desired as a mechanical overrev, but it can be done.

SpartanG37S

iTrader: (1)

I never said driving 33 MPH on flat roads is bad. I said accelerating in 6th gear (lugging the engine) at 33 MPH is bad.

SpartanG37S

iTrader: (1)

Thanks, I'm quite aware of that. However, that's not what we're discussing. We're discussing the effects of accelerating in 6th gear from 33 MPH. Again, it's not good for the engine over time and can cause engine damage over time.

Mike

iTrader: (1)

Why is this discussion even happening? The manual specifically says easy driving and fuel economy when it recommends 33mph for 6th gear.

Is it possible? yes. Can you? yes. Should you? That's completely up to you. That's why you bought a MT.

Mike

iTrader: (1)

I just thought of a (totally retarded) way to make a AT perform a mechanical overrev. Accelerate the car with an outside force in manual mode. Have another G push you to 45 mph in 1st gear. The ECU will cut fuel when you redline, but the G pushing you will make the RPM keep going up....

SpartanG37S

iTrader: (1)

Put the car in 6th at 30 MPH and floor it. It will boooooooog just like a tractor trailer. That's not exhaust drone. That's lugging. And it's VERY bad for the engine, specifically the bearings.

Not sure why this is even up for discussion. So here are the facts:

1. Lugging the engine is bad for cars with aggressive cams such as ours.
2. Lugging the engine is bad for the engine, specifically the bearings and will reduce engine life.
3. Attempting to accelerate in 6th gear at 33 MPH will cause lugging. Again, this is bad for the engine over time.

If anyone disagrees with any of these, I'd like to know why. Just curious how someone can argue something that has been proven by engineers. Why do you think AT vehicles stay in a lower gear at lower speeds? Cars, especially modern cars with modern engines, aren't designed to handle high load at low speeds.

SpartanG37S

iTrader: (1)

You should take what you read in a car manual, or any book, with a grain of salt, grasshopper. If you take everything as gospel, you're bound to end up in the upper room sooner than you'd like.

MSCA

iTrader: (3)

LOL, of course torque multiplication has bearing on lugging an engine. That's why we have transmissions with gears. You have got to be kidding me, right? Is today April 1st?

You really need to understand the relationship between throttle angles, RPM, and torque multiplication. In a nutshell, that's really what we're talking about here. When you have a combination of low torque multiplication (high gear), low RPM, and large throttle openings, this can easily result in lugging the engine.

Now lets remove one of those variables....say we now have high torque multiplication (low gear), but still have low RPM and a large throttle opening. Hmmm....no problem. The engine will not lug. This isn't magic, it's pretty basic stuff.

Of if you want, we can change the variables again. Lets say we have low torque multiplication (high gear), high RPM, and a large throttle opening angle. Again, no problem....the engine is happy.

The point that you seem to be missing over and over again is that the AT will not allow the first scenario. It sill simply shift to avoid lugging the engine. This is the basic premise of an AT. Now the MT on the other hand is 100% controlled by the driver, so there's no ECU involvement whatsoever.

BTW, I know a few things about VVEL. It's great technology and much more advanced than BMW's VANOS. In fact, I fully expect to see 100% variable valvetrains that are electrically actuated and will completely replace the throttle plates (there wouldn't be a need for them at all) while allowing for more power and fuel economy than we experience today. It's all awesome technology, but the only thing holding it back now is the limitations of our 12-volt electrical systems. And that's also why I think we'll see 18-volt systems on cars in the near future.