esses

Clearly it's not gentle on it... but do you honestly think that it'll cause serious problems in the 5-7 year timespan?

I do it fairly regularly... I'm just curious. I used to do it all the time with my 85 jetta... but then again, that car wasn't nearly powerful enough to rip itself apart....

Mike S

but nothing to worry about. It is far more harmful to the clutch and drivetrain. than the motor.

The worst things you can do to your S4 are the following, all of which are worse than frequently running it through the gears hard.

1) Lugging the motor. Example; Flooring the car in fourth, fifth or sixt, with anything less than 2000 rpm on the tach. This causes undue stress on many motor internals, plus is hard on the turbos.

2) Not letting the motor cool down for a few minutes before shutting it off, especially after hard driving. You can never hurt your motor by letting it idle for 1-4 minutes, but you can certainly hurt it by shutting it off after running hard.

3) Running heavy weight oil in your car, including anything in the 10W- to 20W- range. Thi soil is far to thick to immediately lubricate your turbos at start up.

4) Down shifting without matching speeds and/or causing any condition that overrevs the motor past red line (missing a shift heavily). This can easily bend valves and do other internal damage.

5) Getting into the throttle/boost before the oil temp is over 150-175 F on the temp gauge. This can cause premature wear on all motor internals and especially damage an under lubricated turbo.


These are opinions, but are all facutally based. Take it or leave it, but all of the above is hard on your car.

Mike S.

Tostao

The tranny : It whines about it.

esses

Is that considered "lugging" the car?

Mike S

No good for your legs, not goot for your motor.

Mike S.

Augie

I say it won't hurt anything unless you're well under 1000 rpm.

Mike S

Lugging is very hard on the combustion and drive parts, due to the added stress on the car, while you are producing a lot of power that doesn't have a clear path of little resistance. You are also making less oil pressure while at the same time stressing the motor more. Watch your MPG gauge (trip computer) real time output on the S4 when you run 1800 rpm in 6th, than 2500rpm, than 3300 rpm. You will get better MPG out of your car at a sweet spot somewhere in the middle, while most people believe you are saving fuel by having the lowest amount of revs. Instead, the ECM is sending greater amounts of fuel through the injetors, trying to make more HP, and therefore using more fuel, let alone not being at the oppitome of propper gearing, and therfore you are creating a greater resitance.

Connecting rods and rings are put under far more stress this way. Essentially, you are treating the engine and gearbox/drivetrain like you are towing a trailer, and I don't think anyone would disagree that towing trailers cause more wear and tear on tranny's and motors.

As for a turbo, you have a state of more physical resistance in the motor, therefore creating a mass of air that is harder to move through the engine, which is essentially an air pump.

Does this help? It's hard to explain, but I think I was clear.

Mike S.

Augie

...it's not a biggie unless you're well below 1000 rpm.

""Lugging is very hard on the combustion and drive parts, due to the added stress on the car, while you are producing a lot of power that doesn't have a clear path of little resistance.""

What added stress? You are *not* producing a lot of power, because you're very low in the rev range. Are you saying that at say, full throttle, 1800 rpm is harder on your engine than 6500 rpm? Nonsense. That "...clear path of little resistance" thing is silly. If you're in fourth at 1800 or 6500 rpm, where's the change in resistance?

""You are also making less oil pressure while at the same time stressing the
motor more.""

You may have a point - but only below 1000 rpm. Otherwise, forget it.

""Watch your MPG gauge (trip computer) real time output on the S4 when you run 1800 rpm in 6th, than 2500rpm, than 3300 rpm. You will get better MPG out of your car at a sweet spot somewhere in the middle, while most people believe you are saving fuel by having the lowest amount of revs. Instead, the ECM is sending greater amounts of fuel through the injetors, trying to make more HP, and therefore using more fuel, let alone not being at the oppitome of propper gearing, and therfore you are creating a greater resitance.""

My son's 2.7T six-speed gets better mpg at 1800 rpm in sixth than it does at 2500, and *much* better than it gets at 3300. Is there something special about the S4?

I don't know what you're getting at regarding "resistance", but there will most certainly be more at 3300 than at 1800, beccause you have much more wind and rolling resistance at 3300 than you do at 1800.

""Connecting rods and rings are put under far more stress this way. Essentially, you are treating the engine and gearbox/drivetrain like you are towing a trailer, and I don't think anyone would disagree that towing trailers cause more wear and tear on tranny's and motors.""

If you are using heavy throttle at either 1800 or 6500 rpm, you will, in fact, put more stress than if you are using light throttle. Arguably, there will *much* more stress at full throttle at 6500 rpm than at 1800 rpm. The reason is that you don't have to worry about G loads on the rods, etc., incurred through rapid rotation, rapid reversals of movement, etc. when you're at 1800 rpm.

If you have specifics about stress at low engine speeds, please tell me, because I don't see how. Don't tell me it's more stress, tell me *how* it's more stress.

""As for a turbo, you have a state of more physical resistance in the motor, therefore creating a mass of air that is harder to move through the engine, which is essentially an air pump.""

Huh? First of all, there is no more "physical resistance in the motor" at 1800 rpm than at any higher rpm. If the turbos are capable of excess boost, that's what the wastegates are for - at any rpm. I will guarantee you that the turbos are spinning more slowly at 1800 rpm than they are at 6500 rpm.

The *single* area that lugging may affect is increased cylinder and ring wear, and even then, it's only well below 1000 rpm, because the hydrodynamic "ride the wave" effect is reduced at very low rpm.

Nope. Operating the engine at below 2000 rpm is no more detrimental than operating it at above 4000 rpm - it's just that wear patterns change. If you spend a lot of time at 2000 rpm or lower, then at 150,000 miles you'll have more cylinder and ring wear than if you spend a lot of time at significantly higher rpm. However, spending a lot of time at higher rpm means you'll have more cam and valve wear at 150,000 miles than if you spent a lot of time at significantly lower rpm.

Pick your poison. It really doesn't matter.

Mike S

This isn't my view alone, but what has been common knowledge in the engine building world for a long time. I work with Walker Racing (CART and IRL teams- Sarah Fisher and Tora Takagi respectively) as a subconractor at almost all of their events, and I have posed this to some pretty highly qualified engineers and race mechanics, all of whom are FAA certified.

I agree that running a car at 6500 rpm CAN harm an engine, and can casue more wear, should lubrication fail, but you have to take into consideration the amount of time spent at 6500rpm in a one, two, three blast, or with 99.999% of the S4's out there. Most S4's, even hard driven cars, will spend less than one second per gear above 4500rpm, and multipy this by even the 20-60 hgih rev shifts a driver might make per drive, maybe 2-4 times per week. Your talking one to two minutes per week, which is unbelievably minimal.

Comapre this to a race boats motor, where it runs at 90-100% of full throttle, for hours on end. My best friend Brian Seiller of Race Rigged, Inc, in Lake Blff, IL, is one of the leading and best marine race engine builders in this country (builds CHock Norris's and many other race motors). His opinion was exactly that, reving the motor up and down is so minimal, it's not even worth considering.

You can beleive what you want based on your own logic, or you can talk to mechanical race engineers or FAA certified mechanica and believe what they say. I'll take the latter, and so will my 300,000 mile 87 5000S wagon.

On the other hand, the milage example is provable, and has been the case on my S4, and any other I've tested. it was also the case with my past cars. Try running your sons 2.7T at 50mph in sixth (roughly 1800 rpm), compared to 50mph in fifth (roughly 2500 rpm). You will get better MPG at 2500 in fifth, than at 1800 in 6th. At least I and a few friends in our S4's due.

It's akin to bike racers. they try to keep a cadance of around 80rpm, and select their gears to meet that cadance. Any faster, and their buring more energy to speed. Any slower and they are not attaining the highest speed per energy expended. Under you logic, they should pedal in as high a gear as possible, to save as much energy as possible, but this does not account for the extreme pedal pressure (energy) needed to move the bike at the same speed.

I thought the "towing a trailer" example was clear, but somehow you don't get it.

Let me put it this way. If it didn't take more energy to accelerate a car in sixth gear, vs in fourth gear, the car would accelerate just as fast in sixth. Also, why wouldn't the engineers just gear sixth gears twice as tall as it is, so cars could turn 1000 rpm at 60mph? Because the efficiency curve doesn't work that way.


Mike S.

S4PK

Lugging a motor... I.E. low rpm with low gearing, puts stress on the crank and connecting rod bearings. If you ask any engine builder they will tell you the most important part of the crank/connecting rod bearings is to never lose the film of oil that they depend on. By lugging a motor -1000-1400 rpm, full load, 6th gear, you are creating a situation of a slow moving crank, and high stress that can push that film of oil out of the way. This causes pre-mature bearing failure over time.

Also, if you look at how the engine's powerband is developed, max hp is at 5800 rpm, redline at 6800 rpm. This is where the engine designer does his duty to make sure there is generous oiling of all bearings, under maximum hp. He will have a hard time making an engine "Bulletproof" from 800rpm to 6800 rpm. The manual warns against running the motor at less than 1400 rpm in any gear but 1st. Why do they allow 6800 rpm?

Just what I have been told by all of my dads drag racer buddies...