V8's "D" vs "S" mode

[manoftaste]

In S mode the V8 feels different and I wonder if in the S mode we are getting more horsepower and/or torque out of the engine. Is it just the matter of transmission shift mapping or there is more to it that involves engine management?

Is there such a possibility that in S mode engineers put a few more ponies back in the engine from the bunch they took out for the fuel economy' sake? And is it even technically possible to be able to do so on the same engine? Perhaps with varying settings in the engine management controls?

Is getting more horsepower/torque from an engine solely a function of electronic engine management or there are some physical aspects to it?

 

[mbw]

I just use S for hills and keeping it a gear lower for engine braking, in auto. But, I think its just the shift points and gear preference. I dont think it really changes the throttle sensitivity like grass/gravel/snow mode does.

I love that I almost never need more than 2k rpm driving this thing. The low end torque is about all I care about because I never really drive it aggressively. As slow as possible, as fast as necessary applies to my on-road driving also. I am pretty content with people passing me now.

 

[magnumforc]

The S or Sport and Manual shift simply changes the gear aspects of shifting and allows the gears to either remain engaged longer and shift more crisply at different RPM ranges, or to allow you to manually shift at the range you choose within certain parameters allowable by the engine management system, such as a rev limiter. (Which usually only works in the acceleration mode, thus shifting down while at a high RPM can sometimes lead to disaster!)

The net output of the engine is the result of the gross horsepower at the crankshaft or flywheel, reduced by the loss through the drivetrain to the rear wheels. The only really good test of actual horsepower and performance I have found is by a chassis dynamometer that measures the output of the engine and driveline to the wheels. This is rather difficult with a 4WD system as most dynos are designed for 2WD systems only. The 375 SAE Certified HP in the 2013 LR4 is at the crankshaft or output shaft, and not rear wheel horsepower.

So, after that lengthy statement, your vehicle probably does feel and may be a bit quicker with it in Sport mode simply due to the faster shifts available under full acceleration mode. The actual diffference on, say a dragstrip, might be measured in hundredths of a second. But the real feeling that matters to most enthusiasts is measured on the seat of the pants. That extra kick when the gears change.

The final answer is that there is no extra horsepower available no matter which gearing set you choose. The engine wil output the same power; however torque peaks will change depending on the gear selected and when the shift occurs. That accounts for the kick in the pants you feel.

Cheers.

 

[..mg..]

The S or Sport and Manual shift simply changes the gear aspects of shifting and allows the gears to either remain engaged longer and shift more crisply at different RPM ranges, or to allow you to manually shift at the range you choose within certain parameters allowable by the engine management system, such as a rev limiter. (Which usually only works in the acceleration mode, thus shifting down while at a high RPM can sometimes lead to disaster!)

The net output of the engine is the result of the gross horsepower at the crankshaft or flywheel, reduced by the loss through the drivetrain to the rear wheels. The only really good test of actual horsepower and performance I have found is by a chassis dynamometer that measures the output of the engine and driveline to the wheels. This is rather difficult with a 4WD system as most dynos are designed for 2WD systems only. The 375 SAE Certified HP in the 2013 LR4 is at the crankshaft or output shaft, and not rear wheel horsepower.

So, after that lengthy statement, your vehicle probably does feel and may be a bit quicker with it in Sport mode simply due to the faster shifts available under full acceleration mode. The actual diffference on, say a dragstrip, might be measured in hundredths of a second. But the real feeling that matters to most enthusiasts is measured on the seat of the pants. That extra kick when the gears change.

The final answer is that there is no extra horsepower available no matter which gearing set you choose. The engine wil output the same power; however torque peaks will change depending on the gear selected and when the shift occurs. That accounts for the kick in the pants you feel.

Cheers.

Pretty much spot on. However, the part I bolded may have been true 10+ years ago, but there are a plethora of AWD dyno's on the market today. Dynojet, Dyno Dynamics, Dynapack, Mustang, Maha... there are many and widely accessible. Engine tuning is non-existent in this particular market, but think of all the performance cars that are AWD - 911 Turbo, GTR, Subaru STI, Evo's, Lambo's, Audi's, BMW's, soon to be MB's AMG models etc.

Anyway, the shift from D to S just modifies throttle top-in, throttle mapping, and shift points. As magnum stated, what you have in terms of HP and Tq does not change in these beasts... it is what it is. If it was an older M model, then pushing a little button would have opened up a bit more power. Sadly, no little button for us.

 

[mbw]

I don't know of any 4wd dynos near me (But I live in the middle of nowhere compared to most of you). Would anyone with a 5L V8 be willing to go get a couple runs with a dyno? S mode auto (non manual shift) and D?

How about someone with a 2014 V6? We could get some insight into the curves for both engines and transmissions.

 

[manoftaste]

The S or Sport and Manual shift simply changes the gear aspects of shifting and allows the gears to either remain engaged longer and shift more crisply at different RPM ranges, or to allow you to manually shift at the range you choose within certain parameters allowable by the engine management system, such as a rev limiter. (Which usually only works in the acceleration mode, thus shifting down while at a high RPM can sometimes lead to disaster!)

The net output of the engine is the result of the gross horsepower at the crankshaft or flywheel, reduced by the loss through the drivetrain to the rear wheels. The only really good test of actual horsepower and performance I have found is by a chassis dynamometer that measures the output of the engine and driveline to the wheels. This is rather difficult with a 4WD system as most dynos are designed for 2WD systems only. The 375 SAE Certified HP in the 2013 LR4 is at the crankshaft or output shaft, and not rear wheel horsepower.

So, after that lengthy statement, your vehicle probably does feel and may be a bit quicker with it in Sport mode simply due to the faster shifts available under full acceleration mode. The actual diffference on, say a dragstrip, might be measured in hundredths of a second. But the real feeling that matters to most enthusiasts is measured on the seat of the pants. That extra kick when the gears change.

The final answer is that there is no extra horsepower available no matter which gearing set you choose. The engine wil output the same power; however torque peaks will change depending on the gear selected and when the shift occurs. That accounts for the kick in the pants you feel.

Cheers.

Very interesting, thanks.

Since torque seems to vary across the rpm band, S mode engaging the right gear at the right time would mean picking up the torque left off by the last gear just about the right time for that continuing feeling of ******. And this coupled with an appropriate and complimenting throttle mapping definitely would make the most out the the engine power/torque.

I have started to use the S mode a bit more here and there and really am enjoying that continuous ******/momentum it provides.