SCV6 responsiveness off idle

[greiswig]

I'm wondering what is normal for these engines. I know it takes a little time to get pressure from the supercharger, but I've never driven a SC'd vehicle before. I have driven turbo diesels before, though, with variable vane turbochargers. The LR4 seems to take a loooong time to decide to downshift, rev up, and start moving. Is that a normal behavior for these guys?

 

[ftillier]

Superchargers have no boost lag, they are instant response, however boost is proportional to engine rpm, so at low revs you don't get much. Sounds like the issue you have is that the transmission isn't downshifting. Does it do the same in sport mode?

 

[greiswig]

Superchargers have no boost lag, they are instant response, however boost is proportional to engine rpm, so at low revs you don't get much. Sounds like the issue you have is that the transmission isn't downshifting. Does it do the same in sport mode?

Great question, and I don't have an answer. I haven't really tried sport mode except when I wanted to manually shift gears, especially on steep downhills like coming down from Mt. Hood. On mine, the paddles don't work unless you are in sport mode.

But I haven't tried sport mode in any situation other than that, really.

I knew that about the charger boost, but I guess that's what I'm calling "lag": how long between when you put your foot in it and when the engine is revving enough to get up in its power band.

 

[Nechaken]

The SCV6 is pretty reluctant to downshift, even in sport mode. On the V8 model, at least in sport mode, the car was pretty good about downshifting under braking, which would leave you set up to accelerate, say when slowing to make a sharp right-hand turn. This behavior just doesn't seem to occur in the V6. The V6 also feels soft when accelerating from a stop, which is probably a mix of legitimately less torque from the smaller engine, and throttle mapping.

 

[16FujiDisco]

I’ve found that it took some getting used to for me on a drive-by-wire throttle body vs cable linked peddle. Sport mode around town is definitely peppier and if you use paddles in town, you can see that at a dead stop the transmission only goes down to 2nd gear. Not sure why or if that’s the case in regular D mode, but that may also explain the delay. I did notice that it got better after the pulley/tune

 

[greiswig]

I haven't been able to find much about Sport versus Drive mode, really, other than the paddle shifters being enabled in Sport mode. Are there other differences more in line with what you'd expect, such as allowing higher revs, firmer shifts, and so forth?

I've also read that the transmission is adaptive, learning from driving style. Most of the time, I drive like my dead grandmother to save fuel, brakes, and add safety. But there are times when safety means GO. I know I'm spoiled by a Model 3 Tesla now, but...man this is a slug.

And yes, I've already gotten the VAP tune and crank pulley.

 

[16FujiDisco]

From what I can tell, yes, the sport mode has higher revs between shifts and what feels like faster/firmer shifts. I use sport mode every now and then just to exercise those higher revs.

The transmission is adaptive and that will play a role; if I’m at an intersection and know I’m going to have a quick acceleration or on a highway merge, I’ll use sport then change back to regular.

 

[Nechaken]

Sport mode will make the transmission downshift a little earlier, do a little downshifting under braking, and hold gears a while longer.

You can try this while putting around town at 1500 rpm -- shift from D to S, and you'll likely see the transmission downshift one gear.

 

[greiswig]

Drove a bit this evening in Sport mode, and it definitely acts better. Maybe the throttle mapping in Drive mode is just making it feel anemic to me.

 

[ftillier]

Also if you leave the terrain control in snow mode it will start in 2nd and reduces the throttle sensitivity.