peteharvey

I'm not an engineer, so very hard to tell.
However, I have test driven 528i 2.0T and 535i 3.0TT numerous times, and I know that the torque curves are not very flat.
We would have to ask BMW to supply us with multiple torque curve graphs at different throttle openings.
Meanwhile, torque curves in gears look something like this below.
The gearbox actually multiplies the torque.





The flattest torque curve I've ever driven is a Tesla Model S recently, accelerating from 0-60 mph in some 3.0 seconds.
The second flattest torque curve I have sampled is possibly a GS450h, both the first, and second generation models.
I must say that even a Camry 3.5L V6 at half the price of a GS350, the Camry V6 actually has more bottom end torque and a flatter torque curve than the GS350!
In other words, the GS350 has more peak power than a Camry V6, at the expense to the GS350's bottom end torque!
Our cars are not always as great as we'd like them to be unfortunately.

If the BM 4 cylinder and 6 cylinder turbos had perfect torque curves, there would be no need for engineers to waste their time and money developing electric motor powered, or electric motor assisted turbos.
If the hot exhaust gases is that good at accelerating the turbine, there'd be no need to waste time developing electric motor powered turbines which Audi & Subaru are about to debut this year below.



Here is BMW's patents on their "Electric Turbo":
http://www.motor1.com/news/28531/bmw...c-turbocharger
http://jalopnik.com/5855317/will-bmw...-end-turbo-lag
http://f80.bimmerpost.com/forums/sho...d.php?t=597327
http://www.greencarreports.com/news/...ost-efficiency
http://www.motorauthority.com/news/1...-design-report
http://www.topspeed.com/cars/car-new...-ar119350.html

http://www.autonews.com/article/2014...lag-valeo-says

If BMW's torque curve was so flat to the point of boredom, then they wouldn't be spending millions of dollars investing in Electric Turbochargers...
.

metrathon

That's very true and very unfortunate for daily driving. No one likes to drive their GS constantly at 4.5k rpms just because that's where it starts pulling. For God sake, my wife's 2015 RX350 feels more lively at low rpms That's *by far* my biggest gripe with the GS.

I never said they are perfect, just that from all the turbos I've sampled these are the best.

It's not boring for me, I love BMW engines. But if you're used to anything peaky (read NA engines) you might find the flat(er) torque curve boring. There's no dramatic build up of torque, no "wait for it" moment, or anything like that. It just pulls like a train till it runs out of breath.

4sallypat

Having had 2 diesel BMWs, there is no need to rev the engine up to get the turbo to kick in.
Diesels work better at the low RPM end just like a supercharger.

Diesels have the raw power delivery at low to mid RPM plus better economy.
Turbos I am finding work well when engine RPM is revving up.
Superchargers work well from idle to mid RPM.

If I had a choice, my ideal engine would be:
diesel + supercharger + turbo

Here in Southern California, diesel is 25% less money per gallon than gas.!

metrathon

Yeah, but the diesel cars are more expensive and it takes 3 to 5 years to make back the price difference. Plus all the diesel engines in US are tuned for efficiency and not performance. What I wouldn't give for the real 535d with 313hp and 464 lb-ft.

JDR76

I had no idea. Here in Washington state, diesel runs $.10 to $.20 more per gallon than unleaded, so about the price of mid grade or premium unleaded.

Im2bz2p345

+1

Price of diesel is closer to the price of premium gas from what I have seen in many parts of the country.

EDIT: Here is a good comparison chart: http://fuelgaugereport.aaa.com/todays-gas-prices/

~ Im2bz2p345

peteharvey

Yes, turbodiesels have a very flat torque curve, unlike the turbo-gasoline, hence BMW's patents for the electric turbo etc.
Diesel fuel yields more megajoules of energy per unit volume than gasoline, hence diesels have superior economy, and superior torque.

The only problem is that diesels have very low octane rating of only 15-25, such that they have spontaneous combustion, without the need for spark plugs.
Diesels use a "cetane" rating, for how readily it will spontaneously combust.
The problem with diesels is that at high engine speeds, it becomes very difficult to control the spontaneous combustion of diesels such that diesels have a rather low red line ceiling, limiting their maximum power output, before the transmission must change up to the next gear, losing the torque delivered at the wheel early on at low car speeds.

Due to these efficiency, high torque, yet low red line and low power characteristics, diesels are bread and butter for commercial and industrial use like buses, trucks, off road vehicles, and earth moving equipment etc.

wfibear

I've seen this stated in multiple places on CL recently. Is this really the case? Or is what is perceived as more torque in the Camry the fact that a) it weighs 300+lbs less than an RWD GS350 (this is very significant) and b) is front wheel drive, therefore has less drivetrain loss than the GS350, therefore puts more torque to the ground? I mean, I find this hard to believe without seeing some engine dynos of both motors. Technology like VVT-i generally negates the need to tune for only low RPM torque or high RPM power, whereas in older motors without it, you would be restricted to that kind of tuning since the cam angles or valve lift wouldn't change over the rev range (unlike with VVT-i or VANOS or i-VTEC or any of similar technologies).

It's been a while since I saw some information on it, but a long time ago I did see some PDFs on the benefits of D4-S (wish I could find those now), and the 2GR-FSE had a very similar torque curve down low to the 2GR-FE in the Camry, but had a very peaky curve up high, for that max horsepower figure. I surmise that the weight and drivetrain difference along with the top end peakiness gives one the impression that the GS is tuned to the detriment of low end torque vs the Camry, but I honestly can't see why it would actually be so. I really do think what you're seeing is the result of weight and drivetrain loss.

rijc99

Or could it be the Camry is a softly sprung front driver and the torque steer plus squat makes it feel livelier than it really is?

peteharvey

Very clever Wfibear.
I think you are right.
The extra weight of GS kills its bottom end torque.
Pity the direct injection 3.5 doesn't have enough bottom end to compensate for its own extra weight.

Had the 3.5L V6 in the GS had a narrow bore with long stroke, or only two valves per cylinder, then it would have more bottom end torque to compensate for its own extra weight & out accelerate the Camry at low speeds.
An electric turbo in the GS could easily compensate for the GS's extra weight too.

More liberal use of aluminium would ensure that the rear drive multilink suspended GS didn't weigh more than the Camry in the first place.

wfibear

Could also be so. In the case of the GS F-Sport you'd notice even less squat, especially in sport s+.

wfibear

Yeah, those are all areas that could have helped here. Of course though even a premium brand like Lexus is still somewhat controlled by bean counters.

Lexus would probably tell us to get the 450h to make up for the less usable low end torque in the 350.

ItzFilyO

I wonder if u can add a blow off valve sound to the 200t. That sound alone might be enough to get me to jump ship unless they're turboing the 350.

ItzFilyO

I've had both the Camry SE V6 with 2GR engine and the GS350. The Camry seems to be running out of power after 80 MPH while the GS just keeps pushing until I let go at 100+ MPH. The scary part is the Camry felt like it's about to lift off once u go past 80 while the GS just feels more planted at 100 and just cruise with ease. I lowered my Camry and had wider tires too but it still doesn't hold a candle against a stock GS350, let alone an FSport in S+ mode. The GS is just one fine piece of machine!

rijc99

Making the car lighter may be fine for a car you intend to take to the drag strip but I have no desire to make our cars feel less vault like when I close the doors or go over anything but a glass smooth surface. Nor do I want to hear more of the outside environment.