CK6Speed

iTrader: (1)

Fortunately we don't really have an altitude problem, but I agree. I like F/I cars myself. For me, I'm not too hung up on the number of cylinders as long as the power is there. Doesn't matter how you make it, just that you have it.

IS-SV

My preference is also normally aspirated F/I engines with D/I. I agree with you on above points, with one minor exception. My preference is for 6 cylinder and 8 cylinder engine configurations (even if they are small displacement with adequate power) for the superior smoothness, NVH, premium sound quality under load and at high rpm.

IS350jet

You are correct, the Merc feels substantially quicker than the LS430, even though it's not. The determining factor, I believe, is in the throttle control programming, with the Mercedes being much more responsive.

mmarshall

Yep, it's hard to beat D/I for power and smoothness in a normally-aspirated gasoline powerplant. And, all else equal, as you note, in general, the more cylinders, the smoother the operation. But, of course, other things also come into play. The bank-angle and firing-order of V6 powerplants can make a big difference in their smoothness. So can balance shafts. Some V6s can lack a little in refinement, and some can be super-smooth, like the BMW and Lexus in-line 6s and the Honda/Acura 3.5L V6. I tried out the latest Honda 3.5L V6 just a few days ago in the Honda Crosstour, and you couldn't tell the idle from a Lexus V8....turbine-smooth/silent. Honda 4-cylinders are also known for better-than-average 4-cylinder refinement, though they lack torque, especially at low RPMs. Unfortunately, Subaru 2.5L Boxer 4-cylinders, though compact, space-efficient, and with a low center of gravity, tend to lack some in refinement.....as a Subaru fan, I have to admit that.

bitkahuna

iTrader: (20)

not sure your point. you would LIKE the govt to slap tarrifs and taxes on larger displacement engines or more than 4 cylinders?

what's wrong with freedom of choice? why should everyone be punished for wanting to drive something other than a 4 cyl or even a turbo 3.0 'literish' engine?

LexFather

Well the thing is the LS makes 380hp with only 4.6 liters while the S550 makes 382hp with 5.5 liters, nearly a liter bigger! I believe acceleration times are close.

BMW now offers the 740 with the tt I-6 as a new base engine. Will a LS 350 or 450h come?

I don't believe in 4 cylinders just b/c and the assumption they are more efficient. The RX 450h gets 30 mpg, better than most I-4s.

Also the 6 cylinder IS 250 only gets 1 MPG less than the I-4 in the TSX and A4 (they all make around 200hp). I much prefer the extra cylinders.

IS-SV

Good points, because getting hung up on lower "cylinder counts" as the means to gain fuel efficiency isn't the magic configuration. Of course most 4 cylinders get better gas mileage mainly due to smaller displacement combined with advanced technologies. But smoother running V6's and straight sixes of the same displacement with same advanced technologies do just as well.

SLegacy99

But you are missing the point. The Sonata has a DI 2.4L. Its not about what kind of HP you can get out of it. Its about efficiency. Note that the Honda 2.4L is not efficient in comparison to other vehicles in its class.

So the Sonata has 198 HP and gets 35 MPG Hwy. My opinion is that is an uneccessary amount of HP for a base model transportation vehicle. Thus I think that Toyota, Honda, whomever would do well with a direct injected engine of smaller displacement. Presumably it would be more efficient.


Electric motors are nice.

I don't follow. Your preference is for normally aspirated, forced induction engines?

Anyway, yes this is what I am saying. People will always want 6 and 8 cylinder engines and that they don't need to be as large anymore to put down alot of power.


I never said that. I said that if the government did it wouldnt matter because many companies have been able to make alot of power with small engines. Looks at rallying. I have no problem if someone wants to upgrade from say a 4 cylinder Camry to a 6. But as engines continue to become more powerful I just think its kind of silly given said vehicle's drivetrain and purpose.


Two points.

1. I can't believe that you wrote this. Of course the RX450h gets better mileage, it's a hybrid. It has a huge advantage. Nevertheless, Camry, Fusion, Legacy all get better hwy mileage than the 450h. I think that a 2.5L I4 RX hybrid would do better than 3.5L hybrid.

2. The TSX has an ailing 4 cylinder engine in which Vtech craps it up. The A4 is rated for 22/30 (AWD) compared to the 20/26 of the IS (AWD) or 21/29 (RWD). The A4 also has a buttload more torque and is significantly quicker.

IS-SV

Sorry for my sloppy typing, I meant normally aspirated with fuel injection and direct injection (FI, DI).

SLegacy99

Ah. I understand now.

mmarshall

And, of course, some V6s and V8s, like the 3.5L Honda and non-SRT Chrysler Hemi, have the cylinder-deactivation feature that shuts off fuel to half of the cylinders under certain cruise conditions. Its total effect on fuel economy, however, is unclear, since, even without fuel and power-strokes in the cylinders, the other, working cylinders still have to overcome the friction/pumping losses, as the pistons continue to go up and down even without fuel.

mmarshall

Some of that 35 MPG on the highway has to go to the Sonata's new 6-speed automatic. Up to a point, at least (the point at where the engine starts to lug), lower RPMs usually mean more MPG.

mmarshall

Electric motors, though, are air-cooled. While the average air temperature drop (called the lapse rate) usually cools with altitude at 3-5 degrees per thousand feet, so does air density/pressure (usually around 3% for each thousand feet). Less-dense air at high altitudes, of course, provides less cooling for electric motors......just as, for an internal-combustion engine without a turbocharger/supercharger, it provides less oxygen for combustion inside the cylinders.

In the old days, gas-powered aircraft radial engines stayed cool at high altitudes, not only from the low air temps, but because of the propeller blast as well....and they also had cowl flaps which regulated air-flow over the engine. In a gas-powered car, of course, that function is done with the radiator, with some air-flow over the engine....but most pure-electric cars, (to my knowledge) don't have fans.

SLegacy99

Alright, but look at the #s.

2010 Camry
6MT: 22/33
6AT: 22/32

2011 Sonata
6MT: 24/35
6AT: 22/35

Sure, engine speed has to do with it. But so does engine size. And I am not talking about plopping a 1.5L into a midsize. That would more than likely be detrimental to fuel economy.


And this is a topic that hasn't been given as much attention as I had thought, given overheating issues have been a concern for the future of high powered electric vehicles. Do they have to be air cooled?

mmarshall

They actually do that with some mid-sized models in Europe, which are not available here in America. Due to a number of factors involving taxes and gas prices, smaller gas engines are much more popular in Europe than here....so are diesels.




I'm not enough of an engineer to be able to answer that question in detail, but I can see at least some drawbacks to trying to cool an electric motor with a radiator/fan/coolant system like with gas engines. The water pump would place an additional load on the engine, draining even more battery power when you want as much cruising range as possible. What's more, electric motors don't have a "block", with chambers in it for coolant flow/water jackets, like a typical gas-engine does.