natnut

The issue between normal aspirated and turbo-charged is that up till now, at the current level of technology, the best turbo-charged engines still have some lag. Those who say that they don't haven't driven a a NA inline 6 back to back with the TC engine : it is VERY obvious.

I test drove the new F30 335i-Sport (TC inline 6) and the lag was clearly obvious against the new 4th Gen GS350 F-Sport I test drove with its NA 2GR-FSE V6 and my own car (the 2nd Gen Gs300 with the NA inline 6 engine, the 2JZ-GE ).

Perhaps the in between solution for more power and torque without the lag would be supercharged engines. The A6 3.0T I test drove was lag-free (it has the supercharged V6).

bitkahuna

iTrader: (20)

the bmw inline 6 is one of the best sounding/feeling engines i've ever experienced. sure a porsche someone mentioned might have more power, but the sound of porsche flat 6 engines is kinda weird really.

peteharvey

In-line Six
The last time I drove a 1997-05 2GS was back in 1998.
I remember the 3.0 in-line six had bags of bottom end torque.
Natnut, how does the bottom end torque of your 2GS compare with the bottom end torque of today's V6's?
Similarly, the 1st gen 1990-06 1IS 2.0 and 3.0 in-line sixes had bags of bottom end torque.
Remember the old 3.0 in-line six from the Nissan Skyline? It had bags of bottom end torque.
My favorite is the old discontinued 2003-2010 530i 3.0 Magnesium alloy in-line six; this engine is much newer, and therefore smoother than the early Lexus and other in-line sixes.
The in-line sixes have great bottom end torque, and a very linear torque curve, due to the straight inlet tracks and the ability to breath easier.

Camry 60 Degree V6
The Camry 3.0 and 3.5 has good bottom end torque, but no match for the in-line sixes.

Lexus 60 Degree V6
The Lexus V6's use the same block as the Camry, but with direct fuel injection added.
However, the Lexus V6's are designed for top end torque [great for the race track], so they lack the practical bottom end punch of the Camries.
Engineering is often a compromise.

90 Degree V6
Benz 90 degree V6's are built from 90 degree V8 dies for cost cutting.
Due to the bank angles, the 90 degree V6 can't breath as well, therefore the bottom end torque is poor.
This is also true of the 90 degree French built Douvrin V6 shared by Renault, Peugeot and Citreon.
It's been 10 years or more since I have driven a Passat 2.8 liter 90 degree V6, so I don't remember well.
However, this 90 degree V6 may have been a little peaky too.
In general, the 90 degree V6's lack bottom end torque, but deliver top end torque with a vengeance!
The 90 degree V6 torque curve is non-linear, turbo-like, and very peaky.

Flat Six
I have never driven a flat six from Porsche or Subaru before.
However others say it is very peaky, non-linear, and turbo-like, and rough.

Supercharged
The supercharged six has no lag.
However, the supercharged engine still has a very non-linear, peaky, turbo-like torque curve.
Its peak boost, hence maximum power and torque, is not as high as a turbo.

Turbocharged
The turbocharged six has a touch of lag, reduced by using two smaller lightweight turbines [twin turbo], but it still has tremendous turbo characteristics, including a flat spot down the bottom with a peaky torque curve, and is obviously very non-linear power delivery.
However, it can deliver the greatest atmospheric compression to produce the most power and torque.


The Future?
The M3 is going back to the in-line six config.
Mercedes is dumping their range of cost cutting 90 degree V6's, cast from 90 degree V8 dies, in preference for an all new range of in-line sixes to be released in a few years time.

Maybe Lexus should also move back to in-line sixes too???
Straighter inlet tracts, better breathing, more bottom end torque, more linear power delivery, and the ability to distinguish the Lexus range of sixes from the Camry V6 which has already been tuned for greater bottom end torque, embarrassing the Lexus engines at the bottom end.
It is very difficult to fit the in-line sixes transversely, but Toyota already has the V6 for that.

Lexus would also best build the in-line sixes from Mg magnesium alloy, which is less dense and even lighter than Al aluminium alloy.
Lexus would merely have to use slightly longer wheelbases to get the full length and weight of the in-line sixes behind the front axle for near 50:50 weight distribution.

Lexus could then distance itself from Toyota by being: Mg alloy in-line sixes, RWD, Al alloy multi-link suspension, and Al bonnet, Al boot lid and Al doors.
While Toyota could have: Al alloy V6's, front drive, simple single lower link steel MacPherson strut suspension, and all hi tensile steel body construction.

There should always be a supercharged and turbocharged option for power lovers.
Lexus should make a move back into superchargers and turbochargers too.
The Germans are really catching up, and Lexus may be left behind if they don't smarten up...

SteVTEC

uhhh... I don't even know where to begin here.

60* Nissan VQ30DE V6 190hp/205tq Maxima (95-99), very nice bottom end torque but fell off badly at the top-end. This was due to intake manifold design and camming and had little to nothing to do with the bank angle.

60* Nissan VQ30DE-K V6 222hp/220tq Maxima (01-02), same V angle, same block, revised cams and new variable intake manifold with totally different power delivery characteristics. Still maintained most if not all of the low-end torque but was now a top-end screamer too. Pulled and pulled and pulled. Too bad that car gained 200 lbs over the previous one.

60* Honda J30A1 V6 200hp/195tq (Accord 98-02), very nice top-end but absolutely gutless in the low-end and mid-range.

60* Toyota 1MZ-FE V6 (220hp/222tq) (many cars), a nice balance of performance all around. Nice torque delivery in the low-end to mid-range, with a still decent amount of top-end.

60* Toyota 2GR-FE V6 (269hp/246tq) (many cars). I found this engine to be quite gutless in my RAV4 in the low-end, constantly needing downshifts in situations you wouldn't have expected, which got to be very annoying. Even Toyota's own published torque curves for this engine show a very large drop-off in low-end torque. I've had my foot flat to the floor pulling out of 2nd gear corners and it was not able to out run minivans until it got wound up to at least 4000rpm, where I was already breaking the speed limit.

90* GM 3800 Series II/III V6 (I forget the numbers). I don't understand how anybody could generalize all 90* V6 engines as having poor low end torque when this engine had tons of it. Straight off the line it went hard and had a decent amount of pull all the way up to 5000rpm. In fact this is one of my favorite V6 engines of all time. Non-linear peaky turbo-like torque curve? Huh? I don't think so. Go drive one of these as homework and get back to me.

The BMW N55 single twin-scroll turbo Inline-6 under the hood of my 335i has the most linear power delivery of any engine I've ever driven, so I really don't think you have any idea what you're talking about here. There is some turbo lag, but in most situations it's not even noticeable. The Audi supercharged 3.0T engine is very good also. You really think it has a non-linear power delivery? It's probably a better and more responsive engine overall than the BMW Inline-6s and also wouldn't have any turbo lag, but it's likely heavier and not as efficient either. Belt driven supercharged engines suck away engine power constantly, although the newer ones will de-clutch I think to avoid wasting power at light throttle.

BTW Mercedes has already transitioned to 60* V6 engines years ago now. All of the x350 series vehicles are using 60* V6 engines. The x320's and the few x370's were the last of the 90 degree V6 engines. After that they moved their 6-cylinder engines to their own dedicated architecture at the more optimal bank angle of a V-6 of 60 degrees. 90* V6 engines still have the advantage of being able to park a supercharger in the V-valley a lot easier than a 60*. Haven't driven a Benz x350 car, but peak torque at least on the older port-injected version was down around 2500rpm. Another 90* V6 that blows a hole in your theory was the GM 3800 Series II/III supercharged engines. Well known to have tons and tons and tons of low-end torque and very wide powerbands, but fell off at the top-end. 240hp/280tq I think were the ratings.

Bottom line is that V bank angle has little to nothing to do with an engine's overall power characteristics. There's so much more in play such as port and head design, intake manifold design, camming, VVT system setup, exhaust system setup, and more. It's not the bank angle making these differences, I assure you, especially not on street/emissions legal passenger vehicles.

SteVTEC

Correct, the BMW and other turbocharged engines do still have a touch of lag, it IS obvious especially if you drive a good naturally aspirated engine back to back, and stating such on the BMW forums has gotten me flamed. I think the reason that BMW discontinued most of their upper tune NA I-6 engines when the turbo ones came out is so that there wouldn't be as much of an argument. The current de-tuned 230hp/200tq NA I-6 that's been used in the E9x 3-series 2007 isn't really a good comparison. Yes, the A6 3.0T engine being supercharged and having a bit more power I'm guessing would be a bit more responsive and predictable around tracks, but it's less efficient overall (gets 2 mpg less than a 535xi, 19/28/22 combined for the Audi vs 21/30/24 combined for the BMW).

peteharvey

GM 3800 90 Degree V6
To compare the merits of in-line sixes with V6's, we must try to keep all the other factors as constant and as similar as possible.
I did not include this engine, because it has few, if any similar in-line competitors.
(1) The larger the engine capacity, the greater the natural bottom end torque.
In contrast, a motorcycle engine will rev past 10,000 rpm.
This Buick 3800 engine has almost run out of breath at 4,000 rpm.
(2) Furthermore, the Buick 3800 has only one intake and one exhaust valve, therefore even more bottom end torque.
We'd have to compare this Buick 90 degree 3800 cc 2 valves per cylinder, with an equivalent in-line six at 3800 cc and 2 valves per cylinder.
Let's get rid of this Buick 3800 now; it's not a fair example to talk about, in the case for in-line sixes versus V6's.
It's not a true representation of the average 90 degree V6.

Mercedes 60 Degree V6?
The Benz V6's have traditionally been the M112 and M272 range of engines.
Both are 90 degree V6's.
Remember, the original M112 employed Benz's belief that 3 valves per cylinder and SOHC per bank, was the way to go for practical bottom end torque?

Later by 2004, Benz changed their minds, and went to DOHC per bank, with 4 valves per head for top end power.
Recently in 2010, while still in bed with Chrysler, Mercedes and Chrysler spawned the 60 degree V6.
The 60 degree V6 is called Benz's Blue Efficiency engine, or technically Benz's M276.
The 60 degree V6 was only used in the Benz CL and S Class last year, and has recently found its way into the C and E Class.

This 60 degree V6 is sold under the Chrysler name "Pentastar".
Because Fiat now owns Chrysler, Fiat now has the right to use use these Chrysler Pentastar V6's, and plans to use them in the Alfas and Lancias.

I have not had a chance to test this new 60 degree engine yet.
I've been dying to test drive the latest iteration of the E350.
I bet the new 60 degree V6's have more bottom end punch than my 2002 90 degree C240 2.6 V6, and the 2007 C300 3.0 90 degree V6's which we have test driven only a few years ago?
However, we may actually never know, because the new series of Benz engines are only 3498cc.
However, I suspect the Benz 60 degree V6 will still be inferior to the bottom end punch of the recently discontinued BMW 530i 3.0 in-line six naturally aspirated.

Indeed, Mercedes will have an all new range of in-line sixes released from 2015 onwards!
Perhaps that's why there isn't so many variations of the Benz/Chrysler Pentastar 60 degree V6's in Mercedes line-up???
This Benz M276/Chrysler Pentastar 60 degree V6 will probably have a very very short life in Mercedes-Benz's history?


Toyota/Lexus V6
Toyota's older 1MZ-FE engine has no variable valve timing, so it has a punchier bottom end, eg 1996-2001 Lexus ES300.
The current 2GR-FE and FSE [with direct injection] used by the new Lexus 4GS, sports fantastic power figures, however the VVTi compromises the bottom end torque.
They have compromised the bottom end torque for top end torque.
Lexus old 1997-05 2GS300 3.0 in-line six is rougher and louder, but much punchier down the bottom than any of their modern V6's.
Have you had a chance to drive them back to back???

Honda
The Honda J30A1 of 1997-02 did lack bottom end torque, but from 2002-2007, a revised version was released with a punchier bottom end.
We almost purchased the original version.
We ended up purchasing the second generation 2002-07 model back in 2004.
Unfortunately, this 2002-07 Honda Accord 3.0 V6 24 valve is no match for the bottom end torque of the 2003-10 BMW 530i 3.0 in-line six of the same era.

Nissan
As for the Nissan, I have driven both the VQ30DE and updated VQ30DE-K; K for Kaizen, meaning improvement.
I drove them so long ago, and have so little interest, that I cannot remember their exact performance details.
However, it never matched the strong bottom end punch of the Skyline 3.0 DOHC 24 valve from the 1980's!
We need to compare engines, back to back.



Discussion
If you test drive the all these V6's "back to back" with a comparable in-line six of the same era, with matching capacity, and the matching valve configurations, eg the 2003-2010 BMW 530i, and the 1997-2005 Lexus GS300 3.0 in-line six, you will find that the in-line sixes have a punchier bottom end than the V6's, just through superior breathing from the different inlet port design.

As for the superchargers and turbos, I only just drove an Audi A6 3.0 Supercharged AWD 3 weeks ago, and a 535i 3.0 twin turbo 2 weeks ago.
I can tell you, it has a flat spot down the bottom, then comes the big torque surge as the compressor gathers boost.
This is not a linear delivery of power.
Superchargers and turbos have "peaky" performance, unlike an atmospheric engine.
With a linear delivery of power, the power must come on instantly like the Buick 3800 you talked about, but unlike the Buick, the engine hopefully won't run out of breath by 4,000 rpm, but it should surge all the way to 6,500 rpm.


Conclusion
In the end, the engine capacity probably plays the biggest role.
The actual number of cylinders plays a major role too.
For example, let's say we have 4 different engines, all the same 3000cc in capacity, but in 4, 6, 8, and 12 cylinders.
The 4 cylinder will have the most torque, and least revs.
While the 12 cylinder will have the least torque, but most revs.
The engine configuration does play a fairly major role in performance characteristics.
These are only general rules.
It's not the be all, and end all.

Of course you're right in saying that the final performance characteristics will be largely modified by:
bore/stroke ratios
valve number
valve size
valve lift
valve timing
intake port
exhaust port
air cleaner
muffler
fuel injection
ignition timing
etc etc.
For example, a narrow bore + long stroke = hi torque, but low revs.
Whereas a wide bore + short stroke = hi revs, but low torque, etc etc.

All the factors above [and more], added together, play a role in determining the final performance characteristics of a motor car engine...

SteVTEC

I'd like to know what exactly it is about a 90 degree V6 that makes it so great for top-end torque, and why a 60 degree V6 is so much better for bottom end torque. You've yet to explain this, and I've posted plenty of examples that contradict.

You say 90 degree V6 engines are better for top end, and 60 degrees are better for low-end, but the Toyota 2GR-FE has pretty lousy bottom end, and the Nissan VQ series have always had pretty good bottom end but are both 60*. The Buick 90* V6 has always had awesome bottom end but lousy top-end. My old 1999 Maxima's VQ30DE with DOHC and 4 valves per cylinder and a 60 degree bank angle had more similarities than differences in power delivery characteristics when compared to the Buick Series II/III 3800 engines which were the complete opposite with a 90 degree bank angle and 2 valves per cylinder. Both had nearly identical peak torque and peak power RPMs, and both would pull strongly to about 5000rpm and then wheeze. Amazing how different these engines were in terms of specs, yet both had nearly identical power delivery. If you want to say that engine configuration "has a role" in engine power delivery characteristics that's fine and I won't argue, but on street/EPA legal engines it clearly doesn't have a "MAJOR" role like you're trying to imply, as if that's the be all end all difference. It isn't.

On the turbo/super engines, you're describing throttle response and not the linearity of the powerband. I drive a BMW N55 single turbo 3.0L Inline-6 every day and the powerband is extremely linear, but yes throttle response isn't quite as good and super snappy like a good NA engine can be. The "hole" you mention at the bottom end is there, but only if you go looking for it. With an automatic it will downshift to a lower gear in an instant where the turbocharger(s) will also spool immediately. In normal driving, it's tough to tell it's not an NA engine. Most turbocharged/supercharged engines have far flatter torque curves with more linear power delivery than naturally aspirated engines. The Toyota 2GR-FE and FSE engines are peaky engines. So are plenty others, like the Hondas. Long gone are the days where you had to get up to at least 3000rpm to start to spool a turbocharger, like on the 2002 Subaru WRX. Modern turbocharged engines especially with direct injection has the turbo spooling as soon as you start to touch the accelerator, and most are capable of making peak torque below 2000rpm which makes them much better for use with automatic transmissions.

Bore/Stroke also matters a whole lot less for street engines. Plenty of Hondas are under-square in design yet still manage to have great top-end power and be lacking at the low-end. My Nissan VQ30DE was extremely over-square and yet it had great bottom-end and suffocated at the top-end, the exact opposite of what you would expect. It was all in the camming and intake manifold runner design between that and the DE-K, which was a top-end beast.

BTW I have an old SAE white paper on the Toyota 2JZ-GE engine which actually focused on the VVT-i vs non VVT-i versions of the engines. The paper illustrates that the main focus of the VVT-i system was to help improve low-end and mid-range torque, and it showed that it gained 5-10 lb-ft of torque throughout most of the rev range, but not much if anything at the top end. Are you saying that you think the VVT-i system compromises low/mid-range torque?

Och

iTrader: (3)

Low end/top end power is not determined by type/angle of engine - its all about bore to stroke ratio. A V6 engine is inherently unbalanced, and 60 degree configuration is an optional configuration for getting it as balanced as possible, but it has nothing to do with the engine power output. Modern V6 engines are very smooth with the use of all kinds of tricks, including external balances, are often just as good as inline 6, but neither are a match for a properly done V8.

SteVTEC

No and no.

But I do like a good V8 too.

T0ked

iTrader: (2)

Och is correct in that bore and stroke play a much more important role here. And there are other aspects that contribute significantly in determining power output, much more than angle of the cylinder banks (ie valve and ignition timing, compression, piston speed. crank angle, etc). Optimal crank angle does not depend on V angle. Nevermind things extrinsic to the block itself, A/F ratio, fuel delivery, spark delivery, designs of intake and exhaust manifolds, etc.

There are a lot of interesting comments above regarding specific engines from specific manufacturers, but you can't carry that over into generalizations about cylinder configurations. The main benefit of the V config is compactness and weight savings. Comparing 90 degree engines and 60 degree engines between different manufacturers is a futile exercise. The differences are much better explained through the variables I mentioned along with other newer technologies.

V6 engines, even if very unbalanced intrinsically, can be made extremely smooth. Maybe not as smooth as a well developed I6 or V8, but smooth nonetheless. It all depends on how much a company decides to spend on R&D.

Och

iTrader: (3)

Yes and yes.

There's only so much camming you can do before the engine starts to idle like a cold diesel with fuel delivery problems, and aggressive camming isn't suitable for daily driven cars. Most of todays cars are equipped with variable timing systems to extract as much low end and high end power as it is practically possible.

And plenty of todays V6 engines are silky smooth, and have been for the last decade or so. I had an older I6 back in the days (gs300) and have a newer I6 (335), and I've driven cars with V6 engines that felt smoother than both of my I6 engines.

Och

iTrader: (3)

Thats is incorrect. Assuming similar engine design, keeping bore to stroke ratio proportional, with the same displacement the 12 cylinder will have the most maximum torque, but at much higher rpms. The 4 cylinder will have much less maximum torque, but it will be delivered much earlier.

Thus, the 4 cylinder could deliver 200lb/ft at 1400rpm and have a very strong punch down low, but it will run out of breath by 4000, while the 12 cylinder could deliver 280 lb/ft at 5400rpm but have so little torque down low, that you'll have to drop the clutch at 4000rpm to take off without stalling.

Och

iTrader: (3)

You are overlooking many factors here. In the case of old Lexus I6 vs Camry, vs current Lexus V6 - gearing actually plays the most role.

For instance if you take 1GS300 vs 2GS300, the 2GS300 feels like it had twice as much torque on take off, but its all due to increased gear ratios and new 5speed transmission. Also the stall speed of torque converter plays a huge role - for instance the old 3.0 Camry with less than 200hp/tq felt pretty damn peppy off the line, thanks to high stall speed on the converter.


With Mercedes it was long overdue, as their 90 degree V6 was just horrible and unacceptable for premium vehicles. But where are you getting the info on MB inline six engines? They just introduced their new 60 degree direct injected V6 for MY2012 vehicles. I've never hear anything about their plans for an inline six.

In case of BMW, they are going back to the i6, but its not true to its roots, its essentially cost cutting with the turbo charged engine. Unless they make this turbo i6 rev to 8,500rpm of course.

I've driven pretty much every car that competes with GS/IS350, except the new Audis, and I can honestly say that Lexus engine is simply best in class. Silky smooth, rocket like acceleration with very good response through entire range of rpm. I'd love to see Lexus bright high power V8/V12 models, and maybe experiment with turbos, but there's nothing wrong with their current V6.

plex

iTrader: (11)

That would be lovely lol...........3.8L I6 3JZ put a TT version in a new Supra platform along with NA versions in the IS and GS but all wishful thinking.

SteVTEC

Bore to stroke ratio definitely has an impact on power delivery, but it's hardly an "all about" sort of thing. The Nissan VQ30DE engines were extremely oversquare (3.66" bore x 2.89" stroke), yet the first version was best known for its "world class torque" and had a lousy top-end. The K version from 2000-2001 with a variable intake manifold and modified cams was a top-end beast. Many of Honda's engine's are undersquare yet they have lousy torque and good top-end. The fact is, for street/EPA legal engines, you can pretty much give engines any sort of powerband and power delivery characteristics that you want. The real differences that you might see with bore to stroke ratio considerations won't be seen until you're talking about race spec engines. Like Formula 1 engines. They have a 'formula' engine configuration in terms of V-8 or V-10 and displacement, but nothing is said about what their bore to stroke ratio should be, so considerable effort is put into studying this on these engines. Yes, there are significant differences as far as maximum achievable horsepower and mid-range torque, and also fuel consumption. And even on F1 engines, on most of the tracks out there the fastest way around the track is rarely if ever maximum possible horsepower. It's always about striking a balance. When we're talking about run of the mill engines we're not even remotely close to hitting these limits.

Perceived engine smoothness and refinement can be pretty subjective, but I've never driven or felt an engine that was more refined than the I-6 engines. The three 3.0L V6 cars I've owned were all pretty refined, but I haven't been overly impressed from a refinement and NVH perspective with almost any of the 3.5L class V6 engines. They're nice enough for normal driving, but flog them and I dislike the feel and vibrations that a lot of them make. The old Nissan VQ30DE was my favorite. Due to the high bore to stroke ratio keeping the piston speeds very low, it was super smooth and refined even at high RPM. I did accidentally leave it in 3rd gear on the highway once - was going to pass but then didn't and forgot - and was running north of 5000rpm and didn't even notice, it was that smooth.