i've always wondered why BMW used an inline 6, while the majority of car makers use V shaped engines? Can anyone explain? Do inlines get better mileage? never really understood the concept. Roughly by numbers the 3.2 liter M3 inline 6 seem to be better than the 3.2 liter TL V6... 333hp vs 270hp... dats a 60 hp difference... now a 3.0 V6 like an accord pumps out 240 hp while the BMW 330 pumps out 225hp... confused...

 

In-line 6s don't necessarily produce more hp or torque. They are inherently smoother than V-6s. That's why BMW uses them. V-6s are more compact, which is why Acura uses them with their front-wheel drive layout. The only reason the M3 makes so much more than the TL given the same displacement is the the way it is engineered. If you had DOHC heads to the TL and let it have a 8000 rpm, it would produce over 300 hp too.

Deepak

 

can that be done the dohc heads

 

Inline 6's take up a lot more hood space but are smoother, use fewer parts.

Honda likes to make V6's to keep the engine package more compact.

As for the HP in the M3, HP is all about torque multiplied by RPM's, so the M3 engine has to be going at around 7800 rpms to get 333 hp or so.

The NSX is underrated and makes at LEAST 290 (more like 310) and that is an engine that dates back to the early 90's!

 

Good point about hp is just rpm times torque. I think a better indication of how advanced an engine is torque per liter of displacement. BMW has about 30 more lb-ft of torque at similar rpm.

 

The M3's inline 6 is using BMW's own "VTEC" system - stepless double VANOS variable valve timing, and redline at 8000rpm. This system virtually changes both the intake and exhaust timings continously, unlike just the two steps from our V6 - fast cam or slow cam profiles.

This BMW valve timing system is more technologically advanced than the Honda VTEC. This is no surprise given the hefty price tag that comes with the M3.

 

No....the reason most companies use V6 is because they are inherently smoother than inline, just like V8 is smother than V6 and V12 is smother than both.

If Acura uses the same Honda 3.2 V6 engine, but engineered for the NSX, it would probably even produce more power than the M3 engine, but just like the M3 engine it would cost a lot more and it won't give you as good MPG as current 270hp Acura V6 with ULEV.

Honda Vs BMW

2.0 liter RSX displaces 200Hp that is 100hp per liter (very efficient)
3.2 liter M3 displaces 333hp that is 104 per liter (very efficient too)

But one gives you ULEV and better gas mileage. I personally prefer Inline 6 engines, since my favorite engine of all time is the R34 inline 6 twin turbo.

Is all in relation to MPG, reliability, cost, and emissions. I'm sure on the TL, Honda is striving towards all the above at the same time gaining 270hp same goes for the 330i, but for the M3 they are just trying to get the most HP possible with some drawbacks.

They both take the same amount of space, just in different ways, if I was an engineer I would use an Inline engine for RWD or V6 for FWD, but as you know that is not always the case, like the G35. Technology changes everything.

 

V6 is more compact and less space, but it's not as balanced as the inline 6s, therefore u need a balance shaft to make the V6 to be smooth~

i believe the current TL engine can pump out 300hp with SOHC design too, but it's not necessary coz the cost is high.

same to the BMW, the 330i has 225hp only becoz to keep the torque curve flat from low rpm, if u just go for high horsepower, then the torque will come at a higher rpm which is not gd for daily driving, but u can do that in M3 coz of the high performance.

 

Is called I-VTEC in case you didn't know. I know something, BMW didn't know what variable valve timing until it was invented by HONDA for F1 years ago.

The last evolution of Honda's VTEC system was back in 1995 where they introduced the now-famous 3-stage VTEC system. The 3-stage VTEC was then designed for an optimum balance of super fuel economy and high power with driveability. For the next 5 years, Honda still used the regular DOHC VTEC system for their top power models, from the B16B right up to the F20C in the S2000. Now Honda have announced the next evolution of their legendary VTEC system, the i-VTEC.

The i stands for intelligent : i-VTEC is intelligent-VTEC. Honda introduced many new innovations in i-VTEC, but the most significant one is the addition of a variable valve opening overlap mechanism to the VTEC system. Named VTC for Variable Timing Control, the current (initial) implementation is on the intake camshaft and allows the valve opening overlap between the intake and exhaust valves to be continously varied during engine operation. This allows for a further refinement to the power delivery characteristics of VTEC, permitting fine-tuning of the mid-band power delivery of the engine.

Variable Timing Control Operating Principle
Honda's VTC operating principle is basically that of the generic variable valve timing implementation (this generic implementation is also used by by Toyota in their VVT-i and BMW in their VANOS/double-VANOS system). The generic variable valve timing implementation makes use of a mechanism attached between the cam sprocket and the camshaft. This mechanism has a helical gear link to the sprocket and can be moved relative the sprocket via hydraulic means. When moved, the helical gearing effectively rotates the gear in relation to the sprocket and thus the camshaft as well.

 

I read in Road & Track (April 2004) last week that BMW will be using V6 engines in some of their new models, like the 2 and 6 Series.

Mike Smeezy,

 

Yeah, BMW and Toyota get a lot of torque per unit of displacement. Nissan does as well.

But, Honda gets the best MPG, emissions AND HP per unit of displacement overall.

 

so is it safe to say that we can smoke a 528i or even a 530i any day? assuming both cars are AT....

 

I DO know about the existence of Honda i-VTEC technology. But the title was "TL V6 vs an inline 6", and the M3's inline 6 was selected to compare with the TL's SOHC VTEC V6.

Honda's i-VTEC is only available exquisitely to inline-4 engines. As of this moment, no Honda/Acura production V6 car has the i-VTEC technology.

Technology-wise, Honda is among the best engine builders in the world. The 2.0L inline-4 used in the S2000 has an output of 240hp, that's 120hp/L. It is still the record for normally aspirated engines. However, 6-cylinder-engine-wise, the M3's inline-6 still has the upper hand.

 

When discussing RWD, an inline configuration will always be better than a v configration when speaking of weight distribution. Much talk of weight distribution is regarding front-rear distibution. Little is ever said about left-right distribution, but it is equally important. The ideal is to get all the weight as close to the center of gravity as possible. This is why F1 cars have the driver, engine, and fuel tank inboard of the wheels: it is close to the center of gravity. An angled engine take up more lateral room than an inline engine, and therefore spreads its weight further from the center of gravity. Of course, one could argue that an angled engine takes up less space vertically, and therefore has a lower center of gravity. But an angled engine requires the intake system to be mounter on top of the engine assembly, and that counteracts the lower profile in OE applications.

IMO, the optimum setup is a narrow-angle V engine, similar to VW's VR6. It has the benefits of both an inline and a wide-angle V but in a more compact package. Modern F1 cars use a narrow angle V10 between 20 and 60 degrees in most cases. Of course, if one really wants to argue technology, the turbo-era F1 cars used turbocharged I-4s. This is perhaps the optimum setup for weight distibution. Renault's engine was a 1.5l I-4 that pumped out around 1200hp and revved to 14 grand, something I wish I could say of my puny 2.3l SOHC VTEC lump!

 

V6 is NOT smoother that I6. There are only 2 types of engines that are naturally balanced. I6 and V12. E.g. out these 3 cars TL, 530 and 540. The 530's engine is the smooth one. Go drive a car with I6 or read a special literature before talking about something you do not know.

 

I6 configuration results in a longer engine block than a V6. In a FWD transverse layout, the V6 offers better packaging options.

For a given displacement, an I6 will outperform a V6 for a number of reasons. There is less valvetrain mass as a DOHC I6 has 2 cams vs 4 cams for a DOHC V6. The I6 crankshaft does not have to have the balance masses required for the V6. Reduced rotational mass to overcome results in higher specific output.

DOHC allows for dynamic timing and lift on both the intake and exhaust valves. The SOHC design on the TL does not allow intake and exhaust valves to be adjusted independently. DOHC are generally more powerful than SOHC engines.

The V6 is a heavier engine. The intake manifold weighs more and there are 2 headers to contend with. Weight fights against performance. Plus the way Honda combines the 2 headers results in a 180 degree bend for the rear bank which fights against free flowing.

 

dmunjal is 1/2 correct, boxer engines are perfectly balanced also "All boxer engines, regardless of no. of cylinders, provide perfect balance because the movement of a piston is exactly counter by the corresponding piston in another bank."
check out this link

http://autozine.kyul.net/technical_s...smooth3.htm#V6

 

I thought (from readings long ago) that a 90 degree V-8, a 60 degree V-6, and a boxer 4 were all naturally balanced. Where balance shafts are applied to V-6's are in 90 degree V-6's.

Mike

 

Oops, how could I forget about boxers, especially since I used to own a Boxter.

BMW and Mercedes have always been partial to I6s but I was surprised a few years ago when Mercedes went to a V6 as well. Let's see how long BMW holds out. The packaging advantages seem to be worth more than the inherent smoothness. Besides, a V6 can be made just as smooth as an I6 with balance shafts.

 

Well another reason would be, Honda can't put an I-6 in a FWD car, only RWD.

 

The Suzuki Verona is FWD and has an I-6 so you can put in an I-6 with FWD (makes sense as most vehicles are I4)

 

You can, but Honda won't because they usually make cars with shorter/smaller hood compartments.

 

The first V-6 I remember was in a 1961 GMC pickup. Buick also had a V-6 in 1964. Both were rough running engines, since they had no balance shafts. The I-6 is inherently balanced, as most have said. It's interesting that Chevrolet went back to the I-6 engine in the Trailblazer in 2002.

 

Ford played with Variable valve timing in the 50's.

Just a tidbit of info I thought I'd add in there.

 

I would think a transverse mounted straight six would take up less front to rear space than a V6. I've also been thinking a rear engine, RWD, transverse mounted straight six would be pretty dang cool.

 

Transverse I-6 would be far too wide. Exactly why Honda doesn't make an I-6. Toyota makes I-6's because they had RWD cars that could use it.

Someone mentioned V6's made by Buick during the 60's, I think those were 90 degree V6's, basically a V8 chopped. Acura had 90 degree V6's with balance shafts. The Legend, 1st generation TL, '95 -
97 Accord V6 and NSX.

 

S80 T6 has an I6 and Volvo is a front-driver.

 

Yes it is. I am wondering how. I guess i'll have to look under the hood of one.

 

Sure not an I-5 in the Volvo?

 

Nope your correct. Your choice of two smooth, responsive in-line six-cylinder engines provide power output in 194 or 268 hp

 

-dmunjal

you used to own a boxster? but you didn't even spell it correctly.

 

The engine with the most hp per litre (I'm canadian) was 120hp/litre and that is the s2000. 240hp from a 2.0 litre engine.

That was a trivia question from a car show a little while back. I'm pretty sure it's stands true today?

 

Yes I know, I was just using the RSX, because it has better MPG and still an impressive hp per liter.

 

Mazda has the "Most Ballanced" engine design curretlly used in production autos with the rotary. I am interested to see how the RX8 engine ages. If they have fixed the problems with the seals and valves the rotary will be the future.

 

The rotary currently has problems (very BIG problems with flooding). You drive for about 10 seconds, just to move the car out of the way or something like that and then turn it off, you get flooding. Happens A LOT on their forum and the only fix is to tow it to the dealer. A lot of people have been getting TERRIBLE gas mileage (around 15mpg) and of course the rotary burns oil faster than most engines. Until Mazda fixes these problems, I'd rather have my 6-8 cylinder engine.

 

You can get the S80 with an I-6, a turbocharged I-5, or a turbocharged I-6. The turbo models can both be had with AWD.

 

Rotary engines are notorious for their high fuel and high gas consumptions. I guess Mazda still hasn't overcome these inherited problems after so many generations of rotary engine releases.

 

Not to mention their lousy torque curves...

 

An inline engine is long and narrow. In small cars, a long, narrow engine mounted tranverseley (perpendicular to the car's centerline) can allow for a very short hood.

A flat engine(boxer engine, WRX) is wide and flat. This means it has a low center of gravity.

A V engine has the characteristics of both flat and inline designs. Its more square design means it has some of the space saving qualities of inline engines as well as the lowered center of gravity found in flat designs.

Inline 6 and V6 has the same smoothness of a 6 cylinder engine.

 

* Correction *

I mean "engine oil", not "fuel".

"Rotary engines are notorious for their high engine oil and high gas consumptions. I guess Mazda still hasn't overcome these inherited problems after so many generations of rotary engine releases."