I just wanted to get a feel for what people think about I6's vs V6's. As we all know two of the most powerful street racers (Supra and Skyline) came with an I6. Which do you think is better...I6 or a V6 in terms of power, balance, upgradeability, or simply in general? Do I6's have a chance at re-entering the market?

 

Reentering the market? Have you looked at BMW lately? The I-6 layout is the most balanced platform to build an internal combustion engine - granted engineering has narrowed that gap, but in general I-6's are the most ideal and V6's are a good compromise between hp/tq and space.

 

^ I agree. The biggest killer of engines is heat. The I6 disperses heat better than any engine around. The main reason V6's came to the scene was due to improve technology with aluminum metals that made it practical to design. I6's are the simplest but best designed motors ever.

 

I am a Bimmer fan but don't think that I instead of V is the end of it all. Mercedes went from I to V and nobody complained.

I is overrated.

 

I have yet to drive a V6 that was smoother than an Inline6.

 

Both designs have their merits. I vote tie, depending on the application.

 

IIRC, BMW and Volvo are the only car makers still using an I-6 in the US market-- every other maker has gone to a V6 configuration.

The V6 is apparently easier to package in an engine compartment.
All the high-end normally aspirated V6 designs now are putting out 250-330 HP, so I wonder if the V6 is capable of more power and efficiency than an inline 6 as well?

 

An Inline 6 cylinder is inherently balanced (from vibration) front to back. Another engine configuration that is balanced is the boxer engine. Another balanced engine by design is a V12, essentially 2 Inline 6s put together.

The Inline 6 is inherently smoother and balanced. But the packaging is not so great. And the newer V6 have good counter balancers to smooth it out as well. So it is more of a "taste" than anything else. Also, b/c it is well balanced, the I6 is supposed to rev higher.

BMW likes to stick with the I6. Porsche as well, but laid out flat, so it is called a Flat 6.
Subaru makes boxer engines and BMW motorcycles have boxer configurations as well. The BMW Boxer engines are known for their reliability/longevity.

I remember Acura used to have an Inline 5 for their 2.5TL. Volvo uses inline 5 from time to time also. But these configuration is not a balanced design.

 

You have to look at displacement. BMW pushed it to 3.0 then to 3.2 inline 6s. Their M3 engines had torque, hp, flexibility.

Now you got your Nissan's 3.7L V6 which has a great engine architecture. Always within top 10 car engines of modern time. I really like its application in the G37.

BMW did not see cost-benefit in increasing engine size of an inline 6 and reduce RPM. Instead, it just went for a higher revving V8.

 

flat 4 ftw.

 

My inline six has 330HP. Feels good to me.

 

I like both designs personally. The BMW I6 is an exceptional 6 cylinder engine but then again Nissan and Honda both make very good V6's as well...

 

I agree. An inline six is such a wonderfully balanced engine.

Many years ago I had Supra, and that thing was so smooth it was amazing.


Terry

 

 

I6s usually don't have or need balance shafts, and an inline 6 is usually capable of more power and efficiency than comparable V6s. I personally think its a lame way to judge engine efficiency/power BUT in terms of hp/liter inline 6s seem to trump V6s. Its kind of unfair since I6 BMWs are usually lighter than comparable V6 Acuras but in terms of hp/liter, BMW's Euro-market 3.0 V6 with 272 horsepower is untouched by any Honda V6s except for the C30 in the NSX which makes 270 horsepower from 3.0 liters, but its also in a much more expensive car.

However, a naturally aspirated V8 will still always be the best compromise between performance and economy almost regardless of engine displacement - specifically, an OHV layout....

 

i was just going to say my 335i is a twin turbo inline 6

 

Just to correct you, a "flat" engine such as porsche's engine is a horizontally opposed engine and NOT an inline engine "laid out flat". It is closer to a V6 "laid out flat". The "V" would be 180 degrees (one bank of cylinders is opposite the other bank) in a flat 6 engine.

 

Most manufacturers use the V6 because it is smaller and easier to package. Especially in FWD applications. Inlines are inherently easier to and balanced better.

 

From what I understand the I6 is smoother but you get more power out of a V6 in the same amount of space under the hood.

 

Yep with modern technology, a V6 can be designed to be superior overall. Consider modern fighter jets: they are highly unstable and require advanced automated computer control. Yet, the overall stealth, speed and agility exceed those of naturally stable aircraft.

Eventually, BMW will switch from the I6 when their engineering become a bit more sophisticated. But first they must overcome their inability to build basic, functional electrical/electronic components.

 

Poll updated.

 

^

 

Both are very well designed engines and have benefits.

 

 

you've got my vote senator.

 

Despite assertions to the contrary, neither configuration has an "advantage" as far as power output and efficiency go in production cars. Its all down to the specific design, tolerances, quality of machining, technology built into the engine management, port and combustion chamber design, etc. of each individual engine model. Apples and oranges.

Its very different in most racing applications though. Given the choice between a long, heavy inline-6 with a high center of gravity and a short, compact V-6 that can be more optimally placed in the chassis, racers will choose the V-6 every single time. Note, drag racing is an exception to this, where its all about weight transfer front to rear and an inline-6 isn't at much of a disadvantage, if at all.

 

Shouldn't this be in red text?

 

^^^Yeah, I'm still waiting for BMW's "engineering to become a bit more sophisticated"!!

 

Why no, I'm being serious. Read some car mag comparision reviews where the BMW 3 sent for the review had various failures (i.e. ABS) or could not compete at all.

This mirrors real life experiences with people I know personally, including a BMW parts manager (BMW's business plan depends on the out of warranty repair cash cow). That is FAIL... oooohh, I feel so 20 something now

Now the big question is, are their engineers incompetent or are their MBA's brilliant?

Well, let's look at the FIA World Touring Car Championship for 2008. The BMW 3's (4-cylinder in line, longitudinally installed, rear wheel drive) got beaten by the SEAT León (Turbo diesel 4-cylinder in line, transversally installed, front wheel drive) and were a bit ahead of the Chevrolet Lacetti (4-cylinder in line, transversally installed, front wheel drive). The top BMW driver finished 5th in the season.

Now how about SCCA SPEED Touring Car Championship for 2008? Well it was all Acura (TSX) and Mazda (Mazda 6) and the bimmer's didn't even place.

So for (near) production sports sedans, the BMW's can't win against more modern designs. BMW is mounting the engine the wrong way and driving the wrong wheels.

I'd say their engineers are incompetent.

But their MBA's? Brilliant: convince the general public to pay (and pay, and pay) big $$$ for the 3's with a bulkly I6 powering a chassis tuned like a sow.

 

So V6's and FWD are the way to go then? Well, you've convinced me. Now take your message to the world!

Me? Well, I'd better watch out for those TSX's and Mazda 6's.

 

Looks like someone's panties got in a bunch because they couldn't stand to see their worshipped chariot come under the fire of one person's opinion.

Now defend your precious from everything in the world because God knows that there's nothing better out there than your invicible steed!

 

It all depends what the car was built for I'm not saying FWD is the best option, but having a RWD layout doesn't automatically make it a better handling car. When I test drove the IS350 I felt as if I had no control of the car around turns and the steering was insanely numb. I thought the TL had light steering...you could move the steering wheel on the Lex by blowing some air in the general direction.

I think BMW has perfected the I6, although, IMO...the TVR Sagaris has the best I6 on the market ...i'd really like to see what they can do with a V6.

 

actually............ http://www.world-challenge.com/

You should. Acura TSXs and Mazda 6s are manhandling the 3-series....es.

 

[Q
UOTE=Viscous;10166532]Looks like someone's panties got in a bunch because they couldn't stand to see their worshipped chariot come under the fire of one person's opinion.

Now defend your precious from everything in the world because God knows that there's nothing better out there than your invicible steed!

[/QUOTE]

Ya that's it! Its not possible I just disagree with him. I just don't think that bmw uses them because they can't build a good v engine.

I agree my car is a pig, but the engine configuration has nothing to do with that.

 

Whoops, screwed that post up. Anyway in all seriousness if Vs are superior not only in size but in general why isn't everyone using them? I'm honestly curious.

Oh, I'm wearing boy shorts, they show off my ass

 

Wait, what?

Andy Priaulx did just fine in the FIA WTCC with his archaic BMW in 2007, 2006, and 2005, winning the championship three years in a row. Plus, in 2008 the FIA was constantly monkeying with the rules during the year...adding weight or giving weight breaks to various manufacturers making any claims about driveline superiority totally irrelevant. After years of development with the Leon, SEAT finally took advantage and made the most of it. And THAT isn't even getting into the quality of the teams, the restrictive rules package, etc. etc.

In regards to Speed Touring Car, you again have a highly restrictive rules package based on production vehicles. These are race cars with low power to weight ratios (240-290 hp for 2,865lbs.), effectively equalizing any inherent advantage or disadvantage to drivetrain layout. Talk to any Speed Touring Car engineer and they'll tell you its a suspension-chassis intensive series, where drivetrain layout has much less impact on vehicle performance than with higher horsepower series. Then once more, add the quality of the teams, factory support or not, etc. etc.

In short, FWD ends up being a workable platform in the small niche of lower power production based sedan racing. No more, no less. In no way does that preclude some kind of superiority over RWD layouts. Then, if you push horsepower levels past 350, find me ONE race car designer that would prefer a transverse-FWD car over a traditional front engine-RWD layout.

 

After reading this, there should be no way humanly possible for anyone to ever take thing you post seriously again.

 

+ eleventy-billion!!!

This man knows exactly what he it talking about.

/thread

 

BINGO!
+ eleventy-billion + 1

You're totally right and you're only misunderstanding is the context in which I'm making statements. I am in fact staying on the post topic and talking about this specific performance class, where the optimal design isn't of course optimal for other classes.

It is in this very important class that the V6 vs. I6 debate is mostly relevant because BMW is still using the I6 for their 3/5's while the rest: Acura/Audi/Infiniti/Lexus/MB/VW etc. are all using V6's for their comparable models.

As you stated earlier:
"Its very different in most racing applications though. Given the choice between a long, heavy inline-6 with a high center of gravity and a short, compact V-6 that can be more optimally placed in the chassis, racers will choose the V-6 every single time."

So in summary, for production performance sedans, I6's are a very bad choice vs V6's, FWD wins far more races than RWD, and the chassis plays the biggest role in performance.

And for the 3/5's, the BMW engineers have I6=FAILED, RWD=FAILED, chassis=FAILED.

Oh, I forgot, Chris Bangle design=FAILED

 

but add 2 so you have a flat 6...

The I-6 engines are absolutely incredible to build out. My friend has a Supra motor spliced with bigger heads (1JZ/2JZ combo). He's currently at about 500 HP untuned. Once tuned, he'll be at 750 HP..Just sick.