Straight-six vs V6

[Lionel]

How would you guys feel if Ford decided the 2.7 Ecoboost was the last V6 they would make, and all future 6-cylinder engines would be inline?

Jaguar and Mercedes appear to be going down this road, just as Ford will be shutting its straight six and turbo facility in Australia.

 

If MT, Road and Track Jalopnik et al conducted a very thorough comparison of the Australian made straight six and Ecoboost/Duratec V6 engines for smoothness, db, idle speed, etc I think it would make a very interesting comparison, and persuade Ford to continue development on the superior engine. Thoughts?

[theoldwizard]

Never going to happen. They won't fit in front wheel drive vehicles. (The exception was the Volvo/Ford "Short inline 6")

[Lionel]

Well that shows it's possible with clever design. The front- wheel drive cars are getting four-cylinders anyway. Just a shame to see it go and I think it would be an interesting test.

[mackinaw]

Packaging will always favor a V-design, especially today, with FWD being so common.

But a straight-design is better balanced and very smooth, with both primary and secondary vibrations pretty much eliminated.

There are plenty of Ford truck fans out there that consider the 4.9L straight-six the best truck engine ever built in the history of the world.

[ANTAUS]

I remember the Volvo S80 used their 2.9L I-6 traversely and that was a nightmare for them in packaging. They spun it of course and bragged that this was done on purpose to allow for more forward crunch space incase of a frontal accident. They couldn't use any existing manuals so they had to develop their own to make it fit. Also front turning radius was rediculously wide as well because of it. The last we will see of that will probably be with the current S60/XC60 because they keep having packaging issues.

 

We also see them now using a new 2.0L I-4 making upwards of 315HP, and a hybrid version making 400HP, so I doubt they will need any other 6-cylinder engines.

 

I see the industry going into a plug and play power-train design system where it's easily interchangable throughout various vehicles provided the engine bays are engineered similarly.

Edited August 2, 2015 by ANTAUS

[30 OTT 6]

Chevy sold a rebadged Daewoo in Canada called the Epica from around 2004-2006. It had a transverse mounted 2.5L I6.

[Sevensecondsuv]

Everbody loves a straight six. They are superior to V6s in almost every aspect, except one giant, glaring problem - they don't fit in fwd architectures.

 

Unless Ford has major plans to switch Taurus and Explorer over to rwd, there just isn't enough application for one. It'd be useful in the F150s but they just designed the 2.7 for that application.

Edited August 2, 2015 by Sevensecondsuv

[fuzzymoomoo]

Does FCA still offer a straight 6 in the Wrangler? other than that, i don't know of any vehicle offered with a straight 6 option anymore.

[matthewq4b]

With every one going to AWD in most higher end applications mounting configuration is not as much a concern. With all but the entry level stuff not being able to accommodate an inline 6.

 

Engines are now longer stroked and smaller bored making packaging of Inline engines easier.

 

Advantages of inline 6's

 

Better torque curve for the same displacement engine with same bore and stroke and HP output compared to a V6

 

Lower NVH

 

More easily able to component share with Inline 4's

 

Easier packaging of turbo's (especially compound turbo's) and what not

 

Better potential weight distribution

 

 

 

Most vehicles will require the engine mounting to be longitudinal but this is a non issue for most application other than the entry level stuff.

 

Yes it will require vehicles to be redesigned to accommodate it but it will get rid of the ridiculous front over hangs and get the front wheels pushed out to the corners where they belong. (the Ford Fusion is especially guilty of this) This will improve ride quality and handling in the process and allow for lower RPM's to be utilized across the range due to the better torque, curve this will directly relate to a reduction in fuel consumption.

 

Overall I think the V6's days are numbered to be honest. Now only the largest cars will be sporting 6 cylinders and basically all of them could accommodate an inline 6cyl and retain their current exterior dimensions.

 

So are Inline 6's a better idea absolutely they are.

So yes Ford should be following Mercedes lead.

 

 

Matthew

[matthewq4b]

Does FCA still offer a straight 6 in the Wrangler? other than that, i don't know of any vehicle offered with a straight 6 option anymore.

 

 

BMW still uses a 3.0L inline 6

 

Matthew

[Sevensecondsuv]

Does FCA still offer a straight 6 in the Wrangler? other than that, i don't know of any vehicle offered with a straight 6 option anymore.

Wrangler's been Pentastar V6 for a while now.

[Sevensecondsuv]

It's true that you could do a north-south engine in a C or D size fwd/awd platform but then you may as well just make it rwd because it would defeat the point of it being fwd in the first place.

 

Manufactures like fwd because assembly is cheap. The front suspension and powertrain get assembled as a unit and plopped into the car from below. It'd cost more to assemble a north-south setup. Since 90% of buyers in this class couldn't tell the difference, fwd/V6 is here to stay.

[mackinaw]

 

.........Overall I think the V6's days are numbered to be honest........

 

Ford just spent a considerable amount of money the past several years totally revising their engine line. Several new-from-the ground-up six cylinder engines have been introduced. All are of the v-design variety. That should tell you something.

[fordmantpw]

Who cares the configuration, as long as it makes the power and torque and gets the fuel economy, and costs are in line with others, it doesn't matter if it's a V, I, Q, X, Y, Z, etc.

[Moosetang]

Nah let's go all in on dropping the CoG, Flat Sixes all the way.

[mackinaw]

Who cares the configuration, as long as it makes the power and torque and gets the fuel economy, and costs are in line with others, it doesn't matter if it's a V, I, Q, X, Y, Z, etc.

 

There is a difference when it comes to drivability. Both the straight-six or boxer-six are inherently better balanced, and smoother, than a 60 degree V-design.

[jpd80]

That's not a knife....

 

 

Now that is a knife...heh heh

 

 

 

 

 

 

Edited August 3, 2015 by jpd80

[matthewq4b]

It's true that you could do a north-south engine in a C or D size fwd/awd platform but then you may as well just make it rwd because it would defeat the point of it being fwd in the first place.

 

Manufactures like fwd because assembly is cheap. The front suspension and powertrain get assembled as a unit and plopped into the car from below. It'd cost more to assemble a north-south setup. Since 90% of buyers in this class couldn't tell the difference, fwd/V6 is here to stay.

 

All modern cars are assembled this way even rear drivers the engine and tranny sit on a cradle with the suspension that is installed from below in the chassis/body. So that is a non starter.

 

And you are missing the point here.

 

I6's offer much better torqure curves across the rpm range and higher torque figures lower in the rpm range to comparable displacement V6 engines this is why V4's never caught on even though they offer better packaging in modern FWD vehicles.

 

Most modern Inline gasoline 6's reach peak torque under 2000 rpm usually in the 1200- 1500 rpm range with max torque figures all the way up to 4500 or 5000rpm.

 

This has the advantage of allowing for higher gearing for overdrive's , and less throttle required to get a vehicle moving from a stand still. All of this transfers to better fuel consumption.

 

Inline 6's power strokes all over lap each other evenly this is why they are so smooth with little to no vibration issues.

 

Conventional V6's the power strokes do not over lap evenly, this is why conventional V6's have inherent vibration issues and use balance shafts to even out the vibration from the unevenly spaced power strokes.

 

Ford did go with split pin cranks in the Ecoboost V6's to help alleviate the vibration issues and the uneven delivery of the power strokes but this adds considerable cost to the manufacture.

 

The absolute even overlapping of the Inline 6's power strokes is what allows it to have superior low end torque producing capabilities over a conventional V6.

 

And just cause Ford revamped their engine line means nothing. Ford has not exactly led the industry when it comes to engine tech for many years now. Yes they make a big deal out of the Ecoboost but it is not new tech by any stretch , direct injection sequential turbo charging has been on the market for years already and is not new, and Ford certainly were not the first to market with it nor are they really getting the max HP out of it.

 

 

 

Lets look at the BMW N54 3.0L strait 6, it is a sequential turbo charged direct injection gasoline engine architecture that has been knocking around since 2006

Same tech as the Ecoboost.

 

The BMW in top form it is making 425hp and 440 Ftlbs of torque @ 1800 rpm-5000rpm

 

Compared to Fords 2.7L Ecoboost who's top form is 335 hp and 380 lb·ft

 

In fact the 3.0L N55 out performs the 3.5L ecoboost in terms of max HP

 

Mercedes and BMW generally have always been about a decade ahead of the domestics in tech in most areas this is also why they can on occasion get bit in the ass with Initial reliability as they are they sometimes pushing the edge of current technology.

 

We need to look towards the Europeans on occasion to see where auto tech is going as traditionally we have seen the trickle down affect of this tech to the domestics over time.

Certainly not all their tech ends up on this side of the pond and a good portion of it ends up being a dead end (like electrically assisted hyd brakes). But more often than not what is launched in their vehicles finds it's way in to the domestics eventually.

 

 

The Inline 6 offers distinct advantages over a V6. In a package that will be lower cost to manufacture with todays tech applied.

I'm sure this is why Mercedes is looking at going back to Inline 6's it in all likelihood offers a cost and performance advantage. Other wise they would not be exploring it.

 

 

Matthew

 

 

 

 

.

Edited August 3, 2015 by matthewq4b

[jpd80]

Ford has a DOHC TiVCT Inline six, but they are throwing it away in October 3016.

after 56 years continuous production of Falcon and its I-6, all over next year.

 

Edited August 3, 2015 by jpd80

[Pioneer]

Ford has a DOHC TiVCT Inline six, but they are throwing it away in October 3016.

after 56 years continuous production of Falcon and its I-6, all over next year.

 

So, we have 1,000 years to find a replacement?

[twintornados]

What of the Duratorq series inline 5 cylinder? Could Ford bring out a gas version?

[fordmantpw]

 

There is a difference when it comes to drivability. Both the straight-six or boxer-six are inherently better balanced, and smoother, than a 60 degree V-design.

 

I should have added smooth and quiet to my requirements list. Personally, I think the 3.5 V6 in our Flex is rather smooth.

[Project-Fairmont]

GM had an excellent I-6 in its trailblazer. I remember when that Atlas family (I-4, 5, & 6) was being released and GM engineers touted the inline engine wear charactoristics were superior to V or H-opposed engines in terms of piston and cylinder wear on the thrust side. Makes sense, as opposed engines are notorious for oil consumption.

 

While the crankshaft is long and can be unwiedly on an I-6, its usually held in place by 7 main bearing vs. 5 on a V8 and 4 on a V6. A less complicated block with less machining on an I-6 is also a virtue of the I-4 that also has more crank bearings than cylinders (5). Harmonics too are in the octave of a more relaxed place than a busier sounding V6. It really is a shame that they are too long for FWD/AWD chassis.

Edited August 3, 2015 by Project-Fairmont

[matthewq4b]

GM had an excellent I-6 in its trailblazer. I remember when that Atlas family (I-4, 5, & 6) was being released and GM engineers touted the inline engine wear charactoristics were superior to V or H-opposed engines in terms of piston and cylinder wear on the thrust side. Makes sense, as opposed engines are notorious for oil consumption.

 

While the crankshaft is long and can be unwiedly on an I-6, its usually held in place by 7 main bearing vs. 5 on a V8 and 4 on a V6. A less complicated block with less machining on an I-6 is also a virtue of the I-4 that also has more crank bearings than cylinders (5). Harmonics too are in the octave of a more relaxed place than a busier sounding V6. It really is a shame that they are too long for FWD/AWD chassis.

 

For some applications yes they are too long but now with only larger vehicles utilizing a 6 cylinders the switch to housing a longitudinally mounted I6 would be pretty straight forward.

 

Gone are the days of Tempo and Citation sized vehicles housing 6 cylinder engines. With the HP out put of modern 4 cyl engines the 6 pots will be bumped from all but the larger vehicles who are now mostly sporting AWD either standard or optional. We are talking Fusion size and above here. The current Fusion could easily house a 3.0L Inline 6 under hood and drive only the front wheels or AWD.

 

It can be done wit out lot of fuss with the tech available today, 20 years ago such was not the case.

Mercedes is not looking at this cause it is going to cost more than the current V6's they use, there is obviously cost savings and product improvement associated with it.

 

 

Matthew

[RichardJensen]

As has been pointed out earlier, Ford has invested approximately $0 in new I-6 (passenger car) engines.

 

That number matches--roughly--the amount of money invested by Toyota, Honda, Hyundai/KIA, Nissan/Renault, Volkswagen, GM and Fiat.

 

Combined, those companies represent something like 90% of the global auto market (including Chinese JVs).

 

So, no, I don't think the I-6 is on the verge of a comeback.

 

Does the I-6 have advantages over a V6? Yes. Does the V6 have advantages over the I6? Yes. And those advantages are a lot more valuable to manufacturers than the advantages of I6s are to consumers.

Edited August 3, 2015 by RichardJensen