What is the advantage of a FLAT plane crankshaft?

[Kern Dog]

Please forgive the question! I am not trying to stir the pot here, I am actually interested in the answer. I have heard about this concept as applied to certain Ford engines and wondered if there is any inherent advantage in power.
The 4 cylinder engines with opposed rod throws seem to vibrate and seem to need to rev higher to make any power. Is that a common trait ? If so, why? The traditional 90 degree firing order of most V8s produce a similar exhaust tone so I'm guessing the flat plane cranks make a V8 version sound different ?

 

[super-bee_ski]

Kern dog
My post 10 months ago:

Flat Plane Crank:
"So named because its four connecting-rod journals are spaced 180° apart, the shaft appears “flat” in a single plane when viewed head-on. The arrangement generally does away with the large counterweights used in the typical 90° "cross plane" layout which helps reduce crankshaft mass and enables the engine to rev more freely. The new Ford spins to a heady 8000 rpm before fuel cut-off, according to Nair, and has another 250 rpm of safe headroom. This from mildly oversquare 94 x 92.7-mm bore and stroke"

Natural aspirated 750 HP

Rumored to be available in the 2015 Shelby GT 350 R

http://www.forbbodiesonly.com/mopar...lane-crank-being-introduced-in-the-2016-GT350

 

[MarPar]

IIRC Super-Bee-Ski was talking about this a while back...

edit...poof! and there he is!! lol

 

[Richard Cranium]

Kern dog
My post 10 Friggin months ago!!!!

Flat Plane Crank:
"So named because its four connecting-rod journals are spaced 180° apart, the shaft appears “flat” in a single plane when viewed head-on. The arrangement generally does away with the large counterweights used in the typical 90° "cross plane" layout which helps reduce crankshaft mass and enables the engine to rev more freely. The new Ford spins to a heady 8000 rpm before fuel cut-off, according to Nair, and has another 250 rpm of safe headroom. This from mildly oversquare 94 x 92.7-mm bore and stroke"

Natural aspirated 750 HP

Rumored to be available in the 2015 Shelby GT 350 R

http://www.forbbodiesonly.com/mopar...lane-crank-being-introduced-in-the-2016-GT350

Fixed. :toothy6:

 

[Cranky]

RC, are you working today or are you kicking back getting high? :grin:

 

[super-bee_ski]

Too funny RC!

Did I post that?

L O L

 

[Richard Cranium]

 

[Budnicks]

Porsche has used them for decades...

 

[super-bee_ski]

True
-That was a Boxer style engine.
-Now: Ferrari did it with a Race engine. A "V" engine. Small displacement.
-Remember: the size of the displacement is this creatures limiting factor.

But to introduce it into a V8 and be affordable, that was quite a project.
-Kudos to Ford.

More importantly, Ford has seen the writing on the wall.
Ford recognized the trend, and it was not the "all ever lasting" GM LS series engines...
-Even GM is BLIND, that LS series is Archaic.

I'm not saying the Flat Plane is the most advantageous of all of the V8 designs.
I DO believe Ford "Has something up their sleeve" so to speak.

Quite frankly, the Hellcat is top dog right now unless you want to start looking into the Viper V-10 Aluminum engine and associated race packages.

 

[lewtot184]

it didn't work on race hemi's in the late '60's.

 

[Photon440]

Simple answer Kern Dog: flat plane cranks are both cheap and easier to build, and with less weight can rev faster. As you suspect, they do vibrate more.

The first Ford V-8 flathead used a flat plane crank, as did other early makers (1915 Cadillac, 1929/30 Olds and Pontiac for example) but Henry Ford was finally convinced after a couple years to switch to 90 degree cranks for smoothness. Cadillac, with it's higher pricing, already started using the 90 degree cranks in 1923.

 

[Kern Dog]

Thanks gentlemen....

 

[Richard Cranium]

Thanks gentlemen....

Even me?

 

[lewtot184]

those cranks turn a v8 into a v4; two cylinders firing at the same time. it's my understanding that 2.5 liters (153cuin) is the largest a 4 cylinder can be built to due to vibrations. i'm not an expert on the hemi 180 degree crank engines but if the 2.5 liter rule is true then the 426cuin "4 cylinder" hemi must have been awful.

 

[HT413]

Even me?

Let me fix that for ya...

- - - Updated - - -

Thanks gentlemen.

There ya go. Guess he wasn't talking to you after all.

 

[Kern Dog]

those cranks turn a v8 into a v4; two cylinders firing at the same time. it's my understanding that 2.5 liters (153cuin) is the largest a 4 cylinder can be built to due to vibrations. i'm not an expert on the hemi 180 degree crank engines but if the 2.5 liter rule is true then the 426cuin "4 cylinder" hemi must have been awful.

Mitsubishi had a 2.6 inline 4 in the 80s.

 

[lewtot184]

Mitsubishi had a 2.6 inline 4 in the 80s.

it had a balance shaft to keep it smooth and is long obsolete. to my knowledge nobody does that stuff anymore. technology has moved on.

 

[Hemi Rebel]

it had a balance shaft to keep it smooth and is long obsolete. to my knowledge nobody does that stuff anymore. technology has moved on.

Nobody does what? Balance shafts? Sure they do

 

[lewtot184]

Nobody does what? Balance shafts? Sure they do

who?

 

[Photon440]

For starters, the current Chrysler 4 cyl. and the Hyundai / Mitsubishi variants use balance shafts.