Piston Slap: Flat Plane Crankshaft Design?

 

My 98 booming with a trunk of funk, Don't Believe the Hype. (photo courtesy: Ford)

GCH writes:

Sajeev:

Could you/somebody please explain what a "flat plane crankshaft" is in the new Mustang GT350, and older Porsches and Ferraris?

I have seen numerous references to it online and in print but nobody, including Wikipedia explains it in non-calculus terms.

Sajeev answers:

Dumbing it down sadly glosses over hundreds (thousands?) of salient details in casting technology and/or computer-aided design. But I left Engineering school for a reason, so let's simplify: rest a flat plane crankshaft on a table and it's flat like a sheet of paper.

Ford Powerstroke 6.0 crank (photo courtesy: mkmcustoms.com)

Ok, maybe not "paper flat" with those boomerang counterweights at the ends…but compared to the crossplane crank in most V8 passenger vehicles?

LS9 crankshaft. (Photo Courtesy: General Motors)

Crankshafts, like damn near everything else in our lives, benefits from the KISS principle. A flat plane crankshaft has the potential for significant weight savings to optimize a motor's moment of inertia and more even firing to benefit the exhaust stroke, allowing for more revs/horsepower. And that unique sound!

But NVH control is a problem: hence widespread adoption of crossplane crankshafts.

Which means flat plane crankshaft-ed Mustangs shall be completely pointless moot when trapped, idling at a red light in American surburbia…which is precisely where 88.7% of Mustang GT350s shall live. 

The stock Coyote V8 is a better option, cool/brag factor aside. Why? Because it's got a damn good crank, and here's 8000+ reasons why:

Click here to view the embedded video.

When comparing modifications side-to-side, will a modified GT350 rev harder and make more horses than a similar GT?  Probably.

Will it, in the process, lose valuable low-end torque needed on the street?  Probably.

So go kick some GT350 ass with the Mustang GT's phenomenal aftermarket support, of which many retain the factory warranty. Come on Son, were you expecting breathless PR boosting for Ford's latest hot one from TTAC?

 

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you're in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

The post Piston Slap: Flat Plane Crankshaft Design? appeared first on The Truth About Cars.

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