Posted on 11/26/2015 8:03:34 PM PST by MtnClimber
Flat-plane engines This term has become one of the buzz words of 2015 thanks to Ford’s stellar Voodoo V8 (covered previously by us) found in the Mustang GT350. With 526 horsepower and a soundtrack like this, it’s easy to see why it has been attracting attention. Rather than the loping burble of a traditional V8, the sound of a flat-plane engine is much tighter. It’s a tenor to the cross-plane V8’s baritone. However, flat-plane production engines are not a new concept, as Ferrari and Lotus have been using them for years.
The engine in the 458 Italia, for instance, is a flat-plane crank engine. That’s the real term as it describes the construction of the crankshaft of the engine. Before we dive into the technical details, opportunities, and limitations of flat-plane crankshaft engines, watch the short animation below that displays a flat-plane crankshaft and a cross-plane crankshaft, which is what most V8s use, in action.
The Ford GT350 has been getting great reviews. The Ferrari 458 Italia is a legend with it’s flat plane V8.
Crankshafts have always struck me as being extremely difficult to manufacture, tho I guess they have had it figured out for a long time.
I do recall a historical restoration of a Messerschmidt ME-109. They found a crashed one buried in the ground in England. Fortunately they engine was relatively undamaged.
Rolls Royce agree to rebuild it but warned the people who recovered the engine to be extremely careful of the crankshaft as they would never be able to replace it.
A “flat-plane” has the throws on the crankshaft spaced 180 degrees apart, rather than placing successive throws at 90 degrees apart from the adjacent forging.
This does seriously modify the firing order of the pistons, and the exhaust note that results.
Designing an engine is a pretty major accomplishment. Designing one that runs smoothly is an even greater accomplishment.
For smooth, about nothing could beat an old straight-eight.
The balancing has to be very good and there are oil passages needed to supply oil to the connecting rod bearings.
You mean Packard’s Straight 8’s?
I saw a Packard V12 once. Art. (At Peterson Museum in L.A.)
Straight eights were high tech before WWII. The first dragster Don Garlits built had a modified Buick straight8.
When Buick came replaced their aluminum V8 and V6 (selling that 215 cu in V8 to British Leyland was one of the dumbest moves on GM’s part) with the 300 cu in V8, the V6 was basically the same, the obvious difference was the 2 rear cylinders lopped off. Both engines shared piston and valve assemblies, but the V6 crankshaft needed to be balanced differently because of vibration issues specific to a V6 design.
A well-tuned Packard straight-eight at idle speed, you could balance a nickel coin on its edge atop the engine head, and would simply stay upright, no jiggle or roll. Altogether a different piece of machinery than the V-12’s, which were also modified into aircraft engines.
That old Packard could tick over about 300 RPM, and be near whisper-quiet. In the Second World War, three of those V-12’s were used to power a PT boat, and when all three of them were running and engaged, well, that is why the PT boats gained their reputation for fast, top speed about 40 knots. The Packards were well respected.
We were using flat cranks in our race engines 20 years ago.
I test drove a Hudson once... that was one smooth ride... thing was so heavy I think the pavement was yielding under the car.
Yes, but post-war the build quality seemed to take a dive.
Don't know why. Todays metallurgy is more advanced. Modern CNC offset grinding could reproduce virtually anything.
“For smooth, about nothing could beat an old straight-eight.”
True dat. The mechanics of a V-8 can come close with a lot of work (especially before computers), but not really equal what a straight-6 or 8 can do naturally.
“Don’t know why. Todays metallurgy is more advanced. Modern CNC offset grinding could reproduce virtually anything.”
Well, anything can be done if you have enough money. And if the original crank was forged, that might be a heck of a lot of money, CNC or not.
The numbers don't match on the 300 in it... doesn't have the aluminum heads of a '64, and it's got a dinky little 2bbl Rochester.
I am wondering if I should gonapeshit and find a 455 to dump in it and rebadge the thing as a early GS fantasy rig or some such... Riiiiight!
Quarterpanels first... good luck with that.
What kind of race cars were these engines for?
But doing a crank for an ME 109, you're not going to find a casting. It more than likely WILL be a forged billet. Probably in the $3k-$4k range.
Small block chevy in the 600-650 hp range.
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