Flat plane vs. cruciform V8 explained

[matthew1]

I thought this did a good job of explaining it: https://www.motortrend.com/how-to/diffe ... ne-cranks/

What Is A Cross-Plane Crank?
The most common crank we see in our hot rod engine builds is a cross-plane (also referred to as a cruciform) crank. This crank gets its name from the four crank pins that are positioned in two planes, offset by 90 degrees. Typically the two outer pins are perpendicular to the outer and the two end pins are in one 180-degree plane.

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[BlackBart]

That's what gives a traditional American V8 that satisfying rumble at idle and roar at WOT. And what gives a Ferrari, Cosworth, (etc) V8 that high pitched wail at high rpms. They spin faster.





Mustang flat plane crank V8 (bigger displacement)


Corvette C8.R testing at Sebring (5.5 liter)

[abscate]

I’ve never noticed those noises before in the T5 but they are always behind me …..

[BlackBart]

Another fun variation - the traditional cross-plane V8, but with "180 degree" headers, where the 2nd and 3rd primary pipe on each head is routed to the opposite side collector. It helps with exhaust scavenging at high rpms in race motors. Very successful in the Ford GT40 in endurance racing.

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And the best part, it sounds....like this!.....

[BlackBart]

On the topic of a flat-plane V8, this is a really good overview of the design of the new "LT6" V8 in the new mid-engined Z06 Corvette. The most power out of a naturally aspirated (production) V8 ever.

https://www.hagerty.com/media/maintenan ... ombustion/

The V angle and the bore spacing are the same as the classic 1955 small block, for tradition, but it's a completely new engine design.

Their design goals and compromises dealt with making traditional big low end torque while being able to produce high rpm power. The key ingredients were good-sized displacement (5.5 liters), good sized bores, a short stroke, a flat-plane crank for high rpms, very lightweight but strong components, double overhead cams with 4-valve heads, and a very clever induction system to take advantage of cylinder air pulses and timing. All of that conveniently fits the 5.5 liter FIA rules for endurance racing at Le Mans etc next year.

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[BlackBart]

A whole different sound - like two 4 cylinders working together, the difference between a 6-string and 12-string guitar.

[abscate]

My RaceBeetle has a bigger wing