Automotive Engineering - September 2021 - 11

TECHNOLOGY REPORT
each blip of the throttle. Ford's 5.2-L
DOHC flat-plane-crank V8 that powered
the 2016-2020 Ford Shelby GT350
Mustang was known both for its willingness
to rev - redline 8,250 rpm - and its
captivating exhaust snarl.
Road-car engineers, especially
those at Ferrari, relish transferring
these technical advancements from the
track to the street. Before turbocharging
and hybridization were adopted at
Italy's renowned sportscar maker, their
smallish V8s employed flat-plane
crankshafts to produce both exemplary
horsepower and a rousing exhaust
shriek. With their modest displacements,
second-order shaking was less
an issue.
A Ferrari V8 aural " soundtrack " is
more exhilarating than those of
American V8s because their smaller
piston displacement allows them to rev
faster to higher rpm. Also, the exhaust
pulses leaving each bank of cylinders
are evenly spaced.
That last attribute is key to optimizing
volumetric efficiency and maximizing
horsepower. In the cross-plane
crankshaft 6.2-L V8 powering the 2022
Corvette Stingray, the firing order is
compromised with the third cylinder in
the left bank firing immediately after
the first cylinder in that bank. That
means there is only 90 degrees of crank
rotation instead of a Ferrari V8's 180
degrees between those two exhaust
pulses. This diminishes the scavenging
benefit resulting from the flow exiting
one cylinder helping to draw exhaust
out of the next. It's also easier to optimize
intake airflow when each cylinder
bank draws a breath every 180 degrees
of crank rotation.
Flat-plane LT6 only the start
With dual overhead cams, four valves
per cylinder and variable intake and exhaust
timing, SAE-rated output for the
upcoming flat-plane-crank LT6 should
top 600 hp (447 kW) at an estimated
8000 rpm and 450 lb-ft (610 Nm) at
6000 rpm. Experience gained racing the
Corvette C8R powered by a flat-crank
5.5-L DOHC V8 for two seasons in the
IMSA WeatherTech SportsCar racing
S
AUTOMOTIVE ENGINEERING
c a f l
r A t m t v
n i e r n
d C 0 _ 0 1 i d
Free Info at http://info.hotims.com/79444-706
series has expedited development, confirms
a senior engineering executive at
GM Propulsion who was not permitted
to speak on the record.
There's more. Informed speculators
insist there's an LT7 engine next in line to
power the 2024 or 2025 Corvette ZR-1.
This twin-turbocharged variant of the
flat-crank 5.5-L V8 should up the ante to
at least 850 hp (634 kW) and boost
torque to around 800 lb-ft (1085 Nm).
Don Sherman
AE Schaeffler Ad 0921.qxp_1/2 Page Island 8/13/21 6:50 PM Page 1
Nothing is more impressive than a clever
idea that no one expected.
We pioneer motion
Making complete electric motors ourselves may have been a surprising
decision, but it was a logical one, too. We have comprehensive experience
with mechanical components, production processes, and winding
technology, as well as an understanding of how vehicles work as a whole.
This enables us to create a range of exceptionally efficient motors-
something that may surprise many people. we-pioneer-motion.com
h e e _ u o o i e E g n e i g A _ _ 2 2 2 . n d 1
f
2/4/21 3:32 PM
September 2021 11
KATIE JUNGJOHANN
http://info.hotims.com/79444-706
Automotive Engineering - September 2021

Table of Contents for the Digital Edition of Automotive Engineering - September 2021
