The changes were first evolutionary, but around the dawn of the 21st century, new ground-up engine designs like the GM Gen III LS small-block, Ford Modular engines, and Chrysler 5.7/6.1 Gen III Hemi appeared. The goal of 21st-century cylinder head engineering is controlling and managing the combustion process by combining radical combustion chambers with new port layouts to improve mixture motion. By equalizing variations in cycle-to-cycle and cylinder-to-cylinder flow, less compromise in timing and fuel delivery are needed to cover the worst cylinder or valve-lift point.
SWIRL IN IC ENGINES
“Swirl”—the rotational motion of the incoming air charge about the cylinder’s axis as it enters the combustion chamber on a two-valve head—is determined by the intake valve’s position relative to the bore axis, the chamber shape around the intake, and any helix in the induction tract. Swirl is maximized by paying careful attention to a wedge head’s valve positioning. Think of swirl in an IC engine like the vortex generated by a flushing toilet. Swirl should always be in one direction; swirl that changes direction at different amounts of valve-lift leads to unstable combustion, requires more ignition lead, and reduces knock-limited power potential. Optimized swirl-port heads sometimes flow less air on a flow bench but still yield measurable power gains on a running engine.
TUMBLE IN IC ENGINES
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Dress it Up
HOW TO MAKE AN LS ENGINE LOOK AND PERFORM BETTER
Solid & Striped
The Lokar/Street Rodder ’34 Ford 3-Window Coupe 25th in a Long Line of Road Tour Hot Rods
Is It Better to Change Oil Hot or Cold?
It seems intuitive that if time is not a factor, the most thorough way to change engine oil is by letting the car sit overnight, then next morning allowing the oil to drain out of the sump for several hours.
EBONY ICON
Alloway’s Hot Rod Shop Builds the Ultimate LSX-Powered Chevelle
WHEN CHEVROLET INTRODUCED THE “ALL NEW” 1958 IMPALA, IT REALLY WAS!
We take a look back at the introduction—and road test—of the 1958 Chevy Impala.
Classic Car Rust Prevention: How to Seal the Floor Pan of Your Ride with POR-15
So, you bought a “new to you” project car and want to start the build right. That means tearing out the interior and making sure the floor pans are sealed and rust free. If you find Swiss cheese, check out “How to Fabricate and Install Replacement Floor Pans” on hotrod.com on how to replace your floor pans. If you find minor surface rust and the occasional pinhole, keep reading and we’ll show you everything you need to know about classic car rust prevention.
COYOTE COUPE
This 1967 Mustang Is the Perfect Blueprint for an Engine Swap
California Coastal Road Trip
Like many people around the country, we have had little occasion to travel this year. With car shows and events like the Power Tour and Drag Week postponed and rescheduled due to the coronavirus, we’ve mostly been stuck at home. I recently had occasion to travel to Santa Rosa, California, for a photo shoot with Scott Birdsall, owner/builder of Old Smokey, the Cummins-powered Ford F1 that beat the diesel-engine record at the Pikes Peak International Hillclimb. Motor Trend’s William Walker was the shooter, with me serving as assistant and camera car driver. It seemed like as good excuse as any to make a trip out of it.
25 Years of the Crusher Camaro
I’m gonna tell the story of the Crusher Camaro because it’s celebrating 25 years as a project and because it’s presented me with a fresh dilemma. The story begins in 1994 when California law allowed gasoline companies to crush older cars in exchange for smog credits that allowed continued polluting from wells and refineries.
What Is Cylinder Head Swirl and Tumble, and Why Is It Important?
We think of electronic engine management systems and multiport electronic fuel injection (EFI) as primarily responsible for the improved air/fuel distribution and performance as Detroit clawed its way back in the mid 1980s, but—good as they were for that day—initially the new electronics were just Band-Aids grafted onto carryover engine designs. The big change started in the 1990s, when the OEs started tinkering with cylinder head design to induce swirl and tumble in internal combustion engines.
ELECTRIC TRUCK MAKER HITS 100,000 ORDERS AHEAD OF FALL START
An upstart electric vehicle maker said that it now has more than 100,000 orders for its new pickup truck.
The station
A venue with a vintage vibe
PROJECT OBSESSED
COOL DOWN AND STOP IT
COMPLETE OIL CHANGES
REMOVING THE LAST TRAPPED QUART FROM THE DURAMAX, WITH PPE’S UPGRADED OIL PAN
HORSEPOWER WARS
FORD UNDERRATING THEIR 2020 SUPER DUTY?
THE SAME OLD – OVER AND OVER
RELOADER’S PRESS
KEEP ON TRUCKING
NOT EVEN A PANDEMIC CAN STOP AMERICA'S LOVE AFFAIR WITH THE PICKUP TRUCK
2022 GMC Hummer EV Pickup
An Off-Road Icon Reborn
THE TIMELESS DAVE MASON
MIKE GREENBLATT CHATS WITH DAVE MASON ABOUT HIS LATEST ALBUM RELEASE AND, OF COURSE, HIS TRAFFIC DAYS.
STILL SEARCHING
THE SEARCHERS GUITARIST/ VOCALIST MIKE PENDER REMINISCES ABOUT THE BRITISH INVASION AND THE HONOR OF RECEIVING A PRESTIGIOUS AWARD FROM PRINCE CHARLES IN 2020.