Discovery Turbo TV

The Dirt Heads fix up Dave's red Chevrolet to clear 40-inch tires and head out to find bigger rocks; Fred and Dave order big rubber and head to Johnson Valley to attempt the Backdoor Trail.

The crew dives into the relationship among cylinder head flow, liberal application of boost and horsepower.

The guys run back-to-back tests with 87, 91, 110, 116 and even E85 to see if higher octane can make more power, and if an engine's optimal timing even changes with different octane.

The guys outfit their Ford 363 with a Demon 650 blow-through carb and Holley's new Super Sniper Stealth throttle-body-style EFI to determine which will reign supreme.

The guys find out if mandrel-bent exhaust pipes really make more power over the crimped and crunched pipes the local shop bends up.

The crew tests 10 different filters in a hunt for the best units available.

The guys test five carb hats and see how orientation affects performance.

The crew is searching for low air temps and big HP numbers as they compare the heat-extracting power of under-roots intercoolers vs. E85; they aim to bring up the entire curve by swapping the short-runner blower manifold for a tunnel ram.

The crew auditions their 406 SBC with an out-of-the-box Super Victor, a port-matched Super Victor and an off-shelf Wilson-prepped version.

Testing the headers, intake, fuel system and everything else that will be used in David Freiburger's Model A drag car.

Holley carbs have been the standard by which all racing carbs are measured, but CFMs are equal; looking at the difference in power between the smaller-bore, narrower-set 4150 carb and the bigger-bore, wider-base 4500 Dominator.

The crew looks at compression and how it makes power plus how sensitive it becomes to temperature on pump gas.

It's a battle between the iconic 440 Six Pack and the legendary 426 Hemi.

The guys demonstrate how improved airflow on a small motor equals pure RPM.

The crew explains the difference between standard, high-volume and high-pressure oil pumps in terms of pressure, flow and horsepower.

The crew tries to find the right balance of decibel levels and performance.

It's a battle of price vs. power for street-centric wedge cylinder heads.

The crew dives into the waters of individual runner systems, shows how to tune them, and whether all that cool makes any more power than the stalwart carburetor.

The guys study the fueling demands, horsepower, and the pros and cons of running different types of fuel.

The guys explore the cooling benefits of water-methanol injection.

The guys test air filter size, along with cold air system configuration.

Using a basic 150-horse plate system, the crew demonstrates the basics on installation, safety and tuning for a typical carbureted engine.

We explore the differences between single and split-duration camshafts.

Testing intake upgrades for a street car swap; pitting the factory manifold against a worked-up aftermarket piece.

The guys perform what may be the first ever back-to-back comparison of factory-oriented pistons against reverse-oriented pistons.

The General Mayhem 440 is strapped on the dyno and decisions on which intake and headers to run, as well as how to squeeze out more than the 707 Hellcat horsepower, are made.

Some know valve float as the evil that lurks beyond the redline, the dreaded robber of horsepower and destroyer of valves; taking a look at the valve float.

The team tears into a 1962 Chevy truck; Joe Martin plans to create a radical custom lowrider that scrapes the ground; improvements include a new air-ride suspension, tray, front end and paint job.

Joe has big plans for a 1964 Lincoln Continental, but a faulty steering column and a close call in the shop threaten to turn the flip into a never-ending money pit.

Joe and the gang turn a 1953 Ford Ranch Wagon into a mean beach cruiser; an accident occurs in the shop; the race is on to repaint a client's custom-built bike.

Joe and the team work on a 1973 Pontiac Firebird that was damaged by fire; a waterlogged engine puts the brakes on the build.

The team tackles a custom Softail from the ground up; Shag and Amanda discover a 1947 International milk truck in need of repair; a customer brings in a 1955 Chevy race car.

Joe believes that wide wheels and a killer paint job will attract customers to a 1964 Cadillac Coupe DeVille convertible, but hidden rust on the vehicle threatens to spoil his planned improvements.

Martin Bros. Customs prepares to transform a 1970 Chevy C10 into an autocross hot rod; Shag and Amanda desperately search for a sturdy cab for the build.

A 1935 Chevrolet Master rolls into the shop; made famous by the gangsters of its time, the vehicle features a distinctive grill, wood interior and "suicide doors.".