Video: Billy Briggs Turns Out Insane Naturally Aspirated LSX

Putting together a small-block engine to make nearly 1,000 naturally-aspirated horsepower is not a task for the faint-of-heart, but longtime LS engine builder Billy Briggs of Motor City Speed is intimately familiar with the requirements.

Briggs handled the dyno tuning with ease - the engine was shipped to the customer across the pond in Bahrain.

Briggs handled the dyno tuning with ease – the engine was shipped to the customer across the pond in Bahrain.

“We use a dry sump in this engine – at this power level and RPM, we have to use a dry sump system to keep the valvetrain and engine alive,” says Briggs. Experience has taught Briggs the oiling system is paramount in this type of application; he installed a complete dry sump system from Dailey Engineering on this engine.

Naturally-aspirated power comes as a result of one thing and one thing only – airflow. In order to provide the most airflow possible, Briggs spec’d out this particular LS engine with 471 cubic inches of fire-breathing fury. That displacement was achieved through the use of a 4.200-inch bore and 4.250-inch stroke. A tall-deck LSX block from Chevrolet Performance was used, along with a Callies billet crankshaft, Callies Ultra connecting rods, and Diamond pistons that boost the compression ratio to 15.0:1.

In order to support this level of airflow, monster intake and exhaust ports are required to provide maximum performance. Without a power-adder, the engine made 956 horsepower on a soft tuneup.

Interestingly enough, this particular LS engine is destined to be delivered to a customer in Bahrain for a Fox-body Mustang drag machine.

The racing class rules where this engine will compete requires the use of a cast single four-barrel intake manifold, and although it appears to be a billet piece Briggs says that it starts out as a two-piece casting that’s been treated to an immense amount of welding inside and out, prior to being shipped out to be machined to its final dimensions.

The cast intake manifold has been modified to support the massive level of airflow this engine needs.

The cast two piece intake manifold has been fully modified and is topped with an Accufab four-hole throttle body.

The airflow is helped along by a set of fully-ported Mozez cylinder heads from Mast Motorsports, the aforementioned intake manifold, and a monster Accufab 8500 throttle body. The rest of the valvetrain consists of .937-inch diameter Jesel keyway lifters, a Bullet camshaft that uses 60mm bearings, Jesel shaft mount rocker arms, and Trend Performance pushrods.

PAC springs and retainers are used. With valvetrain weight a critical part of the engine’s ability to rev, titanium valves from Ferrea are installed in both the intake and exhaust ports.

“We ran the engine on C16, but it will ultimately be run on alcohol. That’s the reason for the low power numbers; when we ran it on the dyno we were only after the power curve to get the converter figured out, and the engine was 8 to 10 degrees short of full timing. A curve is a curve – there is no need to beat it up on the dyno to get a big number. Since it will run on alcohol and not gasoline, the number is irrelevant anyway,” says Briggs.

Degreeing in the camshaft to the proper specifications.

The video reveals that the engine comes up quickly when the hammer is dropped, screaming to 956 horsepower at 8,000 rpm and 695 lb-ft of torque at 6,700 rpm.

“We used BigStuff3 to tune this engine. We make a base calibration for it from our previous knowledge. We put together a fuel and spark table, monitor the air/fuel ratios and keep plucking away at it until we get the right ratio and the right timing. A lot of it comes down to reading the plugs,” says Briggs. “Our air fuel target is between 12.8 and 13.2:1; that is generally a safe area but is affected by lots of variables.”

About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
Read My Articles

Horsepower delivered to your inbox.

Build your own custom newsletter with the content you love from EngineLabs, directly to your inbox, absolutely FREE!

Free WordPress Themes
EngineLabs NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

EngineLabs

We'll send you raw engine tech articles, news, features, and videos every week from EngineLabs.

EngineLabs

EngineLabs NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

EngineLabs

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...



Late Model LS Vehicles

Drag Racing

Muscle Car & Hot Rods

EngineLabs

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Late Model LS Vehicles
  • Drag Racing
  • Muscle Car & Hot Rods

EngineLabs

Thank you for your subscription.

Thank you for your subscription.

EngineLabs

Thank you for your subscription.

Thank you for your subscription.

Loading