The cylinder head is one of the most vital components of the engine when it comes to building big horsepower, and that’s especially true in an LS application. After all, an internal combustion engine, in a basic sense, is an air pump. The more air and fuel you can burn is determined by the amount of air you can pump into the engine. In turn, more horsepower will be produced.
Being the main component that flows air/fuel in and exhaust gases out, it’s vital that engine builders looking to build high horsepower engines for race applications find a cylinder head that best fits their application. While it might seem like a smart move, utilizing the biggest possible cylinder head is not always the best move.
The LS engine is known for its cylinder heads, and there are tons of options available to upgrade the factory components. However, it isn’t necessarily a platform that needs an upgrade to support high-horsepower outputs. The LS3 and more notably the LS7 are deep breathers – the cylinder heads boast extremely good airflow for factory components.
Optimization is the name of the game, and with such a vital component at play, machine shops and manufacturers are always looking to improve on designs, even if they are already good. When you’re dealing with extreme amounts of horsepower in drag racing applications, you can only go up.
One cylinder head we’ve had the privilege of checking out is made by All Pro Aluminum Cylinder Heads. They’re a small machine shop located outside of Columbus, OH that’s made a name for itself crafting exceptional aluminum cylinder heads for small block Chevy and Mopar engines.
At PRI a couple years back, we visited their booth and checked out their 12-5 cylinder heads for LS engines. Big boost and big rpm are what these heads are made for, as they’re able to support horsepower numbers up to 4,000.
Weight reduction was a huge part of the development process in the design; the deck is 1” thick but many areas of the heads were cut back where possible without forfeiting strength. The head has custom profile exhaust ports that are moved in a different direction than standard LS heads and the intake runner is also located in a non-ordinary position.
All Pro offers these heads with o-ring surfaces on the valve covers and intake face. And there’s even an option for o-rings on the exhaust side too. Combustion chamber sizes are available from 65cc to 40cc.
Cylinder heads that can support power that high are crucial in the drag racing scene. Take Morris Malone’s record setting 2018 half-mile run where his C6 Corvette became the fastest RWD car in the world. The Corvette was powered by a 400 cubic inch Dart LS Next block from Late Model Engines that makes 2,800 horsepower. The beast revs out to about 9,500 rpm, which wouldn’t be possible without a great set of cylinder heads. Edelbrock LS-R canted-valve heads were used to keep it happy.
Houston-based shop, Late Model Engines, specializes in LS and LT engines, and when it comes to performance, they’re always looking to find the next greatest upgrade to manufacture.
“We’re really doing a lot of development with our canted-valve Edelbrock LS-R head,” says Late Model Engines co-owner Bryan Neelen. “It’s been around for quite some time, but it was definitely ahead of its time in terms of reliability and optimization.”
The heads are designed for all-out racing applications and work well with the GM LSX block. Special features include a canted-valve, symmetrical-port arrangement, additional cooling, provisions for additional head bolts and the heads are HIP (Hot Isostatic Pressing) processed for extra strength.
HIP casting has been around for a few years now, but its becoming much more prominent in cylinder head development. Each aluminum casting has microscopic air bubbles trapped in it and using HIP eliminates them and enhances the overall strength of the head. In the process, a raw aluminum casting is placed into a pressurized oven at around 900 degrees F, then the oven is filled with argon to eliminate oxidation. The pressure inside the oven will continue to increase until around 10,000-15,000 psi when the aluminum will compress and squeeze out the air bubbles.
The LS-R heads come with very small ports and 25cc combustion chambers. The exhaust valve has an angle of 7.0 x 2.0 degrees, and the intake has an angle of 8.7 x 3.2 degrees. This allows for machinists to have extra freedom in sizing and shaping the ports and designing the combustion chamber.
“We have more development to go with the LS-R, both in the shop and out on the track,” Neelen says. “What I’m most proud of doing is the use of SolidWorks and other CAD modeling technology that we have to create out ports. It’s given us a lot of versatility in making small changes more rapidly and modeling our ports so that they’re safe, yet maximize airflow.”
That’s ultimately what any builder would want from their cylinder head – it might be nice to have something that can produce a ton of power, but no one wants leaking water due to a crack six months down the road. Reliability and strength is the name of the game. EB
