Tech / Tech Projects

Hardcore LS: LME’s 700-Horsepower LS Engine (Part 2)

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The RHS 502 short block anxiously awaits its top-end assembly.

When it came to the long-stroker generating an ample amount of rpm without much work, LME went with a hearty set of COMP’s short-travel race hydraulic lifters. They chose these hydraulic lifters because they have been specifically engineered from a patent-pending design which allows them to perform at higher engine speeds.

Chevy Hardcore wanted a set of cylinder heads that flowed well but also went on just like a factory cyinder head. They decided on a set of RHS’s new Pro Elite LS7 CNC-ported cylinder heads. These are truly the aftermarket’s first high performance LS-style head. These gems feature a 12-degree valve angle and unique, 0.220-inch raised intake runner design, which provides a better line of sight into the cylinders and allows for an improved short turn. The best part is these cylinder heads also facilitate both the stock and aftermarket LS7 intake manifolds and nearly any aftermarket valvetrain setup.

For the correct compression, LME knocked off 0.018-inch of material for 63cc chambers.

A custom set of Ferrea titanium intake and stainless steel exhaust valves control the intake and exhaust flow to exact specifications, The Ferrea titanium intake valves measured in at 2.200- x 0.313-inch stem with a 5.565 x 0.290-inch tip (hard tip with no lash cap). The titanium benefits the valvetrain from shedding unnecessary weight, essentially freeing up more power for a rev-happy engine. For the exhuast side of things, Ferrea built a custom stainless steel set, which measured in with a 1.615- x 0.313-inch stem with a 5.595- x 0.290-inch tip.

A complete set of COMP components, which included dual springs, titanium retainers, locks, Viton seals with steel jackets and machine steel cups, round out the cylinder head assembly.

From there, it was only a matter of installing each, GM LS7 rocker arm for the intake and exhaust valves. What makes using the GM LS7 rocker arm so unique is the simple fact that these are off-the-shelf components. This not only cuts down on overall cost but it also makes them more available in the event of failure. What’s more, these rocker arms will install easily on the RHS cylinder heads without any modifications.

Since this isn’t the average build, the factory LS7 rockers wouldn’t be able to sustain high-rpm abuse for the long haul. To combat this, each rocker arm was modified with the COMP Cams GM LS series retrofit trunion kit. This modification was necessary to convert the stock LS series rocker arms into captured roller trunions for this specific application. It also keeps the valvetrain reliable throughout the entire rpm range. The kit includes all the necessary hardware including the rocker arm trunions, rocker arm bearings, retaining rings and washers.

RHS intake spacers allow the use of standard style LS7-style intakes with tall-deck (9.750-inch) LS aluminum race blocks. The spacers will work with FAST LSXR LS7 intakes, OEM GM LS7 intakes, or any other intake that is designed to work with LS7 heads. The spacers must also be used with LS7-style cylinder heads.

The FAST LSXR intake manifolds’ 3-piece modular design allows for easy disassembly and porting. This new design gives you the ability to remove individual runners from the manifold for modification. The best part is this intake manifold is 50-state legal and C.A.R.B. approved (E.O.D.-279-8).

The combination of a large FAST intake and throttle body should provide plenty of breathing room.

The LS uses a billet Aviaid dry sump oil pan.

The engine control system is the FAST XFI 2.0 system. There really is no other ignition control system that allows its users to process, analyze, and adjust parameters more quickly. The C-Com XFI Windows-based software is easy to navigate and features field-flashable capabilities. This allows users to download the latest software updates through email or directly from FAST. These XFI control units also feature Qwik Tune for programming without a laptop. You can pre-program up to four different EFI maps allowing the ability to optimize a setting for daily driving, one for racing conditions, and still another for fuel economy.

The engine also utiliizes a bevy of additional FAST components, including the FAST MAP sensor, IAC, ACT, Coolant Temp sensor, TPS Switch, Fuel injector harness, FAST 65-lb Fuel Injectors, Oil Pressure Sensor, AIR Temp Sensor, and FAST Billet Fuel Rails for LS7 LSXR intake Injectors.

Heavy-breathing, the RHS 502 proves it’s no chump when it comes to dyno pulls.

Once dialed in, the engine made an impressive 720.3 horsepower at 6,400 rpm and 669.6 foot-pounds of torque at 5,300 rpm.

In part one of Hardcore LS, we told you how Chevy Hardcore and Late Model Engines (LME) were putting together a stout, 700-horsepower LS motor.

But not just any LS motor.

The guys at Chevy Hardcore were looking to build something that could tear up the track during the day and get you home safely and comfortably at night. So they turned to RHS for an aluminum LS race block and asked the guys at LME in Houston to come up with the recipe for 700 streetable horsepower.

We covered the short block assembly in Hardcore LS (Part 1). Now, we’re ready to share the top-end assembly, which features goodies from COMP Cams, FAST, Chevrolet Performance Parts, and more. Get the details by scrolling through the slideshow above and find the final dyno results in the last slide.

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3 Comments

  1. vernon hudson jr says:

    I have a 350 bird 30 over to a 355 what can do to get more hp out of it I have a 300 shoot of nos on it and I would like to go faster

  2. This would depend on what, if any, modifications you’ve already done. Give the guys on the Summit tech line a call and let them know more about the engine–330-630-0240. A 300 shot is pretty stout for a stock bottom end, so they may want to start there.

  3. David, Using the Aviaid 4 stage pump from this build, how did you do the motor-mounts? I’m installing the same pump in a C5 corvette, and if I mount the lower pump turnbuckle to the same front engine cover bolt, it interferes with the motor mount something terrible! Any pictures of it in a car? Thanks, Ben

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