LS Engine Power Stage Build Up

Wake up your LS-engine with four dyno-tested performance packages that really work

Today it’s all about the total package. You wouldn’t order your eggs without salt, pepper and assorted Tabasco sauces, right? Nor can you be a successful football quarterback without the right playbook and talented linemen to protect you. The same goes for your high tech LS engine – and deriving the best power, reliability, drivability and performance all require a well-designed combination of the right parts to reach your ultimate goal.

To achieve the best bang for the buck, you need to select parts that work together as a team. It’s no longer the case of adding stand-alone parts like a set of headers and expecting perfection. And when you start with a sophisticated piece of engineering such as your LS engine, unless you have a performance plan, you could be in for big trouble.

COMP Cams and the COMP Performance Group companies set out to build a series of performance improving packages that fit both the power and budgetary levels of today’s LS-engine (1997-2007 LS1, 2 and 6) owners. For GM truck enthusiasts, who can never have enough power or torque, this five-stage program allows you to add a little or a lot of horsepower. The choice is yours.

As noted, the COMP Performance Group GM Gen III LS-engine upgrades neatly fall into five stages, each featuring a series of power-matched components. These part combinations were selected after countless hours of dyno testing at the COMP headquarters taking the time to dyno test, tune and retest each package. The results are well documented through the SuperFlow dyno charts supplied with this story. For this installment, we decided to include the first four upgrade stages holding the more sophisticated Racing Head Service cylinder head swap for next month. Note that each stage builds on the last. You can’t skip over stages to increase horsepower, each new stage requiring total completion of the previous level.

Note that all of the testing and information contained here can be accessed through the COMP cams website or by calling their toll free CAM HELP hot line and talking to one of their tech engineers – 800/999-0853). If you have any questions, they’d be glad to help (keep the number handy – they even answer questions about other manufacturer’s parts too).

All of the tests performed here were completed on a factory fresh LS1 engine that was rated at 375 horsepower and 370 lb/ft of torque, numbers verified by our COMP’s baseline dyno tests. That makes this powerplant about as common an LS1 engine as is available and a great universal platform to begin our testing.



Stage I
There are plenty of urban legends about the power of hand held programmers. The fact is they can do great things to improve the power, mileage and drivability of your vehicle. The FAST-FLASH Power Programmer is one of the simplest-to-use programmers on the market. The Power Programmer plugs into the diagnostic port hidden under the dashboard of your vehicle. By reading the text in the viewing screen, you answer a series of questions by pressing of buttons on the face of the programmer. Best of all, the programmer remembers your original engine computer settings so you can revert back to this baseline point whenever you desire. It’s really that simple.


To enhance the power programmer’s abilities, the COMP engineers decided to “repair” one of the most common maladies found with LS-series engines with the intention of creating a solid foundation on which to build future power. Simply stated, the factory-supplied LS1 pushrods are weak, so weak that in our early Spintron testing, camshaft lift and duration were both compromised by the amount of pushrod flex encountered. The fix: a set of 0.080-inch wall, 5/16-inch diameter, 7.400-inch long Hi-Tech pushrods. These pushrods fit in the stock location and do not require any cylinder head modification. The final change was to add a set of ZEX V8 performance spark plugs. These high tech plugs are perfect for a street-based LS engine set for the perfect heat range to deliver increased performance, long life and fouling resistance.

With our new parts installed and the FAST-FLASH Power Programmer hooked up, a number of dyno pulls were completed searching for the greatest amount of power increase while retaining drivability factors. The final result by programming the FAST-FLASH to Power Tune setting #2 and leaning out the mixture slightly with a Minus 5 on the fuel/air setting was 11 additional horsepower and 12 more lb. ft of torque.


Stage II

The LS engine is an excellent engine on which to build significant power – a terrific building block. Our Stage II upgrades were focused on building power and the engine’s power foundation – the same mentality as was executed during the upgrade to better pushrods in Stage I.

The biggest change as the Stage II level was the installation of the innovative COMP Cams beehive valve springs (PN #26918). Beehive springs, in Spintron testing, have proven to deliver a host of performance and durability improvements, not the least of which include reducing valve train weight and increasing valve train stability. These single coil, ovate wire springs feature reduced spring seat pressure for better valve control. In addition, for our street/strip application they retain durability for on-street driving but can also handle more rpm and aggressive cam profiles (up to approximately 0.600-inch lift) for racing conditions. COMP Cams has determined that these springs are quicker to react to compression by the rocker system, a logical assumption based on the spring shape which features smaller diameter top coils, which allow quicker compression.

The beehive valve springs use a much smaller retainer, which for our
purposes (and in keeping within our undefined budget) was 4140 chromemoly steel and significantly lighter than the factory steel units. In essence, the installation of the beehive springs with reduced retainer sizing can reduce valve train weight by twice as much as installing a set of
super-expensive titanium valves would (approximately 928grams, or more than two pounds - a huge difference in weight - and cost, titanium valves being in the realm of $2,000 a set).


To take advantage of the performance benefits inherent in the beehive springs and upgrade the rocker ratio function of the engine, we installed a set of COMP Cams Pro Magnum Rocker arms. These heavy-duty, ultra durable steel rockers (made from 8650 chromemoly and covered by a lifetime warranty on the rocker body) feature a 1.75:1 ratio, a slight change from the factory 1.70:1 ratio units. In addition, we bolstered the valve train with new COMP Cams rocker studs and pushrod guide plates, a critical upgrade for this engine application. It is important to note that all of these valve train component changes still allow usage of the factory-supplied valve covers – so know one needs to know what lurks inside your engine but you. The results from all our modifications: a total of 18 more horsepower than stock and 16 more lb. ft of torque.

Stage III

Time for some big power gains? You bet. And what better way than through a camshaft change. As you also might have guessed, the selection of exactly the right camshaft involved a number of different dyno tests. The key was to select a camshaft that delivered excellent power and torque but also maintained decent idle characteristics and the required vacuum for accessories.


COMP Cams recommends the use of their new Type “R” hydraulic roller lifters which extend the engine’s upper rpm range due to reduced bleed down (they do require a 0.002-4-inch preload mandating an adjustable valve train). After installation, a number of camshafts were tested to determine the most significant power improvement. It was clear that the factory lift and duration figures would not suffice (200-degree intake duration, 210-degrees exhaust at 0.050-inch lift, 0.497-inch intake and exhaust lift, 118-degrees lobe separation) for what we had planned.

COMP Cams Xtreme Energy (XE) line of camshafts are designed for street/strip applications where both improved throttle response and top end horsepower are the targets. Both of these characteristics are achieved by using aggressive lobe profiles that require better than OE valve train components – thus the valve train enhancements completed in Stage II of our upgrade program.



The XE-R (PN# 54-444-11) hydraulic camshaft was installed in the normal fashion along with the addition of a bottle of COMP Cams Break-in Lube (PN# 159), which was poured into the engine. COMP Cams recommends Shell Rotella oil for the initial break in procedure (more important for flat tappet engines) as well as it includes many of the break in ingredients not found in many of today’s more common motor oils.

The XE-R camshaft that netted the best performance results featured specifications of 224-degrees intake and 230-degrees duration at 0.050-inch lift and 0.581-inch intake and 0.588-inch exhaust lift (measured at the valve with 1.70:1 factory rockers) with 114-degree lobe centers. Using the same 1.75:1 Pro Magnum rockers and all previous equipment as noted in earlier stages we generated 56 additional horsepower and 36 lb. ft. of torque.

Stage IV
While most of our modifications had addressed mostly internal engine valve train upgrades, it was time to address air intake. The FAST LSX intake manifold (available in both 78mm and 90mm versions) uses an innovative polymer material and is designed to increase air flow without the standard weight penalty found with other aftermarket intake manifolds offered for LS-style engines. In addition, the manifold is compatible with boosted (supercharging and turbocharging) and nitrous engine upgrades as well as the FAST 90mm throttle body (stock sizing is 78mm).


Because we had installed the new higher lift and duration camshaft, we knew it was a good idea to increase the fuel delivery as well. The FAST Fuel Rail Set bolts up to the LSX manifold and greatly increases the fuel available and averts potential starvation.
Installing the FAST LSX intake is a simple bolt up operation and, as was quickly apparent, considerably more substantial than the factory intake. The FAST 90mm throttle body looks massive compared to the factory 78mm unit (the factory intake opening is actually more like 75mm from our personal measurements) and requires a larger inlet air intake system when installed in your car. The 90mm throttle body not only performed well, but also looked great.

Important note: The FAST throttle bodies are only available with a cable throttle system, so those owners using "drive by wire" systems would be best served by installing a factory GM LS2 throttle body (90mm intake only). COMP engineers noted that for those folks focused on torque, the 78mm intake system actually produced slightly better torque numbers than the 90mm, but was not able to hit the same horsepower level.



With our new parts torqued in place and no apparent leaks, it was time to run the dyno again. As we suspected, the horsepower and torque figures once again increased. Compared to stock figures, the new combination with the 90mm throttle body netted 64 additional horsepower and 40 additional lb. ft. of torque.






Stage V
To make really big horsepower, an engine requires increased air and fuel flow. While the factory LS engine is a vast improvement over the small-blocks of yore, its still begs for enhancement. Enter Racing Head Service (RHS), with its Pro Elite fully assembled cylinder heads. (Bare assemblies are also available.)


When it comes to LS-appropriate RHS products, there are two choices relative to the volume of the intake runners: 210 and 255cc. So what is the difference? Well, the obvious difference is the amount of air provided to the engine. Depending on your engine setup, one version will likely perform better than the other.

According to RHS Tech Rep David McCarver, “If you are just bolting a cylinder head to your engine or have done mild modifications, the 210cc head is the right choice. In an engine such as this, you can actually push too much air into the cylinder. Regardless, you will probably see as much as 50 more horsepower from such as swap. It is important to remember, however, that you will need to change the pushrod length here as well, as these heads have a much thicker deck height requiring longer pushrods.”



In fact, the RHS heads have a 0.800-inch-thicker deck, making them suitable for high-power and supercharged applications where the stock head structure can be less than adequate. With the RHS head, it is recommended that you not only step up to a 3/8-inch-diameter pushrod when possible, but that you also utilize a Comp pushrod-length checker (Part #7703-1) to make sure you’ve selected the correct part. Considering that the stock-length pushrods are 7.400-inch long, the new heads will require somewhere between 8.050- and 8.150-inch units.

“The 225cc heads are for high-horsepower, nitrous-equipped, and boosted engines with superchargers or turbochargers,” says McCarver. “If you put the 225cc heads on a stock engine, you will increase the horsepower, but it might make the engine a bit lazy for street driving. While both heads feature CNC machining for consistent performance—and the added benefit of the 4-degree rollback on the valve angle for better port configuration—the 225cc head is definitely the better head for high horsepower and torque, especially when the engine has been...stroked for larger displacement.”



As noted earlier, the 210cc (Part #54210-02) and 225cc (Part #54225-02) heads can be purchased bare or assembled. The assembled heads feature three valve-spring configurations depending on the requirements of the engine builder. For applications where 0.600-inch-lift-or-less camshaft profiles are used, the Comp beehive springs (Part #26918) can be used. For engines running up to 0.650-inch lift, the Comp dual springs (Part #26921) should be specified. For extreme applications where a solid roller camshaft is used, the ultra-performance Comp #943 spring (which will handle up to .750-inch lift) is recommended. (Note that this is a solid-roller-only spring. Using these springs with a hydraulic roller cam will cause engine damage.)






Results
Our Stage V test involved the installation of the RHS 225cc cylinder heads equipped with beehive valve springs. The 225s and beehives were recommended based on our previous modifications, specifically because of the enhanced airflow from the FAST LSX intake and the significantly hotter-than-stock Comp cam.

In addition to the switch to the longer pushrods, we had to revert to the stock rocker-arm configuration. The RHS heads currently are not compatible with the Comp Pro Magnum roller rockers without modification, so the factory rockers were installed along with the appropriate Cams rocker stands (Part #54201). New stock-style head gaskets were used, along with fresh head bolts. (LS engines use “torque to yield” bolts, which cannot be reused.) All of the components used in Stages I through IV (save for the Comp rockers) were reinstalled, including the FAST intake and 90mm throttle body.

Based on the results of our previous test, we were hoping for big things. We were not disappointed. When the dyno finished its calculations, the engine with the RHS 225cc heads increased power a full 108 hp and 68 lb-ft over stock.

It goes without saying that we were pleased with the results of our testing. The five upgrade stages resulted in plenty of horsepower and street compatibility that can be duplicated on any LS1, LS2, or LS6 engine.











Sources:

COMP Cams
Memphis, TN
(800) 999-0853


FAST Products
Memphis, TN
(877) 334-8355


ZEX
Memphis, TN
(888) 817-1008


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Parts List

Stage I
Comp Cams #7638-16 pushrods
FAST #170382 programmer
ZEX #82070-8 spark plugs

Stage II
Comp Cams #26918-16 beehive valve springs, #774-16 retainers, #4854-8 guide plates, #4554-16 high tech rocker studs, #1375-16 rocker arms

Stage III
Comp Cams # 54-444-11, XER273HR-14 camshaft

Stage IV
FAST 90mm intake # 54003, 90mm throttle body #54008 & fuel rails #54023

Stage V
RHS Pro Elite Fully Assembled Cylinder Heads*
- #54210-02 (210cc intake runner)
- #54225-02 (225cc intake runner, used in testing)
*Both heads in this configuration use Comp #26918 beehive valve springs and appropriate hardware.

Additional Parts
Comp Cams #7703-1 Pushrod Length Checker, #54201 Rocker Stands (for factory LS rocker arms)
Extended-length pushrods for compatibility with RHS heads
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