As a country and a society that lives for the latest and greatest technological advances, it's often helpful to reflect back on our progress. Before the latest GM offerings in the small-block lineup a clean-slate design small-block was introduced to the public in 1997 as the LS1. Initially put into the Corvette C5 and later transplanted into almost every GM performance vehicle, the Corvette spec LS1 put out 345 hp at 5,600 rpm and 350 ft-lbs of torque. Seeing that the latest mouse motor displaced 346 ci, the LS1 was right at the magical mark of 1 hp per cubic inch. Although phased out of production in 2004 and replaced by the evolutionary 364ci LS2, the LS1 continues to receive its fair share of attention, along with cutting edge research and development. Within the LS1 community, nothing is more tried and true than finding the "right" camshaft or bolting on a set of ported heads to transform the little 346ci engine into a truly beastlike, mega cube performer. The aftermarket has stepped up and supplied almost every imaginable grind of camshaft along with a far-reaching palate of factory and ground-up cylinder head designs. Although the trend in the industry is to "step-up" to larger cubic inches by either stroking the LS1 or LS2, the budget-conscious stock cube LS1 owner still wants a magic bullet to maximize the potential of the engine at the most reasonable cost.
Enter Texas Speed and Precision Race Components. As a full-service speed shop and manufacturer of race quality components, the Lubbock, Texas-based business has been at the forefront of the industry in developing late-model GM components and packages designed to maximize the power of the LS1. The 8,000 square-foot complex includes a showroom and shop along with a chassis dyno. Recent additions to the business include dedicated areas that house state-of-the-art CNC machines for cylinder head porting and performance valve jobs plus diagnostic and testing equipment.
According to Jason Mangum, co-owner of Texas Speed, "In 2004 we formed Precision Race Components to fill a void in the market for low-cost, high-quality factory-based ported heads and related valvetrain components. Although there are all manners of aftermarket heads available on the market to satisfy the hard-core racers, the average enthusiast is more focused on maximizing engine performance on a budget. With the stock displacement LS1, cam-only and heads/cam packages are extremely popular. By utilizing a set of our PRC Stage I heads, the enthusiast gets a set of brand-new, CNC-ported castings that will support significant horsepower gains. To that end, we are now introducing the fourth revision to our "Magic Stick" line of camshafts, designed to be the largest cam out there for 346ci applications without having to perform any modifications to provide adequate piston to valve clearance. Our '98 automatic Z28 previously went a best of 10.51 at 125 mph with a Magic Stick 3 and stock unported 241 casting cylinder heads."
With a max-effort affordable LS1 in mind, it was off to the flat-lands of West Texas to join up with Texas Speed and spend some quality time inside an engine dyno cell to find out just how much power could be coaxed out of an LS1 on a budget. In addition to a cam-only test, a set of Precision Race Components CNC-ported LS6 heads with stock valves will be put under the microscope. But why stop there--let's find out if additional horsepower lies in wait in the induction system, namely by swapping in a F.A.S.T. intake, Precision Tool & Machine 80mm throttle body and SLP 85mm MAF.
Co-owners Jason Mangum and Trevor Doelling, along with lead technician Joseph Potak, will be thrashing on the LS1. After wrenching and replacing the parts, we'll show you how much power was added to a bone stock 2000 LS1 engine. Just how much power can be elicited from the mighty mouse, and what will it cost the consumer? Let's find out.
Testing Facility and Protocols: All testing was completed at Sunset Racecraft of Lubbock, Texas. The dyno facility is equipped with a Dynamic Test Systems, Inc. (DTS) model 4000G engine dyno operated by Steve Figueroa, a School of Automotive Machinists graduate. All testing was done with the stock 2001 LS1 computer which was connected to the motor via a Superior Harness aftermarket wiring harness. VP 101 octane unleaded was utilized in the cell, fed to the engine via the shop's Aeromotive fuel pump and regulated to 58 psi. Dyno headers provided by Sunset were a set of Kooks 1.875-inch units that were modified with longer primaries and collectors (35-inch primaries and 8-inch collectors) to provide adequate clearance on the dyno. In order to ensure consistency in the test results, the various combinations were pulled after the engines had recorded 165 degrees on the test cell's DTS model S-1007M engine cooling system. The DTS specific cooling system provides for the cooling requirements of the engine, and no engine accessory belts were required since a Meziere electric water pump was utilized. Once the engine reached temp, the dyno operator took it to 3,800 rpm and then applied a dyno load. Once loaded, the engine was slowly brought up to 3,000 rpm and then pulled until the specified redline. Standardized SAE calculations were used to correct the horsepower and torque to industry standards. Reference temperatures for SAE calculations are 77 degrees Fahrenheit, and a barometric pressure of 29.23 inches of mercury. With an altitude of 3,200 feet above sea level and blistering humidity and temperatures on tap for the testing, it was reassuring to know that the DTS had had a recent calibration and was in top working order. Baseline: The test engine was a stock 2000 LS1 that formerly resided between the wheel wells of an F-body. With over 60,000 miles on the odometer, the test engine is just your run of the mill '00 LS1. The engine had stock 853 casting cylinder heads (12559853) and the 2000 camshaft that specs in at 202/210 duration at .050 with .496/.496 intake and exhaust lift (116 lobe separation angle). The intake and fuel injectors were updated to 2001 F-body specs that included an LS6 intake and 28-lb. fuel injectors. Aftermarket accessories were limited to a set of PRC Gold double valve springs, MSD 8.5 plug wires, NGK TR55 spark plugs and a Hypertech 160 degree thermostat. The factory springs were replaced due to the number of miles, but more importantly for the second test which would necessitate a valve spring that could handle lift exceeding .600. The factory computer program was left intact, but timing was locked at 26 degrees with LS1Edit to ensure that the computer didn't pull timing. Since there were not any knock sensor provisions provided, it was decided that VP 101 octane fuel would be used to keep the engine from potential detonation problems.
In the baseline dyno run, the stock LS1 surprised everyone by churning out a whopping 400.4 hp at 5,600 and 411.3 ft-lbs of torque at 4,800 rpm. Average power and torque (from 3,000-5,800 rpm) was 330.7 and 394.8, respectively. Reflecting back on the pull, Jason Mangum stated, "The baseline was about 10 percent higher than I anticipated since the average rear wheel horsepower of a 2000-02 F-body is normally in the 305-315 range. If we factor in drivetrain losses of 10 to 15 percent depending on transmission types, theoretically the factory SAE net crankshaft rating could range from 335 to 362 hp. The difference in what we found on the dyno versus our expectations must be attributed to the lower overall parasitic drag from the electric water pump and the lack of accessory drive belts. Another point to consider is that when GM eliminated the EGR on the 2001 F-body and went with the LS6 intake, their marketing suggested that the engine had better mid-range, even with the lower overall duration and lift of the '01-02 camshaft (197/202 at .050 and .467/.479 on a 116 LSA). The hotter '98-00 cam, in combination with the overall better flowing LS6 intake, probably picked up 10-15 horsepower by themselves, or roughly equivalent to what we see when a '98-00 car replaces the LS1 intake with an LS6. No matter how you analyze it, the stock LS1 is a potent engine with outstanding power and torque for the available head flow and camshaft." Magic Stick Time
Texas Speed has been designing custom camshafts for many years and fielded one of the country's fastest cam-only LS1 combinations in their '98 Z28 test car. The automatic equipped car with stock heads and a Magic Stick 3 camshaft went a best of 10.51 at 125 mph. From the beginning, the Magic Stick cam was designed to be the largest camshaft a stock cubic inch LS1 (346 ci) could run safely without having to cut valve reliefs in the pistons. Designed as a max effort street cam, it's intended for naturally aspirated or nitrous applications. Loud, rowdy and proud, the latest revision to the Magic Stick line is the MS4 (part number 25-MS4, retail price $399.99). Now on the fourth revision to the Magic Stick line of cams, the Magic Stick 4 measures in at 239/242 duration at .050 with .649 intake and .609 exhaust lift. Built on a 111 LSA (optional 112 LSA for smoother idle) and 109.5 intake center line the MS4 provides a lumpy idle that settles in between 850-900 rpm. The latest revision features an even more aggressive intake ramp, reduced lobe separation (MS3 was 113 LSA) and built in advance to bring the power band in earlier. Custom tuning is of course a necessity but with a power band of 2,300-6,800 rpm, only the die-hards will be daily driving this stick.
As previously discussed, a valvespring capable of handling high lifts was a requirement so PRC's Double Gold springs were used (part number 199-spkit, retail $269.99). Included in the package are steel spring seats, titanium retainers and viton valve seals. Capable of .660 lifts, this is a stout spring. Complementing the springs was a set of Texas Speed & Performance hardened chromemoly pushrods in the standard 7.400-inch length (PN 25-7400, retail price $109.99). Although the stock pushrods could have been used, the addition of a stronger pushrod would ensure that the valvetrain remained stable, without any unwanted harmonics disturbing the valvesprings due to the notorious flex exhibited by the stock pushrods in above stock valve lift events.
After a quick cam swap, the little 10:1 compression 346 was warmed up and unleashed. With just a cam swap, the engine responded with peak horsepower of 482.3 at 6,400 rpm, for a staggering 82hp gain over the stock cam. Torque also increased to a peak of 439.1 at 5,100 rpm for a gain of 28. According to Jason Mangum, "By increasing the initial advance and incorporating real quick intake ramps, the cam starts exceeding the stock power levels right at 3,000 rpm. Although the peak horsepower was at 6,400 rpm, the cam will pull to 7,000 rpm with very little drop-off." In addition to the peak gains, average power and torque (from 3,000-6,500 rpm) was 370.9 and 407.3, respectively. Average horsepower increased by 40, while peak torque clocked 12 ft-lbs. From a tuning perspective, Jason added 2 percent fuel under 3,000 rpm and 1 percent above 5,800 rpm via the PE tables on LS1Edit.
PRC Stage I Heads
Next up was a set of PRC Stage I heads. The Stage I heads are based on new LS6 castings (PN 199-PRCLS61 retails for $999.99 each) and are CNC-ported to achieve 310-cfm flow on the intake, while retaining the factory valves and LS6 valvesprings (capable of .550 lift). The head was designed to utilize the stock combustion chamber and valve sizes of the LS6. Texas Speed & Performance suggested testing the LS6 version of the Stage I head because of the casting's popularity with enthusiasts, especially for naturally aspirated applications. According to Mangum, "The 64.7cc chambers yields a compression ratio of 10:9:1 when utilizing a .040-inch Cometic head gasket. Optioned with our performance valve job and optional PRC Gold double valvesprings we feel that the Stage I head offers a tremendous value." For people who will run over a .550 lift but don't need a spring capable of .660 lift, COMP Cams' 26918 beehive valvesprings can be added for $150. A replacement set of Texas Speed & Performance chromemoly pushrods (PN 25-7350, retail $109.99) in a 7.350-in size are used to compensate for the .005 of head milling performed to ensure a flat sealing surface.
After a quick swap to the PRC Stage I heads, the engine was warmed up to 165 degrees while Jason edited the tuning files to put in an additional 2 percent fuel down low and 1 percent over 5,800 rpm. Timing was locked at 26 degrees as in the previous tests. Once the initial dyno run was complete the engine responded with peak horsepower of 525.1 at 6,500 with 462.1 lb-ft of torque at 5,200. That's a 43 horsepower gain from cylinder heads alone. But wait, the engine's air fuel ratio registered between 12.6 and 12.8 between 3,000 and 6,500, which is a bit rich for the target of 13:0:1. Rather than edit the PE tables again, this time the timing was bumped up to 29 degrees from 3,200 rpm up through the redline. Would the extra timing bring more power and achieve the targeted air fuel ratio? In a word, yes. Horsepower jumped to 529.5 at 6,600 rpm, while torque nudged up slightly to 464.3. The air fuel averaged just a bit over 13.1, which led Jason to conclude, "The extra 3 degrees of timing really helped out the cam's power production. Not only did the peaks come up but the average horsepower (398.4) and torque (431.7) jumped by 6 hp and 2 lb-ft of torque. A total gain of 48 hp and 25 ft-lbs of torque were achieved. Based on the positive results of adding timing, Jason says "I believe the cam only combination would have benefited from additional timing as well. Hindsight is a great tuning aid but 5-10 hp worth of gains was probably on the table for the taking."
Rather than stepping up the airflow in the heads by going to a Stage II or 2.5 head, this was the perfect opportunity to see how well the little 346 would respond to bolt-ons designed to increase airflow through the motor. According to Trevor Doelling, "The F.A.S.T. 90mm composite intake manifold [PN 111-54003, retail price $849.99] has consistently shown power gains when used on engine combinations where the airflow ability of the heads exceed 285 cfm." In addition, cubic inch displacement plays a significant role in the gains achieved with larger displacement engines benefiting the most. When combined with a Precision Tool and Machine (PTM) 90mm billet throttle body (PN PTM90, retail price $389.99) we routinely see 15-20 horse improvements, although the gains are greater when upgrading from an LS1 intake manifold. To supplement airflow, the stock LS1 75mm MAF is replaced with a specially calibrated SLP 85mm composite MAF (PN 33-23060, retail price $170.99). With the claimed ability to flow some 895 cfm (versus 805 cfm for stock), the MAF supports greater power potential." After removing the LS6 intake and all supplementary hardware such as the fuel injectors, the F.A.S.T. intake was installed, followed by the PTM throttle body and SLP MAF.
After repeating the warm-up procedures, the engine was loaded up and run to redline. Peak horsepower responded with 544.7 at 5,600, while peak torque came out to 472.8 ft-lbs. Gains attributable to the bolt-ons were 15.2 hp and 8.5 ft-lbs of torque. Interestingly enough, the air/fuel ratio registered at 12:7:1 at 3,300 rpm, but progressively fattened up all the way to 12:1 at 6,600 rpm. Clearly the target air fuel ratio of 13:1 wasn't achieved, so Jason once again went into LS1Edit and adjusted the tables. After a cool-down period, the engine was warmed back up to temp and pulled. When all was said and done, the air/fuel averaged 13:0 and the engine responded with additional power. Peak power jumped to 551.0 hp at 6,600 rpm and torque was also gained, showing 476.3 ft-lbs. Average horsepower registered at 403.3 with torque averaging 440.2 lb-ft.
The little LS1--all 346 ci of it--is clearly a remarkable piece of engineering hardware. Any engine that can put out 400 hp with over 410 lb-ft of torque in stock configuration is phenomenal. Although it is commonly accepted that the SAE correction factors reward an engine in a minimal fashion as the heat increases and the atmospheric conditions degrade, there was no denying that this garden-variety used LS1 gained a phenomenal 151 hp and 65 lb-ft of torque while on its relatively short stay on the dyno. For a cam-only enthusiast looking to maximize the horsepower of their engine, the Magic Stick 4 is an excellent choice. According to Trevor Doelling, "The mainstay of our business is providing the enthusiast with the best value in terms of performance and quality for their hard earned pay. For owners that can afford to step up to a ported cylinder head, our Stage 1 series of GM casting cylinder heads are very economical yet they flow exceptionally well for a stock valve size. By using the smaller valves an enthusiast can not only save money but they can retain the factory piston to valve clearance." Let's face it, not everyone can afford to build a custom short-block or buy a set of heads designed to flow 350 cfm on their weekend race car. For the average enthusiast that has a stock-block car and wants reliable big power, the Texas Speed and Performance camshaft packages and Stage I heads offer a tremendous value.
Cylinder Head Development
Precision Race Components was founded in 2004 to satisfy a need in the market for quality, affordable ported GM cylinder heads. Fresh factory castings are utilized and all machine work is done on premises using state of the art CNC machinery. According to Jason, "In 2004 we purchased a Haas 5 axis CNC machine and a Newen Countour BB CNC seat and guide machine and embarked upon an extensive R&D effort to develop a street port that would flow over 300 cfm while still retaining the excellent swirl and velocity characteristics of a stock head. Modifications include port work to the intake, exhaust and bowl area. The combustion chambers remain stock, except for the 5.3-based heads that are reworked to flow to the LS6 capacity. Optional to the customer is a performance valve job (retail $100) that we offer for all of our Stage heads. The Newen CNC machine and our proprietary valve angles really improve the low and low-mid flow characteristics of the head." Various GM castings are available including the LS6 (12564243), LS1 (12564241), 5.3 (12561706) and 6.0 LQ9. With combustion chamber sizes ranging from 61.15 cc on a 5.3 casting to 71cc on a 6.0 variant, the enthusiast has a wide range of available compression ratios, depending on their application specific needs. Stage I heads are shipped using the stock valves which feature 2.00-in intake and 1.550-in exhaust valves. Stage II and 2.5 heads are recommended for power adder or larger cubic inch applications and feature increased intake and exhaust flow (318 cfm at .625 lift versus 310 cfm for Stage I) due to increased port volume and oversized stainless steel valves. The investment in stainless valves from either Manley or Rev increases flow and is a critical longevity enhancer when the valves are subjected to boost and/or elevated temperatures from nitrous oxide or forced induction.
Dyno Configuration AIT HP RPM Torque RPM +/- HP/TQ
Stock 93 400 5,600 411 4,900 N/A
Camshaft Only 84 482 6,400 439 5,100 82/28
PRC Stage 1 heads/Cam 88 530 6,600 464 5,200 48/25
PRC plus Bolt-Ons 97 551 6,600 476 5,600 21/12
Total 551 476 151/65
Key Engine Parameters: Maximum values noted, *unless otherwise noted
Cylinder Head Flow-
All flow numbers quoted at 28" test pressure. Components SuperFlow SF600 flow bench. LS1 heads are casting number 12559853, LS6 and all stages of PRC heads tested are casting number 12564243.
Head .100 .200 .300 .400 .500 .600 .625
Stock 853 (Intake) 67 122 178 215 219 227 227
Stock 853 (Exhaust) 52 97 133 156 170 180 180
PRC Stage 1 (Intake) 72 149 205 255 287 307 310
PRC Stage 1 (Exhaust) 63 121 154 191 214 220 228
PRC Stage 2 (Intake) 75 151 209 260 293 315 318
PRC Stage 2 (Exhaust 66 124 160 194 217 227 234
PRC Stage 2.5 (Intake) 75 151 209 260 293 315 318
PRC Stage 2.5 (Exhaust) 66 124 160 194 217 227 234
Head Combustion chamber Intake Exhaust
LS1 cc 66.7 cc 200 cc 70 cc
LS6 cc 64.5 210 cc 75 cc
PRC Stage 1 cc 64.5 cc 237 cc 75 cc
PRC Stage 2 cc 64.5 cc 238 cc 75 cc
PRC Stage 2.5 cc 64.5 cc 238 cc 75 cc
Valve Sizes Intake Exhaust
LS1 2.00 1.550
LS6 2.00 1.550
PRC Stage 1 2.00 1.550
PRC Stage 2 2.02 1.570
PRC Stage 2.5 2.04 1.575