Clean Cast and Fast Clean Cast and Fast By Justin Cesler Can an “as cast” cylinder head make big power Photography by the author and keep money in your pocket?
layout remains similar to the OEM heads with the stock angles and centers intact, a move that allows the heads to work with both factory and aftermarket valvetrain components, should you chose to upgrade them along with the cylinder heads. For those of you looking to do your own valve job, you can even buy the RHS heads with as-cast P-Port chambers, a nice touch for the machinist or builder looking for that personalized piece. Along with testing the affordable new cylinder heads, we also ordered a camshaft from Comp Cams that was cut on a fairly aggressive 232/234-duration at .050, along with just under .600-inches of valve lift (.595/.598 at .050-inches) and a lopey 112-degree lobe separation angle. With those specs, we felt the hydraulic roller Comp Cam would make a great choice for a street/strip LS1 and work well with both the 205cc runners on the RHS heads and the stock units that we planned to replace. We also ordered a new set of 7.400-inch pushrods and a new adjustable timing set from Comp to help strengthen the valvetrain and give us some additional reliability in the upper RPM range. To really see how well the Pro Action “clean cast” heads could do, we broke the install down into two separate parts, performed by the crew at EFI Alchemy over the course of two grueling days (21-hours on Day 1, 16-hours on Day 2). What we In a world of CNC-this and CNC-that, downtime and hassle of a CNC-ported found may surprise you and, combined is it possible to build anything worth a competitor. According to RHS, these “LS with the extremely affordable price point, buck using regular old cast aluminum and cathedral port heads combine race-proven may make these the budget heads to beat some quality design? It’s a question the head design and Clean Cast Technology to in the cathedral port market. One last note aftermarket has been trying to answer for create ‘as cast’ ports that flow like they’ve before we begin, if the baseline numbers years and one that until recently, no one already been ported.” With both a 205cc in this article seem low for a bolt-on had really seemed to get right. Sure, GM and 225cc version of the heads that cost equipped LS1, it’s because they are. We has had some great results with “as cast” just under 600-dollars apiece, the idea haven’t seen many LS1 engines make this cylinder heads in the past, but we’re talking sounded great to us on paper and we knew little power with long-tube headers, an about bolt-on performance here, not just run it was a must-test piece for 2011. LS6 intake, a somewhat decent tune and of the mill factory stuff. Enter Racing Head The 205cc RHS Pro Action heads that we an underdrive pulley but as they say, it is Service (RHS) and the company’s new line picked up feature 2.020-inch intake valves what it is. Take note of the gains alongside up of Pro Action “Clean Cast Technology” paired with 1.600-inch exhaust valves and the overall numbers to get a real feel for cylinder heads, which are being cast to multi-angle intake and radiused exhaust the budget performance offered by this improve horsepower without the cost, valve seats to improve airflow. The valve package. 058 \ JANUARY 2012 \ GM HIGH-TECH PERFORMANCE
GHTP-120100-RHS.indd 58 9/13/11 6:29 PM 1 The EFI 2 Interested Alchemy in seeing crew wasted the gains no time from each digging modification into our ’99 separately, Camaro test we broke this car, which install into two came to us parts, tackling with a slew the camshaft of typical first and then bolt-on adding the parts (long- new RHS tube headers, LS6 intake manifold, underdrive pulley), a cylinder heads 6-speed manual transmission and the stock 10-bolt rear second. Here end. With a 323.41-rwhp baseline dyno, we were sure a new you can see set of heads paired with a quality camshaft would really the EFI Alchemy crew removing the stock radiator to make wake the old fourth-gen up. room for the camshaft to slide out of the block.
3 With the radiator and 4 Pulling the stock hoses removed, aftermarket the EFI Alchemy team underdrive pulley got to work tearing proved to be quite down the front of the a difficult task as LS1 to gain access the three tapped to the camshaft and bolt-holes were timing components. damaged prior to Not shown here, the our removal. If this EFI Alchemy crew had been a stock already pulled the unit, removal would spark plugs, wires, coils, coil brackets and valve covers in have been a simple affair using a traditional pulley removal order to remove the factory rocker arms and pushrods, then tool, which you can rent from a parts store or buy from a removed the factory water pump (shown). vendor like Summit Racing.
5 After a lengthy 6 On paper the fight with the Comp Cams underdrive XE-R 281HR pulley, EFI camshaft (PN Alchemy’s 54-446-11) technicians looked like a unbolted winner, with the factory 232/234-degrees timing cover of duration and began at .050, removing .595/.598-inches the oil pump, of valve lift and timing set and 112-degrees of cam retainer lobe separation. plate to gain Designed for use access to the factory bumpstick. Remember to line the from 2400-7200 timing set up “dot-to-dot” prior to disassembly to help line rpm, the XER281HR is aggressive for the street, but should everything back up during reassembly. make big power in any combination.
7 It’s possible to 8 Built specifically install the new for three-bolt LS camshaft using camshafts, the new the stock timing timing set bolts in set, but we chose place easily and to upgrade to can be adjusted an adjustable using the three- set from Comp way keyway crank (PN 3158KT), sprocket (bottom) which includes or the “infinitely” a pre-stretched adjustable camshaft and heat-treated sprocket, which single roller you can see to the timing chain right of the three camshaft bolts. A quick adjustment here along with an can move the camshaft up to 6-degrees in either direction, induction hardened steel billet gear set and Torrington which is a great feature. Even with all of this adjustability, roller thrust bearing to reduce rotational friction. we chose to install it straight up, dot-to-dot.
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9 If you’ve 10 Reinstalling ever tried to the timing install an oil cover may pump back seem like an into an LS1, easy and trivial you know step, but it exactly what is important bolt this is. to remember If not, here’s that the cover a little tip. is an integral The oil pump part of the slides over engine and oil and bolts to pan assembly the pickup and needs tube with a to be lined bolt that sits inside the oil pan and is practically impossible up properly to get to with the pan still bolted onto the engine. Marc before tightening everything down. If you don’t have a factory- Sever uses a thin wire to hold the bolt, which helps fish it style alignment tool like EFI Alchemy, make sure you work all into place before getting a wrench on it. the bolts down before final assembly.
11 Installing the old 12 With the new camshaft underdrive pulley in place, the EFI Alchemy is really a three- team got to work on the step process that stock cylinder heads, begins with a pulley swapping the factory installer tool to get valve springs out for a the unit in place. pair of single beehive Once installed, springs from Comp use the old crank Cams. Even though we bolt (the one you would only be running removed during the these springs (and disassembly) to tighten the balancer into place and then heads) for a couple of remove the old bolt, install a brand-new one and torque it dyno pulls, it wasn’t down to spec using a torque wrench and an angle gauge. worth the risk to keep the stockers in place for the testing.
13 Through the 14 On the dyno, magic of we saw photography and immediate magazine time, gains in both we’re skipping horsepower ahead to the and torque final engine bay although they shot, showing did come at how everything the expense of looked once low-end power reinstalled and production. Up double-checked. top, the cam- With a quick only LS1 laid PCM tune by down 361.74 Harrison “Doc” rear wheel horsepower with torque pulling through at 335.87 Wall, the owner of EFI Alchemy, our test Camaro roared lb-ft. Compared to stock, that is a gain of 38.33-rwhp and 1.21 to life and sounded great thanks to the 232/234-duration ft-lbs, which isn’t bad considering the rest of the combination, camshaft cut on a nice 112-degree LSA. even though the numbers seemed a bit lower than expected.
15 Happy with the 16 Gross! The stock power increase ’99 cylinder from the heads have camshaft alone, clearly seen the EFI Alchemy many years team drove the worth of abuse car back around and it shows to the lift, let in the intake it cool down ports. While overnight and decent for the jumped back day, the factory to work in the LS1 heads morning, tearing flow poorly everything back compared with apart to install the new cylinder heads. Here you can see today’s stock Travis Gillespie removing the intake manifold and air intake and aftermarket pieces and replacing them with new heads can assembly in one piece. really help free up some horsepower.
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Removal of the stock heads is pretty simple and begins with removing the coil packs and factory valve covers. Once out of the way, Travis pulled the factory rocker arms off of the heads and then removed the pushrods. We were planning to use both on the new heads, so Travis made sure to keep everything in good shape for proper reassembly. 18
Loosening and removing the head bolts was all that remained, and it was easy as pie to get them out of the way to pull the factory heads off of the Camaro. Pulling these out of the way is a one-man job, but make sure you take care not to scratch anything on the way out. 19
With both heads removed, Travis jumped in with the air tools and got to work cleaning up the cylinder head deck surface on the factory LS1 block. During our teardown we found a set of graphite head gaskets installed on the engine, which made us wonder if and why someone had been in here before. Either way, a good cleaning ensures a good seal, so don’t neglect this step!
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Please welcome the star of this show: the RHS Pro Action 205cc LS1 cylinder heads (PN 54301), which retail (bare) at just under 600-dollars a piece! Built from an entirely new Looking closely at the 62cc combustion chamber reveals casting, these 205cc heads from RHS feature 2.020-inch the “clean cast” ports and this same finish carries on intake valves paired with 1.600-inch exhaust valves and into both the intake and exhaust runners. These efficient were designed to flow well and make big power in their chambers were engineered by RHS to “improve airflow “as cast” form using a “clean cast” technique that RHS has and flame propagation” and feature multi-angle intake and spent years perfecting. radiused exhaust seats to further improve airflow. 22 23
Our RHS heads shipped from the factory wearing a pair of single beehive springs rated to .615-inches of total lift, which was in the range for the camshaft we previously installed. Note the factory style rocker arm bosses, which are machined to accept the factory pieces for a quick, easy and affordable swap. 24
Even though the RHS heads are a “bolt-on” affair, we did find that the stock rocker arm guide plate had to be modified to bolt in place. In stock form, the guide plate Finally, it was time to slide the new Pro Action RHS heads has four small tabs that help locate it on the factory head; in place and get the rest of the top-end back together. EFI these must be removed prior to bolting the guide plates to Alchemy provided a new set of OEM GM LS1 head gaskets the RHS units. The EFI Alchemy crew also swapped over for the install and we reused the factory block-to-head a couple of parts from the stock units, which just dropped dowel pins to locate the cylinder head in the correct place. right into place on the new heads.
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GHTP-120100-RHS.indd 62 9/13/11 6:29 PM 25 Properly installing 26 With the grueling head factory-style torque bolt procedure out of the to yield head bolts is way the rest of the install a bit of a process and is a breeze. Up first, the it is always nice to EFI Alchemy crew dropped have a factory manual the modified guide plate on hand to make sure below the rocker arms you get the sequence and dropped the entire correct. If you don’t assembly on the RHS have a factory manual, cylinder heads. Note the get up close to this Teflon paste (white) on the photo and write everything down, it is crucial to get this end of the studs. This ensures a leak free seal as the rocker step perfect if you want a good, hassle free seal. stud holes actually enter the intake ports on the RHS heads. 27
The rest of the assembly is just a reverse of the disassembly and since the RHS heads are a direct replacement for the old stock units, everything bolts on without issue. Power production aside, the new heads certainly helped clean up the look of the engine bay and the large RHS logo will definitely put people on notice at the track or local cruise spot. 28
Back on the dyno at EFI Alchemy, Doc loaded in a new tune file and hit the rollers to see what the RHS cylinder heads added to the combination. Peak power jumped up from 361.74 to 381.51-rwhp and torque also jumped substantially, adding as much as 17.5 lb-ft in the mid-range. From 3500- to 6500- rpm, the RHS heads really shined, adding both power and torque exactly where we needed it, transforming our 321 horsepower Camaro into a 381 horsepower street monster.
Sources Comp Cams EFI Alchemy 800/999-0853 904/531-9367 www.compcams.com www.efialchemy.com Racing Head Service 877/776-4323 www.racingheadservice.com
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