Clean Cast and Fast. Clean Cast and Fast

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Hilary Rice
5 years ago
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Can an as cast cylinder head make big power and keep money in your pocket?

It s a question the aftermarket has been trying to answer for years and one that until recently, no one had really seemed to get right.

Enter Racing Head Service (RHS) and the company s new line up of Pro Action Clean Cast Technology cylinder heads, which are being cast to improve horsepower without the cost, downtime and hassle of a

1 Can an as cast cylinder head make big power and keep money in your pocket? By Justin Cesler Photography by the author In a world of CNC-this and CNC-that, is it possible to build anything worth a buck using regular old cast aluminum and some quality design? It s a question the aftermarket has been trying to answer for years and one that until recently, no one had really seemed to get right. Sure, GM has had some great results with as cast cylinder heads in the past, but we re talking about bolt-on performance here, not just run of the mill factory stuff. Enter Racing Head Service (RHS) and the company s new line up of Pro Action Clean Cast Technology cylinder heads, which are being cast to improve horsepower without the cost, downtime and hassle of a CNC-ported competitor. According to RHS, these LS cathedral port heads combine race-proven head design and Clean Cast Technology to create as cast ports that flow like they ve already been ported. With both a 205cc and 225cc version of the heads that cost just under 600-dollars apiece, the idea sounded great to us on paper and we knew it was a must-test piece for The 205cc RHS Pro Action heads that we picked up feature inch intake valves paired with inch exhaust valves and multi-angle intake and radiused exhaust valve seats to improve airflow. The valve 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 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 found may surprise you and, combined with the extremely affordable price point, may make these the budget heads to beat in the cathedral port market. One last note before we begin, if the baseline numbers in this article seem low for a bolt-on equipped LS1, it s because they are. We haven t seen many LS1 engines make this little power with long-tube headers, an LS6 intake, a somewhat decent tune and an underdrive pulley but as they say, it is what it is. Take note of the gains alongside the overall numbers to get a real feel for the budget performance offered by this package. \ JANUARY 2012 \ GM HIGH-TECH PERFORMANCE 058 GHTP RHS.indd 58

1 The EFI Alchemy crew wasted no time digging into our 99 Camaro test car, which came to us with a slew of typical bolt-on parts (longtube headers, LS6 intake manifold, underdrive

41-rwhp baseline dyno, we were sure a new set of heads paired with a quality camshaft would really wake the old fourth-gen up.

Not shown here, the EFI Alchemy crew already pulled the spark plugs, wires, coils, coil brackets and valve covers in order to remove the factory rocker arms and pushrods, then

5 After a lengthy fight with the underdrive pulley, EFI Alchemy s technicians unbolted the factory timing cover and began removing the oil pump, timing set and cam retainer plate to

7 It s possible to install the new camshaft using the stock timing set, but we chose to upgrade to an adjustable set from Comp (PN 3158KT), which includes a pre-stretched and

2 Interested in seeing the gains from each modification separately, we broke this install into two parts, tackling the camshaft first and then adding the new RHS cylinder heads

4 Pulling the aftermarket underdrive pulley proved to be quite a difficult task as the three tapped bolt-holes were damaged prior to our removal.

Racing. 6 On paper the Comp Cams XE-R 281HR camshaft (PN 54-446-11) looked like a winner, with 232/234-degrees of duration at.050,.595/.

2 1 The EFI Alchemy crew wasted no time digging into our 99 Camaro test car, which came to us with a slew of typical bolt-on parts (longtube headers, LS6 intake manifold, underdrive pulley), a 6-speed manual transmission and the stock 10-bolt rear end. With a rwhp baseline dyno, we were sure a new set of heads paired with a quality camshaft would really wake the old fourth-gen up. 3 With the radiator and stock hoses removed, the EFI Alchemy team got to work tearing down the front of the LS1 to gain access to the camshaft and timing components. Not shown here, the EFI Alchemy crew already pulled the spark plugs, wires, coils, coil brackets and valve covers in order to remove the factory rocker arms and pushrods, then removed the factory water pump (shown). 5 After a lengthy fight with the underdrive pulley, EFI Alchemy s technicians unbolted the factory timing cover and began removing the oil pump, timing set and cam retainer plate to gain access to the factory bumpstick. Remember to line the timing set up dot-to-dot prior to disassembly to help line everything back up during reassembly. 7 It s possible to install the new camshaft using the stock timing set, but we chose to upgrade to an adjustable set from Comp (PN 3158KT), which includes a pre-stretched and heat-treated single roller timing chain along with an induction hardened steel billet gear set and Torrington roller thrust bearing to reduce rotational friction. 2 Interested in seeing the gains from each modification separately, we broke this install into two parts, tackling the camshaft first and then adding the new RHS cylinder heads second. Here you can see the EFI Alchemy crew removing the stock radiator to make room for the camshaft to slide out of the block. 4 Pulling the aftermarket underdrive pulley proved to be quite a difficult task as the three tapped bolt-holes were damaged prior to our removal. If this had been a stock unit, removal would have been a simple affair using a traditional pulley removal tool, which you can rent from a parts store or buy from a vendor like Summit Racing. 6 On paper the Comp Cams XE-R 281HR camshaft (PN ) looked like a winner, with 232/234-degrees of duration at.050,.595/.598-inches of valve lift and 112-degrees of lobe separation. Designed for use from rpm, the XER281HR is aggressive for the street, but should make big power in any combination. 8 Built specifically for three-bolt LS camshafts, the new timing set bolts in place easily and can be adjusted using the threeway keyway crank sprocket (bottom) or the infinitely adjustable camshaft sprocket, which you can see to the right of the three camshaft bolts. A quick adjustment here can move the camshaft up to 6-degrees in either direction, which is a great feature. Even with all of this adjustability, we chose to install it straight up, dot-to-dot. gmhightechperformance.com \ 059 GHTP RHS.indd 59

tech 9 If you ve ever tried to install an oil pump back into an LS1, you know exactly what bolt this is. If not, here s a little tip.

Marc Sever uses a thin wire to hold the bolt, which helps fish it into place before getting a wrench on it.

13 Through the magic of photography and magazine time, we re skipping ahead to the final engine bay shot, showing how everything looked once reinstalled and double-checked.

15 Happy with the power increase from the camshaft alone, the EFI Alchemy team drove the car back around to the lift, let it cool down overnight and jumped back to work in the morning,

10 Reinstalling the timing cover may seem like an easy and trivial step, but it is important to remember that the cover is an integral part of the engine and oil pan assembly and needs to

12 With the new camshaft in place, the EFI Alchemy team got to work on the stock cylinder heads, swapping the factory valve springs out for a pair of single beehive springs from Comp Cams.

14 On the dyno, we saw immediate gains in both horsepower and torque although they did come at the expense of low-end power production. Up top, the camonly LS1 laid down 361.

3 tech 9 If you ve ever tried to install an oil pump back into an LS1, you know exactly what bolt this is. If not, here s a little tip. The oil pump slides over and bolts to the pickup tube with a bolt that sits inside the oil pan and is practically impossible to get to with the pan still bolted onto the engine. Marc Sever uses a thin wire to hold the bolt, which helps fish it into place before getting a wrench on it. 11 Installing the old underdrive pulley is really a threestep process that begins with a pulley installer tool to get the unit in place. Once installed, use the old crank bolt (the one you removed during the disassembly) to tighten the balancer into place and then remove the old bolt, install a brand-new one and torque it down to spec using a torque wrench and an angle gauge. 13 Through the magic of photography and magazine time, we re skipping ahead to the final engine bay shot, showing how everything looked once reinstalled and double-checked. With a quick PCM tune by Harrison Doc Wall, the owner of EFI Alchemy, our test Camaro roared to life and sounded great thanks to the 232/234-duration camshaft cut on a nice 112-degree LSA. 15 Happy with the power increase from the camshaft alone, the EFI Alchemy team drove the car back around to the lift, let it cool down overnight and jumped back to work in the morning, tearing everything back apart to install the new cylinder heads. Here you can see Travis Gillespie removing the intake manifold and air intake assembly in one piece. 10 Reinstalling the timing cover may seem like an easy and trivial step, but it is important to remember that the cover is an integral part of the engine and oil pan assembly and needs to be lined up properly before tightening everything down. If you don t have a factorystyle alignment tool like EFI Alchemy, make sure you work all the bolts down before final assembly. 12 With the new camshaft in place, the EFI Alchemy team got to work on the stock cylinder heads, swapping the factory valve springs out for a pair of single beehive springs from Comp Cams. Even though we would only be running these springs (and heads) for a couple of dyno pulls, it wasn t worth the risk to keep the stockers in place for the testing. 14 On the dyno, we saw immediate gains in both horsepower and torque although they did come at the expense of low-end power production. Up top, the camonly LS1 laid down rear wheel horsepower with torque pulling through at lb-ft. Compared to stock, that is a gain of rwhp and 1.21 ft-lbs, which isn t bad considering the rest of the combination, even though the numbers seemed a bit lower than expected. 16 Gross! The stock 99 cylinder heads have clearly seen many years worth of abuse and it shows in the intake ports. While decent for the day, the factory LS1 heads flow poorly compared with today s stock and aftermarket pieces and replacing them with new heads can really help free up some horsepower. 060 \ JANUARY 2012 \ GM HIGH-TECH PERFORMANCE GHTP RHS.indd 60

17 Removal of the stock heads is pretty simple and begins with removing the coil packs and factory valve covers.

We were planning to use both on the new heads, so Travis made sure to keep everything in good shape for proper reassembly.

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.

4 17 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! gmhightechperformance.com \ 061 GHTP RHS.indd 61

tech 20 21 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

600-inch exhaust valves and were designed to flow well and make big power in their as cast form using a clean cast technique that RHS has spent years

Looking closely at the 62cc combustion chamber reveals the clean cast ports and this same finish carries on into both the intake and exhaust runners.

further improve airflow. 22 23 Our RHS heads shipped from the factory wearing a pair of single beehive springs rated to.

Note the factory style rocker arm bosses, which are machined to accept the factory pieces for a quick, easy and affordable swap.

EFI Alchemy provided a new set of OEM GM LS1 head gaskets for the install and we reused the factory block-to-head dowel pins to locate the cylinder head in

5 tech 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 casting, these 205cc heads from RHS feature inch intake valves paired with inch exhaust valves and were designed to flow well and make big power in their as cast form using a clean cast technique that RHS has spent years perfecting. Looking closely at the 62cc combustion chamber reveals the clean cast ports and this same finish carries on into both the intake and exhaust runners. These efficient chambers were engineered by RHS to improve airflow and flame propagation and feature multi-angle intake and radiused exhaust seats to further improve airflow 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 Finally, it was time to slide the new Pro Action RHS heads in place and get the rest of the top-end back together. EFI Alchemy provided a new set of OEM GM LS1 head gaskets for the install and we reused the factory block-to-head dowel pins to locate the cylinder head in the correct place. 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 has four small tabs that help locate it on the factory head; these must be removed prior to bolting the guide plates to the RHS units. The EFI Alchemy crew also swapped over a couple of parts from the stock units, which just dropped right into place on the new heads. 062 \ JANUARY 2012 \ GM HIGH-TECH PERFORMANCE GHTP RHS.indd 62

25 Properly installing factory-style torque to yield head bolts is a bit of a process and it is always nice to have a factory manual on hand to make sure you get the sequence

27 26 With the grueling head bolt procedure out of the way the rest of the install is a breeze.

Note the Teflon paste (white) on the end of the studs. This ensures a leak free seal as the rocker stud holes actually enter the intake ports on the RHS heads.

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.

6 25 Properly installing factory-style torque to yield head bolts is a bit of a process and it is always nice to have a factory manual on hand to make sure you get the sequence correct. If you don t have a factory manual, get up close to this photo and write everything down, it is crucial to get this step perfect if you want a good, hassle free seal With the grueling head bolt procedure out of the way the rest of the install is a breeze. Up first, the EFI Alchemy crew dropped the modified guide plate below the rocker arms and dropped the entire assembly on the RHS cylinder heads. Note the Teflon paste (white) on the end of the studs. This ensures a leak free seal as the rocker stud holes actually enter the intake ports on the RHS heads. 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 to rwhp and torque also jumped substantially, adding as much as 17.5 lb-ft in the mid-range. From to 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 800/ Racing Head Service 877/ EFI Alchemy 904/ gmhightechperformance.com \ 063 GHTP RHS.indd 63

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