Cylinder Heads explained
Here is a pretty simple explaination on heads :
Heads:
Stage 1, 2 and 3 doesn't mean much. Sometimes they relate to valve sizes, sometimes they relate to double springs, you get something more than the previous stage, that's all. They typically all include a 3 angle valve milling job for better flow.
Valves:
2.00 or 2.02 intake and 1.57 exhaust is typically Stage 1, but others have this on stage 2 and even 3. This is the size (diameter) of the holes for the respective valves. Basically means you can push more air through your engine, this is where the power comes from.
2.055/1.60 is typically Stage 2 but again no real relation. Even bigger valves means you can push even more air through. Larger valve seats are required, the factory ones won't take this size, so that is part of the additional cost.
2.08/1.60 is even bigger on the intake, but this seems too big for stock bore engines, better flow on the bench but can cause problems on the car. Doesn't seem to line up well with the stock bore diameter. Again larger seats would be required for this.
Higher stages typically buy you new hardened valve seats (instead of stock-ish ones), maybe valve seals, bronze valve guides, better quality valves, better springs, etc.
Some product info on various heads :
In the market for a huge power increase? Then you're probably looking at getting a set of ported aluminum heads on your GM car or truck. Here's a sampling of what's available from the aftermarket community. Note that each head is just an example of what that company has to offer, so check their Web sites for a myriad of other heads available as well as possible options for the head listed (such as combustion chamber cc). Compression ratios quoted are for an otherwise-stock 5.7 LS1.
Wow! What a cylinder head. With a reputation for absolute excellence in flow design, it seems the engineers at TFS have finally turned their attention to the LS1, and for the first time in these heads, the LS2. We waited and waited, and finally these heads showed up. They were worth the wait. Are these good examples of what you'll get when you open the box on your own set of LS2 heads by TFS? We really don't know because it would appear that we got ourselves a hand-finished set of heads just for this comparison. These were clearly the most "worked" heads in the group. Mirror polishing, perfect ports, and a very racy look told us that these things were serious. Regardless of their status in the TFS catalog, TFS did a great job with these LS2 heads.
As they did when they revolutionized the Ford small-block market, TFS looked at the LS1 cylinder head with an open mind. From their Web site, we learned that "during the development stage, Trick Flow engineers determined that the valve angles needed to change from 15 to 13.5 degrees. This change decreased valve shrouding, increased mid-lift airflow, and increased rocker arm-to-valve cover rail clearance. Testing also proved that relocating the spark plug position in the combustion chamber further enhanced mid-lift airflow and increased the rigidity of the casting to prevent cracking in the chamber area. Furthermore, additional material was added to the rocker arm mounting points for high-rpm valvetrain stability."
On the flow bench, the TFS units flowed over 327 cfm at .600-inch lift--a real number for the cam we were using in this study. They also offered up solid low-lift numbers that bested--or at the very least kept pace--with the other heads in this study.
On the engine dyno, the TFS heads recorded the highest measured horsepower and torque. Again, we want to remind our readers that this isn't the point of this test, especially given the detailed heads (let's call them what they are: prototype LS2 heads) from TFS. And, looking at the dyno graph, the LS2 outfitted with these heads shows a nice horsepower curve that gets to a peak number and just stays there.
If you are serious about making power with your LS2, you have to look at the TFS. We like the fact that, like the AFR, you can get them with a CNC port from the factory, and if TFS is going to offer the hand finishing that we got on our test heads, it's a bargain. Big inches, monster cams, blowers, nitrous--bring them all on. We can't wait to see where these heads take us in the future
AFR LS1 Mongoose Street Head
Company: Air Flow Research
Intake cc: 205
Chamber cc: 66
Approximate Compression: 10.2:1
AFR's heads are its own casting, and the Mongoose Street head is no exception. This fully CNC-ported head features the same intake port cc as the stock LS1 head, yet outflows it by over 70 cfm. Fully emissions-legal, this direct bolt-on head features the same .75-inch deck as all other AFR heads for reliable sealing, and also features thick port walls and reinforced rocker stud bosses. Add in AFR's new double-quench pad area combustion chamber, and you have a winner hands-down. AFR's suggested retail price is $2,499. A 76cc version is also available for lower compression applications. If you like to "port your own," an as-cast version of this head is also available and comes without valvetrain parts.
Edelbrock/Lingenfelter CNC-Ported LS1 Head
Company: Edelbrock
Intake cc: 205
Chamber cc: 65
Approximate Compression: 10.3:1
Relying on Lingenfelter's many years of CNC experience, Edelbrock now offers a new head--its own casting, mind you--that is a bolt-on replacement for all '97-and-later GM V-8s. After being ported by Lingenfelter it is shipped fully assembled, and it includes titanium retainers and COMP Cams valvesprings as well as Edelbrock proprietary valve guides. This head is brand-new, so emissions legality is pending, as is pricing. If you want to do your own porting, an unported version featuring stock dimensions so that any LS1 or LS6 CNC program can be run on it also available.
ET Performance CNC-Ported LS1 4.8/5.3 Head
Company: ET Performance
Intake cc: 230
Chamber cc: 64
Approximate Compression: 10.5:1
ETP pours its own casting that is different in several ways from other heads on the market. A raised valve cover rail as well as an 11-degree valve angle (versus the factory 15-degree) make for a serious head for serious applications. Intake runners from 215cc up to--get this--255cc in volume are also available, as well as killer C5R heads, all on ETP's own aftermarket castings. Any kind of porting you want is available; you name it, ETP will do it. Check with the company for the latest pricing.
Patriot LS6-style CNC Heads
Company: Patriot Performance
Intake cc: 227
Chamber cc: 59
Approximate Compression: 11.1:1
Patriot says there are several things that set its heads apart. First, it offers combustion chamber sizes from 59cc to 72cc while maintaining the stock deck height. In addition, these sizes are offered for any bore in the range of 3.90 to 4.125 inches. A choice of valve sizes is available, ranging between 2.02 and 2.08 inches, and the heads come out the door fully assembled with goodies such as titanium retainers, viton rubber seals, and Patriot's own Gold Dual valvesprings. Pricing is $1,195 per pair, assembled.
GMPP CNC-Ported Gen III Aluminum Racing Cylinder Head
Company: GM Performance Parts
Intake cc: 250
Chamber cc: 44
Approximate Compression: 13.9 to 1
This particular item is a fully machined and CNC-ported C5R head with 2.18-inch intake valves and 1.625-inch exhaust valves. You may as well just ignore the above-quoted LS1 compression ratio because with valves that big, you're going to need a bigger-bore block to bolt these heads to! Call your local GM dealer for pricing on this and other heads available from GM Performance Parts. If you have several-thousand dollars lying around, pick up a C5R block while you're at it.
HPE Stage 3 4.8/5.3 LS1 head
Company: Horsepower Engineering
Intake cc: 230
Chamber cc: 64
Approximate Compression: 10.5:1
Optimal power and torque is the name of the game with HPE's Stage 3 4.8/5.3 head. Featuring a high-velocity port to maintain good drivability, 40-50 rwhp over stock can be had with these heads. Full Rev valvetrain hardware, such as valvesprings good to well over 0.600-inch lift are included, all for the price of $2,195. Horsepower Engineering also offers a Stage 2 head package for the best "bang for the buck."
Lingenfelter CNC-Ported LS1 Cylinder Heads
Company: Lingenfelter Performance Engineering
Intake cc: Customer-specified
Chamber cc: Customer-specified
Approximate Compression: Customer-specified
Precision CNC-machined in-house, Lingenfelter offers ported LS1 heads designed to yield improved port velocity as well as high-flow capabilities. This combination gives a strong torque curve as well as high horsepower. Lingenfelter claims that the elimination of hand-porting each and every head provides more consistency from port to port. However, the CNC program itself is derived from an LS1 head that was hand-ported by Lingenfelter, so in effect, you do get a "hand-ported" CNC head that Lingenfelter put many hours into perfecting. Pricing is $1,595 for the above-described units, not including refundable core charge.
Precision Porting and Coatings Stage 3 LS-series Heads
Company: Precision Porting and Coatings
Intake cc: Customer-specified
Chamber cc: 58
Approximate Compression: 11.3:1
PP&C says its $1,499 Stage 3 head package offers the best possible setup for a street/strip vehicle. Hand-porting gives balanced runners matched to the customers' camshaft profile and driving style. All of Precision's heads (or any head you wish to send in) get their valve faces and combustion chamber coated with their thermal barrier coating, which reduces hot spots and helps to prevent detonation. Precision says customers can expect oil and coolant temperatures to drop significantly thanks to these coatings, particularly during hard driving. A range of combustion chamber sizes is available and 6.0L castings can be used to lower the compression for forced-induction applications.
FLP Stage 3 LS6 heads
Company: Finish Line Performance
Intake cc: 236
Chamber cc: 65
Approximate Compression: 10.3:1
Ported by Scott Fulkerson of Midwest Engine Tech in Mokena, Illinois, FLP's Stage 3 LS6 heads flow 317 cfm on the intake and 217 cfm on the exhaust, and feature a 2.10-inch intake and 1.60-inch exhaust valves. Pricing for a set of these particular heads is $2,299. You can supply your own head cores or FLP can use its own to minimize your ride's downtime. All of FLP's heads can be milled to achieve a higher compression ratio for a nominal charge. In addition to the LS6ers, LS1 and 5.3 heads can also be used.
TPIS Stage 2 Ported LS1 Cylinder Heads
Company: Tuned Port Induction Specialties
Intake cc: 218
Chamber cc: 64
Approximate Compression: 10.5:1
TPIS starts off this package with a set of 5.7 LS1 heads and fully CNC ports the chambers and runners, installs 2.02 and 1.56-inch lightweight stainless valves, and puts on titanium retainers and springs appropriate to the customer's camshaft selection. A full three-angle valve job is also performed. The going rate on a set of these heads is $1,700 on an exchange basis. Even larger valves are available if desired, as are porting work on 5.3 and 6.0L cylinder heads.
PRC Stage 2.5 5.3L Heads
Company: Precision Race Components
(Texas Speed & Performance)
Intake cc: Customer-specified
Chamber cc: 62
Approximate Compression: 10.7:1
Precision Race Components and Texas Speed and Performance are two faces of the same company, so don't get confused. This particular 5.3 head package goes for $1,529 and includes 2.04- and 1.575-inch stainless steel valves. Large valves are available if the customer wishes to upgrade to the Stage 3 package. This company's heads are sold outright as new castings, so no core swap is involved, though Precision Race Components will gladly port castings a customer supplies as well. All heads are hand-finished, bowl-blended, assembled, decked, and flow-tested by a full-time cylinder-head specialist trained by the School of Automotive Machinists.
SLP AFR Cylinder Heads
Company: SLP Performance Parts
Intake cc: 225
Chamber cc: 62
Approximate Compression: 10.7:1
SLP has teamed up with AFR to bring these CNC-ported street/strip heads to the market. Despite features such as 2.08-inch intake valves and 1.60-inch exhaust valves, they are fully emissions legal--even in California. Flowing up to 320 cfm at 0.600-inch lift, these heads are fully assembled, ready to bolt on, and ready to make power! Like with all AFR head castings, these heads have many high-durability features, like reinforced rocker stud bosses and interlocking ductile iron valve seats. $2,649 makes them yours.
Race Prep Phase IIILSR Heads
Company: Race Prep Performance Engineering
Intake cc: Customer-specified
Chamber cc: 66
Approximate Compression: 10.2:1
Using factory 6.0L castings, Race Prep's Stage IIILSR heads get their chambers welded, cryogenically treated, and machined to accept larger valves, yielding a more efficient chamber design and 340-cfm flow figures. This is a full race package, and thermal barrier coatings on the chambers and valves can be had as well. This full package goes for $3,675. Race Prep prides itself on offering the customer exactly what they need for their application and not just something "off-the-shelf," and larger chamber sizes are available. The company also offers ported AFR castings that will outflow even the Stage IIILSR heads.
TEA Stage 1.5 5.3 Heads
Company: Total Engine Airflow
Intake cc: Customer-specified
Chamber cc: Customer-specified
Approximate Compression: Customer-specified
Total Engine Airflow's biggest mover is its ported Stage 1.5 5.3 head. Designed for a 3.90-inch bore, these heads get a blended competition multi-angle valve job, Ferrea 2.02-inch intake valves, and TEA 0.650-inch lift dual valvesprings (COMP Cams springs are optional). The price of $1,575 includes new GM head castings. Choose from stock exhaust valves or REV 1.57 inchers. Or, select from TEA's Stage 1, 2, or 3 cylinder head packages.
More Performance Profiler
Company: More Performance
Intake cc: TBA
Chamber cc: TBA
Compression: TBA
More Performance's brand-new Profiler head flows nearly 330 cfm on the intake as-cast and can be ported for even higher flow numbers based on a particular engine application. In fact, by virtue of its extra-thick port walls, the head converts into a C5R head; that is, it can be ported all the way to C5R valve angles and flow up to 400 cfm. Other features of the head include raised valve cover rails and dual valve cover bolt patterns for both pre-'99 and '99-and-later applications. Details on this head, including pricing, are still being worked out as of print time, so check its Web site for more information, as well as other products More Performance markets.
RGR Performance Stage 2 Heads
Company: Speed Inc.
Intake cc: 243
Chamber cc: Customer-specified
Approximate Compression: Customer-specified
Hand-ported by Rich Groh Racing exclusively for Speed Inc., these heads feature 2.02-inch intake and 1.57-inch exhaust valves, along with titanium retainers. A lightweight valve option is also available for a slight charge. Speed Inc. relies on these heads for many of its own projects, as well as record-breaking customer build ups. Though it admits the lead-time will be longer to procure a set of these RGR heads than some of the CNC units offered, Speed Inc. claims the results are always worth the wait. They'll go for $1,799 on an exchange basis.
Katech Stage III 2.100-inch LS6 Cylinder Head Assembly
Company: Katech Engine Building and Development
Intake cc: 240
Chamber cc: Customer-specified
Approximate Compression: Customer-specified
Katech says the 2.100-inch hollow-stem intake valves are the secret to this head's awesome across-the-board flow numbers. Though they can only be used on engines with at least a 4-inch bore, these heads will provide 330 cfm of flow at only 0.600-inch lift, and their modest intake port volume will preserve mid-range torque. Katech says the countless hours it put into CNC machine programming has resulted in a 100 percent repeatable intake port that cleans up perfectly on the machine and doesn't require hand finishing, thereby assuring each intake port flows identical numbers. Pricing on this head is $2,759.
West Coast Cylinder Heads Stage 2 6.0L Heads
Company: West Coast Racing Cylinder Heads
Intake cc: 233
Chamber cc: 74
Approximate Compression: 9.4:1
With 2.02 and 1.57-inch valves, West Coast's ported 6.0 heads flow just under 300 cfm at 0.600-inch lift. Its large combustion chamber drops compression for blown LS1 applications. Many custom options are available, and West Coast is constantly updating its CNC profiles to maximize performance in specialized applications. Several other heads are available as a starting point, and coming soon are CNC porting profiles for the new Edelbrock head castings. Please call for the most up-to-date pricing.
TTP Stage 4R AFR 225cc CNC Heads
Company: TT Performance Parts
Intake cc: 225
Chamber cc: Customer-specified
Approximate Compression: Customer-specified
TT Performance Parts starts off with AFR's 225 CNC heads and does its own special in-house porting job to achieve what the company claims are record-breaking flow and horsepower numbers. A '98 Camaro equipped with one of TTP's Equalizer head and cam packages included a set of these heads and made 505 hp at the rear wheels, even with the stock bottom end. This easily put the customer's previously installed head and cam package to shame. Several other head packages are available, all starting with the solid foundation of AFR heads. Call TTP for current pricing.
Ok some good reading here people
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