The intake valve diameter is 2.16" & the Exhaust valve diameter 1.60"
Intake valve 2.16" Exhaust valve diameter 1.60"
Big Block Valves in a Small Block... Hmmm
Cathedral Heads in the LS1 & LS2 were "Good"... The Rectangle Ports are even Better!
Rectangular port – L92 style – Similar to the LS7 design, but the ports are a little taller and a little narrower. They flow more than cathedral-port heads, but not as much as LS7 heads. In addition to the L92 6.2L engines, this port shape is also used on LS3 engines and some 6.0L truck engines, as well as the Corvette ZR1’s LS9 and Cadillac CTS-V’s LSA supercharged engines. Intake manifold bolt patterns are unique to this port design. They do not come with any sort of porting from the factory.
These are the 3 Types of LS Head Port Designs
Most "Old School" ECM's & Engine Harnesses used two different water temp sensors. One for the ECM and one for the Gauge. The LS harnesses / Sensors that we deal with do not have a wire for a Water Temp Gauge. So... we cheated by buying this new GM sensor (GM # 12551708) with 3 wires. The Gauge will not be accurate, but you'll know where you stand as far as "Hotter or Colder" than normal. Pig tails for this sensor are available at GM or NAPA stores too. We got "Crafty" on the pigtail for our build and snagged one off the Oil Sending unit for a 2003 (And newer) Silverado LS engine! They where also used on the older throttle body sensors!
ALL Gen III heads are interchangable. How ever, They need to be matched up with the proper engine combo to see any gains.
Here is a list of a known production casting #'s:
933 97 aluminum perimeter bolt 5.7 806 97-98 aluminum perimeter bolt 5.7 853 99-00 aluminum center bolt 5.7 241 01-03 aluminum center bolt 5.7 (some late MY00 cars got 241 castings) 243 04 up LS6 aluminum center bolt 5.7 ***These castings were also used around 05 in truck applications*** 862 99 and up 4.8-5.3 Truck heads 706 99 and up 4.8-5.3 Truck heads 799 05 and up 4.8-5.3Truck heads ***reportedly came on a few corvette's too*** These are basically 243 Heads 873 99-00 LQ4 6.0 Iron center bolt heads 317 01 and up LQ4 and LQ9 6.0 aluminum center bolt heads 035 01 - 04 LQ9 6.0 aluminum center bolt heads
What you need to know: The standard issue LS1 heads is best all-around head for the street / strip engines . A thorough porting and millimg job plus a valve upgrade on these will really wake up your engine.The heads have undergone only minor revisions since their introduction in 1997 , most notably a switch from perimeter to center valvcover bolt configuration for the 1999 model year. Each style has its own dedicated valvecovers and coilpacks mounting apparatus.
Casting Number 243 Head: 2001 LS6 5.7 Liter Passenger Car Material: Aluminimum Part Number: 12564243 Combustion Chamber Volume: 64.45cc Compression Ratio: 10.5:1 Intake Port Volume: 210cc Exhaust Port Volume: 75cc Intake Valve Diameter: 2.00 inches Exhaust Valve Diameter: 1.55 inches
What you need to know: The LS6 cylinder heads is essentially a tuned-up version of the LS1 head. At 65cc, the combustion chamber is slightly smaller and more efficient than the LS1. The more efficient design shortens burn times and ultimately means less ignition timing advance is required to produce the same power. And because less timing allows more efficient combustion, the Ls6 heads allow the engine to produce more torque. The exhaust port is a unique D-shape that improves flow. LS6 heads are the best choice only when all-out power is needed. Be prepared for a big price tag at the dealer or steep core charge from your head porter.
Casting Number 706 and 862 Head: 1999+ 4.8L / 5.3 Liter Truck Material: Aluminimum Part Number: 12559862 12561706 Combustion Chamber Volume: 61.15cc Compression Ratio: 9.5:1 Intake Port Volume: 200cc Exhaust Port Volume: 70cc Intake Valve Diameter: 1.89 inches Exhaust Valve Diameter: 1.55 inches
What you need to know: These small combustion chamber truck heads offer no advantage over an LS1 head except the smaller combustion chamber. This along with milling of the deck surface will allow a slightly higher compression ratio to be achieved. Because of the smaller intake valve installed in these heads a valve upgrade is practically mandatory.
Casting Number 873 Head: 1999-2000 LQ4 6.0 Liter Truck Material: ***Cast Iron*** Part Number: 12561873 Combustion Chamber Volume: 71.06cc Compression Ratio: 9.5:1 Intake Port Volume: 210cc Exhaust Port Volume: 75cc Intake Valve Diameter: 2.00 inches Exhaust Valve Diameter: 1.55 inches
Casting Number 317, 035 Head: 2001+ LQ4 and LQ9 6.0 Liter Truck Material: Aluminimum Part Number: 12562317 -LQ4 12572317 -LQ9 12572035 -LQ9 Combustion Chamber Volume: 71.06cc Compression Ratio: 10:1 LQ9 Flat top pistons Compression Ratio: 9.6:1 LQ4 Dish piston Intake Port Volume: 210cc Exhaust Port Volume: 75cc Intake Valve Diameter: 2.00 inches Exhaust Valve Diameter: 1.55 inches
Stock Head Flow Numbers Chamber 71.06cc----0.100---0.200--0.300--0.400--0.500--0.550--0.600 Intake 210cc-----------66-----142-----196---228----236---238-----240 Exhaust 75cc----------59-----104-----137---155----167---173-----177
What you need to know: The LQ4 head received aluminum heads starting in models year 2001. All other features are the same as previous years iron heads. This is the workhorse head for street / strip turbo and blower cars. They offer a large combustion chamber that lowers compression ratio making them perfect for a forced induction application. Swapping on the LQ4 head drops the compression ratio of a typical LS1 engine to 9:5.1 The Cast-iron casting are heavy!
So you want to figure out how much to mill:
It takes about .005" milling of the block deck to remove 1cc of volume. It takes .007" milling to remove 1cc from an LS1 head
Simple Milling Math:
You have a stock 66cc chamber and you want to get down to 63cc
66-63 = 3. You have to remove 3cc's
.007 x 3 = .021. So to get your 66cc chambers down to 63cc you'd have to mill ~.021.
You can also do the reverse, say you want to mill a head .030 to figure out how many CC's that removes you take .030 / .007 = ~ 4.28. Milling a stock 5.7 head .030 puts your chamber at ~ 62.
241 cast heads were Die Cast which is a process that smooths up the ports a bit compared to the Sand Cast procedure that was done on the 806 and 853 heads. Once ported any "advantage" the 241 cast had is moot.
Same Info applies to the: 4.8L/5.3L Truck 862 and 706 Head castings While the 706 Heads are a SPM = Semi Permanent-mold And considerd to be a more consistant head casting then the 862 wich are Sand cast, Once ported There Is no difference.
This appears to be one of the common misconceptions about heads having the 243 casting no. -- they are not necessarily LS6 head assemblies. The LS2 heads (243 or 799 casting) have the "heavy" standard LS1 valves. However, they do have the LS6 springs.
Only the true LS6 engine heads have stainless steel (not titanium) hollow stem valves (the exhaust stems are sodium filled). These valves are slightly longer than LS1 valves too.
The LS7 heads do have titanium valves.
New LS2 heads are about half the price of new LS6 heads (check sdparts.com). GM is "really proud" of those hollow stem valves!
Oh, if you have the 799 castings -- the only thing "Corvette" about them is the valve springs/retainers! Still a desirable set of LS1 heads though!
Supposedly, the 243 mold was done at GM Research, the 799 mold furnished to other vendors. The same vendor may have the 243 and 799 mold.
Head: GMPP C5R Material: Aluminum Part Number: 12480005/12480025 Combustion Chamber Volume: 38cc Intake Port Shape: Rectangle Port Exhaust Port Volume: 70cc
Casting Number 2716/5364/823 Head: L92 2007+ LS3 2008+ Material: Aluminum Part Number:12582713 Combustion Chamber Volume: 68cc Intake Port Volume/Shape: 257cc/Retangular Exhaust Port Volume/Shape: 86cc/D Shape Intake Valve Diameter: 2.165 inches Exhaust Valve Diameter: 1.59 inches
Casting Number 8452 Head: LS7 2006+ Material: Aluminum Part Number: Combustion Chamber Volume: 70cc Intake Port Volume/Shape: 270cc Exhaust Port Volume: 90cc Intake Valve Diameter: 2.20 inc Exhaust Valve Diameter: 1.61 inch
Cylinder Heads- Port Design Cylinder head interchangeability enables great parts mixing to build custom LS engine combinations, but the heads must be matched with intake manifolds that have compatible intake port configurations. The port sizes and shapes include:
Cathedral port- Introduced on the LS1 engine and used also on the LS6 and LS2, cathedral-port heads are named for the unique shape of the top of the intake port. Intake manifolds for LS1, LS2, LS6 and Vortec engines with cathedral-port heads are mostly interchangeable.
Rectangular port- LS7-style - The second LS intake runner design debuted on the Corvette Z06's LS7 engine. This rectangular design supports the straight-through airflow design of the heads. They feature 270cc intake ports and the ports and combustion chambers are CNC-ported from the factory. Use only with the LS7 intake manifold.
Rectangular port- L92 style - Similar to the LS7 design, but the ports are a little taller and a little narrower. They flow more than cathedral-port heads, but not as much as LS7 heads. In addition to the L92 6.2L engines, this port shape is also used on LS3 engines and some 6.0L truck engines, as well as the Corvette ZR1's LS9 and Cadillac CTS-V's LSA supercharged engines. Intake manifold bolt patterns are unique to this port design.
C5R heads- These heads pioneered the rectangular-port design, but because they are designed for professional finishing, their final shape and size depends on whoever is performing the porting.
Head-to-Block Compatibility Because of their comparatively small bores - 3.89 inches - LS1 and LS6 engines can only use LS1, LS6 and LS2 heads. Using heads designed for larger engines will cause the valve-to-block interference. The larger, 4.00-inch bore of the LS2 enables it to use LS1/LS6 heads, as well as L92-style heads (including LS3, LS9 and LSA engines). The 6.2L engines (LS3, L92, etc.) can use any head except for the LS7 and C5R, while the 7.0L LS7 and C5R blocks can use any LS-series head. LS7 blocks should be matched with heads designed for at least 4.10-inch bores; and 4.125-inch bores are preferred.
Most LS production cylinder blocks share the came cylinder head bolt pattern and the same size head bolts - four 11mm bolts per cylinder (10 in total) and five upper, 8mm bolts. Early LS1 and LS6 engines used different-length 11mm bolts, but engines from 2004 and later use same-length bolts. LS9 engines use stronger, 12mm head bolts.
Non-production blocks, such as GM Performance Parts' LSX block and the C5R, offer the same head-bolt pattern as production blocks. All LS heads will bolt up to them, but care must be taken to select the most compatible heads based on the appropriate bore size. Because of their large bores, heads designed for at least 4.10-inch bores should be used and 4.125-inch bores are preferred, such as the L92/LS3 or LS7 heads; otherwise valve-to-block interference is an issue, as is sufficient cylinder sealing.
GM Performance Parts' new LSX cylinder heads use 10 11mm and 13 8mm head bolts, or eight more than a regular-production LS head. That's more than 50 percent more head bolts than production heads, supplying superior clamping strength.