6L engine--which heads?
09-28-2010, 03:22 PM
#14
TECH Resident
iTrader: (16)
Join Date: Jul 2009
Location: Brunswick, GA
Posts: 790
Likes: 0
Received 0 Likes
on
0 Posts
most likely the heads that are coming on the engine are 317 heads unless its an aluminum block 6.0L(LS6). 317 heads are great for boost not so much for NA, If you have the extra little cash then I would do L92 heads and intake mani. They flow awesome stock. But 243 heads which are LS6 heads and are slightly cheaper than L92s and will get you to your crank hp goal. I am running milled 243 heads on my new setup..
317 and 243 heads flow exactly the same, but 317 is a 72cc head and the 243s are a 64cc head, 243s will give you a higher compression.
317 and 243 heads flow exactly the same, but 317 is a 72cc head and the 243s are a 64cc head, 243s will give you a higher compression.
Aluminum 6.0 is a LS2 not LS6. LS6 is a 5.7. If you find a ls2 your most likely going to end up paying out the ***. But it will already have the 243s on it. Or you can look for an iron ly6 or aluminum l76 which will both come with the l92 rectangular style heads. But these cost a good bit more than the reagular ol lq4 or lq9. cheapest route to get close to your goal "flywheel numbers" would be the lq4/lq9 with 243s, good intake, and decent cam. and the regular both ons.
09-28-2010, 08:03 PM
#18
Mine is an 04 and has both the LS2 full-floating wrist pin rods, and coated pistons. I knew the pistons should be coated but was unclear on when the rod change happened. Here are some details PMd to me by Jake Man. Note the large bold text.
For model year 2005, modifications were made in the LQ4 that increased the power ratings to 335 Horsepower @ 5200 rpm and 375 FtLb of Torque @ 4000 rpm, all on regular unleaded 87 Octane gasoline. Compression Ratio remained at 9.4:1.
Source: GM specifications for the 2005 Yukon/Yukon XL (not Denali), as found on GM's website in 2005 (and printed out at the time, since GM now only publishes data for current model year vehicles they are selling).
As for what specific changes GM made to the LQ4 to increase it's power rating, I do not know. I did read that programming changes were made to the PCM calibrations, and this I truely believe. I also read that the air flow management in either the intake manifold or the heads was improved, but I would need to verify that with a corroborating source from GM before stating that hard parts were changed to make the improvement.
Some hard parts were definitely changed... the exhaust system for one... with several relocations of the Cat converters being the most obvious clue when comparing 2000-2006 model years.
As for differences between the LQ4 and the High Output LQ9, which was initially a 6.0L amped up for to make the Cadillac trucks unique, but later was passed along to GMC (Denali) and Chevrolet (SS), and then eventually evolved to and was renamed the "Vortec MAX" in 2006 and made available in certain Sierras and Silverados, there are several credible GM sources that discuss the hard part differences between these 6.0L engines.
The most significant difference is the pistons... the LQ9 pistons are flat topped, which is how the compression ratio got increased from 9.4:1 to 10.0:1.
The next difference is the cylinder heads. The LQ9 heads are designed to work with flat top pistons, so the valves don't crash into them.
Then there is the new steel camshaft, which according to GM, was designed to increase valve lift and duration.
And there is the intake manifold, which was improved with a new "purge isolator - the rubber device used to mount the solenoid that manages excess fuel vapor - to reduce noise and vibration."
The new intake manifold also received a new, "more durable injector director plate, with two large holes rather than four smaller ones to reduce the potential for fuel clogging."
(The above two changes to the intake manifold may have migrated their way to the LQ4 eventually, but I don't know for certain)
When the LQ9 was released, it was built with tighter tolerances in the crankshaft main bearings to allow for a more precise fit and to reduce cold knock... the slapping noise that was endemic to the 6.0L at the time (2001). It is highly probable that this improvement to the bottom end also made it's way to the LQ4... since common complaints of cold knocking/slapping seemed to evaporate by the 2003 model year.
I beleive the LQ9 requires Premium fuel of 91 Octane or higher, due to the high compression ratio. That's a deal killer for me right there. No sense in spending 40 cents more per gallon for 10 horsepower that is only obtainable at an rpm I'll never reach in my lifetime of driving 2004 Improvements/Changes to the LQ4:
1. Floating Pin Pistons
"The Vortec 6000 RPO LQ4 is fitted with new floating pin pistons. Introduced on the Vortec High Output LQ9, these pistons feature wrist pins that "float" inside the rod bushing and the pin bores in the piston barrel. Other Vortec V-8's (read and weep 5.3L owners) use a fixed pin assembly, in which the connecting rod is fixed to the piston's wrist pin, and the pin rotates in the pin bore.
"In the (2004 LQ4) Vortec 6000's (ah yes, in the province of Denali's), snap rings retain the wrist pin in the piston, while the rod moves laterally on a bushing around the pin. the floating pin assembly allows tighter pin to bore tolerances and reduces noise generated during engine operation."
(Can us say 'this is how we address cold start knock, aka piston slap' about which common complaints seemed to quietly disappear by the time the 2004 models came out? Not convinced? Read the next improvement
2. Re-Profiled Polymer Coated Pistons
Still not flat tops, still not the same pistons used in the higher power (but higher octane requirement) LQ9, but the LQ4 did in fact get improved pistons as a running change, and the better news is that this change occured even BEFORE the 2004 model year began production...
"Application of floating pin pistons is accompanied by a changeover, begun in model year 2003, to re-profiled polymer coated pistons. The polymer material allows tighter piston to cylinder bore clearances without bore scuffing, extending the benefits of the floating pin piston and rod assembly and reducing the noise generated by the piston's movement within the cylinder. The net result is a quieter engine."
(The prosecution rests. The changes to the LQ4 piston profile, piston coating, and piston attachment system were clearly postured to address a noise concern. That the technology need simply be borrowed from the LQ9 probably made these improvements better candidates for immediate implementation into production, at the lowest cost, as the tooling existed. These paranthetical comments are merely my extrapolation from the factual data posted and procured exclusively from GM Powertrain) 3. Returnless Fuel Injecton for Full Size PickUps and SUVs
All Vortec 6.0L (LQ4 and LQ9) engines "installed in GM's 2004 full-size pickups and sport utility vehicles are equipped with a new 'returnless' fuel injection system that eliminates fule reutrn lines between the engine and the fuel tank."
"Before model year 2004, fuel pressure was managed by a return line that bled off excess fuel and returned it to the tank. The new system eliminates the return lines, and moves the electric fuel pressure regulator from the fuel rail on the engine to the fuel tank, which in turn eliminates heat transfer from the engine to the tank, ultimately reducing the amount of vapor created in the tank."
4. New Intake Manifold Gaskets
New for 2004 model year, the Vortec 6000 (both variants) has "new intake manifold sealing gaskets manufactured from a rubberized fluorocarbon material known by several brand names, including Dupont Viton." (Note that GM doesn't necessarily commit that they actually used Dupont Viton itself, only that they used a fluorocarbon material that is known by several brand names, including Dupont Viton. Lawyers or PR people must have written that.)
"The new manifold gaskets are black, replacing the former silicon based gaskets that were manufactured in several different colors. The fluorocarbon gaskets represent some of the best sealing technology available... resistant to most chemicals for maximum durability, and particularly impermeable to small hydrocarbon molecules. Gasoline vapor cannot penetrate the fluorcarbon."
(Reaon for the expense of improved gasket? Evaporative emissions)
Speaking of emissions, here is another change:
4. Tamper resistant fixed orifice PCV valve
"All Vortec 6000's are fitted with a new fixed oriface Positive Crankcase Ventilation Valve", that is "fixed in a grommet pressed into the rocker cover, and cannot be removed. Previously, the PCV valve was attached to a tube, which was in turn attached to the rocker cover. The new valve virtually eliminates the possiblility of inadvertant disconnection... or deliberate tampering."
(Oh come on, who actually disconnects their PCV valve "deliberately"? For like, less than ZERO performance gain, and a whole lotta smell?)
So, to review the changes to the LQ4 (some of which also applied to the LQ9, particularly the emissions related changes, like returnless fuel supply, permanent PCV valve, and a Viton-esque intake manifold gasket)
2004 LQ4 Improvement Summary:
1. FLoating Pin Pistons
2. Polymer Coated Pistons (running change begun mid 2003)3. Piston ReProfile (need more information on what this may mean)
4. Returnless Fuel Injection (applies to both LQ4 and LQ9)
5. Baffled fuel supply line to manage pulsing and reduce noise (didn't mention this earlier, but this was a byproduct of a returnless system)
6. Tamper Resistant PCV valve (applies to both LQ4 and LQ9)
7. Low Permeability Intake Manifold Gaskets (applies to LQ4 and LQ9)
8. Oh yeah, GM finally ditched the EGR out of the LQ4 in the Express / Savana full size vans... the last hold out 6.0L Vortecs to have EGR I don't know if someone could say it isn't worth it or not, for me it would be boil down to whether or not it would be financially worth it. The swap to 243 heads usually net around 20hp on a LQ4, primarily from the increase in compression. The gain will be about one point of compression on the LQ4. Due to the ports being just about identical between the 317 and 243 heads, they flow just about equally. From flow test's performed by WCCH, the 243's do flow just a tad better due to the combustion chamber shape from the smaller chamber. Also all 243's are not equal, the LS6 versions having sodium filled valves lightens up the valve-train, extending the rpm range slightly and allowing the motor to rev quicker. While the LS2 versions have the standard valves. SO - is 20hp worth the money and the amount of work it would take for the swap?
For model year 2005, modifications were made in the LQ4 that increased the power ratings to 335 Horsepower @ 5200 rpm and 375 FtLb of Torque @ 4000 rpm, all on regular unleaded 87 Octane gasoline. Compression Ratio remained at 9.4:1.
Source: GM specifications for the 2005 Yukon/Yukon XL (not Denali), as found on GM's website in 2005 (and printed out at the time, since GM now only publishes data for current model year vehicles they are selling).
As for what specific changes GM made to the LQ4 to increase it's power rating, I do not know. I did read that programming changes were made to the PCM calibrations, and this I truely believe. I also read that the air flow management in either the intake manifold or the heads was improved, but I would need to verify that with a corroborating source from GM before stating that hard parts were changed to make the improvement.
Some hard parts were definitely changed... the exhaust system for one... with several relocations of the Cat converters being the most obvious clue when comparing 2000-2006 model years.
As for differences between the LQ4 and the High Output LQ9, which was initially a 6.0L amped up for to make the Cadillac trucks unique, but later was passed along to GMC (Denali) and Chevrolet (SS), and then eventually evolved to and was renamed the "Vortec MAX" in 2006 and made available in certain Sierras and Silverados, there are several credible GM sources that discuss the hard part differences between these 6.0L engines.
The most significant difference is the pistons... the LQ9 pistons are flat topped, which is how the compression ratio got increased from 9.4:1 to 10.0:1.
The next difference is the cylinder heads. The LQ9 heads are designed to work with flat top pistons, so the valves don't crash into them.
Then there is the new steel camshaft, which according to GM, was designed to increase valve lift and duration.
And there is the intake manifold, which was improved with a new "purge isolator - the rubber device used to mount the solenoid that manages excess fuel vapor - to reduce noise and vibration."
The new intake manifold also received a new, "more durable injector director plate, with two large holes rather than four smaller ones to reduce the potential for fuel clogging."
(The above two changes to the intake manifold may have migrated their way to the LQ4 eventually, but I don't know for certain)
When the LQ9 was released, it was built with tighter tolerances in the crankshaft main bearings to allow for a more precise fit and to reduce cold knock... the slapping noise that was endemic to the 6.0L at the time (2001). It is highly probable that this improvement to the bottom end also made it's way to the LQ4... since common complaints of cold knocking/slapping seemed to evaporate by the 2003 model year.
I beleive the LQ9 requires Premium fuel of 91 Octane or higher, due to the high compression ratio. That's a deal killer for me right there. No sense in spending 40 cents more per gallon for 10 horsepower that is only obtainable at an rpm I'll never reach in my lifetime of driving 2004 Improvements/Changes to the LQ4:
1. Floating Pin Pistons
"The Vortec 6000 RPO LQ4 is fitted with new floating pin pistons. Introduced on the Vortec High Output LQ9, these pistons feature wrist pins that "float" inside the rod bushing and the pin bores in the piston barrel. Other Vortec V-8's (read and weep 5.3L owners) use a fixed pin assembly, in which the connecting rod is fixed to the piston's wrist pin, and the pin rotates in the pin bore.
"In the (2004 LQ4) Vortec 6000's (ah yes, in the province of Denali's), snap rings retain the wrist pin in the piston, while the rod moves laterally on a bushing around the pin. the floating pin assembly allows tighter pin to bore tolerances and reduces noise generated during engine operation."
(Can us say 'this is how we address cold start knock, aka piston slap' about which common complaints seemed to quietly disappear by the time the 2004 models came out? Not convinced? Read the next improvement
2. Re-Profiled Polymer Coated Pistons
Still not flat tops, still not the same pistons used in the higher power (but higher octane requirement) LQ9, but the LQ4 did in fact get improved pistons as a running change, and the better news is that this change occured even BEFORE the 2004 model year began production...
"Application of floating pin pistons is accompanied by a changeover, begun in model year 2003, to re-profiled polymer coated pistons. The polymer material allows tighter piston to cylinder bore clearances without bore scuffing, extending the benefits of the floating pin piston and rod assembly and reducing the noise generated by the piston's movement within the cylinder. The net result is a quieter engine."
(The prosecution rests. The changes to the LQ4 piston profile, piston coating, and piston attachment system were clearly postured to address a noise concern. That the technology need simply be borrowed from the LQ9 probably made these improvements better candidates for immediate implementation into production, at the lowest cost, as the tooling existed. These paranthetical comments are merely my extrapolation from the factual data posted and procured exclusively from GM Powertrain) 3. Returnless Fuel Injecton for Full Size PickUps and SUVs
All Vortec 6.0L (LQ4 and LQ9) engines "installed in GM's 2004 full-size pickups and sport utility vehicles are equipped with a new 'returnless' fuel injection system that eliminates fule reutrn lines between the engine and the fuel tank."
"Before model year 2004, fuel pressure was managed by a return line that bled off excess fuel and returned it to the tank. The new system eliminates the return lines, and moves the electric fuel pressure regulator from the fuel rail on the engine to the fuel tank, which in turn eliminates heat transfer from the engine to the tank, ultimately reducing the amount of vapor created in the tank."
4. New Intake Manifold Gaskets
New for 2004 model year, the Vortec 6000 (both variants) has "new intake manifold sealing gaskets manufactured from a rubberized fluorocarbon material known by several brand names, including Dupont Viton." (Note that GM doesn't necessarily commit that they actually used Dupont Viton itself, only that they used a fluorocarbon material that is known by several brand names, including Dupont Viton. Lawyers or PR people must have written that.)
"The new manifold gaskets are black, replacing the former silicon based gaskets that were manufactured in several different colors. The fluorocarbon gaskets represent some of the best sealing technology available... resistant to most chemicals for maximum durability, and particularly impermeable to small hydrocarbon molecules. Gasoline vapor cannot penetrate the fluorcarbon."
(Reaon for the expense of improved gasket? Evaporative emissions)
Speaking of emissions, here is another change:
4. Tamper resistant fixed orifice PCV valve
"All Vortec 6000's are fitted with a new fixed oriface Positive Crankcase Ventilation Valve", that is "fixed in a grommet pressed into the rocker cover, and cannot be removed. Previously, the PCV valve was attached to a tube, which was in turn attached to the rocker cover. The new valve virtually eliminates the possiblility of inadvertant disconnection... or deliberate tampering."
(Oh come on, who actually disconnects their PCV valve "deliberately"? For like, less than ZERO performance gain, and a whole lotta smell?)
So, to review the changes to the LQ4 (some of which also applied to the LQ9, particularly the emissions related changes, like returnless fuel supply, permanent PCV valve, and a Viton-esque intake manifold gasket)
2004 LQ4 Improvement Summary:
1. FLoating Pin Pistons
2. Polymer Coated Pistons (running change begun mid 2003)3. Piston ReProfile (need more information on what this may mean)
4. Returnless Fuel Injection (applies to both LQ4 and LQ9)
5. Baffled fuel supply line to manage pulsing and reduce noise (didn't mention this earlier, but this was a byproduct of a returnless system)
6. Tamper Resistant PCV valve (applies to both LQ4 and LQ9)
7. Low Permeability Intake Manifold Gaskets (applies to LQ4 and LQ9)
8. Oh yeah, GM finally ditched the EGR out of the LQ4 in the Express / Savana full size vans... the last hold out 6.0L Vortecs to have EGR I don't know if someone could say it isn't worth it or not, for me it would be boil down to whether or not it would be financially worth it. The swap to 243 heads usually net around 20hp on a LQ4, primarily from the increase in compression. The gain will be about one point of compression on the LQ4. Due to the ports being just about identical between the 317 and 243 heads, they flow just about equally. From flow test's performed by WCCH, the 243's do flow just a tad better due to the combustion chamber shape from the smaller chamber. Also all 243's are not equal, the LS6 versions having sodium filled valves lightens up the valve-train, extending the rpm range slightly and allowing the motor to rev quicker. While the LS2 versions have the standard valves. SO - is 20hp worth the money and the amount of work it would take for the swap?
Thread
Thread Starter
Forum
Replies
Last Post
03regcab sierra
INTERNAL ENGINE MODIFICATIONS
2
09-09-2015 02:02 PM
sauldgold
GM Engine & Exhaust Performance
3
07-23-2015 02:15 PM
