More LS2/LS7 info
01-05-2004, 06:45 AM
#1
6600 rpm clutch dump of death Administrator
Thread Starter
More LS2/LS7 info Good stuff:
http://corvetteactioncenter.com/specs/2005/index.html
GM says the block oil galleries were revised to supply oil pressure for the special valve lifters used by the Displacement on Demand (DoD) system. At this point, the changes in oil galleries are of no consequence because the LS2 does not use DoD. The six-liter's, 5.3-liter GEN IV cousin (due in '05 on mid-sized SUVs) will, so, in the interest of efficiency at the foundry; all Gen IV aluminum blocks have the same oiling system. DoD cannot be used on a Corvette because of a structure resonance problem which makes it obvious the engine is running as a four-cylinder.
The new heads use the same valve sizes and the port configurations of the LS6. It's interesting that the six-liter Gen IV gets within 100 rpm of the LS6 without the LS6's hollow stem valves. Almost 11:1 compression is just short of amazing on pump gas, especially the 91-octane fuel (rather than the recommended 93-octane) which is all you can get (short of 100-octane unleaded racing gasoline) in some parts of the country, especially out West. No doubt, when running 91, on anything else but a cool day, the engine controls will rely on knock retard (and the toll it takes on performance) to keep the engine out of detonation. Like the LS1 and LS6 before it, we suspect LS2 will take 93.5-to-94-octane to eliminate knock retard under all conditions.
OK, this is tranny related, but I found it interesting.... All Z51s cars will have Z06 ratios. Plus , the M6 cars will have integrated trany and diff coolers with gear driven pumps... Also, the 6 spd auto (in the next few years) sounds pretty cool.....
Both transmissions have been revised for the sixth-generation car. The Tremec T56 six-speed manual shifts smoother and more precisely. For shorter-throw shifts, there is a new, shorter, gear shift lever and synchronizers with 10 percent less travel. A new linkage and new shift-rail bearings inside the trans enhance shift feel and reduce effort. 2005 Corvettes ordered with Z51, will get all these revisions along with the higher-ratio gearset used in 01-04 Z06es and a transmission cooler. This cooler is an oil-to-coolant heat exchanger and the pump is gear driven and inside the trans. The dreaded Computer Aided Gear Selection (CAGS) continues as a fuel-economy enhancement for the manual transmission. We have never understood the stress CAGS causes. When a Corvette is driven properly, it's rare that CAGS is enabled.
C6's automatic is the Hydra-matic, 4L65-E, electronically-controlled, four-speed automatic. Originally developed for high-performance light trucks as the "4L60-E HD" this transmission is a beefed-up version of the 4L60-E, used on Corvette from 1993 to 2004. The 4L65-E uses the same gear ratios but has a higher input torque rating of 380 lbs/ft. The key features behind its higher capacity are:
Input and reaction planetary gearsets with five rather than four pinion gears. Spreading the load over five pinions rather than four increases the torque capacity of the gearsets.
The stator shaft splines, which engage the stator's roller clutch, are heat-treated.
The turbine shaft, which transfers torque from the converter to the input planetary gearset, is induction hardened.
Stronger low/reverse roller clutch assembly.
Seven plates in the 3-4 clutch rather than six.
Shotpeened output shaft.
A revised valve body and controller calibration.
Note that the LS2 puts out 400 lbs/ft. torque and the "L65" can tolerate only 380. Though GM did not elaborate on that apparent problem, we suspect the LS2's PCM applies some torque management to the engine, when the trans. shifts at WOT high rpm. Some media outlets rumored that C6 would share the Cadillac XLR's 5L50-E five-speed auto. Those who actually understand GM Powertrain's product line, know that the 5L50 (311 lb/ft. input torque rating) is not strong enough for an engine of 400 lbs/ft. torque. Additionally, it's debatable whether a five-speed automatic would offer a valuable performance improvement over a four-speed when used with a engine having the LS2's torque curve.
GM Powertrain announced in 2003 that it was developing six-speed automatic transmissions for rear-drive applications. It is unknown if this project will result in a "6L65-E" but the marketing clamor for a six-speed automatic continues to grow and we figure there's a good chance it's in the cards for the C6 at some later date. We also won't deny the gadget freaks' constant lament about the lack of a paddle shifter in the Corvette. We suspect that may arrive with the "6A" transmission.
C4 rear axle ratios carry-over to C6. Though GM did not release any information to this effect, we'll guess that, because of the 25-40 lb/ft increase in torque, the base C6 rear axle gets the reliability/durability enhancements used in 01-04 Z06 axles. For '05, the limited-slip preload was increased to improve handling and stability on corner entries when the car is really being pushed hard. Another interesting new feature of rear axles on C6 Z51s is a gear oil cooler. Like the one in the trans, it's internal and gear driven. It pumps the gear lubricant through an "oil-to-oil" cooler that is inside the transmission. Basically, the rear axle lubricant is cooled by the trans. lube which is, in turn, cooled by the radiator-an elegant engineering solution, indeed.
Technical data:
Displacement (liters/cu in/cc): 6.0 / 364 / 5970
Bore & stroke (in / mm): 4 x 3.62 / 101.6 x 92
Block material: cast aluminum
Cylinder head material: cast aluminum
Valvetrain: OHV, 2 valves per cylinder
Fuel delivery: SEFI (sequential electronic fuel injection)
Compression ratio: 10.9:1
Horsepower (hp / kw @ rpm): 400 / 298 @ 6000
Torque (lb-ft @ rpm): 400 @ 4400
Recommended fuel: 93 octane recommended, not required
Maximum engine speed (rpm): 6500
Estimated fuel economy (mpg city / hwy / combined): 19 / 28 / 23 (man) & 18 / 25 / 21 (auto)
http://corvetteactioncenter.com/specs/2005/index.html
GM says the block oil galleries were revised to supply oil pressure for the special valve lifters used by the Displacement on Demand (DoD) system. At this point, the changes in oil galleries are of no consequence because the LS2 does not use DoD. The six-liter's, 5.3-liter GEN IV cousin (due in '05 on mid-sized SUVs) will, so, in the interest of efficiency at the foundry; all Gen IV aluminum blocks have the same oiling system. DoD cannot be used on a Corvette because of a structure resonance problem which makes it obvious the engine is running as a four-cylinder.
The new heads use the same valve sizes and the port configurations of the LS6. It's interesting that the six-liter Gen IV gets within 100 rpm of the LS6 without the LS6's hollow stem valves. Almost 11:1 compression is just short of amazing on pump gas, especially the 91-octane fuel (rather than the recommended 93-octane) which is all you can get (short of 100-octane unleaded racing gasoline) in some parts of the country, especially out West. No doubt, when running 91, on anything else but a cool day, the engine controls will rely on knock retard (and the toll it takes on performance) to keep the engine out of detonation. Like the LS1 and LS6 before it, we suspect LS2 will take 93.5-to-94-octane to eliminate knock retard under all conditions.
OK, this is tranny related, but I found it interesting.... All Z51s cars will have Z06 ratios. Plus , the M6 cars will have integrated trany and diff coolers with gear driven pumps... Also, the 6 spd auto (in the next few years) sounds pretty cool.....
Both transmissions have been revised for the sixth-generation car. The Tremec T56 six-speed manual shifts smoother and more precisely. For shorter-throw shifts, there is a new, shorter, gear shift lever and synchronizers with 10 percent less travel. A new linkage and new shift-rail bearings inside the trans enhance shift feel and reduce effort. 2005 Corvettes ordered with Z51, will get all these revisions along with the higher-ratio gearset used in 01-04 Z06es and a transmission cooler. This cooler is an oil-to-coolant heat exchanger and the pump is gear driven and inside the trans. The dreaded Computer Aided Gear Selection (CAGS) continues as a fuel-economy enhancement for the manual transmission. We have never understood the stress CAGS causes. When a Corvette is driven properly, it's rare that CAGS is enabled.
C6's automatic is the Hydra-matic, 4L65-E, electronically-controlled, four-speed automatic. Originally developed for high-performance light trucks as the "4L60-E HD" this transmission is a beefed-up version of the 4L60-E, used on Corvette from 1993 to 2004. The 4L65-E uses the same gear ratios but has a higher input torque rating of 380 lbs/ft. The key features behind its higher capacity are:
Input and reaction planetary gearsets with five rather than four pinion gears. Spreading the load over five pinions rather than four increases the torque capacity of the gearsets.
The stator shaft splines, which engage the stator's roller clutch, are heat-treated.
The turbine shaft, which transfers torque from the converter to the input planetary gearset, is induction hardened.
Stronger low/reverse roller clutch assembly.
Seven plates in the 3-4 clutch rather than six.
Shotpeened output shaft.
A revised valve body and controller calibration.
Note that the LS2 puts out 400 lbs/ft. torque and the "L65" can tolerate only 380. Though GM did not elaborate on that apparent problem, we suspect the LS2's PCM applies some torque management to the engine, when the trans. shifts at WOT high rpm. Some media outlets rumored that C6 would share the Cadillac XLR's 5L50-E five-speed auto. Those who actually understand GM Powertrain's product line, know that the 5L50 (311 lb/ft. input torque rating) is not strong enough for an engine of 400 lbs/ft. torque. Additionally, it's debatable whether a five-speed automatic would offer a valuable performance improvement over a four-speed when used with a engine having the LS2's torque curve.
GM Powertrain announced in 2003 that it was developing six-speed automatic transmissions for rear-drive applications. It is unknown if this project will result in a "6L65-E" but the marketing clamor for a six-speed automatic continues to grow and we figure there's a good chance it's in the cards for the C6 at some later date. We also won't deny the gadget freaks' constant lament about the lack of a paddle shifter in the Corvette. We suspect that may arrive with the "6A" transmission.
C4 rear axle ratios carry-over to C6. Though GM did not release any information to this effect, we'll guess that, because of the 25-40 lb/ft increase in torque, the base C6 rear axle gets the reliability/durability enhancements used in 01-04 Z06 axles. For '05, the limited-slip preload was increased to improve handling and stability on corner entries when the car is really being pushed hard. Another interesting new feature of rear axles on C6 Z51s is a gear oil cooler. Like the one in the trans, it's internal and gear driven. It pumps the gear lubricant through an "oil-to-oil" cooler that is inside the transmission. Basically, the rear axle lubricant is cooled by the trans. lube which is, in turn, cooled by the radiator-an elegant engineering solution, indeed.
Technical data:
Displacement (liters/cu in/cc): 6.0 / 364 / 5970
Bore & stroke (in / mm): 4 x 3.62 / 101.6 x 92
Block material: cast aluminum
Cylinder head material: cast aluminum
Valvetrain: OHV, 2 valves per cylinder
Fuel delivery: SEFI (sequential electronic fuel injection)
Compression ratio: 10.9:1
Horsepower (hp / kw @ rpm): 400 / 298 @ 6000
Torque (lb-ft @ rpm): 400 @ 4400
Recommended fuel: 93 octane recommended, not required
Maximum engine speed (rpm): 6500
Estimated fuel economy (mpg city / hwy / combined): 19 / 28 / 23 (man) & 18 / 25 / 21 (auto)
Last edited by J-Rod; 01-05-2004 at 07:17 AM.
01-05-2004, 09:21 AM
#4
TECH Apprentice
Join Date: Jan 2002
Location: Texas
Posts: 356
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by J-Rod
Good stuff:
The new heads use the same valve sizes and the port configurations of the LS6. It's interesting that the six-liter Gen IV gets within 100 rpm of the LS6 without the LS6's hollow stem valves. Almost 11:1 compression is just short of amazing on pump gas, especially the 91-octane fuel (rather than the recommended 93-octane) which is all you can get (short of 100-octane unleaded racing gasoline) in some parts of the country, especially out West. No doubt, when running 91, on anything else but a cool day, the engine controls will rely on knock retard (and the toll it takes on performance) to keep the engine out of detonation. Like the LS1 and LS6 before it, we suspect LS2 will take 93.5-to-94-octane to eliminate knock retard under all conditions.
The new heads use the same valve sizes and the port configurations of the LS6. It's interesting that the six-liter Gen IV gets within 100 rpm of the LS6 without the LS6's hollow stem valves. Almost 11:1 compression is just short of amazing on pump gas, especially the 91-octane fuel (rather than the recommended 93-octane) which is all you can get (short of 100-octane unleaded racing gasoline) in some parts of the country, especially out West. No doubt, when running 91, on anything else but a cool day, the engine controls will rely on knock retard (and the toll it takes on performance) to keep the engine out of detonation. Like the LS1 and LS6 before it, we suspect LS2 will take 93.5-to-94-octane to eliminate knock retard under all conditions.
Although this is just speculation, I believe with the cam specs mentioned and the fact the LS1 responds to increased bore so well, the new LS2 engine is under-rated powerwise by 5 to 10%, IMO.
Todd
