L76 6.0 Engine General Information

[HSV-GTS-300]

G8 L76 6.0 Engine Information
General Info
http://media.gm.com/us/powertrain/en/product_services/2008/Spec%20Sheet/Gen%20IV/2008%20Gen%20IV%20Car/08_L76.xls Excel 86kB
http://archives.media.gm.com/us/powertrain/en/product_services/2009/Spec%20Sheet/Gen%20IV/2009%20Gen%20IV%20Car/09_L76c_n.xls

Active Fuel Management (AFM) explained
http://media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Gen%20IV/Gen%20IV%20Car/08_L76.doc
Word Doc 71.5kB
http://archives.media.gm.com/us/powertrain/en/product_services/2008/Whats%20New/Gen%20IV/Gen%20IV%20Car/08_L76.doc

Oil Flow Schematic (same as LH6)
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/0405phr_gmdod_07_z.jpg

Lifter Oil Manifold Assembly (LOMA) used instead of LS2 style valley cover
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/0405phr_gmdod_04_z.jpg

Under the LOMA you see the switching solenoids for Deac lifter oil supply
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/0405phr_gmdod_05_z.jpg

Deac Lifters 8x fitted to cylinders 1,4,6,&7
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/0405phr_gmdod_03_z.jpg

http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/0405phr_gmdod_02_z.jpg

[HSV-GTS-300]

Q: Any truth in the de-ac cylinders having a different lobe profile to the normal cylinders ??

A from GMPP: AFM cylinders have slightly different grind ( a bit taller) to accomodate additional compliance of AFM parts --intent is lift event equivalence.



1.70 Exhaust Rocker Ratio
1.69 Intake Rocker Ratio

Lift:
@Cam @Valve
Exhaust: 0.282 0.479
Intake: 0.279 0.472

Cam Timing@0.004" Tappet Lift:
Open Close Adv. Duration
Exhaust: 71 BBDC 33 ATDC 284
Intake: 11 BTDC 91 ABDC 282


Cam Timing@0.050" Tappet Lift:
Open Close Duration
Exhaust: 40 BBDC 12 BTDC 208
Intake: 17 ATDC 37 ABDC 200

200/208 0.472 0.479


Further Cam Info just received:

* Camshaft Lobe Lift - Exhaust - Non Active Fuel Management Cylinders
7.17 mm
0.282 in

* Camshaft Lobe Lift - Exhaust - Active Fuel Management Cylinders
7.3 mm
0.287 in

* Camshaft Lobe Lift - Intake - Non Active Fuel Management Cylinders
7.08 mm
0.279 in

* Camshaft Lobe Lift - Intake - Active Fuel Management Cylinders
7.2 mm
0.283 in



* Valve Lift - Exhaust - Non Active Fuel Management
12.19 mm
0.480 in

* Valve Lift - Exhaust - Active Fuel Management
12.41 mm
0.489 in

* Valve Lift - Intake - Non Active Fuel Management
12.04 mm
0.474 in

* Valve Lift - Intake - Active Fuel Management
12.24 mm
0.488 in

[keliente]

Awesome info.

[NONo443]

Thanks for the information about AFM, I have been looking this whole past week for that information.

[HSV-GTS-300]

Originally posted by NONo443
Thanks for the information about AFM, I have been looking this whole past week for that information.

You're welcome. ;)
I have a fully assembled L76 crate engine sitting here in my shed if you want pics of anything just ask.

[QWIKLS1]

So do the same 4 cylinders always deactivate when the engine goes into 4 cyl mode?

[HSV-GTS-300]

Originally posted by QWIKLS1
So do the same 4 cylinders always deactivate when the engine goes into 4 cyl mode?

Yes, only the 4 cylinders fitted with the de-ac lifters.

[QWIKLS1]

Originally posted by HSV-GTS-300
Yes, only the 4 cylinders fitted with the de-ac lifters.

I'm not an engineer, but you'd think a long cruise would do some weird things to the block and heads if heat is only coming from (a fixed) half of the cylinders.

:o

[HSV-GTS-300]

Originally posted by QWIKLS1
I'm not an engineer, but you'd think a long cruise would do some weird things to the block and heads if heat is only coming from (a fixed) half of the cylinders.
:o

The only official reply I have seen to a similar question was regarding the LH6 (5.3L aluminium block with AFM). The following question was asked of Chris Meagher, assistant chief engineer of small-block truck engines at GM.

"With four cylinders working the entire life of the engine and four cylinders working for approximately half that time, is there any extra maintenance or any deviation of maintenance from a normal V-8?"

To that Meagher says: "The service life of the engine will be the same as normal current engines. There are a couple of reasons for not making the service requirement any different for these four cylinders. One would be to avoid any confusion; the second, quite frankly, is that it's not necessary."

[HSV-GTS-300]

Originally posted by QWIKLS1
I'm not an engineer, but you'd think a long cruise would do some weird things to the block and heads if heat is only coming from (a fixed) half of the cylinders.
:o

You'll still get some constant nett heat out of the deactivated cylinders....just nowhere near the amount from cylinders where there is combustion still taking place.

For each deactivated cylinder you'll still have:
Heat generated due to air compression on every upstroke.
Heat loss due to air expansion on every downstroke.
Heat generated from friction.


"In order to eliminate the pumping losses," says Meagher, "you need to disable both the intake and exhaust valve." This results in a completely sealed, deactivated cylinder, which is essentially an air spring being acted upon by a piston. Virtually all the work put into it during compression is returned to the crank during decompression, finally giving credence to the old joke about piston-return springs."

[Robs98SS]

do you have any idea if the cylinder deactivation lifter has a allowable maximum lift? Can you go to a cam with a larger lift and still maintain your cylinder deactivation?

I would think with the spring in the lifter there is a maximum lift that is probably higher than what the stock cam has.

We just cant leave well enough alone =)

[HSV-GTS-300]

Originally posted by Robs98SS
do you have any idea if the cylinder deactivation lifter has a allowable maximum lift?
I would think with the spring in the lifter there is a maximum lift that is probably higher than what the stock cam has.


The deactivation lifter which is used in the 5.3L LH6 has a maximum allowable lift at the valve of 0.590". I do not know if the same de-ac lifter is used in the L76.
The stock L76 cam has lifts at the valve of :
Exhaust:0.479"
Intake: 0.472"


Originally posted by Robs98SS
Can you go to a cam with a larger lift and still maintain your cylinder deactivation?
The cam swaps on L76's in Aus up to this point of time have also involved replacing the de-ac lifters with all normal style lifters.....but the cylinder deactivation was never functional in our cars to begin with. So the answer isn't there.

You might have to look towards what people are doing with cam upgrades in AFM cars/trucks with such engines as the LH6, truck L76 and L92.

[Note the details at the start of post #2 above, the stock L76 cam has slightly taller lobes only in the de-ac cylinders] + a single bolt cam core......getting more lift and maintaining AFM would involve a very special camshaft.

[HSV-GTS-300]

Originally posted by Robs98SS
Can you go to a cam with a larger lift and still maintain your cylinder deactivation?

So far I've only seen one Vendor who offers this.


There have been enough reported cases of DOD lifter failures on stock cams to make a person think it would be crazy to try them on a custom camshaft.

The general consensus for higher lift is to :

Permanently disable DOD
Swap out DOD lifters for LS7 lifters
Fit custom camshaft
Swap out L76 valley plate for LS2 valley plate
Fit LS2/LS7 lifter trays

Pic of dis-assembled DOD lifter

http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/L76/DOD20DEAC20Lifter20Disassembled.jpg

[HSV-GTS-300]

I'm not an engineer, but you'd think a long cruise would do some weird things to the block and heads if heat is only coming from (a fixed) half of the cylinders.
:o

The cylinder de-activation gets cycled on and off.

"If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, and then return to V8 mode for 1 minute."

[HSV-GTS-300]

Cylinder Deactivation (Active Fuel Management) System Description

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.

When commanded ON, the ECM will determine what cylinder is firing, and begin deactivation on the next closest deactivated cylinder in firing order sequence. The Gen IV engine has a firing order of 1-8-7-2-6-5-4-3. If cylinder number 1 is on its combustion event when cylinder deactivation is commanded ON, the next cylinder in the firing order sequence that can be deactivated is cylinder number 7. If cylinder number 5 is on its combustion event when cylinder deactivation is commanded ON, then the next cylinder in the firing order sequence that can be deactivated is cylinder number 4.

Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing. The pin housing contains the lifter plunger and pushrod seat which interfaces with the pushrod. The outer housing contacts the camshaft lobe through a roller. During V8 mode, the locking pins are pushed outward by spring force, locking the pin housing and outer housing together causing the lifter to function as a normal lifter. When V4 mode is commanded ON, the locking pins are pushed inward with engine oil pressure directed from the valve lifter oil manifold (VLOM) assembly solenoids. When the lifter pin housing is unlocked from the outer housing, the internal pin housing will remain stationary, while the outer housing will move with the profile of the camshaft lobe, which results in the valve remaining closed. One VLOM solenoid controls both the intake and exhaust valves for each deactivating cylinder. There are 2 distinct oil passages going to each cylinder deactivation lifter bore, one for the hydraulic lash-adjusting feature of the lifter, and one for controlling the locking pins used for cylinder deactivation.

Although both intake and exhaust valve lifters are controlled by the same solenoid in the VLOM, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event. During an intake event, the intake cam lobe is pushing the valve lifter upwards to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve. However, when cylinder deactivation is commanded ON, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately, and deactivate the exhaust valve.

By deactivating the exhaust valve first, this allows the capture of a burnt air/fuel charge or exhaust gas charge in the combustion chamber. The capture of exhaust gases in the combustion chamber will contribute to a reduction in oil consumption, noise and vibration levels, and exhaust emissions when operating in V4 mode. During the transition from V8 to V4 mode, the fuel injectors will be turned OFF on the deactivated cylinders. The ignition system secondary voltage or spark is still present across the spark plug electrodes on the deactivated cylinders. If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, and then return to V8 mode for 1 minute.

Switching between V8 and V4 mode is accomplished in less than 250 milliseconds, making the transitions seamless and transparent to the vehicle operator. The 250 milliseconds includes the time for the ECM to sequence the transitions, the response time for the VLOM solenoids to energize, and the time for the valve lifters to deactivate, all within 2 revolutions of the engine crankshaft.
__________________

[HSV-GTS-300]

2008 Pontiac G8 | G8 Service Manual | Document ID: 2043668
Engine Mechanical Specifications (L76)


* Engine Type
V8

* Displacement
5976 cu cm
364 cu in

* RPO
L76

* Bore
101.618-101.636 mm
4.0007-4.0017 in

* Stroke
92.0 mm
3.622 in

* Compression Ratio
9.67:1

* Firing Order
1-8-7-2-6-5-4-3

* Active Fuel Management Cylinders
1-4-6-7

* Spark Plug Gap
1.02 mm
0.04 in

Block
* Camshaft Bearing Bore 1 and 5 Diameter
59.58-59.63 mm
2.345-2.347 in

* Camshaft Bearing Bore 2 and 4 Diameter
59.08-59.13 mm
2.325-2.327 in

* Camshaft Bearing Bore 3 Diameter
58.58-58.63 mm
2.306-2.308 in

* Crankshaft Main Bearing Bore Diameter
69.871-69.889 mm
2.75-2.751 in

* Crankshaft Main Bearing Bore Out-of-Round
0.006 mm
0.0002 in

* Cylinder Bore Diameter
101.618-101.636 mm
4.0007-4.0017 in

* Cylinder Head Deck Height - Measuring from the Centerline of Crankshaft to the Deck Face
234.57-234.82 mm
9.235-9.245 in

* Cylinder Head Deck Surface Flatness - Measured Within a 152.4 mm (6.0 in) Area
0.11 mm
0.004 in

* Cylinder Head Deck Surface Flatness - Measuring the Overall Length of the Block Deck
0.22 mm
0.008 in

* Valve Lifter Bore Diameter
21.417-21.443 mm
0.843-0.844 in


Camshaft
* Camshaft End Play
0.025-0.305 mm
0.001-0.012 in

* Camshaft Journal Diameter
54.99-55.04 mm
2.164-2.166 in

* Camshaft Journal Out-of-Round
0.025 mm
0.001 in

* Camshaft Lobe Lift - Exhaust - Non Active Fuel Management Cylinders
7.17 mm
0.282 in

* Camshaft Lobe Lift - Exhaust - Active Fuel Management Cylinders
7.3 mm
0.287 in

* Camshaft Lobe Lift - Intake - Non Active Fuel Management Cylinders
7.08 mm
0.279 in

* Camshaft Lobe Lift - Intake - Active Fuel Management Cylinders
7.2 mm
0.283 in

* Camshaft Runout - Measured at the Intermediate Journals
0.05 mm
0.002 in


Connecting Rod
* Connecting Rod Bearing Clearance - Production
0.023-0.065 mm
0.0009-0.0025 in

* Connecting Rod Bearing Clearance - Service
0.023-0.076 mm
0.0009-0.003 in

* Connecting Rod Bore Diameter - Bearing End
56.505-56.525 mm
2.224-2.225 in

* Connecting Rod Bore Out-of-Round - Bearing End - Production
0.004-0.008 mm
0.00015-0.0003 in

* Connecting Rod Bore Out-of-Round - Bearing End - Service
0.004-0.008 mm
0.00015-0.0003 in

* Connecting Rod Side Clearance
0.11-0.51 mm
0.00433-0.02 in


Crankshaft
* Connecting Rod Journal Diameter - Production
53.318-53.338 mm
2.0991-2.0999 in

* Connecting Rod Journal Diameter - Service
53.308 mm
2.0987 in

* Connecting Rod Journal Out - of - Round - Production
0.005 mm
0.0002 in

* Connecting Rod Journal Out - of - Round - Service
0.01 mm
0.0004 in

* Connecting Rod Journal Taper (Maximum for 1/2 of Journal Length - Production)
0.005 mm
0.0002 in

* Connecting Rod Journal Taper (Maximum for 1/2 of Journal Length - Service)
0.02 mm
0.00078 in

* Crankshaft End Play
0.04-0.2 mm
0.0015-0.0078 in

* Crankshaft Main Bearing Clearance - Production
0.02-0.052 mm
0.0008-0.0021 in

* Crankshaft Main Bearing Clearance - Service
0.02-0.065 mm
0.0008-0.0025 in

* Crankshaft Main Journal Diameter - Production
64.992-65.008 mm
2.558-2.559 in

* Crankshaft Main Journal Diameter - Service
64.992 mm
2.558 in

* Crankshaft Main Journal Out - of - Round - Production
0.003 mm
0.000118 in

* Crankshaft Main Journal Out - of - Round - Service
0.008 mm
0.0003 in

* Crankshaft Main Journal Taper - Production
0.01 mm
0.0004 in

* Crankshaft Main Journal Taper - Service
0.02 mm
0.00078 in

* Crankshaft Rear Flange Runout
0.05 mm
0.002 in

* Crankshaft Reluctor Ring Runout (Measured 1.0 mm (0.04 in) Below Tooth Diameter)
0.7 mm
0.028 in

* Crankshaft Thrust Surface - Production
26.14-26.22 mm
1.029-1.0315 in

* Crankshaft Thrust Surface - Service
26.22 mm
1.0315 in

* Crankshaft Thrust Surface Runout
0.025 mm
0.001 in


Cylinder Head
* Cylinder Head Height/Thickness (Measured from the Cylinder Head Deck to the Valve Rocker Arm Cover Seal Surface)
120.2 mm
4.732 in

* Surface Flatness - Block Deck (Measured within a 152.4 mm (6.0 in) Area)
0.08 mm
0.003 in

* Surface Flatness - Block Deck (Measuring the Overall Length of the Cylinder Head)
0.1 mm
0.004 in

* Surface Flatness - Exhaust Manifold Deck
0.13 mm
0.005 in

* Surface Flatness - Intake Manifold Deck
0.08 mm
0.0031 in

* Valve Guide Installed Height (Measured from the Spring Seat Surface to the Top of the Guide)
17.32 mm
0.682 in


Intake Manifold
* Surface Flatness (Measured at Gasket Sealing Surfaces and Measured Within a 200 mm (7.87 in) Area that Includes 2 Runner Port Openings)
0.3 mm
0.118 in


Lubrication System
* Oil Capacity - with Filter
8.3 Liters
8.8 Quarts

* Oil Pressure - Minimum - Hot
41 kPa at 1,000 engine RPM
124 kPa at 2,000 engine RPM
165 kPa at 4,000 engine RPM

6 psig at 1,000 engine RPM
18 psig at 2,000 engine RPM
24 psig at 4,000 engine RPM

* Active Fuel Management Relief Valve Oil Pressure - as Measured at Oil Pressure Sensor Location
379-517 kPa
Maximum
55-75 psi
Maximum


Oil Pan
* Front Cover Alignment - at Oil Pan Surface
0.0-0.5 mm
0.0-0.02 in

* Crankshaft Rear Oil Seal Housing Alignment - at Oil Pan Surface
0.0-0.5 mm
0.0-0.02 in

* Oil Pan Alignment - to Rear of Engine Block at Transmission Bell Housing Mounting Surface
0.0-0.1 mm
0.0-0.004 in


Piston Rings

* Piston Ring End Gap - First Compression Ring (Measured in Cylinder Bore - Production)
0.20-0.41 mm
0.008-0.016 in

* Piston Ring End Gap - First Compression Ring (Measured in Cylinder Bore - Service)
0.20-0.41 mm
0.008-0.016 in

* Piston Ring End Gap - Second Compression Ring (Measured in Cylinder Bore - Production)
0.37-0.69 mm
0.015-0.027 in

* Piston Ring End Gap - Second Compression Ring (Measured in Cylinder Bore - Service)
0.37-0.69 mm
0.015-0.027 in

* Piston Ring End Gap - Oil Control Ring (Measured in Cylinder Bore - Production)
0.22-0.79 mm
0.009-0.031 in

* Piston Ring End Gap - Oil Control Ring (Measured in Cylinder Bore - Service)
0.22-0.79 mm
0.009-0.031 in

* Piston Ring to Groove Clearance - First Compression Ring - Production
0.030-0.10 mm
0.0012-0.0040 in

* Piston Ring to Groove Clearance - First Compression Ring - Service
0.030-0.10 mm
0.0012-0.0040 in

* Piston Ring to Groove Clearance - Second Compression Ring - Production
0.035-0.078 mm
0.0014-0.0031 in

* Piston Ring to Groove Clearance - Second Compression Ring - Service
0.035-0.078 mm
0.0014-0.0031 in

* Piston Ring to Groove Clearance - Oil Control Ring - Production
0.013-0.201 mm
0.0005-0.0079 in

* Piston Ring to Groove Clearance - Oil Control Ring - Service
0.013-0.201 mm
0.0005-0.0079 in


Pistons and Pins

* Pin - Piston Pin Clearance to Piston Pin Bore - Production
0.002-0.01 mm
0.0008-0.0004 in

* Pin - Piston Pin Clearance to Piston Pin Bore - Service
0.002-0.015 mm
0.0008-0.0006 in

* Pin - Piston Pin Diameter
23.952-23.955 mm
0.943-0.943 in

* Pin - Piston Pin Fit in Connecting Rod Bore - Production
0.007-0.02 mm
0.00027-0.00078 in

* Pin - Piston Pin Fit in Connecting Rod Bore - Service
0.007-0.022 mm
0.00027-0.00086 in

* Piston - Piston Diameter - Measured Over Skirt Coating
101.636-101.649 mm
4.0014-4.0026 in

* Piston - Piston to Bore Clearance - Production
-0.022-0.08 mm
-0.0009-0.0012 in

* Piston - Piston to Bore Clearance (Service Limit with Skirt Coating Worn Off)
0.024-0.08 mm
0.00094-0.0031 in


Valve System
* Valves - Valve Face Angle
45 degrees

* Valves - Valve Face Width
1.25 mm
0.05 in

* Valves - Valve Lash
Net Lash - No Adjustment

* Valve Lift - Exhaust - Non Active Fuel Management
12.19 mm
0.480 in

* Valve Lift - Exhaust - Active Fuel Management
12.41 mm
0.489 in

* Valve Lift - Intake - Non Active Fuel Management
12.04 mm
0.474 in

* Valve Lift - Intake - Active Fuel Management
12.24 mm
0.488 in

* Valves - Valve Seat Angle
46 degrees

* Valves - Valve Seat Runout
0.05 mm
0.002 in

* Valves - Valve Seat Width - Exhaust
1.78 mm
0.07 in

* Valves - Valve Seat Width - Intake
1.02 mm
0.04 in

* Valves - Valve Stem Diameter - Production
7.955-7.976 mm
0.313-0.314 in

* Valves - Valve Stem Diameter - Service
7.95 mm
0.313 in

* Valves - Valve Stem-to-Guide Clearance - Production - Exhaust
0.025-0.066 mm
0.001-0.0026 in

* Valves - Valve Stem-to-Guide Clearance - Service - Exhaust
0.093 mm
0.0037 in

* Valves - Valve Stem-to-Guide Clearance - Production - Intake
0.025-0.066 mm
0.001-0.0026 in

* Valves - Valve Stem-to-Guide Clearance - Service - Intake
0.093 mm
0.0037 in

* Rocker Arms - Valve Rocker Arm Ratio
1.70:1

* Valve Springs - Valve Spring Free Length
52.9 mm
2.08 in

* Valve Springs - Valve Spring Installed Height
45.75 mm
1.8 in

* Valve Springs - Valve Spring Load - Closed
340 N at 45.75 mm
76 lb at 1.8 in

* Valve Springs - Valve Spring Load - Open
980 N at 33.55 mm
220 lb at 1.32 in