Active Fuel Management/Dynamic Fuel Management
August 9, 2019
Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) is available on a number of recent GM models to help improve fuel economy, including 2014-2019 Corvette, Silverado LD, Sierra Limited; 2015-2019 Escalade, Suburban, Tahoe, Yukon; 2016-2019 CTS-V, Camaro; 2019 Silverado 1500, Sierra 1500; 2020 Silverado 2500/3500 and Sierra 2500/3500 models.
Active Fuel Management
AFM was designed to provide maximum fuel economy under light load driving conditions by deactivating the lifters on specific cylinders. On V8 engines, half of the cylinders are deactivated and on V6 engines, two of the cylinders are deactivated.
Under certain operating conditions, the Engine Control Module (ECM) commands the cylinder deactivation system to deactivate engine cylinders 1, 7, 6, and 4 on V8 engines or to deactivate engine cylinders 3 and 6 on a V6 engine. The engine will operate on all cylinders during engine starting, engine idling and medium-to-heavy throttle applications.
The Lifter Oil Manifold Assembly (LOMA) is only used on AFM applications.
Dynamic Fuel Management
DFM is the next generation in cylinder deactivation systems. It features AFM technology with the additional ability to deactivate any combination of cylinder valves to optimize fuel consumption. The control of every cylinder event allows peak efficiency to be obtained throughout the range of engine operation. (Fig. 15)
By extending cylinder deactivation to all cylinders, DFM allows for a large variety of firing sequences. DFM can have rotating cylinder deactivation patterns, such as 1/5, 1/3, 2/5, or 2/3, as well as fixed patterns, such as 1/4, 1/2, or 3/4. For rotating patterns, which are only available on small block engine (L84,L87), the cylinders being deactivated can change with each subsequent engine cycle. Transitions between firing sequences is done in a continuous fashion, making the transitions seamless and transparent to the driver.
Oil Control Valves (OCV), only used on small block engines, replace the LOMA. OCVs provide faster response times than the LOMA and are required for DFM. OCVs also are used on L82 engines with AFM.
You can take a cheaper iron block motor 4.8L / 5.3L / 6.0L and add a LSA blower.
Shipping to Auckland, Wellington or Lyttleton via Kiwi Shipping in a box cost approx $1100NZ.
GST on the declared value adds 15% and there are approx. $200NZ in government inspection and paperwork fees.
You also need a free importer code number. Click Here.
Both these systems can be deactivated or removed if desired.
I can supply GMC Blower kits starting at $3800US / $5400NZ using a TBS 6V-71 which is great if you want to make blower whine. For more effective use you'll want an 8-71.
Moving on, the Gen 4 engine looks like the Gen 3, but has a few improvements most notably the cylinder heads.
Compression Ratio 10.4:1
Horsepower Rating400 hp
Torque Rating410 ft./lbs.
Compression Ratio 10.5:1
Horsepower Rating 403 hp
Torque Rating 417 ft./lbs.
Compression Ratio 10.7:1
Horsepower Rating 426-436 hp
Torque Rating 420-428 ft./lbs.
Actual measured power on an engine dyno with headers is closer to 450Hp
Compression Ratio 9.1:1
Horsepower Rating 556-580 hp @ 6,300 rpm
Torque Rating 551-556 ft./lbs.
The following is not intended as a history of the Gen 3 & 4 engines but a guide to help you compare options to price.
1997 the Generation 3 small block Chevrolet engine LS1 and LS6 5.7L (350 CID) were the first car engines having cathedral port heads, aluminum block and rods good enough for under 500Hp.
These blocks can still be found, but tend to have over 200,000 miles on them because the are so old now.
A Camaro or Corvette LS1or LS6 engine starting around $3000US, with transmission $4000US.
The LQ4 and LQ9 where 6.0L (366 CID) iron block motors used in trucks, SUV and Caprice. A few had iron heads, most aluminum.
They are popular to use for boosted (super/turbocharged) builds.
Coming soon, pages for old school engines and parts.
The intake manifold is taller and than the car manifold. It might be ugly but it makes a better torque curve than the lower car version.
There are also 4.8L (293 CID) (LR4) and 5.3L (327) (LM4, LM7, L59, L33) iron block motors.
These because of the lack of US popularity for engine swapping cost much less. $3000US will buy a complete engine with transmission, sometimes $2500US will get one.
A 6.0L LQ motor can be had for $3000 with a transmission it depends on mileage.
An LQ4 has a lower compression ratio than the LQ9, so regular versus super petrol.
The LS2 is a 6.0L aluminum block engine and was introduced as a replacement to the 5.7.
It was very popular in Holdens.
The L76 version introduced Active fuel management (AFM).
AFM is a system controlled by the ECU AKA ECM AKA the computer to control oil pressure to the lifters.
At cruising loads 4 cylinders a deactivated.
The loss of power is unnoticed and the fuel consumption is decreased.
This is a good thing especially with NZ petrol prices.
However the lifters can malfunction spoiling operation.
Malfunction is not common but it does happen.
Clean oil of the correct viscosity is important.
Repair or replacement of fail lifters will add cost.
Engine sold by salvage yards in the US are described as running when removed.
It will likely provide years of trouble free operation, BUT THERE IS NO GUARANTEE.
Sure, the yard offers it, but are you going to pay shipping two more times to get the replacement offered by the yard?
A repair out there will likely cost less.
You are considering a used engine, there is some risk, but there will be no deception.
This is the new Holley Sniper Duel Plenum Manifold.
This dyno test was conducted by Holley.
This page is laid out for a desktop viewing.
If you are using a phone scroll down past the photos to read the text.
On a cell phone there is difficult to follow all the information I have packed into this page.
If you want a simplier site go here.
AFM or VVT Deletion Kit
Let's discuss transmission.
This compares an LS1 car manifold to the Trailblazer SS manifold
Most used LS engines come with the factory ECU ECM PCM whatever you call it, the computer and wire harness. As the wire harness is removed from the vehicle you will lack a place to plug it in so you will not have an OBD-II port to program the ECU. Therefore I strongly encourage you to spend $750ish on a standalone harness.
To find the right one you first select the type of ECM.
The Gen III PCMs were released in two different cases. The 1997–1998 PCMs which uses the same wire harness connectors as other LS-series PCMs, but they are not pinned the same. The 1997- 1998 PCMs are scarce and generally not commonly used with LS conversions.
Then they introduce the E series of which there are 3.
See images above of these ECU and a Terminator X
Next the crank sensor tooth count 24 or 58.
Injector type EV1 or EV6
Then DBW drive by wire or DBC drive by cable throttle body.
Then the transmission type. 4L, 6L, 8L.
Aftermarket ECU such as Holley Terminator X MAX can drive a 4L, but no 6 or 8 or 10 speed transmissions, therefore you must use the factory ECU.
You might want a copy of these books with your engine.
This is the comparison to the FAST XFI manifold
Let's stop and talk power.
Torque (Tq) is the measured power of an engine.
It can be represented as acceleration speed or ability to pull a heavy load.
I is primarily generated by cubic capacity, therefore a 7.4L will make more Tq than a 6.0L and a 6.0L more than 5.3L.
Compression ratio plays a very small part, stock motors all a short duration camshaft, so no gains there.
As mention the intake will play a factor.
So how much is the Tq differences?
Simply multiply CID of a Gen 3 SBC by 1.0 to get peek ft/lbs of torque.
Therefor a 5.3L will make 327Tq and a 6.0L 366Tq.
Horsepower (Hp) is Tq X RPM :- 5252.
The higher the Tq can climb in the RPM range the higher Hp.
To achieve this you need to increase airflow beyond the supplied factory settings.
A longer duration camshaft holds the valves open for longer allowing more air to flow in and out.
This will raise the RPM where peek Hp is produced.
However, a corresponding loss of Tq (or Hp) will occur below 3000 RPM.
Vacuum at idle is reduced for the power brakes and the sound of the idle becomes choppier.
"Porting" the cylinder heads or replacing them with higher performance heads also allows more air to flow through the engine increasing Hp.
Increasing Hp can win races, but will not increase the pulling power use by a truck.
The most effective way to increase both Tq and Hp is with an aftermarket longer stroke crankshaft making more CID, for example 426 7.0L
Used Remachined 383 Blocks
$1000US = $1700NZ
New GM 383 Machined Block
$1400US = $2350NZ
New Dart SBC SHP Unmachined Block
$1700US = $2900NZ
Machined $2250US = $3825NZ
Need a Ford, Mopar, Pontiac Block?
I am from Timaru. I live in Apple Valley California.
I am a performance V8 engine builder and exporter.
In addition to the engines I build I also send partial engines built by ATK and used engines I find for you.
I am working on new pages for other engines and parts.
Also, click on my USA-NZ page above
The most popular in the GM line of LS style engines.
There are quite a few models to choose from.
The images showing LS engine was copied from eBay and is out of date.
Anyone can search eBay USA and look at pricing.
Most engines have free shipping but not all.
Whatever the price is whether $3000US or $12,000US add $500US multiple by 1.7 (June 2020 subject to change) and you will have the NZ price you will pay.
Shipping to NZ first requires putting the motor in a crate and transporting to one of the shipping companies I use.
This adds $500NZ to the cost.
Kiwi Shipping delivers to Auckland, Wellington and Lyttleton for approx. $600NZ (dependent on current exchange rate).
NZ government inspection fees approx. $200NZ.
GST on declared value 15%.
If you add up the numbers you can then compare to a similar engine found on eBay Australia and decide where to buy.
From experience, a motor advertised in Australia for $8000AU can be purchased from me at $1000NZ less with shipping.
But do compare. The goal is to get you the best deal. I do this as a service to New Zealanders.
GM has announced that all V-8 powered Chevrolet and GMC trucks now feature variable valve timing (VVT) for the 2010 model year. A quick trip back to engineering 101 reminds us that VVT is a piston technology that enables continuous control of valve opening and closing. The end result is better engine breathing, with fewer emissions and improved fuel economy.
VVT has already been available on GM’s small-block 6.0L and 6.2L V-8s. The widely-anticipated addition of VVT to the 4.8L and 5.3L V-8s completes its rollout in the truck small block V-8 engine line. GM made VVT possible by adding a cam phaser to the end of the camshaft that electro-hydraulically controls cam position by taking in information from a sensor and the engine control module.
GM is reporting that when paired with cylinder deactivation (Active Fuel Management) on the 5.3L V-8, VVT helps deliver segment-leading fuel economy in the 2010 GMC Sierra and Chevy Silverado pickups:
The Sierra and Silverado are EPA estimated at 15 mpg city and 22 mpg highway, which is better fuel economy than the less powerful 2010 trucks from Ford and Toyota. (Toyota Tundra 4.6L V-8 EPA estimates 15 mpg city and 20 mpg highway. Ford F-150 292 hp 4.6L V-8 EPA estimates are 14 mpg city and 20 mpg highway.)
This is music to the ears of GM truck fans the world over. Now if we could only get those Colorado and Canyon replacements… like… today – that would be great!
Here is an excpect from testing VVT on a performance engine. The L99 produced maximum torque with the cam advanced 5 degrees. In this configuration, the motor put out 591 hp at 6,100 rpm and 563 lb-ft at 5,000 rpm. When it came time to maximize peak hp, the 416 responded best to 4 degrees of retard. This arrangement yielded a peak output of 609 hp at 6,400 rpm and 553 lb-ft at 5,400 rpm. The results are precisely what would be expected, with the L99 making 10 lb-ft more at 400 fewer rpm with the cam advanced and 18 additional horsepower at 300 rpm higher in the powerband with the cam retarded. In a standard non-VVT motor, this would typically be the point where you'd have to decide to sacrifice low-end for top-end, top-end for low-end, or shoot for a happy medium between the two.SEE MORE