Chevy variable valve timing

Chevy variable valve timing DEFAULT

How to Delete Chevrolet Variable Valve Timing (VVT)

Cost-conscious engine swappers know that eBay Motors is an excellent resource for finding the right engine because of its nationwide searchability and easy payment and shipping options, that's how we came across this LY6 L () Chevy truck engine for our build. It came factory-equipped with variable valve timing (VVT) and a drive-by-wire (DBW) throttle body. The DBW throttle body is easily replaced by a manual version, but the VVT requires more work.

The VVT system operates by advancing and retarding the cam timing to suit the speed and load of the engine. Generally speaking, advancing the cam (from 0) tends to improve low-speed power, while retarding it improves power higher in the rev range. The factory VVT system provided the best of both worlds, while greatly improving things like idle quality, part-throttle response, and even fuel mileage. Unfortunately, if you aren't running the factory ECU, VVT can be difficult to control. Most people looking to swap an LS into an early muscle car, or other non-factory LS application, tend to replace the VVT cam, cover, and mechanism. These swaps are so popular, that many performance companies offer complete VVT-delete kits, which allow LS swappers to replace the VVT with conventional (fixed) cam timing. The VVT-delete cam swaps are popular for either improved performance or ease of tuning.

For this swap, we chose the dirt-cheap route by selecting a used, factory LS9 cam. Why the LS9? Despite being designed for a supercharged application, the LS9 was actually the most powerful factory cam profile offered for the LS engine family. Full disclosure: It shared this title with the nearly identical LS7 cam, but the LS9 cams are much easier to come by, and therefore cheaper in the marketplace. On eBay, used LS9 cams sell for as little as $50 to $60, while a new one will still only set you back $ to $ Best of all, the LS9 cam specs (/ lift, / duration, LSA) work with the existing LY6 (LS3-style) valve springs.

Installation of the LS9 cam required removal of the VVT front cover, dedicated cam sprocket, and camshaft. These components were replaced by a GM LS2/LS3 front cover (PN ), a 4X, 3-bolt cam sprocket (PN ), and of course, the LS9 cam itself (PN ). To gain access to the VVT cam and sprocket, the press-fit damper needed to be removed using a pulley puller. We then rotated the engine to TDC on the No. 1 cylinder by lining up the dots on the cam and crank sprockets as shown. Then we pinned the timing chain tensioner in place using a small Allen wrench and removed the cam retaining bolt. Note the holes in the VVT bolt designed to provide oil flow to the VVT mechanism. Once the bolt was removed, off came the cam sprocket, followed by the cam retaining plate and finally, the VVT cam itself. We made sure to install the lifter retaining tools to keep the lifters in place during the cam swap.

With the VVT cam removed, we oiled, then installed the used LS9 cam. The cam retaining plate was then installed using blue Loctite on the Torx retaining bolts (torque to 18 ft-lb). We then installed the new 4X cam sprocket, using the existing VVT timing chain. The sprocket was positioned to line up the dots between the cam and crank sprockets (with the No. 1 piston still at TDC). With the sprocket positioned properly, we tightened the three retaining bolts to 26 ft-lb, making sure to use blue Loctite on the cam bolts. With our cam and sprocket installed, we positioned the new front cover in place using a new cover gasket. The bolts were torqued to 18 ft-lb, but only after installation of the factory damper. The damper (torque to ft-lb) was used to locate the front cover prior to tightening the cover bolts. With our cam swap complete, we installed the LY6 on the dyno with headers, a manual throttle body and Holley HP management system. The LY6 produced hp at 5, rpm and lb-ft of torque at 5, rpm. With impressive power and torque, this eBay Motorssourced LS9-cammed, LY6 was ready to log another , performance miles.

Graph 1: L LY6-LS9 Cam Swap
Equipped with factory LS9 cam, the L LY6 produced peak numbers of hp at 5, rpm and lb-ft of torque at 5, rpm. Despite being designed for a supercharged application, the LS9 cam allowed the L to produce an effective torque curve, bettering lb-ft from 3, rpm to 6, rpm. Though the L produced a peak of lb-ft, the torque peak was more of a torque plateau, exceeding lb-ft from 4, rpm to 5, rpm. The impressive numbers put down by these LS engines have spoiled us, but hp is more than enough to motivate any classic muscle car or truck. Not only will the L LY6 effortlessly pump out hp, this combination will do so for the next , miles. Not bad for a junkyard engine with a cam swap!

Parts
Description PN
4X, 3-bolt cam sprocket
Front cover
LS9 camshaft

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LS Tech: How to Delete Variable Valve Timing (VVT) on an LS Engine

Variable Valve Timing (VVT) is a system that automatically adjusts valve timing.

GM used VVT on the following engines within the LS family.

(Summit Racing’s Paul Spurlock and Brian Nutter contributed to this article.)

How Does VVT Work?

The computer senses engine load. It also monitors valve timing through the camshaft position sensor. It then uses that VVT data to determine the best valve timing for the current conditions.

The computer sends a signal to a solenoid on the timing cover. The solenoid controls oil flow through a special control valve in the camshaft bolt. The valve sends oil into the phaser control chambers.

The actuator rotates one way or the other, depending on the oil flow. That rotation is used to advance or retard the camshaft as needed.

How Does VVT Affect Performance?

VVT gives you the best of both worlds. It can advance valve timing for a smooth idle and low-end torque. It can also retard the valve timing for more top-end power. And, it&#;s all done automatically.

VVT becomes an issue when swapping a cam:

  • Piston-to-valve clearance can be a problem.
  • Your choices for valve lift and duration are limited.
  • The high spring pressure required for performance cams can overpower the actuator.

If you want to upgrade your camshaft and keep the VVT system, you will need a Camshaft Phaser Limiter.

If you want high performance from a bigger cam, you will need to delete the VVT system. (More on that in a second.)

How You Can Tell Whether Your LS has VVT

Engines with VVT will have a camshaft phaser actuator on the timing cover. They also have a five-pin connector for the VVT and camshaft sensor.

Engines without VVT will not have the actuator. They only have a three-pin connector for the camshaft sensor.

LS Gen 4 Timing Covers VVT

These are two LS engine timing covers. The one on the left has the camshaft phasing actuator, indicating that it is from an engine with VVT. The one one the right has no actuator, so it is from an engine without VVT. (Image/Summit Racing)

GM used two different actuator designs.

In , the actuator has degree rotation. GM part number .

In , the actuator has degree rotation. GM part number .

How Can I Delete the VVT on my LS Engine?

Eliminating the VVT system is required when swapping to a non-VVT camshaft. These cams offer higher valve lift and longer duration for more performance.

A VVT delete kit removes the VVT components and replaces them with standard parts. At a minimum, they include:

  • A Gen. 4, non-VVT timing cover
  • A new, 4X, non-VVT upper timing gear
  • A new harmonic balancer bolt
  • New camshaft bolts

Some kits will also include additional parts, such as:

  • A new lower timing gear
  • A new timing chain
  • A new timing chain guide

The type of VVT Delete Kit you need depends on the camshaft you are using.

1-Bolt Camshafts

3-Bolt Camshafts

Eliminating the VVT system is required when swapping to a non-VVT camshaft. These cams offer higher valve lift and longer duration for more performance.

After installing one of these kits:

  • You will be locked-in to the valve timing.
    • The computer will no longer automatically adjust the valve timing.
  • You will also need to tune the computer.
    • This will optimize the fuel and ignition curves for the new camshaft, and turn off the VVT system in the computer.

&#;

NOTE: You can find engine specs and detailed engine upgrade advice for every LS and LS-based Vortec truck engine in one place: The Definitive Guide to LS Engine Specs and LS Engine Upgrades.

Tags: engine tech, GM LS engines, LS engines, VVTSours: https://www.onallcylinders.com//12/05/ls-tech-how-to-delete-variable-valve-timing-vvt-on-an-ls-engine/
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Variable Valve Timing (VVT) Solenoid Replacement Service

How much does a Variable Valve Timing (VVT) Solenoid Replacement cost?

On average, the cost for a Chevrolet Silverado Variable Valve Timing (VVT) Solenoid Replacement is $ with $51 for parts and $ for labor. Prices may vary depending on your location.

CarServiceEstimateShop/Dealer Price
Chevrolet Silverado VL HybridService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VL HybridService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $
Chevrolet Silverado VLService typeVariable Valve Timing (VVT) Solenoid ReplacementEstimate$Shop/Dealer Price$ - $

Show example Chevrolet Silverado Variable Valve Timing (VVT) Solenoid Replacement prices

What is the Variable Valve Timing (VVT) Solenoid all about?

Variable valve timing (VVT) helps to provide smoother idling, better power delivery for everyday needs, improved fuel economy, and superior emissions control. In order to achieve all of these tasks, your VVT system requires a number of different components including the variable valve timing solenoid. The VVT solenoid is responsible for changing the position of the camshafts in the engine. It works on oil pressure, and can either advance or retard cam position to provide the right performance from the engine. Each camshaft is equipped with a VVT solenoid, which is capable of altering the supply of oil pressure to the camshaft depending on the speed and load of the engine. If the VVT solenoid is not working properly, the Check Engine light will come on and your engine will perform noticeably worse.

Keep in mind:

  • The most common cause for VVT solenoid problems is dirty oil, which clogs the screen that sits between the solenoid and the VVT pressure switch.
  • If the solenoid doesn’t operate, the VVT system will remain disengaged, which can adversely impact engine performance, fuel economy and more.

How it's done:

  • The faulty variable valve timing actuator (VVT) solenoid is located and identified
  • The variable valve timing actuator (VVT) solenoid is removed
  • The new variable valve timing actuator (VVT) solenoid is installed
  • The engine is tested with a scanner for proper variable valve timing actuator (VVT) solenoid operation
  • The vehicle is road tested and checked for proper variable valve timing actuator (VVT) sensor operation

Our recommendation:

Because the solenoid is located at the camshaft (near the VVT switch), it cannot be inspected on a regular basis. The only time it will be inspected is if you are experiencing problems with the VVT system, or the Check Engine light illuminates and the computer provides a camshaft position or VVT system related code. If you do experience variable valve timing issues, have one of our expert mechanics diagnose and repair the issue.

What common symptoms indicate you may need to replace the Variable Valve Timing (VVT) Solenoid?

  • Vehicle gets poor fuel economy
  • Engine performance is diminished
  • Check Engine light is on

How important is this service?

If your vehicle is equipped with a variable valve timing system, it needs to operate as designed for proper performance and fuel efficiency. If your vehicle’s VVT solenoid is faulty, have it replaced as soon as possible to regain your lost performance.

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GM's Variable Valve Timing System Performance Test - 15 Degrees Of Separation - Speed Parts Testing

| How-To - Engine and Drivetrain

We Put GM's Variable Valve Timing System To The Test And Picked Up Dozens Of Horsepower Without Sacrificing Any Torque.

The tough guy in you says to stab that cam in retarded a few degrees for maximum top-end horsepower, while your more practical alter ego suggests advancing it a hair for improved low-end torque and driveability. As tempting as it may be to let your tough side deliver a swift kick to your practical side's shins, the installed centerline you settle on is often a compromise between the two extremes. However, as the Big Three have started integrating variable valve timing (VVT) into production V-8s, that needn't be the case anymore. Now you can have the best of both worlds.

The performance potential for VVT in a hot rod motor is huge, but relatively few enthusiasts have embraced it. To test the merits of VVT in a high-performance application, we strapped one of Mast Motorsports' hp L99 small-blocks to the company's dyno and phased the cam back and forth to see its effects in action. By simply advancing and retarding the cam, the VVT system swung the peak horsepower and torque curves by 18 and 10 numbers, respectively. Furthermore, in the case of the all-important power after peak metric, the difference was as large as 41 hp. The beauty of VVT is that an improvement in high-rpm power doesn't sacrifice bottom-end torque, and in the case of GM LS-series small-blocks, it's extremely easy to retrofit onto any non-VVT motor.

Timing is Everything
How much, how long, and when the valves open and close all profoundly impact the shape of the power curve. Since lift and duration can't be changed without regrinding a camshaft, the only parameter that can easily be tweaked once the lobe profiles have been finalized is the cam timing (when the valve events take place in relation to the position of the crankshaft and therefore pistons). Among the valve events in a four-stroke internal combustion engine-intake valve opening, intake valve closing, exhaust valve opening, and exhaust valve closing-most engine builders agree that intake closing is king. In fact, some contend that intake closing is more important than the other three combined.

Simple physics dictates why this is the case. Internal combustion engines are nothing more than glorified air pumps, and the opening and closing of the intake valves determine how much air can be drawn into the cylinders on the intake stroke. With a typical performance camshaft, it's not uncommon for the intake valve to close up to 60 degrees after bottom dead center, which means after the piston has already started to move up during the compression stroke. This isn't ideal at low rpm, as the pistons will push the air/fuel mixture back past the intake valve and into the intake manifold, which hurts low-end torque and idle quality. On the other hand, a delayed intake closing point is exactly what an engine needs at high rpm.

"As long as the inertial charge of the incoming air/fuel mixture is greater than the force exerted by the piston, the cylinder will still get filled with more air even as the piston moves back up the bore from BDC," explains Horace Mast of Mast Motorsports. "To take advantage of the pressure wave of air going into the cylinder at high rpm, it's imperative to close the intake valve at the right time, or else you're just wasting energy. That's why getting the intake closing point just right is so important, because closing it later allows more time for the cylinders to fill with air."

While the OEs often use VVT technology as a means of boosting fuel economy and cleaning up emissions, in performance applications, its primary purpose is to optimize the intake closing point. The intake and exhaust lobes are ground onto a single, in-block camshaft core on OHV motors like the Gen IV small-block, and phasing the cam means that all four valve events are changed in unison. Ideally, the intake and exhaust lobes should be phased independently, which requires either a DOHC design or a trick cam-in-cam layout like in the 'and-up Dodge Viper V Fortunately, the other three valve events are so inconsequential compared with intake closing that it's nothing to split hairs over. For instance, exhaust opening is most commonly accepted as the second most important valve event, as it contributes to determining the lobe-separation angle of a camshaft. Retarding exhaust opening improves bottom-end torque, while advancing it allows spent fumes to exit the cylinders sooner, which generally im-proves high-rpm power with long-duration camshafts. This is exactly the opposite of what happens when advancing or retarding intake closing, which means that optimizing intake closing actually compromises the exhaust opening point. Nonetheless, the effects of intake closing are so much more profound that the exhaust event really doesn't matter much.

How VVT Works
Back in the Aug. '09 issue, we outlined the operational dynamics of the various variable valve timing systems used by the Detroit Three, so here's the condensed version of GM's setup. Much like the VVT systems in Ford's three-valve mod motors and Chrysler's L Hemi, the GM design utilizes a hydraulically actuated phaser integrated into the cam gear. The engine management computer and cam position sensor communicate with each other and send instructions to an electric solenoid mounted inside the timing cover. The solenoid then presses on a hydraulic valve bolted into the nose of the cam, which manipulates oil flow into the phaser assembly to advance or retard the cam.

"The Gen IV's VVT system is very flexible and allows advancing the cam 7 degrees and retarding it 45 degrees for a total of 52 degrees of latitude. Piston-to-valve clearance can become an issue when you're moving the cam that far from the installed centerline, so we use Mahle pistons with big -4cc valve reliefs in our L99 crate engine packages," Mast says.

Big valve notches are just part of the package. Since the phaser assembly is essentially a rotor that moves inside of a stator, the only thing preventing the cam from wobbling erratically within its degree range of travel is hydraulic pressure. "Even when you lock the cam phasing into a straight-up position, the engine management software is constantly adjusting oil pressure into the phaser to keep the cam in a fixed position. Otherwise, the pressure exerted on the phaser from the valvesprings could force it into full mechanical retard," Mast explains. Moreover, the fact that GM's VVT system relies on hydraulic pressure to overcome the force of the valvesprings means there's a practical limit to how much spring pressure it can handle. "On the dyno, we've noticed that once you exceed pounds of open spring pressure, the VVT system starts losing control of the cam phasing at engine speeds above 5, rpm. Spring selection is critical on a VVT motor, and you can't get too aggressive with cam duration, either. Nonetheless, using a hydraulic roller cam and beehive valvesprings, we're still able to get hp out of our VVT-equipped L99 crate motors," Mast says.

Pulling the Handle
To see if all this VVT hoopla works as well in the real world as it does in theory, we loaded one of Mast Motorsports' ci L99 crate motors into the dyno cell and thrashed away. Dubbed the L99 SS, Mast's combo features a L aluminum block bored to inches, a Callies inch steel crank and rods, Mahle pistons, a custom Mast /at hydraulic roller cam with /inch lift and a degree lobe-separation angle, CNC-ported factory LS3 cylinder heads, and a stock L99 intake manifold. Mast conservatively rates the at hp. To test the virtues of the VVT system, we made several pulls on Mast's SuperFlow dyno with the cam phased in three different positions: advanced for maximum torque, retarded for maximum horsepower, and with the VVT system engaged. Timing changes were performed on the fly using Mast's stand-alone M ECM. The results were quite impressive to say the least.

The L99 produced maximum torque with the cam advanced 5 degrees. In this configuration, the motor put out hp at 6, rpm and lb-ft at 5, rpm. When it came time to maximize peak hp, the responded best to 4 degrees of retard. This arrangement yielded a peak output of hp at 6, rpm and lb-ft at 5, rpm. The results are precisely what would be expected, with the L99 making 10 lb-ft more at fewer rpm with the cam advanced and 18 additional horsepower at 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.

In theory, this is the sort of compromise VVT promises to eliminate, and on Mast's dyno, it did just that. With the VVT system switched on, the L99 cranked out hp at 6, rpm and lb-ft at 5, rpm. These dyno runs prove that the results live up to the hype, and VVT is quite literally the best of both worlds. Engaging the VVT system yielded horsepower and torque output that was spot on to the prior tests in which the cam was retarded for max power and advanced for max torque. Sure, the motor made 1 hp less on the VVT dyno pull, but that's well within the 1/2 percent run-to-run variation limit of what's considered acceptable for even a very consistent dyno cell. What's most astonishing, however, is the difference in power after peak when comparing the dyno numbers with the cam advanced versus the dyno numbers with VVT enabled. At 6, rpm, the advanced dyno pull netted hp, while the VVT run produced hp. That's a difference of 41 hp. Timing really is everything.

VVT Swap Part List
The beauty of GM's VVT system is in its simplicity. Bolt up a VVT-specific timing cover, phaser assembly, cam bolt, and tooth reluctor wheel to any Gen III/IV small-block-which can all be purchased from Scoggin-Dickey (sdpccom) for a total of $and you're almost ready to get variably timed. To control it all, you'll also need a Mast computer and wiring harness and a VVT cam from a company such as Mast or Comp. The retrofit isn't exactly cost effective for cars already powered by LS-series motors, but for anyone building a Gen III/IV motor from scratch to drop into a muscle car, all the components necessary for pulling off a VVT swap are parts you'd have to purchase anyway.

ITEMPNPRICE
L92/L99 timing cover$
Phaser assembly
Cam bolt/valve
tooth reluctor wheel
Mast M ECM and harnessMDBW 1,
Total $1,
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Variable valve timing chevy

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VVT Disable in HP Tuners, Getting Rid Of Variable Valve Timing

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