The LS4 engine is a Gen. 4, 5.3L, aluminum small block engine used in GM cars between 2005 and 2009. It is unique because it was the only LS engine used in front-wheel drive vehicles.
The FWD LS4 had cathedral port cylinder heads and used Active Fuel Management (AFM). The engine was not Flex Fuel (E85) capable and did not use Variable Valve Timing (VVT) technology.
Mechanically similar, General Motors’ LS and LS-based Vortec engines wound up on almost every branch of the GM family tree: Chevy, Pontiac, GMC, Cadillac, Buick—heck, even Saab, Hummer, and Isuzu got some LS love.
Since LS and Vortec engines are so common, they’ve become the go-to performance and swap engines of the modern era.
These motors are capable of making a lot of horsepower, and respond well to upgrades like turbos, superchargers, high-flow cylinder heads, intake systems, cams, and nitrous oxide.
[Looking to upgrade your LS4 engine? Check out LS4 5.3L FWD Engine Upgrade Guide: Expert Advice for LS4 Mods to Maximize Performance.]
The aftermarket is strong, crate engines are available, and used motors are often cheaply sourced through junkyards.
Summit Racing has created a series of comprehensive guides for each engine in the LS family, so engine builders and tuners can have a handy reference for their projects.
This guide is specifically about the GM LS4. You can find our other LS engine spec guides and LS-related tech articles here.
(Summit Racing’s Paul Spurlock and Brian Nutter contributed to this article.)
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Chevy LS4 Engine Specs
LS4 Basic Stats
| RPO Code (2005-09) | VVT | AFM | Flex Fuel (E85) | Cylinder Head Intake Port Shape |
|---|---|---|---|---|
| LS4 | No | Yes | No | Cathedral |
To make this engine work, GM made several modifications to the engine:
- The engine was mounted in a transverse position, using unique motor mounts.
- The intake manifold was smaller than other LS manifolds and reversed, placing the throttle body over the flexplate.
- The engine used a metric, 60-degree, Chevrolet V6 bellhousing.
- The starter was mounted on the transmission, not the engine block.
- The timing cover, crankshaft, and accessory drive were all modified to fit in the FWD engine bays.
Because of its unique configuration, the LS4 is usually NOT a good candidate for an engine swap.
The information listed here is for a stock engine.
LS4 Performance Specifications
| LS4 Engine Ratings | |
|---|---|
| Compression Ratio | 10:1 |
| Horsepower Rating | 303 hp |
| Torque Rating | 323 ft.-lbs. |
LS4 Applications
| LS4 Applications | |||
|---|---|---|---|
| VIN 8th Digit | Year | Make | Model |
| C | 2005-08 | Pontiac | Grand Prix GXP |
| C | 2006-07 | Chevrolet | Monte Carlo SS |
| C | 2006-09 | Chevrolet | Impala SS |
| C | 2008-09 | Buick | LaCrosse Super |
LS4 Engine Block Specs
| LS4 Block Specs | |
|---|---|
| Casting Number | 12569004 |
| Material | Aluminum |
| Displacement | 5.3L / 325 c.i.d. |
| Bore Dia. | 3.780 in. |
| Stroke | 3.622 in. |
| Deck Height | 9.240 in. |
| Bore Spacing | 4.400 in. |
| Thrust Bearing Location | #3 Main |
| Main Cap Style | 6-Bolt |
| Main Housing Bore Dia. | 2.751 in. |
| Cam Housing Bore Dia. | Bore 1/5 = 2.346 in. Bore 2/4 = 2.326 in. Bore 3 = 2.307 in. |
| Cam-to-Crank Centerline | 4.914 in. |
LS4 Rotating Assembly
| LS4 Rotating Assembly Specs | |
|---|---|
| Piston Material | Hypereutectic Cast Aluminum Alloy |
| Piston Style | Flat Top |
| Piston Volume | 0cc |
| Wrist Pin Dia. | 0.9431 in. (Full Floating) |
| Connecting Rod Material | Powdered Metal |
| Connecting Rod Style | I-Beam |
| Connecting Rod Length | 6.098 in. |
| Connecting Rod Housing Bore | 2.225 in. |
| Connecting Rod Bolts | M9 x 1 x 43 |
| Connecting Rod Part Number | 12649190 |
| Connecting Rod Casting Number (Last 3 Digits) | 143 |
| Crankshaft Material | Cast Iron |
| Crankshaft Part Number | 12568920 |
| Crankshaft Casting Number (Last 3 Digits) | 216 |
| Crankshaft Main Journal Dia. | 2.559 in. |
| Crankshaft Rod Journal Dia. | 2.100 in. |
| Crankshaft Length | 13mm Shorter than Standard (-10mm snout, -3mm rear flange) |
| Reluctor Wheel (2005-Early 2007) | 24X |
| Reluctor Wheel (Later 2007-09) | 58X |
LS4 Cylinder Heads
| LS4 Cylinder Head Specs | |
|---|---|
| Casting Numbers | 799, 243 |
| Material | Aluminum |
| Combustion Chamber Volume | 65cc |
| Intake Port Shape | Cathedral |
| Intake Runner Volume | 210cc |
| Exhaust Port Shape | D-Port |
| Exhaust Runner Volume | 75cc |
| Intake Valve Diameter | 2.000 in. |
| Exhaust Valve Diameter | 1.575 in. |
| Cylinder Head Bolt Style | Torque to Yield (TTY) |
| Cylinder Head Bolt Size | (10) M11 x 2 x 100, (5) M8 x 1.25 x 45 |
LS4 Camshaft Specs
| LS4 Camshaft Specs | ||
|---|---|---|
| Years | 2005-07 | 2007-09 |
| Camshaft Part Number | 12569525 | 12625436 |
| Duration @ .050 in. (int./exh.) | 193°/193° | 196°/201° |
| Valve Lift (int./exh.) | 0.482 in./0.482 in. | 0.481 in./0.481 in. |
| Lobe Separation Angle | 114° | 116° +2 |
| Cam Gear Attachment | 3-Bolt | 1-Bolt |
| Cam Gear Poles | 1x | 4x |
| Active Fuel Management (AFM) | Yes | Yes |
| Variable Valve Timing (VVT) | No | No |
LS4 Valvetrain
| LS4 Valvetrain Specs | |
|---|---|
| Lifter Style | Hydraulic Roller |
| Lifter Link Style | Plastic Lifter Tray |
| Lifter Body Diameter | 0.842 in. |
| Pushrod Length | 7.385 in. |
| Rocker Arm Mounting Style | Pedestal |
| Rocker Arm Style | Die-Cast, Roller Fulcrum |
| Rocker Ratio | 1.7 |
| Rocker Offset | None |
| Valve Spring Style | Beehive |
| Valve Spring Color | Natural |
| Valve Angle | 15 Degrees |
| Intake Valve Material | Steel, Solid Stem |
| Intake Valve Dia. | 2.000 in. |
| Exhaust Valve Material | Steel, Solid Stem |
| Exhaust Valve Dia. | 1.575 in. |
| Timing Chain Guide Style (2005-06) | Plastic |
| Timing Chain Guide Style (2007-09) | Spring Loaded Tensioner |
Other Key LS4 Specs
| LS4 Throttle Body, Fuel Injector Specs & More | |
|---|---|
| Intake Manifold Part Number | 12604786 |
| Intake Manifold | Car-Style (Reversed) |
| Intake Manifold Part Number (2005-07) | 12568580 |
| Intake Manifold Part Number (2008-09) | 12631016 |
| Throttle Body | 76mm, 4-Bolt, Gold Blade (Non-standard Bolt Pattern) |
| Throttle Control | Electronic, Drive-by-Wire |
| Fuel Injector Part Number | 12580681 |
| Fuel Injector Flow | 30 lbs./hr. @ 58 psi |
| Fuel Injector Length Between O-Rings | 1.73 in. |
| Fuel Injector Connector | EV6 / USCAR |
| Computer (2005-2007) | E40 |
| Computer (2007-09) | E67 |
| Crankshaft Reluctor Ring (2005-Early 2007) | 24x |
| Crankshaft Reluctor Ring (2007-09) | 58x |
| Camshaft Sensor Location | Timing Cover |
| Oil Pan | Centered Sump |
| Oil Pump | High Volume, 1.25 c.i./rev. |
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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.
[…] LS4 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More […]
My question is LS4 good swap into 2004 Grand Prix with front drive transmission. Is transmission same for 3.8 and 5.3. Project think about doing
The transmissions on these are weak and need to be modified and a transmission cooler installed. There is a HD one that goes with the engine.. With the price of them now adays your better off just buying a GXP
Get a 4t80e needs a little fabrication work but it fits and it works. It has a strong trans axle and look up ls4 king he has more about fabrication and such
are gxp cars good if taken care off ?…… or will the tranny eventually melt
Great car. I perform routine maintenance on.my 2008 with no problems. I also have a good mechanic at M & L automotive, Waterford, Wi. Car has 82,000 miles.
Does ls4 have a crank shaft sensor &where is it located or does it only have a camshaft sensor (location) ? ,on timing cover ?
[…] are three LS engine family exceptions from what we’ll discuss here (the LS4, LQ4, and LR4), but mostly yes. The LS4 is the one LS engine designed for front-wheel-drive, […]
Min ls4 is from å avalance pickup is it any diferent from The front weel drivs engine
You’re avalanche does not have an LS4. No LS4 was put in any truck or SUV. Putting one in a truck/suv won’t work as bellhousing is the V6 60 degree for transverse transmission.
Can I use a LS4 block to replace the block in my Sierra 5.3?
No
I have a 2009 impala ss and had to drop the subframe to get the oil pan down to change the gasket. While I had the oil pan down I found the long nylon side and the metal spring of the timing chain tensioner. I was just wondering do I need to pull the engine to get the timing chain cover off so I can put a new tensioner/guide in?
[…] [Every engine spec you’ll need can be found here: LS4 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More.] […]
I have a 09 impala ss ls4 engine n tranny (60,000 miles), I’m looking to find a hi mile 08-09 buick lacross super to put it in, this should work , correct ?, and if so I’d like to know what is the best cam upgrade I can put into it as well ?
I have a ls4 so to hook up a 4l60 I’d need a v6 bell housing?
The LS based 4T65E is specific to the engine OR you can swap in a 4T80E using LS4 Kings parts but if you have a decent 6 cyl car, I’d just sell it and pick up an 05-08 GXP the. You get all the goodies and a LOT less work trying to adapt things.
I have a 2014 Chevy impala need a new engine would you consider the ls4 on the 6 speed Chevy impala
Going a little old school here. Have a 92 Lumina Z34 with the 3.4L engine. It’s toast and wasn’t really wanting to put a 3.8L like everyone has. If I have the complete car to rob all necessary parts would it make sense to put the LS4 in, or better yet would it even fit????
When ordering a camshaft for these cars can you use a cam for the 5.3 iron blocks or it everything different I have a 2006 gxp and I want more power out of it at the same time making it reliable