The LR4 is a 4.8L iron block truck engine that was introduced in 1999.
Along with the LM7 and LQ4, they were the first LS truck engines. The LR4 was available in GM pickups, vans, and SUVs until 2007. The 4.8L engine is also known as the Vortec 4800.
The engine specs and information here is for a stock LR4 engine.
These engines are strong and durable. Many people use them with boost or nitrous. With upgraded internals, the blocks can handle over 1,000 hp.
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 LR4 engine? Check out LR4 4.8L Engine Upgrade Guide: Expert Advice for LR4 Mods to Maximize Performance.]
The aftermarket is strong for LS swap engines. 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 LR4 4.8L iron block engine. 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.)
GM LR4 4.8L Engine Specs
- The 1999-2000 LR4 with a manual transmission had a crankshaft with a 1.250 in. long rear flange. (Casting #12553312)
- All other LR4 engines had a crankshaft with a 0.857 in. rear flange. (Casting #12553482)
- In 2001, the LR4 and LM7 were upgraded with MLS gaskets.
- The 1999-2003 LR4 and LM7 had a return-style fuel injection system.
- They went returnless in 2004 (except in the Express).
The information listed below is for the stock engine.
LR4 Performance Specifications
|LR4 Engine Ratings|
|Horsepower Rating||255-280 hp|
|Torque Rating||285-295 ft.-lbs.|
|VIN 8th Digit||Year||Make||Model|
LR4 Engine Block Specs
|LR4 Block Specs|
|Casting Number||12567392, 12567393, 12551358|
|Displacement||4.8L / 293 c.i.d.|
|Bore Dia.||3.780 in.|
|Deck Height||9.2309.240 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. (1999-2003)||Bore 1/5 = 2.326, Bore 2/4 = 2.317, Bore 3 = 2.307|
|Cam Housing Bore Dia. (2004-2006)||Bore 1/5 = 2.346, Bore 2/4 = 2.326, Bore 3 = 2.307|
|Cam-to-Crank Centerline||4.914 in.|
LR4 Rotating Assembly
|LR4 Rotating Assembly Specs|
|Piston Material||Hypereutectic Cast Aluminum Alloy|
|Piston Style||Flat Top|
|Wrist Pin Dia. (1999-2004)||0.9447 in., 0.9448 in. (Pressed)|
|Wrist Pin Dia. (2005-2006)||0.9429 in., 0.9431 in. (Floating)|
|Connecting Rod Material||Powdered Metal|
|Connecting Rod Style||I-Beam|
|Connecting Rod Length||6.275 in.|
|Connecting Rod Bolts||M9 x 1 x 43|
|Crankshaft Material||Cast Iron|
|Crankshaft Main Journal Dia.||2.559 in.|
|Crankshaft Rod Journal Dia.||2.100 in.|
|Flywheel Mounting Flange (1999-2000)||1.250 in.|
|Flexplate Mounting Flange (1999-2000)||0.857 in.|
|Flexplate Mounting Flange (2001-2006)||0.857 in.|
LR4 Cylinder Heads
|LR4 Cylinder Head Specs|
|Combustion Chamber Volume||61cc|
|Intake Port Shape||Cathedral|
|Intake Runner Volume||200cc|
|Exhaust Port Shape||Oval|
|Exhaust Runner Volume||70cc|
|Intake Valve Diameter||1.890 in.|
|Exhaust Valve Diameter||1.550 in.|
|Cylinder Head Bolt Style||Torque to Yield (TTY)|
|Cylinder Head Bolt Size (1999-2003)||(8) M11 x 2 x 155, (2) M11 x 2 x 100, (5) M8 x 1.25 x 455|
|Cylinder Head Bolt Size (2004-2006)||(10) M11 x 2 x 100, (5) M8 x 1.25 x 45|
LR4 Camshaft Specs
|LR4 Cam Specs|
|Duration @ .050 in. (int./exh.)||191°/190°|
|Valve Lift (int./exh.)||0.457 in./0.466 in.|
|Lobe Separation Angle (1999)||115.5°|
|Lobe Separation Angle (2000-06)||114°|
|Cam Gear Attachment||3-Bolt|
|LR4 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|
|Valve Spring Style||Beehive|
|Valve Spring Color||Natural|
|Valve Angle||15 Degrees|
|Intake Valve Material||Steel, Solid Stem
|Intake Valve Dia.||1.890 in.|
|Exhaust Valve Material||Steel, Solid Stem|
|Exhaust Valve Dia.||1.550 in.|
LR4 Throttle Body, Fuel Injector Specs & More
|More LR4 Engine Specs|
|Throttle Body||78mm, 3-bolt|
|Throttle Control (1999-2002)||All Cable Operated|
|Throttle Control (2003-2004)||Drive-by-Wire phased in on most models|
|Fuel Injector Flow||1999 - 21.8 lb/hr., 2000 - 24.8 lb/hr., 2001-2006 - 25.2 lb/hr.|
|Fuel Injector Length Between O-Rings||1.900 in.|
|Fuel Injector Connector||Mini-Delphi / Multec2|
|Crankshaft Reluctor Ring||24x|
|Camshaft Sensor Location||Rear mount, 1x on Cam|
|Oil Pan||Deep Rear Sump|
|Oil Pump||Standard Volume|
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.
I know the V8 is king, but for how long?4.3 V6 Versus 4.8 ? I would like to know where I can find upgrades for 4.3 V6,s, and the 2014 on 4.3 aluminum block 285 horse truck engine????
For the older 4.3 litre engines, there is a fair amount of performance upgrades available in the aftermarket. Especially given that a fair number of components are carry over from the earlier 350 and 5.7 litre engines. Given that the LV3 in the newer pickups is based on the current Generation 5 V8 architecture, finding performance upgrades may be a challenge even without taking into account that it is an engine that does not have a large calling for aftermarket performance upgrades. There is also the direct fuel injection that is a bit of a hurdle to overcome.
In terms of the 4.3 versus the 4.8, the 4.8 engines have more power potential over the 6 cylinder. And, the 4.8, even being an older design, is going to have better NVH characteristics, likely to have better fuel economy, and a much larger base of available parts and upgrades.
Nah …. he’s talking about the newer LS based 4.3L V6, the LV3, not the old “even-fire” 4.3L.
Howard I feel you I have both engines and plans to upgrade both i have found an article/guide to get 450hp out the V6 before boost using lots of the 350s pro parts cant find it anymore but found this one https://www.hotrod.com/articles/chevy-43l-262ci-v6-engine-build/
4.3 and 4.8 are not comparable. Easy aftermarket upgrades to the 4.3 vortec include S10 superchargers or turbo kits. On a stock motor with a mild tune you’re looking at 250 hp & 320-350 tq. A stock 4.8 is around 250-280 hp & 280 tq. 4.8s take to boost much better than the 4.3. There are examples in the 500 hp range on stock block internals.
The LB4 sy/ty 4.3’s are a different animal than the 96+ 4.3 vortecs.
How far can you bore one of these blocks out, looking to build a big bore short stroke motor, and with a 4.125 piston comes out go 5.7 liters, but is there enough metal to go that far
Max bore on these is in around 3.900 inches. The only factory LS block that has the ability to run a 4.125 inch bore on the original sleeves is the LS7 block. Any other factory LS block will require sleeving to achieve a bore that big.
Aonde encontro em.bostom a bomba da direção hidráulica do motor 5.3 vortec v8 da avalanche ou tahoe, para ser enviada para o Brasil
You can source the power steering pump from E-bay to ship to brazil.
Wow. A person really shouldn’t bore these motors!! The cylinder walls; I feel, can’t really handle it.
Big inches are no longer the way to go. I’ve SLOWLY learned this.
I’m the type of guy that like BIG motors.
Have 242000 miles on my silverado 4.8 runs like new
04 Tahoe 2wd with same mileage also runs like a top. No tuneup in years, minimal oil usage less than a qt. Btw changes. Replaced water pump , alternator, and that’s it other than normal maintenance items. Biggest issue is body rust!
I have a 1999 chevy silverado 4.8 and got it up to 308,000 miles. Did a rebuild because I lost compression on cylinder 1.
332619 miles 7735 engine hours 2007 Silverado 1500 classic 4.8
I have a 2000 Chevy Silverado 1500 it’s a extended cab it has a 4.8 5.3 LSGEN3 block it has over 399999 send it stops there and that’s been a year and a half ago and it still runs like brand new I just bought a sloppy stag 3 cam I came with all the springs push rods I bought a new engine kit comes in on the boat all new gaskets I bought new spark plugs call packs fuel pump if you injectors in long tube headers hoping it will increase horsepower significantly
I have a 65 Chevy II with a tired 283. I was wondering if a 4.8 swap could be done? It will still be close to the same cubes. Can I keep the powerglide? Thanks for the info.
Yep, you sure can! Carbed or EFI…
Do some online research, call TCI for the proper torque converter. It’s all pretty much a bolt in swap these days. The great things about the 4.8’s are they can be found cheap, and you can bore and stroke to about 383 CI, just like the 5.3 truck and 5.7 ls1.
I need a build book for my 2007 4.8 from an express 2500. Going to add boost with your guide for Baja style truck. Can you point me in the direction. Great read too
I would like to know the gap on the way spark plugs for an 03 GMC Sierra 1500 with a 4.8 engine?Thank you!
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So the 04 sierra with a 4.8 the trans feels like it’s starting to slip at 170k miles. Looking at swapping the trans what model would that be? Do you happen to know off hand?
Im likely a bit late but i had to do my 05 and ended up getting an older transmission leading me to research more into this. The transmission you want will be the 4l65e(it will still say 4l60e i dont know why) but theres a few changes including the bellhousing. The most noticeable is at the top of the bellhousing in the center there is a bolt hole that isnt on the older generations. Good luck.
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What’s the 5 speed transmission name that came behind these? And will an np208 transfer case bolt up to them? Thinking about swapping this setup into my 4×4 4runner
I am looking to upgrade the cam on what I believe is a ’99 4.8 liter before putting it in my S10. I would like to know what the most lift that the stock valve springs can handle? I am also looking for suggestions on a cam that would make the most torque. With such a light weight vehicle, I don’t think that I need 800 hp, but 350-400 would be perfect.
Question for on all cylinders, I have a 2000 Silverado with a 4.8 LR4, would I be able to install a 5.3 LM7 crate engine? Truck is in mint condition but just want more power to tow small travel trailer. Also would I need to to change computer or any of the electronics.
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i have a 1999 silvarodo 4.8 4×4, 259000 miles, awsome truck. good 4×4 very dependable, but the frames on 1999 to 2005 rust and break easy.
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Bought 99 1500 4.8/5spd ,2dr/8’bed in 15 w/125gmi @ 5500.
15-20 drove infinite & parked 12/20 @ 180gmi.
Sat till 5/22 ,son decided he wants see what’s up, 10 mos now running strong w/ Mia 4th gear only issue .
Great motor, great truck, still looking for tranny