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LS1 -GEN III Facts and specs.

Guest plainswolf

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Guest plainswolf

Some interesting facts about the GEN III engines including the LS1:


ENGINE: Liters: Cubic I: Bore: Stroke: Rod Length: Comp:

LR4 4.8 293 3.780 3.268 6.276 9.5

LM7 5.3 325 3.780 3.622 6.098 9.5

LS1 5.7 346 3.898 3.622 6.098 10.1

LS6 5.7 346 3.898 3.622 6.098 10.5

LQ4 6.0 364 4.00 3.622 6.098 9.4



Engine: HP TQ Application

LR4, 4.8L 255@5,200 285@4,000 '99 Silverado

270@5,200 285@4,000


LM7, 5.3L 265@5,000 320@4,000 '99 Silverado

285@5,200 325@4,000


LS1, 5.7L 305@5,200 335@4,000 '98-99' Camaro

335@5,200 335@4,000 '98-99' SS Camaro

345@5,600 350@4,400 '97-99 Corvette

350@5,600 350@4,400 2000 Corvette

350@5,600 375@4,400 '01 Corvette

350@5,600 360@4,000 '01 Corvette Auto

310@5,200 340@4,000 '01 Camaro Auto

325@5,200 350@4,000 '01 Camaro six-speed


LS6, 5.7L 385@6,000 385@4,800 '01 Corvette


LQ4, 6.0L 300@4,800 355@4,000

300@4,400 360@4,000

all ratings are up to 2001 models



Significant Gen III

Engineering Points:

1. All Gen III truck engines use iron blocks. Only the Camaro (F-Car) and Corvette (Y-car)LS1/LS6 engines feature aluminum blocks.


2. All Gen III engines have aluminum heads except for the '99 LQ4 engines that were equipped with iron heads. These engines received aluminum heads for the 2000 model year.


3. All Gen III engines share common main,rod,and cam-bearing journal diameters for ease of interchange. All blocks use a cross-bolted six-bolt main cap.


4. All Gen III engines are completely metric.


5. All valvetrain pieces are completely interchangable. The standard rocker ratio for all Gen III engines is 1.7:1.


6.All Gen III truck engines use cast aluminum oil pans that are deeper than the camaro or corvette pans.


7. All intake manifolds interchange. The truck intakes are roughly 3-4 inches taller than the passenger-car intakes.


8. All Gen III engines employ reusable gaskets for sealing surfaces except for the head gaskets. This makes it much quicker and easier to service the engine.


9. There are only two intake valve sizes for all the Gen III engines. Exhaust valves are all the same diameter.


10. Truck and camaro engines use cable throttle linkage while the corvettes use an electronic throttle. There are also some SUV engines with traction control that use electronic throttle control.


11. Bellhousing patterns are the same for all Gen III engines. The crank flange is basically the same depth as the bellhousing flange.


12. The Gen III firing order has been revised from 1-8-4-3-6-5-7-2 to 1-8-7-2-6-5-4-3. Note that the pairings 1-8, 4-3, 6-5, 7-2 remain the same, but the pairing order is different for reduced vibration.


13. The valve angle on all Gen III engines is 15 degrees versus 23 degrees for the origional and Gen II small-blocks.


14. The Gen III bore spacing is the same as the origional small-block, but each cylinder is ringed with only four head bolts instead of five.



Custom Cubes:

If you are fortunate enough to get your hands on an LQ4 6.0L engine block, you can bore it .030-over and purchase a 4.250 Lunati stroker crankshaft to produce a 434ci. GenIII engine.


Add a set of GM Performance Parts ZO6 cyclinder heads (PN 12560801) or have the stock LS1 heads ported and you've got yourself a serious engine.



All information is taken from Chevy High Performance Magazine May 2002 edition.


Just thought these would be some handy facts/ references to post for everyone and especially new people wondering about the Gen III chevy engines.



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I would take issue with number 8 as I spent over half a day scraping gasket material from the water pump and it's corresponding spot on the block on a 98 F-car LS1. However, I can vouch for o-ringed valve covers and intake.

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  • 3 weeks later...
I would take issue with number 8 as I spent over half a day scraping gasket material from the water pump and it's corresponding spot on the block on a 98 F-car LS1. However, I can vouch for o-ringed valve covers and intake.


gasket remover works wonders, just dont get it in any cuts or scrapes and stuff a rag in the hole your working on :)

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I would take issue with number 8 as I spent over half a day scraping gasket material from the water pump and it's corresponding spot on the block on a 98 F-car LS1. However' date=' I can vouch for o-ringed valve covers and intake.[/quote']


gasket remover works wonders, just dont get it in any cuts or scrapes and stuff a rag in the hole your working on :)


That's why it was half a day instead of a week. I was helping a friend do a cam swap on his 98 1LE Camaro. Got ready to put the water pump back on and had to clean the gasket off. After several hours of scraping with minimal progess, I told him we'd finish up the next day when I came back with some Permatex Gasket Remover from my house. It worked extremely well. :-D

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I have some info to add to this:


The 2001 and 2002 Trans Am and Camaros with LS1s also had LS6 intakes. GM did not let the public know about this because that'd detract people from buying Corvettes. That was generally a good gain of 5-8WHP. Also, after doing MANY dyno runs on MANY LS1 Corvettes and F-bodies, it's been proven that the rated HP on the LS1 F-bodies were identical to the Corvettes, meaning that they were also 350BHP, not 325. On average, the LS1 Corvettes and F-Bodies both put down 315HP through the automatics and 320HP through the manuals.


In addition, the LS1's in the 01-02 F-bodies had a completely different smog system, and there was a power gain from this. You can see the differences at the top of the intakes just behind the throttle bodies. The 01-02s have no EGR hoses coming out of the top.


Although not affecting the HP on the car, half of the 2002 LS1 F-bodies were made with an LS6 block as well. The only real difference between the two blocks being a special oil breathing window in the LS6 block. This was common.

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Significant Gen III

Engineering Points:

1. All Gen III truck engines use iron blocks. Only the Camaro (F-Car) and Corvette (Y-car)LS1/LS6 engines feature aluminum blocks.

Not totally accurate. You are missing the LM4 and L33, aluminum block versions of the LM7.


The LM4 was available only in 2004 in AWD Trailblazers, Envoys and Buick Rainiers, and the SSR. Same power rating as the LM7.


The L33 was only available in extended cab, AWD Silverados and Sierras from 2005-2007. It was rated 15hp more than the LM7 with the same torque.


I have an LM4 from a Trailblazer EXT in my '98 Sonoma Stepside and turbo'd an LM4 from a Rainier in an RX7.

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This thread had been bugging me for a couple months now due to its outdated info such as Scotty pointed out, (back when that original post was made, 2003, it was mostly accurate).


I'll get around to cleaning it up later.

For now, here is the 5.3 and 6.0 Vortec Truck/SUV aluminum block line up, Gen III and IV, from inception to the current '09 model year.




'03-'04 LM4

'05-'07 L33


Gen IV


'05-present LH6, DOD

'07-present LC9, DOD, Flex Fuel

'08-present LH8,



'07-present L76, DOD, truck versions got VVT



'07-present L92, VVT


DOD = Displacement On Demand or AFM as GM calls it.

VVT = GM's Variable Cam Timing.

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For those who are interested in swapping, I am told (FWIW) that the 6.0L LQ4 iron motors are about 80 lbs heavier than the aluminum variant and are essentially an LS2 block cast in iron. Likewise, they have dished pistons and are pretty good for boosting out of the box. The nicest thing is that they are quite a bit cheaper than Camaro/Corvette motors, etc.

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Block weight alone, for the LSx engines, aluminum vs iron, is in the 60-70 lb range, depending on 5.3 vs 6.0, LS1 vs LS2 vs L33, etc. Worst case is 70 lbs. That means comparing an iron block truck engine built up with the same exact external components as an aluminum block LS1/2/33, i.e. intake, exhaust, accy, oilpan, etc, you can expect a 60-70 lb weight penalty for the iron block variant, again, the only difference being the block-pistons, rods, everything else being equal! :wink:

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Gen III/IV crankshaft flywheel flange thickness differences…



Courtesy of AERA public info;



Crankshaft Replacement Caution For

1998-2005 GM 4.8' date=' 5.3, 5.7 & 6.0L Engines


The AERA Technical Committee offers the following information on crankshaft replacement caution for 1998-2003 GM 4.8, 5.3, 5.7 and 6.0L engines. Design changes in the flywheel flange thickness have been made to some crankshafts used in the above-mentioned engines. This bulletin is being re-published with additional information.


The later crankshafts are shorter on the flywheel flange as seen in the listing below. These changes are due to the many different vehicle / transmission combinations being built by GM.


A flywheel spacer ring GM Part #12563532 and a longer bolt set GM Part #12563533 is required when using a thin flange crankshaft to replace a thick flange crankshaft. Also, if the crankshaft is being used in a vehicle, which is a standard shift application, you also need pilot bushing GM Part #12557583 or 12479894.


Note: GM part numbers correct as of 12-18-04.


Years Liters Casting # Trans Flange Thickness


1999-2000 4.8L 312 V-8 M/T 1.250 thick flange

1999-2000 6.0L 215 V-8 1.250 thick flange

1999-2005 4.8L 482 V-8 A/T .857 thick flange

2001-2005 4.8L 482 V-8 M/T .857 thick flange

1999-2005 5.3L 216 V-8 A/T .857 thick flange

1997-2005 5.7L 216 V-8 .857 thick flange

2001-2005 6.0L 216 V-8 .857 thick flange


All GEN III crankshafts used in Camaro, Corvette and Firebird have a .857 thick flange and also have an expansion plug installed at the bottom of the pilot shaft hole. The 4.8, 5.3 + 6.0L don’t have the expansion plug. The drilled hole thru the centerline of the 5.7L LS1 & LS6 crankshafts allows a path to balance crankcase pressure within the lower crankcase. Doing so has eliminated possible oil consumption when the engine is operated over 4800 RPM.


Caution: Early crankshafts use a flat reluctor wheel and late have a recess. Recess will work on all years. Do not use a flat reluctor on late applications as it will cause an engine misfire.


The AERA Technical Committee[/quote']

Edited by BRAAP
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Not sure if you are looking at a 5.3L or 4.8L? This article helped me immensely. If the engine is assembled, about the only way to find out is to remove the spark plugs, find a piston at TDC and using a flashlight and a keen eye and suitable probes, look and feel across the piston top for the edges of a dish as pictured below. If it is a dished piston, it is a 5.3L. If it is a flat top piston, then the engine is a 4.8L.



Courtesy of PERA;



Is That A 4.8L Or A 5.3L GM Gen III Engine?


by Roy Berndt

During our research of the General Motors Gen III engine family we continued to run up against a stumbling block of exterior identification between the 4.8L and 5.3L engines. It seemed that no matter who we spoke with, be it core suppliers, wrecking yards, engineers or rebuilders, when asked how they differentiated between the 4.8L or 5.3L engine from the exterior, no one had a solid answer. As a matter of fact no one had any answer.

So we thought we would look at the internal component differences between these two engines and perhaps come to some solution of external identification.


These engines came on the scene in 1999 in General Motors truck applications and were the upcoming replacement for the original design small block engines (GenIE). They were a spinoff of the LS1, 5.7L passenger applications used in the Corvette, Camaro and Firebird two years prior. Just so we have all the ducks in a row, both of these engines are OHV, pushrod V8 engines with cast iron blocks and aluminum cylinder heads.

Because both engines use the same block (c/n 12551358), GM seemed to play what may be described as a cruel, twisted joke on us since it cast "4.8/5.3" right on the block both in the front and in the rear in large numbers. The only problem is that you never really know which engine that you have from the exterior. The standard cylinder bore for both engine applications is 96mm (3.779˝) however the stroke for the 4.8L is 83mm (3.268˝) and has a crankshaft casting number of 12553482 while the stroke for the 53L is 92mm (3.622˝) and that crankshaft casting number is 12552216. Looking at the two crankshafts just standing next to each other they do not have what you would consider an obvious difference in appearance.




The connecting rods for the two engines do provide us some visual identifiable differences. The 4.8L connecting rod is longer in length and has the casting number 121 with an additional boss on the thrust face. The 5.3L connecting rod is shorter with casting number 143 and no additional boss on the thrust face. Both connecting rods are PM (powder metal) with a "crack" parting face.




There is also a difference between the pistons of these two engines, the 4.8L has a flat dome and the 5.3L has a cup dome. Another thing that we noticed is that the 4.8L pistons from OE had a pink ink mark in the pin area and the 5.3L had a green mark.




The cylinder head for both engines is aluminum with a casting number of 862, however on the deck face area in a small cavity there is a 4.8 cast onto the cylinder head. Do not be confused by this cast number for the cylinder head is for both 4.8L and 5.3L engines.

So how does any of this help with our ability to discern between these two engines from the exterior? If the oil pan is off, you could look at the crankshaft casting number, only every time you want to do that your odds are about as good as an open face peanut butter and jelly bread hitting the floor face up. But you can look at the connecting rods and see if that additional boss is there, you have eight chances to do that! But do you really want to pull the oil pan if you don’t have to?

That leaves us with one option, pull a single or multiple spark plug(s) and look down the hole. Optimally, if you have a bend-a-light that will go into the spark plug hole you will have a better view. If you see a flat top piston, it is a 4.8L.


If you have a cup top piston you have a 5.3L. That is the best we were able to find as a quick identifier. But it works and it is relatively easy. Best of all, it is definitive. So if you have someone who is trying to sell you a 5.3L you might want to pull a plug and make certain that it has a cup top piston, otherwise ...well, I guess it could always be an honest mistake.

SourcePERA casting identification research continues to be the best available information for the engine remanufacturing industry. Also be on the lookout for the new 2004 PERA Engine Application and Identification Catalog. For more information go to http://www.pera.org and contact Roy Berndt via email link.

Thanks for the numerous emails and phone calls in reference to the Gen III crankshaft reluctor wheel. For your information, the GM superceded part number for all applications is 12559353. The only available installation tooling we are aware of (including GM) is available from Goodson Shop Supplies, Winona, MN.


For technical questions, contact the Production Engine Remanufacturers Association (PERA) at: royberndt@pera.org.

©2007 PERA 28203 Woodhaven Road, Edwards, MO 65326

417-998-5057 / FAX: 417-998-5056

E-Mail: nancieboland@pera.org

Edited by BRAAP
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Also, all years of the LS6 were under rated. The '01 LS6 was rated at 385BHP but was closer to 400BHP and the '02+ LS6 was rated at 405BHP but was closer to 425BHP.


Pup-cats were used on the '01 LS6 reducing the amount of power the 01 Z06 saw to the ground, and in 02 those cats were removed. In addition, the 02 had air box and maf changes that helped to increase break horse power.


There are reported consumption issues with the '01 LS6, and the valves are different from the '02+ LS6 in that the valves in the 02+ are sodium filled to make them lighter. The 243 heads between the 01 and 02 shouldn't be mixed unless the valve train is being replaced all-together.


Just a little extra info.

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