799 casting 4.8/5.3 truck heads.
05-03-2009, 02:27 PM
#1
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799 casting 4.8/5.3 truck heads. Has anyone messed with any of these yet. I just recently got my hands on a 5.3 aluminum motor out of a 05 Z71. It was supposed to have had a rodbearing knock, but the bearings were fine. For some reason the pistons had a ton of carbon on them and a bunch of loose chunks in the cyls. Which im sure was the knock that was heard. But anyhow to cut to the chase. This thing come with 799 heads which looks just like an LS6 head as far as the chamber shape. It has 2.00/1.55 valves. I tooked one off and got it on the flowbench at work. As cast they went 275 @ .600 int and 198 on the exh. I did some port work and a 5 angle valve job and got it up to 313 on the intake with alot of airspeed on the shortside. The exhaust went 243, both at .600 lift. I still got some work to do on the intake. Im pretty sure i can get 325ish outta it. Soon as i get them done ima write the CNC program on them. I just thought that was pretty impressive numbers for a production head. Im planning to put a victor junior and a 750 holley on it with a cam to drop it in my 87 El Camino. Just wondering if anyone knew much about these heads and thought i would share what i have learned from them.
05-03-2009, 04:06 PM
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The #799's are the same as the #243 LS6/2 heads. Standard 24N Stainless valves, 2.00I, 1.55E, 210cc intake runner. The come standard on the L33HO 5.3L and 07+ 5.3L's.
My 08 Sierra has the #799's.
My 08 Sierra has the #799's.
05-04-2009, 06:45 PM
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5.3L, VIN B (8th digit, opt L33) comes in some 05+ Trucks
2004 (only) Chevy SSR, 2004+ Isuzu Ascender, 2004+ Buick Rainier, 2004+ GMC Truck Envoy XUV, 2004+ Chevy TrailBlazer EXT: 5.3L (VIN P, 8TH DIGIT)
2004 (only) Chevy SSR, 2004+ Isuzu Ascender, 2004+ Buick Rainier, 2004+ GMC Truck Envoy XUV, 2004+ Chevy TrailBlazer EXT: 5.3L (VIN P, 8TH DIGIT)
05-05-2009, 03:18 AM
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05-05-2009, 08:54 AM
#9
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I just picked up a L33 also. This was pulled from another thread.
They had the LM4.
Here ya go, I found this on GM powertrain.com.
RPO L33 FOR CHEVROLET SILVERADO AND GMC SIERRA
The Gen III Vortec 5300 is available in a new lighter, higher output variant optional on some 2005 Silverados and Sierras. RPO L33 will be introduced in short bed, extended cab versions of these pickups. The L33 features an aluminum engine block, new cylinder heads and a high-lift cam. Torque will increase, and horsepower is expected to exceed 300 in final production trim.
One of the L33’s distinguishing features is its engine block. As with the 2004 LM4 Vortec 5300, the L33’s foundation is a cast-aluminum block with pressed-in iron cylinder liners, similar to the block used for GM Powertrain’s LS1 and LS6 car V-8s. The L33 block is exceptionally light; as a result, a fully dressed L33 is 100 pounds lighter than cast iron-block Vortec 5300s (RPOs LM7 and L59).
The L33 takes its cylinder heads from the LS6. Originally developed for the Z06 Corvette, these heads improve airflow in and out of the engine. With their pent-roof combustions chambers and new flat top pistons (the pistons in other Gen III Vortec 5300s have a slight sump in the piston deck), the L33’s compression ratio increases from 9.5:1 to 9.9:1. This increase improves the engine’s volumetric efficiency yet still allows it to achieve full power with regular grade gasoline.
Finally, the L33 is equipped with a higher-lift camshaft. Maximum valve lift increases from 11.6 mm on the LM7 and L59 to 12.5 mm. The new cam and compression ratio are the primary sources of the L33’s increased horsepower.
The L33 camshaft and cylinder heads were developed in conjunction with the new Gen IV Vortec 5300 (RPO LH6). The design objective was more horsepower for customers who need it, without requiring a step up to the Vortec 6000 (and an increase in operational costs). RPO L33 expands GM Powertrain’s lineup of Vortec V8s and gives GM’s truck customers even more flexibility and choice.
The L33 Vortec 5300 will be built at Powertrain’s Romulus, Mich., engine plant. With its introduction, Powertrain will cease production of Vortec 5300 RPO LM4. The Buick Rainier, Chevrolet Trailblazer EXT and GMC Envoy XL, previously equipped with the LM4, will now be powered by the Gen IV Vortec 5300 with Displacement on Demand. The 2005 Chevrolet SSR will be powered by the new LS2 truck V-8.
RPO L33 FOR CHEVROLET SILVERADO AND GMC SIERRA
The Gen III Vortec 5300 is available in a new lighter, higher output variant optional on some 2005 Silverados and Sierras. RPO L33 will be introduced in short bed, extended cab versions of these pickups. The L33 features an aluminum engine block, new cylinder heads and a high-lift cam. Torque will increase, and horsepower is expected to exceed 300 in final production trim.
One of the L33’s distinguishing features is its engine block. As with the 2004 LM4 Vortec 5300, the L33’s foundation is a cast-aluminum block with pressed-in iron cylinder liners, similar to the block used for GM Powertrain’s LS1 and LS6 car V-8s. The L33 block is exceptionally light; as a result, a fully dressed L33 is 100 pounds lighter than cast iron-block Vortec 5300s (RPOs LM7 and L59).
The L33 takes its cylinder heads from the LS6. Originally developed for the Z06 Corvette, these heads improve airflow in and out of the engine. With their pent-roof combustions chambers and new flat top pistons (the pistons in other Gen III Vortec 5300s have a slight sump in the piston deck), the L33’s compression ratio increases from 9.5:1 to 9.9:1. This increase improves the engine’s volumetric efficiency yet still allows it to achieve full power with regular grade gasoline.
Finally, the L33 is equipped with a higher-lift camshaft. Maximum valve lift increases from 11.6 mm on the LM7 and L59 to 12.5 mm. The new cam and compression ratio are the primary sources of the L33’s increased horsepower.
The L33 camshaft and cylinder heads were developed in conjunction with the new Gen IV Vortec 5300 (RPO LH6). The design objective was more horsepower for customers who need it, without requiring a step up to the Vortec 6000 (and an increase in operational costs). RPO L33 expands GM Powertrain’s lineup of Vortec V8s and gives GM’s truck customers even more flexibility and choice.
The L33 Vortec 5300 will be built at Powertrain’s Romulus, Mich., engine plant. With its introduction, Powertrain will cease production of Vortec 5300 RPO LM4. The Buick Rainier, Chevrolet Trailblazer EXT and GMC Envoy XL, previously equipped with the LM4, will now be powered by the Gen IV Vortec 5300 with Displacement on Demand. The 2005 Chevrolet SSR will be powered by the new LS2 truck V-8.
They had the LM4.
01-18-2012, 12:31 PM
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Ok so i'm bummed out that my truck didn't come with L33, but I have found a 07' (new body style) with 799 heads, but an iron block, dose this motor share the same pistons and camshaft as the L33? Also, the motor has a different throttle body and intake than mine ( looks like a better pice )
01-18-2012, 02:28 PM
#12
L33 engines come with flat top pistons and coated piston skirts and, floating pins...regular 5.3 have dishes...the l33 also has the newer style rods too. I just got an L33 for -$100 lol, but anyway when I pulled oil pan I was suprised to see that the stock rods look much nicer than my buddies eagle rods he bought for his stang...L33 is a great engine because you get just bout 10 to 1 comp, as well as the good ls6 heads, and you get the 80 pounds of weight savings over an iron block
01-29-2012, 05:01 PM
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I am planning to get a hand on a set of 799 castings. Does AI have the power to CNC'D these things to potentially lay down 500RWHP?(with other mods of course)
01-29-2012, 06:40 PM
#17
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The Gen IV 4.8l/5.3l 2007 up motors have the 799/243 heads. All 4.8's are iron blocks. 5.3L are a mix of iron and AL block. And all the 5.3L are flat tops now. Also both have a 87mm intakes and TB's.
I have even seen a GMT900 truck (2007-up) with one 799 on one side and a 243 on the other. On the same motor from GM.
Also the 2010 plus truck motors ALL have VVT save for the old 4.3L!
I have even seen a GMT900 truck (2007-up) with one 799 on one side and a 243 on the other. On the same motor from GM.
Also the 2010 plus truck motors ALL have VVT save for the old 4.3L!
01-29-2012, 08:01 PM
#18
I have an iron block 4.8 with flat top pistons, came equipped with 243 heads. But the truck/suv engines with 243/799 heads did not come equipped with hollow stem valves.
So they are not ls6 heads. Ls6 heads only came on ls6 5.7 engines and nothing else
So they are not ls6 heads. Ls6 heads only came on ls6 5.7 engines and nothing else
01-29-2012, 08:51 PM
#19
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But correct on the heads, the truck 243's are not the LS6 heads exactly, just the same castings.
