Heads
03-05-2013, 09:00 PM
#12
Staging Lane
Okay I believe all the old gen3 5.3/4.8 are either 799/853 heads. I do know what you are talking about. I own a 2000 silverado with a 4.8 and a 2001 with a 4.8 and the 2001 is night and day. She pulls way harder and is way faster than my 2k. The book doesn't have that listed either so I would go with what we know..the 1999/2000 are different than later 2000/2001, however I would think it is because of the cam/tune.
I agree with the other guys, ditch the 5.3 ones. I am going a little cheap and using the pro comp heads. They flow better than the 799/243 heads for 400 bucks bare. They are a 62cc chamber though. You would need to have them milled down.
I can't speak of a stall, I am going to get the Circle D 3000 and see if I like it. I just don't want it to be spinning 2000RPM going 30 through town lol.
03-06-2013, 08:37 AM
#14
LS6 5 7L GM Aluminum Cylinder Heads Casting 799 | eBay
the 799's arent expensive... and they are most definitely worth that extra couple hundred. I know you are really trying to keep to a strict budget, but they are probably worth 25 HP over the 5.3 heads you bought when they have the correct size combustion chamber.
Hell a similar cam and head package makes a big difference on a 6.0. The LS2 uses the exact cam that you are putting in and 243 heads. The LQ9 comes with a bigger cam than your 5.3, and 317 heads, which people say have the same intake port design as the 243's (again, the 317 will greatly outflow the 5.3 heads you bought). The LS2 is rated at 400 HP, while the LQ9 is only rated at 345. You do the math.
the 799's arent expensive... and they are most definitely worth that extra couple hundred. I know you are really trying to keep to a strict budget, but they are probably worth 25 HP over the 5.3 heads you bought when they have the correct size combustion chamber.
Hell a similar cam and head package makes a big difference on a 6.0. The LS2 uses the exact cam that you are putting in and 243 heads. The LQ9 comes with a bigger cam than your 5.3, and 317 heads, which people say have the same intake port design as the 243's (again, the 317 will greatly outflow the 5.3 heads you bought). The LS2 is rated at 400 HP, while the LQ9 is only rated at 345. You do the math.
03-06-2013, 02:17 PM
#15
On The Tree
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The intake question comes up. Is the tbss intake the same as the 6.0 intake? Also would there be any gain from a 6.0 intake? I'm just looking around.
I just dropped the heads off to be cleaned up, new valves seals, 3 angle, port and pollished and milled. I am sure that with the 799s i could have gotten a better result but again where do i stop. I had the heads so this is where is is.
So now i have cam, headers and rebuilt heads. I guess the intake might as well happen at the same time. So any thoughts would be great.
I just dropped the heads off to be cleaned up, new valves seals, 3 angle, port and pollished and milled. I am sure that with the 799s i could have gotten a better result but again where do i stop. I had the heads so this is where is is.
So now i have cam, headers and rebuilt heads. I guess the intake might as well happen at the same time. So any thoughts would be great.
03-07-2013, 09:09 AM
#17
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Okay consulting my big book of fun the LM7 released in 1999 is said to produce 295hp, the L59 released in 2002 is 295HP as well but it is a flex fuel engine. The LM4 released in 2003 is good for 300HP; that is a aluminum block. The only gen3 5.3 that made more power was the L33 released in 2005 and that has a compression ratio of 9.9:1. That engine made 310HP. All other engines were 9.5:1. It got to 9.9:1 by using the flat top pistons used in the 4.8. Of course these are stock numbers but I think any gains would be in the area of error if there are any.
It really depends on what you want out of the engine. Raising the compression ratio is better. You are already using 93 octane so you could go up into the 10s. That might net more for you. In theory also you get more MPG because you are getting more energy out of the fuel as well. If you got the money to drop why not?
It really depends on what you want out of the engine. Raising the compression ratio is better. You are already using 93 octane so you could go up into the 10s. That might net more for you. In theory also you get more MPG because you are getting more energy out of the fuel as well. If you got the money to drop why not?
1999 4.8(5.3) was rated at
255hp@5200rpm (270hp@5000)
285 lb/ft@4000rpm (315lb/ft@4000rpm)
2000-01was
270hp@5200rpm (285@5200)
285lb/ft@4000(325@4000)
rev limit
manual 5600rpm
auto 6000rpm
2002-2003
275hp@5200rpm (285hp@5200)
285lb/ft@4000rpm (325@4000)
rev limit
5600 rpm with manual transmission
5900 rpm with automatic transmission and electronic throttle control
6000 rpm with automatic transmission without electronic throttle control
2004
285hp@5600RPM (295@5200RPM)
295LB/FT@4000RPM (330@4000RPM)
rev limit
5600 rpm with manual transmission
5900 rpm with automatic transmission and electronic throttle control
6000 rpm with automatic transmission without electronic throttle control
2005-2007 lr4/(lm7)
285HP@5600RPM (295HP@5200RPM)
295LB/FT@4000RPM (335LB/FT@4000RPM)
revlimit
5600 rpm with manual transmission
5900 rpm with automatic transmission and electronic throttle control
6000 rpm with automatic transmission without electronic throttle control
2006-2007 L33 5.3 (243/799 LS6 casting with normal non-LS6 valve heads, slightly more lift cam, alum block, flat top pistons increase c/r from 9.4 to 9.9:1)
310HP@5200RPM
335LB/FT@4000RPM
5600 rpm with manual transmission
5900 rpm with automatic transmission and electronic throttle control
6000 rpm with automatic transmission without electronic throttle control
2007.5-2009(799 heads on 4.8 and 5.3)
4.8=LY2 (5.3=LH6)
295hp@5600rpm (315hp@5200rpm)
305lb/ft@4800rpm (338lb/ft@4400rpm)
2010+with VVT
4.8=L20 (5.3=LC9)all have 6000 rev limit
302hp@5600rpm(315hp@5200rpm on gas/326hp@5300rpm on E=85)
305lb/ft@4600rpm(335@4000rpm on gas/348@4400rpmon E-85)
peace
Hog
Last edited by hog; 03-09-2013 at 04:52 PM. Reason: to expand on missing L33 changes from LM7
03-07-2013, 03:59 PM
#18
Staging Lane
Figured I would finish this up. There is more to the L33. If anyone actually cares to know that is ha.
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.
03-08-2013, 09:35 PM
#19
Holly crap this thread is so full of miss information!!!If you want head specs look here... https://www.performancetrucks.net/fo...g-info-434396/
As far as the mechanical of the engines, Lets start with the Iron LM7 and L59 5.3L engines. They both had an -8cc dish piston. The engines were rated at 9.5:1 compression. The pistons still go about .010 above the deck. The MLS head gaskets are rated as .051 thick compressed.
They both use the 706 or 862 head castings from 99-07 classic. These heads feature a 1.89 intake valve and a 1.55 exhaust valve with roughly a 60 cc combustion chamber. The intake chamber is 200 CC and flows about 226 CFM at .600 lift.
The L33 5.3L Is an aluminum block engine that was only available for 2 years that uses a flat top piston with the same pin height. Yes, this is the same piston in the 4.8L engine. This engine is rated at 9.9:1 compression. Again this piston is also roughly .010 out of the hole. The MLS gaskets for this engine are also .051 thick compressed.
The L33 has the 799/243 heads that feature a 2.0 intake and a 1.55 exahust valve. They feature a 64 CC combustion chamber. The intake chamber is 210 CC and flows about 257 CFM at .600 lift.
The difference in the 99-00 is that they used a fiber material head gasket and in 2001 they went to an MLS type gasket. If there is any change in the cam, it is going to be very minimal netting possibly 5-10 Hp. The operating systems (AKA the Tune) and the tables within are very different between an 99-00 and the 01-02. The 05 Is different as well and is not back wards compatible. Tuning is a whole different discussion.
As far as the changes to the cam's over the years in the standard 5.3, they were so minor that you would hardly notice the difference. You could put 2 of the same cam's with the same part numbers ground on the same machine in 1 engine and get 2 different readings. The HP and TQ ratings Provided by the manufacture are just a base number of what a new healthy engine should produce. So many things can effect the readings you get and the numbers can change between the equipment used to measure them.
Don't get hung up on numbers from 1 year to the next. A simple cold air intake can add up to 10-15 HP
To answer the Question of the original poster,
Keep the heads you have and do just a little work in the bowl area. It's good for up to 40 CFM when done properly. That's the same flow range as the 799/243 heads. A little shave of the heads won't neat you much power (maybe 5-10 Hp at most) but with the Higher octane you are using, the engine will burn it much more efficiently. If you cleaned up the bowls your self and took the heads to a machine shop for the needed work, you would be in it less then $400.
HTH
03-09-2013, 06:02 PM
#20
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Thanks Fastbrick..
Along with cam changes, there was the 2000 injector change In 2000 GM was using 2 different injector sizes, manual transmission trucks in 2000 and all 2001+ trucks used the larger injector while all 1999 trucks and 2000 auto trucks got the smaller injector.
I just looked up prices for brand new GM L33's and they are going for $3100. Not bad IMO.
I think that the 05-07 L33 was an experiment by GM to see how the 799 head was going to be received by the public. They werent available in the lightest of the GMT800 1/2 ton trucks. When the GM900's came out in 2007.5 the GEN IV LH6 5.3 is pretty much an L33, aluminum block and all. It made 315hp@5200rpm and 338lb/ft@4400rpm.
peace
Hog
Along with cam changes, there was the 2000 injector change In 2000 GM was using 2 different injector sizes, manual transmission trucks in 2000 and all 2001+ trucks used the larger injector while all 1999 trucks and 2000 auto trucks got the smaller injector.
I just looked up prices for brand new GM L33's and they are going for $3100. Not bad IMO.
I think that the 05-07 L33 was an experiment by GM to see how the 799 head was going to be received by the public. They werent available in the lightest of the GMT800 1/2 ton trucks. When the GM900's came out in 2007.5 the GEN IV LH6 5.3 is pretty much an L33, aluminum block and all. It made 315hp@5200rpm and 338lb/ft@4400rpm.
peace
Hog
Last edited by hog; 03-11-2013 at 02:33 PM.
