nighthawk08

gm media

http://media.gm.com/us/powertrain/en...k/2007_LMG.xls

trever1t

iTrader: (14)

Interesting for sure. This is an Iron block too. I dont see where it claims to have a 90mm tb though?

nighthawk08

i actually linked the wrong doc...

http://media.gm.com/us/powertrain/en...New/07_LMG.doc

i'm not sure it has it in there either...but the GEN IV trucks have the same intake manifold as the LS2 TBSS. I think its really like 87 mm or something.

nighthawk08

here's a quote from the LH6, which is just an aluminum version of the GEN IV 5.3

The LH6 takes its cylinder heads from the LS6 V-8 that powers Cadillac’s high-performance CTS-V sedan. Originally developed for the Corvette Z06, these heads improve airflow in and out of the engine. With their pent-roof combustions chambers and new flat-top pistons (the pistons in Gen III Vortec 5300s have a slight sump in the piston deck), the Gen IV Vortec 5300’s compression ratio increases from 9.5:1 to 9.9:1. This increase improves the engine’s volumetric efficiency and increases horsepower.

Typically, however, high compression engines require high-octane gasoline to produce maximum power, or to avoid the potentially damaging effects of spark knock or “detonation.” The Gen IV Vortec 5300 does not require premium fuel to achieve peak horsepower. The seemingly incompatible objectives of high compression and regular gas were achieved by optimizing combustion chamber design and airflow to the engine, and through advanced engine management.

With the new heads, the Gen IV Vortec 5300’s valve springs feature a new winding geometry and more durable alloy. The LH6 also uses the solid Silcrome 1 valves originally introduced on GM Powertrain’s LS1 V-8. Compared to conventional iron-alloy valve material, Silcome 1 includes tungsten, vanadium, manganese, silicone and higher chromium content. It is harder, and improves durability.

IMPROVED INTAKE MANIFOLD WITH LARGER THROTTLE BODY
The Gen IV Vortec 5300’s carbon composite intake manifold offers several advantages over a conventional metal manifold, including less weight, improved airflow and better noise dampening It is manufactured with a refined lost-core molding process that improves assembly efficiency and drastically reduces post-molding finish work.

With the new manifold, the engine is equipped with an 87-mm throttle body, compared to the 75-mm throttle body used on Gen III Vortec 5300s. The larger throttle body increases maximum airflow into the engine; it also prepares the Gen IV Vortec 5300 for further horsepower increases in the future. Moreover, the throttle body is now tilted upward 12.5 degrees, as opposed to flat to the horizontal plane of the engine. The upward tilt virtually eliminates moisture collection in the throttle body when the vehicle sits idle for long periods, and reduces the chance of throttle icing. Previous versions of the Vortec 5300 have used a heated throttle body to help manage emissions by warming intake. Thanks to the engine’s overall efficiency, the Gen IV Vortec 5300’s throttle body does not require heat. This eliminates coolant jackets around the throttle body and plumbing that delivers coolant to those jackets, reducing assembly complexity and eliminating a potential leak source.

trever1t

iTrader: (14)

Well I believe the first paragraph is true for the L33's as well (I have 799 heads), but damn the manifold and tb design changes sound awesome!

nighthawk08

yeah, the L33 seems to be very similar to a GEN IV, besides the manifold/tb and AFM.

.T.

Thanks for that info! Now, which is the engine code for the 5.3 truck motor?

ChevyThunder17

iTrader: (45)

Gen III (LM7) or Gen IV (no idea, L33)?

ap2002

iTrader: (8)

a member on here did put some 243 heads milled .030 and he said it bumpe his compression slightly and he said the SOTP feel is definately there... if its true, then that is a good mod to do... and thats on a 5.3

nighthawk08

LM7 and L59 (e85) and L33 (alum blk) and LM4 (TB alum blk) are GEN III

LY5 and LMG (e85) and LC9 (alum blk E85) and LH6 (TB alum blk) are GEN IV