LM7 vs L33

[T.B]

Looking for a little help, going to do A twin turbo set up on a 5.3 in stock form. Trying to make 500-600 rwhp. Is there a advantage to ether the LM7 or L33? I belevie the L33 has a higher compression and better heads from what I read but not sure.

[andrewb70]

Looking for a little help, going to do A twin turbo set up on a 5.3 in stock form. Trying to make 500-600 rwhp. Is there a advantage to ether the LM7 or L33? I belevie the L33 has a higher compression and better heads from what I read but not sure.

Tim,

L33 also has an aluminum block, while the LM7 is cast iron. Both engines are Gen 3, so they will have the less desirable rods and pistons. A better option would be a Gen IV 5.3L, but that presents other issues, like dealing with AFM and VVT, but you will get better rods. A desirable Gen IV 5.3L is the LH8. It's aluminum block and no VVT or AFM.

Andrew

[T.B]

Thanks Andrew I'll do a search to try and find a LH8, looks like they may be hard to find..

[andrewb70]

Thanks Andrew I'll do a search to try and find a LH8, looks like they may be hard to find..

I believe they are one year only (2009 I think) in the Colorado truck and H3 Alpha.

Andrew

[LS1-IROC]

I'm pretty sure the L33 has the updated floating pins and stronger rods from the Gen IV motors. It also has a 24X wheel on the crank. This is probably the most desirable aluminum 5.3.

[T.B]

yep looks like LH8 was only in 2009 in the canyon, and Colorado. Only one I could find they want 3500. I'm going to give the L33 a try found a few for less the 1500 with under 100,000 miles. Going to put around 9lbs to it and see how long it will last. It should be a fun little truck to drive..

[LS1-IROC]

9lbs on a L33 will last a long time if the tune-up is good. I run 10lbs on my stock LS1 with weaker rods and pistons no problem.

[andrewb70]

I forgot that the L33 was a transitional model and had the Gen IV internals. Good catch. As for 24x or 58x, that's mostly personal preference. I like the Gen IV blocks with the knock sensors on the sides and the cam sensor up front. I also like DBW, which is mandatory for 58X engines and OEM style ECUs. Gen 3 is nice because you can go DBW or cable TB...lots of little differences that mostly fall into the personal preference category.

I scored the LH8 that is in my Cougar for $2200 delivered and it had 386 miles on it. Looks like the salvage yards are getting wise to them. If you want another Gen IV aluminum block option, the LH9 also works, but I believe it has both AFM and VVT...

Here is the truck engine line up for 2010.

https://archives.media.gm.com/us/powertrain/en/product_services/2010/gmna/10truck_us.htm

There are a lot of pictures and both Word and Excel documents that are linked and contain useful information about features, etc...

Andrew

[stevenb8]

I have L33 I paid 500 for with 799 heads, has thick cylinder walls, gen 4 rods with flat tops, 24 tooth etc.. Lots of people have tried to buy as it's basically one of the best 5.3. Have several friends running boosted, supercharged ones with no issues.