Buying a Performance Short Block vs. Buying a PreLoved Complete Engine

[Charles_Colfax]

Screen shots below are from a previous thread.

 

I'm working up a mild performance build 5.3 for my 06 Z71 Suburban.

 

Looking to open up the power it has.

 

More low to mid-range power and torque, DD is and to tow a 6000# travel trailer several times a year.

 

But enough "higher end" for comfortable multiple hour Interstate runs at 70-80-ish.

 

Keeping stock crank/stroke, would like to go to close to 5.7/350 total cid like the short block linked below.

 

243/799 heads, forged flat tops, and a cam in the 215/215 and 110-114lsa range, longtubes and a good tune.

 

(Essentially an LS1 with a truck cam.)

 

Am I on the right path?

 

Would you go with buying the short block linked (or something like it)?

 

Or a complete pre-loved donor like this one:

 

https://norfolk.craigslist.org/pts/d/l33-aluminum-53l-ls1/6648385001.html

 

 

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[swathdiver]

BlackBear recommends keeping the duration at or below 210.  Mine own preference is 200 and a single patter like my motor and the L33.  Lift no higher than .502 or so.  This keeps torque down low where we need it for our big trucks.  These aren't RCSBs!  

 

If you can get the part numbers for the blocks you come across, go to Summit's database which will have a list of the blocks used for that particular engine.  It's not perfect but pretty close to it.

[Charles_Colfax]

BlackBear recommends keeping the duration at or below 210.  Mine own preference is 200 and a single patter like my motor and the L33.  Lift no higher than .502 or so.  This keeps torque down low where we need it for our big trucks.  These aren't RCSBs!  
 
If you can get the part numbers for the blocks you come across, go to Summit's database which will have a list of the blocks used for that particular engine.  It's not perfect but pretty close to it.

Well the seller with the complete L33 flaked, just completely ignored my text messages after I asked him if he had any "wiggle room" in his asking price.

His loss. I have cash available to start collecting the parts for this project.

I believe I've got a good LM7 block lined up, seller already had it bored to 3.898, has new oil pan, original crankshaft, a matched set of rods and pistons and an OE intake.

(I won't need the pistons.)

He decided to build an LQ9 6.0 he accquired instead.

What are your thoughts on keeping the cam "single pattern" or both intake and exhaust duration the same?

Most off the shelf profiles in the 204-215 degree range seem to be close, but not equal, with a few degrees between them.

Most also seem to be between .500 & .550; .525 seems pretty common.

With the 243 or 799 heads, I plan on running the LS6 "blue" behive springs and the Comp trunion upgrade.

I know I don't want to go any bigger than those ranges, because, like you said, I want my power in the low to mid-range at most.

And don't want that big lumpy cam, it's not a street rod, it's a 5600# DD'ed truck!

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[Charles_Colfax]

I wonder if I can get the #blackbear folks on the board to chime in with their take?

Is there a way to "tag" them?

And what would the specific block part number tell me?

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[Charles_Colfax]

Moving from other thread

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[swathdiver]

54 minutes ago, Charles_Colfax said:

I believe I've got a good LM7 block lined up, 

What are your thoughts on keeping the cam "single pattern" or both intake and exhaust duration the same?

Most off the shelf profiles in the 204-215 degree range seem to be close, but not equal, with a few degrees between them.

 

The stock LM7 camshaft is a dual pattern.  The L33 and early LY5, LMG and LC9 Gen IV engines had the same profile as the L33 but also provisions for AFM.

 

LM7 = 191-190 .457-.466 116

L33 = 193-193 .482-.482 116

 

Remember, the LM7s camshaft was optimized for the 706/862 heads and not the 243s like the L33.

 

Crane Cams, Vinci and Cam Motion all offer camshafts with low duration and lifts that do not require heavier valve springs.  

 

https://ls1tech.com/forums/dynamometer-results-comparisons/1741621-cam-motion-5-3-drop-cam-results-41rwhp-22rwtq.html

 

https://www.performancetrucks.net/forums/internal-engine-modifications-158/cam-motion-5-3-stage-2-drop-cam-testing-results-depth-531293/

 

http://markenperformance.com/n-8673-crane-cams-direct-fit-cams-for-ls-stock-oe-valve-trains-4-8l-to-6l.html

 

 

51 minutes ago, Charles_Colfax said:

I wonder if I can get the #blackbear folks on the board to chime in with their take?

Is there a way to "tag" them?

And what would the specific block part number tell me?

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@BlackBearPerf

 

The purpose of the block numbers is so that someone doesn't sell you a Gen IV 4.8 when you're after a 5.3 Gen III.