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Black 07 AWD
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Discussion Starter #1
I've seen lots of posts of guys mentioning swapping out their engine with different engines for whatever reasons. However, what I have not seen is anyone providing a review of their engine swap after an extended amount of time has gone by, like a year or more. I am interested people's thoughts, perception, likes, dislikes, what they wish they did and so on, regarding their engine swap.

The reason for this post is because i am on the verged of pulling the trigger on buying a GM crate engine, either an LS3/480 or an LS3/525 (just debating if the extra 30 hp is worth the extra $1000). I am also toying with the idea of simply rebuilding my engine, especially since I finally have time to devote to such a project. However, I must say a GM Performance crate motor and GM mated transmission with a warranty is pretty darn appealing. I am looking to get more power with increased reliability, this is not a race truck, just a daily driver.

Anyways, all of that to say can anyone who has already gone down this path and has put on some mileage please provide some kind a review of the completed project?
 

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I originally swapped my 5.3 for a LS2 crate engine, then swapped that for a LSA based stroker. Probably 50k+ miles on these newer engines. For a max effort build, build something cool. For a bit more power in a daily driver, let GM do it for you. Their crate engines are good bargains and should have better reliability than anything you could build (if sticking to factory power levels).

Tim
 

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07 tbss awd
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Only issue is your going to end up with cam specs more geared towards a lighter car then a heavy truck.


If you’ve got time why not buy a short block then you can pick your own, cam heads and intake manifold better geared towards a heavy truck.
 

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07 TrailblazerSS
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If those are the two you are going between, I would just get the regular LS3 and do a better cam later on. The cam in the 525 isn't much to write home about. You can either put the $1k difference into a better aftermarket cam/springs off the bat, or save up for later.

I'm a big fan of GM motors, we've done a few LS3's and they are usually my favorite for anything under 650-700rwhp or so, the GM reliability is great, they are quiet, etc.
 

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2008 TrailblazerSS
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I had the same dilemma. Buy a crate engine or rebuild my stock one. I can’t provide any real world feed back as I have not driven my project yet. Hopefully Friday.
These are the pros and cons I weighed out.
Pros of a crate L94
  • New GM build quality
  • LS3 heads and truck intake already on it
  • Not sweating an engine builder to build the motor correctly
  • Warranty
  • I can do most of the work myself sans the tuning.
Cons of a crate L94
  • I still have to do a cam and valve train swap
  • I still need to buy oil relocate kit
  • The parts swap voids any warranty GM gives you with a new crate motor
  • Most crates had a core charge
  • The cost comes out to about the same if not more than a rebuild after it’s all said and done
  • It will need a transmission upgrade
Pros of a rebuild
  • Sick stroker displacement
  • Have it built how I want it (A la carte parts options)
  • The builder I chose warranties his work
  • Full professional inspection of the existing motor
  • I get to learn about LS motors doing the tear down
  • no core charge or returning the block to the seller
  • motor is rebuilt to support some serious mods down the road
  • I know this one sounds cheesy but I get to support a lot of local businesses for the different facets of the rebuild.
  • upgraded hardware throughout the motor (ARP)
Cons of a rebuild
  • I will have to hire someone to build the motor
  • Trusting the builder to do it right
  • Picking the parts myself (can be overwhelming making these decisions)
  • Working with all of the different parts vendors
  • It will still need a transmission upgrade
Basically mine came down to, do I want a stroker with ported 243’s or do I want a cammed LS3 with rectangular port heads and truck intake already on it?
I chose the rebuild because,
  • It would produce the most N/A power
  • In the grand scheme of things, the rectangular heads and intake are an easy fix if I decide to switch things up.
  • It will support some serious mods down the road if I choose to do so.
  • I got to support a lot of local and non local businesses that are small, privately owned operations.

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Black 07 AWD
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Discussion Starter #7
awdvette - Forgive my ignorance with regards to cams, some cams are better than others based on the weight of the vehicle? I never realized weight was a factor for cam performance, I guess I thought the HP output was without regards.


MX763 - Thank you for you reply, that is some pretty good insight into the decision you made regarding your engine swap vs rebuild. A problem I deal with in my location is the machine shops are not very reputable unfortunately. I can put the engine together no problem, however, I lack the ability to machine and do not hear good things about the local talent.
 

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awdvette - Forgive my ignorance with regards to cams, some cams are better than others based on the weight of the vehicle? I never realized weight was a factor for cam performance, I guess I thought the HP output was without regards.


MX763 - Thank you for you reply, that is some pretty good insight into the decision you made regarding your engine swap vs rebuild. A problem I deal with in my location is the machine shops are not very reputable unfortunately. I can put the engine together no problem, however, I lack the ability to machine and do not hear good things about the local talent.
Not having a machine shop close could be a deal breaker. That’s up to you to decide. I am fortunate to have quite a few options in my area. My builder was about 45 minutes away and I would have still taken it there if he was 2 hours away. The only times I was there was to drop it off and pick it up. Not having the ability to machine or inspect the block might lead you straight to the short/ long block option.

As for the cam, I picked a cam that would perform where the motor spent most of its life. Based off of the way these are geared, it would spend most of its life in the lower to middle part of the midrange. I chose a cam that would make this pig shine right in that area and carry it up to the higher RPM’s without signing off before redline.


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07 tbss awd
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Vehicle weight is really only a factor because it takes more low end torque to get all that weight moving. So you want your cam spec’d with that in mind.

They other factor there, is that ls3 rectangular port heads and car intakes make more top end power but less low end torque typically.

IMO an ideal NA setup for a DD tbss would be a moderate to mild cam with cathedral port heads and an lsxrt or stock tbss intake on a ls3 block or a stroked ls2 block.

In some regards this is all just splitting hairs, if you put a crate ls3 in it you will be pretty happy. But having the setup optimized for the way you want to drive and the weight of the vehicle will make for a better overall driving experience. Just my .02 cents.
 

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Hey Kelly, how about putting a LS7 compared to a LS3 crate engine from GM. Or is it better to stay with LS2 and do upgrades? Can you do and LS7 conversion into a TBSS?

Price, hp comparison best option


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Discussion Starter #11
awdvette, thank you for dumbing that down for me, that all makes more sense now.
 

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07 tbss awd
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I wasn’t trying to dumb it down, just explaining my previous post.

Pailitoii- the problem with the ls7 is that it’s a tall deck block and nobody makes a tall deck header for the tbss. Which means that you would have to extended the primaries on the headers to accommodate for the extra height.

I believe a standard deck LS is 9.2xx” and the tall deck ls7’s are 9.7xx”
 

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I wasn’t trying to dumb it down, just explaining my previous post.

Pailitoii- the problem with the ls7 is that it’s a tall deck block and nobody makes a tall deck header for the tbss. Which means that you would have to extended the primaries on the headers to accommodate for the extra height.

I believe a standard deck LS is 9.2xx” and the tall deck ls7’s are 9.7xx”
LS7 is standard 9.240" deck, but presents other problems with the FEAD and the unique intake layout.
 

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07 tbss awd
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LS7 is standard 9.240" deck, but presents other problems with the FEAD and the unique intake layout.
Hmm, I was under the impression that all ls7’s were tall deck. I stand corrected.

In that case unless your going to use an aftermarket or lsx block that comes in a tall deck configuration my previous post isn’t really relevant.
 

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Discussion Starter #15
awdvette, I know you were not actually dumbing it down, I was attempting to reply with humor, but I see I failed... Nonetheless, I appreciate the clarification.
 

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Discussion Starter #16
Wouldn't the the dry sump aspect of an LS7 present an even bigger problem?
 

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Wouldn't the the dry sump aspect of an LS7 present an even bigger problem?
Yes, packaging is certainly an issue! In reality, the LS7 is not a very good return on your dollar. In fact, there has been assorted issues with them since their inception. At first there were valve dropping issues that caused catastrophic engine damage, followed by leaching of titanium rod material into the rod bearings and finally there were issues with sleeve cracking on some blocks! It's only a 505 hp engine - you can obtain way more hp for way less $!
 

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07 TrailblazerSS
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Hey Kelly, how about putting a LS7 compared to a LS3 crate engine from GM. Or is it better to stay with LS2 and do upgrades? Can you do and LS7 conversion into a TBSS?

Price, hp comparison best option
You can do an LS7 also...just IMO it's not a great bang for the buck. They are $12k-13k new from GM (where as an LS3 is $6k-7k). For almost twice the money you are not getting twice the power. If you are after more displacement than the LS3 or you know you want 700hp+ with f/i, then at that point it is better to go aftermarket IMO. $6k-$8k gets you a really solid set up (402-427ci, full forged, etc). There are downsides with aftermarket of course (often noisier, not as reliable, hard to find a trustworthy engine builder) but generally they will hold more power than a stock, new, expensive LS7 will.

Also something else to keep in mind is that once you start going past say 408ci or so, the added stroke makes it harder to keep oil temps/coolant temps under control.
 

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You can do an LS7 also...just IMO it's not a great bang for the buck. They are $12k-13k new from GM (where as an LS3 is $6k-7k). For almost twice the money you are not getting twice the power. If you are after more displacement than the LS3 or you know you want 700hp+ with f/i, then at that point it is better to go aftermarket IMO. $6k-$8k gets you a really solid set up (402-427ci, full forged, etc). There are downsides with aftermarket of course (often noisier, not as reliable, hard to find a trustworthy engine builder) but generally they will hold more power than a stock, new, expensive LS7 will.

Also something else to keep in mind is that once you start going past say 408ci or so, the added stroke makes it harder to keep oil temps/coolant temps under control.
Do you have experience or thoughts on the LSX376-B7 and B15 engines for going FI versus a custom built engine?
 
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