SuzukiDan7

I'm looking at a car (2008 z51 car) that the seller claims had a hydrolocked engine due to hitting a deep puddle, and had the engine replaced by a Chevy dealership using a "gm performance ls376 by summit racing" . He claims 540 hp but the closest I can find is this one:

https://www.summitracing.com/parts/nal-19370413

However the part number he quoted for the engine swap is this one:

https://www.summitracing.com/parts/nal-19244549

But is this a gm performance engine? And maybe the 540hp was after tuning?

Can anyone explain the link between gm performance and summit, and help me understand what engine is likely in the car?

Also, what are your thoughts on buying a car with a crate engine swap like this? If it was done years ago by the dealership and the car has been driving well ever since, should I be worried or would you consider this a good thing?

How would you rate these engines as far as reliability and power capabilities compared to stock the engine?

Thanks!
Dan

Iceaxe

Documentation and paperwork are your best friend on a car like this. Why was the engine replaced, who replaced it, what exactly did they replace it with, what all was replaced, and can you prove any of the above.

I have no problem buying a car with a create engine, but I'd want to know all of the above and probably more. Having all this documentation will also help you greatly whenever you sell the car.

Without any of the above documentation the car had better be priced damn cheap. YMMV

SuzukiDan7

He was actually able to send me a print out when the work was done at the dealership, it shows a $7,000 charge for the second engine I linked to based on that part number.

However I'm still waiting on the paperwork showing the tuning work that was done by the separate performance shop.

So overall I agree with you, I would need to see all the paperwork before I would write a check. I just wasn't sure how this type of crate engine swap was generally perceived.

Also worth noting, he is currently asking a little over book values, so I wasn't sure if something like a crate engine swap would justify a higher value to the car or if people generally think it should lower the value slightly.

Kingtal0n

for starters I always assume the engine In the car I am looking at buying, is trash.

Always contemplate the cost of the vehicle as if it were just a shell.

The only time I drop this rule is if the vehicle in question is neither a performance car nor has it had any modifications whatsoever.
Something as small as an aftermarket filter or just the air filter being installed wrong can mean significant wear in the engine.
Something as small as a shifting habit or foot resting on the clutch or other dumb stuff can mean a worn out transmission in need of a rebuild.

Most owners do not pressure test their intake systems or crankcase. Most owners are unaware of the finer points of automotive cleanliness.

Basically always assume that you will need to re-do everything, engine and transmission, and possibly the suspension and differential situation.
And you will never be surprised.


Its one of those things where, if you have to ask, you probably should know better.

Kingtal0n

Ah the value question. Neither the factory corvette engine nor any crate replacement is very valuable IMO. Neither of those species is truly designed with what I traditionally think of in terms of 'high performance' in mind.

The vette engines from a factory have pros and cons, so do crate engines, and instead of listing them here (you can ask if you want though and I would) let me just suffice to say that both come with heavy implications.
The one thing about a factory vette engine however is going to be the reproducibility, or rather it's expectation-ness. Or whatever word could be used to describe the fact that if you bought 10x or 100x of the same exact year/model vette with the same exact engine you would probably get the same exact experience more or less (in terms of reliability). Whereas with anything aftermarket (crate or otherwise) its a complete and total gamble, trash or treasure.

I would say crate engine just based on the loss of a factory reliability specimen lowers the value of the vehicle. IMO
Keep in mind power is meaningless in this venture. A crate engine with 1000hp is worth less than a factory vette engine with 500hp if for no other reason than it was produced, assembled, built using the factory recipe which again is 100x or in this case (they make ALOT of corvettes) 50,000+ perhaps 150,000+ produced with a very small ratio of actual factory mistakes/issues. Well, it depends on the year of course. But under normal circumstances... the factory does way better than anything aftermarket at giving the reliability aspect its best odds. And when we couple that to an untouched installation (engine never removed) well it generally speaks volumes because 9/10 engine 'installations' do not put everything back to factory or like a factory would. For example I bet the pcv on the crate engine and the air filter is already F@(#*'ed the engine somehow. I say without even seeing it yet because 9/10 is 90% of the time

1RFLMAN

From the description for this engine on Summit Racing's site (https://www.summitracing.com/parts/nal-19244549), it shows 480hp. I believe that's a production LS3 engine with a GM "hot cam" substituted for the stock cam. Most of GM Performance Parts crate engines are standard assembly line engines with available options, such as the cam, intake manifold, and other parts. They also produce the LSX iron block GMPP crate engines that are not standard assembly line engines. I understand that the GMPP crate engine above includes a 24mo/50,000mi warranty if installed by a GM dealer or other ASE Certified shop. They should be as reliable as any other factory engine, as long as the installation was done right.

Here's a current link to a GMPP crate engine that replaces that part number: https://paceperformance.com/LS3-Crat...-19370411.html It has a good description of the specs and components included in that engine.

GMPP crate engines are sold through GM dealers, as well as Summit Racing, Jeg's, etc.

SuzukiDan7

Thanks! I actually found another thread on this forum where they determined the same thing you just did, it's basically a factory engine with a hot cam and supporting mods.

​​​​​​

FAUEE

Book values on Corvettes are typically a few grand below actual value anyways.

If the work was done at a dealership, I would say it adds value. How much depends on the buyer.

Kingtal0n

my friends I just want to point out that "should be" and "reality" are often quite different

You would think so. But again its trash/treasure random. I have seen (on this forum and others) people tearing down never-run crate engines and finding all manner of missed machine work and poor prep inside crate engines. The fine sand and grit which reduces an engine life expectancy some 80 or 90% still allows 20k miles or 1-2 years of driving before it ruins the block making it unsalvagable in many cases, you can't even rebuild it at that point. Too much fine metal grit has been embedded along oiling orifices to properly be cleaned. And its not the kind of thing that happens to factory engines, when they are untouched. Therefore very easily avoidable by avoiding crate engines.

get 10 crate engines in 10 corvettes from 10 different places and seven to 9 are poor installations. 'not done right'. I bet not even 5/10 are done right at best random.
If you want something done right, do it yourself. You know why we say that?

Corvette_Ed

Care to expand on where you're getting your data from?

cv67

New GM Crate would be a lot more attractive to me than an older motor with miles
Original engine stuff has nothing to do with modern day vehicles imo

Kingtal0n

I didn't post any data. If you are looking for references, I can share a couple off the top of a search

Info is littered about...

https://ls1tech.com/forums/generatio...l#post19473302
https://ls1tech.com/forums/generatio...ml#post5928055
https://ls1tech.com/forums/generatio...y-control.html
All it takes is an O-ring
https://ls1tech.com/forums/generatio...-pressure.html
"not the engine's fault" installation / setup error
https://ls1tech.com/forums/generatio...l#post19846717


Oh this is one of my favorites
https://www.corvetteforum.com/forums...ine-parts.html
https://www.corvetteforum.com/forums...post1594940065




between **** machine work and **** installation take your pick, combine the two with a novice and you get a disaster.
-> Buy a car with a known good, unmodified, mid-high mileage stock engine unless you are capable of tearing down the crate engine, inspecting every orifice and repairing/cleaning the missed machine work, and putting it back together properly and back in the car installed correctly.
rood ruck

cv67

Wow...If Gm cant build em right who would except yourself.
Guess theres no such thing as budget building .

Corvette_Ed

Actually you did. Several times. And to be fair, your examples are from forum posts on the Internet where people are more likely to complain than praise. I find it hard to believe that GM would still be selling crate engines if, as you say, 90% aren't built right.

Kingtal0n

Well, I never said anything specific about GM. I was never specific: 'Crate engines' I am referring to are not all from GM or not assembled by GM or whatever.
Any non-factory built/installed engine without thousands of 'duplicates' (other identical engines assembled using the same exact parts) with track records will pose risk.

When I quote those percentages it isn't data. Its not like I extrapolated statistical data from multiple sources
What I am referring to is natural induced error i.e. human error in this case. Which is a form of statistics partially based on randomness of animal behaviors that one would encounter naturally. Its also implied that human error goes beyond the engine itself:

Setting machines to do machine work
cleaning the machine that do machine work
maintaining the machines that do machine work (is the machine so worn or out of shape that the surface finish procured is no longer adequate unbeknownst to the operator?)
quality control of machine work and inspection of each process
cleanliness of machine work

buying the correct parts
installing the correct parts, properly (upside down pistons, reversed seals, missing bolts, too much thrust etc)
cleaning the parts and engine properly (did they remember to wash the camshaft before oiling and installing it? etc)
re fitment of parts (balancing, clearances, gasket thicknesses, matching, etc)

And before the person doing all of that even gets the parts, there are all the other people who make the actual parts:
manufacturing process of parts being purchased
inspection and quality of parts being produced
the bag they sent actually has the right parts in it
etc

So it isn't just a guy building an engine. Its also the numerous people/machines that make the parts, package parts, deliver parts. Its the people cleaning and maintaining the facility used to machine the engine. The person responsible for checking every little detail is at the bottom of such a list, but just as important.

The factory OEM streamlines these issues into a coordinated process where error is minimized, but not gone completely obviously. For example OEM must buy bulk items i.e. 10,000 or 100,000 wrist pins at a time or whatever, each get a batch number or some way to identify where they came from, and samples are thoroughly measured and tested(often by purposeful destruction) at random to ensure fidelity throughout the batch.
I am not an expert in this part, I Just know that the factory doesn't buy 1 bag of connecting rods at a time and blindly install them into an engine like an engine builder might. The OEM like to use 'batches' of parts that are all known to be within a certain specification, tested at random to their breaking points (Stress and Strain testing), etc... Which is something that one-off engine builders are NOT doing for the sake of completeness.
And even with all the precautions, mistakes are made at OEM all the time.

The bottom line is that when it comes to having somebody build a single engine you are at the mercy of hundreds of invisible players, one wrong part in a bag or one filthy fingerprint or one human hair and the whole thing collapses from the inside out. And it won't happen immediately. Most of those engines will start and run... for say 10,000 miles give or take. And then fail. It is common to see aftermarket engines failing with 5% of the mileage that a typical OEM engine will achieve in a factory install. "idk why the rod bearings look like that, I never ran it hard or starved for oil".

Good example is the picture I posted of the built engine above. It would have started just fine- and run fine. I wish to emphasize that here, most people buy crate engines and never open the engine to find these mistakes. Thus for every person who 'never complained about their engine' there is an equal or greater number of people who 'never checked in the first place' which is why that argument doesn't make any sense (how can you complain if you never checked?).
Yes they run fine.... For a while. Then the burrs and various missed metallic objects would begin coming off and bit by bit the oil would carry these metal fragments of various sizes around the oiling orifices and between the constant smashing/working high pressure of engine movements at high speed those metal debris would gradually ruin parts and cause failure, after say, 10,000 miles. Which is fairly typical, no surprise there.

Why does it happen so frequently?
The sheer scope of building an engine is often missed. You can slap a motor together in a couple hours; or you can spend hundreds of hours going over it little by little, prepping every surface, using a microscope to find out how the surfaces look up close and then applying techniques to refinish or improve them. Go through every internal orifice to ensure no metal debris remains after machine work. Send samples of the engine parts and engine block to be tested for hardness, finish, whatever other properties of materials. Then adjust all of these details and do it all again trying superior techniques each time.
Basically you need to build at least two or three engines here; one or two for testing all your parts and machine work processes and surface finishes and parts fitment etc... Which you will sacrifice to test the stress/strain and so forth of those materials. And the last engine to actually build using what you learned from the first engines that were sacrificed.

But nobody does that

Well, the OEM does. They always build models, prototypes, before venturing into the final production sequences. To minimize error of course as outlined above. This is the correct way to assemble a machine in our age.


"OEM is reliable"
"OEM is reliable" you may hear that alot. It isn't because the parts in the engine are always reliable from the factory; Its because the parts in the engine are KNOWN reliable after many years to have been built properly before they went into the engine, and then installed correctly, and we KNEW that to be the case because it happened 10 or 20 years ago. In other words, 'OEM is reliable' becomes a 'thing' once many years have passed and thousands or hundred thousands of vehicles using those parts produced by various factories have exceeded criterion/critical threshold (lets say half of them have reached over 150,000 miles is one threshold) that we can safely assume the rest of the population of engines with LESS mileage will be sufficiently reliable in the future. ex. If 500,000 people each own a 05' tahoe and all of them have over 150k miles without issue, I know around half those people didn't even maintain the engine properly, but I can still safely assume that because so many have gone so far using that exact model that I could buy one with much lower mileage and do the same thing without suffering a known parts or installation failure (10+ years have gone by we would have known by now).
Consequently 'OEM is reliable' does not apply to brand new engines/vehicles because they have no historical data for us to reference, and therefore could be unreliable, even if assembly went well it could still be a part that fails due to manufacturing i.e. titanium shaving in the oil and dropped valves or whatever, straight from the OEM. We don't know about it until many years and many failures.

Corvette_Ed

Well, since this is a thread about GM crate engines we'll just discount the majority of what you've had to say about crate engines since it doesn't apply specifically to GM crate engines.


Okay, so we'll throw out your 9 out of 10 and 90% numbers as well since you have no real facts to base these numbers on.

Do you have anything specific to answer the OP's question about GM crate engines in particular, or just more generalizations that aren't backed by any data other than your own guesstimate and opinion? Not to say I don't agree in a very small part in the point you had to make, but I'm not going to believe 90% of crate engines across the market are bad otherwise there wouldn't be a crate engine market to begin with.

Kingtal0n

I think you are a little confused how statistics is being used in this case. The number of 'things' that needs to be done between A and B of building an engine is significant enough that it is safe to assume there will be at least one error, regardless of how big of an error. In other words the error rate is nearly 99.99% or 100%, there will always be one or more in a project of that scope.
Nothing is ever 100% so we adjust the decimal to 'make reality' because surely 1/1,000,000 engine will be 'perfect' (but clearly not).

So the question isn't, "are there errors". There is always an error term that must be accounted for and minimized in engineering equations. This is what the factory attempts to do when purchasing, testing, installing, etc... their numerous parts as an attempt to minimize error.

But it isn't enough to say in this instance that "every engine will have errors" because then the playing field would be level and it wouldn't matter where you had your engine built.
What we need to establish is the difference in the error terms between two basic engineering operations.

That is, factory assembly vs aftermarket assembly

Immediately, regardless of the equations or math or statistics, we can use historical data to eliminate sources of error in the factory build.
For example, I know 'all' 4.8L truck engines made from 04-07 have "good parts" inside them i.e. good: connecting rod bearings, wrist pins, thrust setting, cylinder finish, valve guide install, etc...
because thanks to 10-20-30 years of historical evidence we can conclude these reasonable details, and there are maybe a hundred parts and a hundred different installations that have taken place successfully,
Thus as an engine salvager/expert/installer, I could safely assume that a good running engine from one of those trucks, taken from the truck with say 100,000 miles, has a 99% chance of going another 100k or 200k miles if I choose to use that engine (its close to 100% that we can assume 99% again)
The percentage is based on the fact that the owner at 100,000 miles has more than a 99% chance to wake up in the morning and go to start their engine that has 100k on it and it will start right up without any issues and continue as if nothing had ever happened. 99.9999% that all the trucks do this if they are maintained. Its a safe percentage to assume if take that engine and put it into a car it will yield the same reliability 99.9%.

So lets discount the historical evidence for a minute and go back to nothing. Pretend like there is no factory track record. We will use it again later but for now what other sources of error reduction can we find?

Well the factory tends to build multiple of the same engine. There are perhaps 500,000 of the same identical truck engine out there or more. Each has similar 'batches' of parts/installs, i.e. the same 'brand' connecting rods and the same cylinder wall finish and the same oil pickup... etc..
To be plain, factory assembly has the advantage of mass quality control (otherwise it becomes mass lack of quality control e.g. Every engine made between year1-year2 needs a specific part or installation error to be fixed),
This significantly reduces the error during assembly, and it also makes the job much easier to pinpoint an error when a BUNCH of engines have the same problem. Like everyone knows about the noisy lifters in 5.3L engine from 02-05 for example. Diagnostics is increased/improved for every factory assembly again with the help of historical evidence, which greatly reduces the error terms for every part and installation procedure involved. Notice how the history and fact that there are so many is what makes factory installations push 99.9% reliability at 100k mileage when there are so many out there that have gone 250,000 miles and more without issue, produced with the same parts and procedures.

What about parts?
An interesting trend emerges if we were to examine the number of engines produced (or vehicles produced) vs the rate of typical failure. As the number of engines/vehicles is increased (i.e. many more corollas than _____) the number of failures decreases almost linearly, until it reaches close to 0%. In other words, new corollas and old corollas are both typically 200k to 300k mileage reliability cars regardless of the year (from 02+ this entire discussion is based on modern 02+ tech) as long as they are maintained. And any vehicles or engines which have a lower production number tend to accumulate issues as evolving technology combines with lack of historical data with which to derive future engineering designs. For example the brakes on a corolla likely have changed very much since 02, and rarely ever fail if ever, because the parts have become a standard OEM piece with close to 99.9% reliability. Thus very few corolla have brake issues, even brand new ones.
The part has a 99.9% chance of success when it was used successfully in the past (say, for 20 years) and relatively unchanged after all this time. The factory uses parts like this wherever it can; generally only replacing them when technology presents an opportunity for improved performance or savings or a combination of those. or maybe materials become different or the process becomes outdated.

When the factory has to use a new part, lets say they cant make the same old valves that they used to, and need to 'improve' the process. So they do that and make a new part. Yet, even though there is so much data and history, because the part is being made a new way there may be some undiscovered or unrealized potential for a problem. Thus we lose that 99.9% success rate and go back to unknown? rate of failure. Until history tells us.

So any new parts or processes the factory use cause those 99% success rates to drop back to ?? unknown, and wait for data. For example those engines of specific year range that drop valves or titanium shavings. Now that we have data, we know there is much less than 99.9% chance of survival rate for those engines. We dont know exactly what the percentage is, but we know it is NOT close to 100% like so many other engines are.

In the end
When we combine the historical data (99.9% successful installations) with the inherent 'batch processing' of factory assembly (all engines from year1-year2 got known good parts from reliable sources 99.9% success)
We have a tangible, reliable statistic, so long as every assumption is satisfied; e.g. we perform the diagnostics ourselves, we pull the engine ourselves, we cleaned the engine ourselves, etc... for engine transplants and the like.

With that in mind, now lets look briefly at what a 'crate' or one-off engine build entails:
1. for every 1 of the 100+ parts acquired to build an engine, instead of 99.9% derived success there is an unknown ??% percentage risk
2. for every 1 of the 100+ parts machined/altered to build an engine there is an unknown risk associated
3. for every 1 of the 100+ parts created/manufactured to build an engine there is an unknown risk
4. for every 1 of the 100+ labors involved with cleaning and building an engine, there is an unknown risk
5. etc...

How can we mathematically compare something with a 99.9% success rate statistic with a process such as engine building and parts buying/machining when there are hundred thousands of different engine builders and parts suppliers out there? How can we reliably garner a percentage of significant failure rate when we don't even know who built the engine (non factory assembly)

We can't directly compare the whole process but we can compare parts of it individually. For example the process of setting thrust. We can assign an arbitrary percentage to this one specific labor and in this way build a sort of table of likelyhoods for the rate of making a mistake. Bear with me,
percentage chance of making a mistake when setting thrust: 1%

And we can do that for every process, e.g.
percentage chance of making a mistake when installing guides: 1%
percentage chance of making a mistake when finishing deck: 1%
percentage chance of making a mistake when bore'ing block: 1%
percentage chance of making a mistake when balancing assembly: 1%
percentage chance of making a mistake when ___________: 1%


Alright so you got this far and realized some things. First, 1% probably isn't accurate. There may be much higher or lower percentage chance depending on who is doing what and where.
Nevertheless, again assumptions will come to the rescue. If we so choose we can make "safe" assumptions, i.e. an assumption which is not only reasonable, it is very likely to be an 'over' or 'under' estimation of the real percentage.
For example, Lets say the true percentage for one particular engine builder to set the thrust incorrectly is 0.3754%.
But since we don't know the true percentage, we need a 'safe' value. So we could choose 0.01% or 0.05% instead and be a whole entire magnitude of 'safety' factor away from the true value without even knowing it.
In other words, by using obviously "way too low of a percentage" we are protecting our statistics from over-estimating the chances of a mistake actually being made. It gives the engine an impossibly 'great' chance of not having any mistakes made. In other other words, our final computations of any percentage chance of making a mistake while building the engine are going to be enormously under-stated when doing this.

If we could do this for every single part, and make a loooong list, with exceptionally small percentages of making a mistake when performing each individual task i.e. ordering the parts and cleaning the block, everything....
percentage chance of making a mistake when installing guides: 0.01%(times 16 guides)
percentage chance of making a mistake when finishing deck: 0.05% (times 2 decks), etc
percentage chance of making a mistake when bore'ing block: 0.001%
percentage chance of making a mistake when balancing assembly: 0.025%
percentage chance of making a mistake when ___________: 0.01%
percentage chance of making a mistake when ordering parts: 0.0005%
percentage chance of making a mistake when cleaning block: 0.05%
percentage chance of making a mistake when installing pistons: 0.001%
percentage chance of making a mistake when installing head: 0.0001%
percentage chance of making a mistake when ___________: 0.001%
percentage chance of making a mistake when installing oil pump O-ring: 2.5%
percentage chance of making a mistake when installing oil pan: 0.005%
etc
For every part and procedure there is some percentage chance

If the majority of our assumptions are well within a safe approximation then any resulting statistics will be an 'under' representation of the actual chance to make a mistake when building the engine, just one engine.
Notice that error percentages are affected by each other, i.e. two procedure each with 1% chance to make a mistake does not add up to a 2% total chance to make a mistake. Because it is possible to make one of those mistakes, or both of them together, the actual percent chance is going to be higher by another 1/4 fraction. In other words there are now 4 states: 0 0, 0 1, 1 0, and 1 1, and only 1 of them (1/4) is mistake free, even though it was two separate procedures and should have been a 50/50 by inspection. Its like if you roll two dice at the same time, the odds of getting a 0 0 is much harder than getting a single 0 from a single die.

And I would love to continue with some error terms approximations but this has gone on long enough. If you can read then by now you clearly are able to compare the enormous list of potential errors with the factory installation's contemptuous 99.9% success rate and derive one final conclusion: 99.9% is a hell of a lot higher than whatever the result from the above will become even as we underestimate the rate of potential for mistakes in any one-off build whether it be a crate or built built by a professional.

1RFLMAN

To Corvette_Ed... you know that saying: "Don't feed the animals, or they'll keep coming back!"