Hey CF fam,

I posted the following in the road race section but I figure this would be a good place to ask the same question. After 6 years and 126K miles of bliss my Drysump LS3 decided it was time to say goodbye. It is currently seized and the shop has found bearing material in the oil. Based how I use my car and the situation in which the engine died does anyone have better options or ideas than what the shop presented me with?

How I've used the car:

• year round daily driver & road trip car
• track car for 3-5 event per year for the last 4 years (mostly VIR)
• Rip around western NC mountain ranges
• Drag strip a couple times ( I don't think I'll do this again )

How the engine died:
Went to the drag strip to do some WOT testing and data collection (car has headers and tune). I did roughly 3 runs and the car felt way down on power for the 2nd & 3rd runs. I thought it was just me and my bad shifting but after the 3rd run I heard some pretty bad knocking. To make a long story short: engine seized leaving drag strip, towed home, couple days later troubleshot the problem and got it running again briefly, drove a couple times to figure out knock, seized during last test, towed to shop.


Shops ball park options without tearing into the motor:

1. Build a new engine to "my specs" -- around 10K depending on what I ask for
2. Get a new LS3 GM engine and drop it in -- roughly 10K
3. Tear my engine apart see how bad it is and rebuild it -- best case scenario 5K
4. Buy a used motor -- price undetermined

 

I'd vote for the first part of #3. Pull it and examine the extent of damage before taking the next step. It's possible that grinding the crank .010 and new bearings, plus a thorough cleaning is all you need. If you find major damage I'd be looking for a used engine for your used daily driver car.
Just my opinion.

 

Corvette aluminum block is worth good money.

 

If you're paying somebody else to do the work: option 2. Do a clutch and torque tube refresh while you're in there and you've got a brand-new drivetrain.

If you're doing much of it yourself: take the engine apart and have a look around.

 

If you didn't have valve issues, sounds like you might get off cheap. (relatively speaking). I agree with the others, dig in first and see what needs replaced. Do a nice job freshening it up and slap it back in.

 

I don't have the time or space/tools to pull and work on the engine so I'm having someone else do the work. I had a spoke with them today and we discussed the clutch, torque tube and diff.


I didn't have any valve issues but I was told there were chunks of metal in the oil and oil filter so it didn't look good. Based on how I use the car I'm asking them to put together an officially quote for a drysump crate motor + oil cooler replacement. I'll should know more next week.

 

If it seized up after drag racing it, you most likely spun a bearing. Pull it out, tear it down and have it rebuilt. You should be able to get it done for WAY less than $5K.

 

For me, I wouldn't consider #2 just because while it is out, for the same cost or less you can build a nicer more robust motor. Can do a nice 416 stroker or something to bump the power for same or less cost than a new ls3.

Either just have the minimum done to fix it, or do a nice build to your specs.

Hell I have a 4" dry sump crank laying around if you land up needing a crank or want to upgrade.

 

So I think I'm going to ask the shop to pull my motor and see what happen before I go forward with a new crate engine. But in the mean time I've been going through my data and I'm not sure why this happened. Unfortunately I don't have full data on the 2nd & 3rd runs because my computer crashed, but I do have AIM Solo DL data for all three and temps and pressures correlate with the 1st.

In general these are my big take aways:

The computer doesn't register the engine loosing oil pressure during any of the runs
Oil was 160F during first run... is that problem?
I missed the 1st to 2nd shift in the first couple of runs so the engine free spun to 7K in neutral.

There was really bad spark knock during the first run but my AFR and advance appears normal.
- I did clean my Attack Blue filter the day before, but there are roughly 80 miles between my house and the track so I figure any weirdness should have worked itself out.
- I now wonder if the MAF malfuctioned and caused a lean condition but Wideband doesn't back up that guess.
- Also I did fill up with roughly 1.5gal of gas at a BP near the track, so it is possible I didn't get the 93 I paid for.
- I've never seen the engine knock like this before. Could something have been going on with a fuel injector or the fuel pump?

 

4.7* of Kr is not that bad. Certainly not enough to grenade engine.

 

My point about a valve issue would be, if it dropped a valve or something in the valvetrain broke, often times it destroys everything else and now a crate motor is the only option. If it's just metal in the oil, it can all be washed back out and then replace any parts which are ruined rather than replacing the entire engine. It is a whole lot cheaper and it's the same thing.

 

10k $$$$?????

5.3 iron motor, $500

blower from A&A, $6k

makes 550whp easy.

or ill buy the car as is.

 

Motor getting pulled early next week so hopefully I'll know exactly what happened. Not sure why a valve would break because once it finally died and seized it was turning less than 1700 RPM.

 

An iron motor is a no-go for me need a they dry-sump, also I don't want a HP build. I daily the car year round, road race it, and go on +1K mile long road trips. It gonna take a few weeks but hopefully it'll be better than new by the time I'm done.