[AspiringCarGuy]

Hi all. I'm always impressed by the depth of knowledge and experience here. I was hoping for some advice.

2018 ZL1 (not 1LE). 70,000 miles total. About 15,000 track miles (VIR, WGI, Pitt Race, etc)- roughly 170 hours on track.

Quick history:
- had the oil pump problem my first track event with the car in 2018
- had misfire on cylinder #2 18 months ago. New injector, lifter, pushrod, etc later, still had the problem. Eventually diagnosed to be the catalytic converter. I posted about that a while ago
- at WGI 2 weeks ago, got misfire on cylinder #7

I tried the easy stuff- swapped plugs, wires, and coils. No change. Plug out of cylinder 7 was definitely wet compared to the others. Removed spark wire from cylinder 7 while running. Verified spark was there but no change in how the engine ran so it appeared to be a totally dead cylinder, not just a sporadic misfire (confirmed by how rough it was running).

Towed it to a garage. Compression test on cylinder 7 showed 60 PSI max, and not sustained for very long. Definitely a problem. Other cylinders all measured roughly 150 psi. However, cause of loss of compression is still under investigation. I was hoping it was a simple head gasket failure, but that does not appear to be the case. It looks fine visually, and there was no white smoke or other drama on track. Sent the head to a machine shop to see if it's warped or maybe has a hairline crack you can't see, and they'll pressure test it and verify the valves are working correctly. Still waiting for results.

Let's assume for the moment it is the head (unlikely). A new one installed is $5k. I have gotten some good counsel from track friends that it doesn't really matter what the issue is, I should get a new engine regardless. The engine is basically end of life. If I put a new head on, the next failure will be imminent and could be catastrophic, and I just wasted $5k. It would be better to spend the $20k on a new Lt4 crate engine installed, and get the 3 year GM warranty.

Being relatively new to the tracking scene, I was surprised that an engine is end of life after about 100 hours on track. I got 170 track hours on mine, so maybe I did ok? I see from iwk2much that he had 22,000 track miles and was not too upset the oil pump issue killed his engine.

So, how many track hours do we expect from an LT4? Should I just get a new one, and maybe have this one rebuilt for a future track toy application? Or should I try to get this engine repaired?

Any recommendations on a machine shop that can rebuild an LT4 in the mid-Atlantic region?

[Trochoidal]

Not apples to apples comparison here, but the Ultra car that I help out at the track gets freshened up around 40-50 passes. It’s cheaper to pull the engine and give it attention versus waiting for a catastrophe. This is in a 7 second car.

I know you’re not talking drag racing but you’re still talking money and time. If the winter months are your off season and it was my money, there’s a rebuild in my future.

Of course if you don’t trust the rebuild now, what would make you rebuild it later after a new engine install? (No negative tone here)

[DangerZL1]

You’re at 170 track hours and a total of 70k miles. This is a lot of hard driving and wear. An engine rebuild or replacement at this point wouldn’t be out of the question.

[iwk2much]

Wanted to clarify my issue.

It wasn't the oil pump that was the demise of my engine. #7 valve broke and peices found its way pretty much throughout the top and bottom part of the engine. Prior to this, a prior Sebring track day, spark plug on #7 was melted. In hindsight, a clear warning that trouble was brewing. Prrio to this, I got a couple of misfire code on the same bank that I was able to clear by putting new plugs.

I will update my thread to share my new engine experience. Based on my experience, go with the crate engine, eliminate most unknown variables and enjoy another 70K trouble free miles

[Stephen12ZL1]

my feeling is to swap out the short block or find a turn key replacement LT4 and just change it out...otherwise you will be frustrated and chase your tail. It will likely save you time, money, and sanity.

[Jus Cruisin]

If I blew up my engine out of warranty, I'd buy one from LME in Houston.

[Gunkk]

I'd say spend the time at least to tear it down to ID the cause of lost compression, which is incrementally low effort given what you're in for either way. If it's trash, it's trash and you probably learned something. If it's rebuildable, you can make that make vs. buy decision with full information.

Originally Posted by iwk2much

I will update my thread to share my new engine experience.

Was wondering what happened to yours.

Sorry to hear about both your losses.

[Revalot]

Originally Posted by Jus Cruisin

If I blew up my engine out of warranty, I'd buy one from LME in Houston.

A brand new LME engine would be great, but a lot of $, I noticed you keep having issues with cylinder #7, from my study of LS motors, I know this is a LT4 makes me wonder if a steam port is needed for all 4 corners like the LS set up when turbocharged. I've read that air pockets can cause all kinds of turbo issues, I have a ZL1, but I'm collecting my last few parts for my twin turbo chevelle set up on a LQ4/6 speed. It has to have a 4 corner steam kit and ring gap to survive, Does the LT4 come or need a 4 corner steam kit? That road racing has to bring some heat ! And I love road racing by the way.

[AspiringCarGuy]

Thanks for the inputs all. It seems a new engine is the consensus so far, so I'll probably go that route. As for the old engine, I'll continue diagnosing the compression problem, and if it's rebuildable, I'll get that done at some point. Then I have a spare engine to swap back in 3 to 5 years from now when the new one is not so new anymore. Cheers.

[AspiringCarGuy]

Hi all. To update this thread, I have decided to go with a new crate engine. My goal is to replace the stock engine with another stock engine and get all new parts from oil pan to supercharger in the hopes of getting a reliable solution. The crate engine I am considering is this one:

https://www.summitracing.com/parts/n...31955#overview

As far as I can tell, it's the same as stock. Same horsepower, displacement, etc. The installer says that this is not the stock engine- it has different heads, valves, (valve timing?), pistons, and the supercharger is "higher flow." The installer is concerned that the stock engine control computer will throw codes with it.

Does anyone have experience with this type of crate engine with the stock control module?

[JTS]

Buy it from a Chevrolet Performance Dealership direct , same price, no middle man , that's big money , I have no idea what you mechanic is telling you about a different motor. Scoggin Dickey is
high volume Chevrolet Dealership I think in Texas, most likely other Dealership can sell you for same price . JMO

[AspiringCarGuy]

Thanks JTS. Latest update is that installer claims the Chevy Performance engine will not work with the stock ECM. So, that engine ($16,500) plus a new control module and a clutch (might as well while we're in there) plus labor is $28,500. KBB values the car in good condition at about $40K. So, basically the car is totaled. I need to re-evaluate my options. If I can get the crate engine installed and then get the stock computer flashed with a mild tune to work with it, that might be a better option.

[JTS]

Call Ted , he's a member here and offers the LT 4 and I'm sure he can give you the Information to help you and maybe able to do for less than the shop that giving you that information . The price is the same just got cut off the screenshot, check out his website.

[Gen_Nick3.8]

Originally Posted by AspiringCarGuy

Hi all. I'm always impressed by the depth of knowledge and experience here. I was hoping for some advice.

2018 ZL1 (not 1LE). 70,000 miles total. About 15,000 track miles (VIR, WGI, Pitt Race, etc)- roughly 170 hours on track.

Quick history:
- had the oil pump problem my first track event with the car in 2018
- had misfire on cylinder #2 18 months ago. New injector, lifter, pushrod, etc later, still had the problem. Eventually diagnosed to be the catalytic converter. I posted about that a while ago
- at WGI 2 weeks ago, got misfire on cylinder #7

I tried the easy stuff- swapped plugs, wires, and coils. No change. Plug out of cylinder 7 was definitely wet compared to the others. Removed spark wire from cylinder 7 while running. Verified spark was there but no change in how the engine ran so it appeared to be a totally dead cylinder, not just a sporadic misfire (confirmed by how rough it was running).

Towed it to a garage. Compression test on cylinder 7 showed 60 PSI max, and not sustained for very long. Definitely a problem. Other cylinders all measured roughly 150 psi. However, cause of loss of compression is still under investigation. I was hoping it was a simple head gasket failure, but that does not appear to be the case. It looks fine visually, and there was no white smoke or other drama on track. Sent the head to a machine shop to see if it's warped or maybe has a hairline crack you can't see, and they'll pressure test it and verify the valves are working correctly. Still waiting for results.

Let's assume for the moment it is the head (unlikely). A new one installed is $5k. I have gotten some good counsel from track friends that it doesn't really matter what the issue is, I should get a new engine regardless. The engine is basically end of life. If I put a new head on, the next failure will be imminent and could be catastrophic, and I just wasted $5k. It would be better to spend the $20k on a new Lt4 crate engine installed, and get the 3 year GM warranty.

Being relatively new to the tracking scene, I was surprised that an engine is end of life after about 100 hours on track. I got 170 track hours on mine, so maybe I did ok? I see from iwk2much that he had 22,000 track miles and was not too upset the oil pump issue killed his engine.

So, how many track hours do we expect from an LT4? Should I just get a new one, and maybe have this one rebuilt for a future track toy application? Or should I try to get this engine repaired?

Any recommendations on a machine shop that can rebuild an LT4 in the mid-Atlantic region?

On track days did you run the thicker oil?