Interesting GM 2.7 Turbomax failure and tear down

[Nessism1]

Honestly I find the way he takes things apart like that funny cause we have all gotten frustrated and wanted to destroy things, but couldn't

Anyways, I watched the video and man does that look like a complicated little engine! I have nothing against turbo 4's (obviously, there's two in my signature) but man that is definitely way over-engineered!

Normally, Eric is careful with engine harnesses; each connector is properly preserved for reusing the harness, if possible. Rubber hoses, water pumps, cam chain guides, not so much. He views these parts as mandatory replacement, so he doesn't even try to save them, even if in good condition.

Regarding this engine being complicated, I agree! There is a LOT going on here. It's got every trick in the book applied.

One thing I wonder about is the bottom end. This engine makes over 400 lb-ft of torque, but the crank main bearing caps are simple two bolt type. Most engines making this much torque use 4 or 6 bolt mains. Some using a bed-plate design, which ties everything together. I wonder if that had anything to do with the bottom end failing on this engine?

 

[Delta]

Normally, Eric is careful with engine harnesses; each connector is properly preserved for reusing the harness, if possible. Rubber hoses, water pumps, cam chain guides, not so much. He views these parts as mandatory replacement, so he doesn't even try to save them, even if in good condition.

Regarding this engine being complicated, I agree! There is a LOT going on here. It's got every trick in the book applied.

One thing I wonder about is the bottom end. This engine makes over 400 lb-ft of torque, but the crank main bearing caps are simple two bolt type. Most engines making this much torque use 4 or 6 bolt mains. I wonder if that had anything to do with the bottom end failing on this engine?

People wanted to talk smack about the new Toyota 2.4 turbo 4, but it is a whole lot less complicated. I'll gladly take it over something like the GM 2.7.

 

[Nessism1]

People wanted to talk smack about the new Toyota 2.4 turbo 4, but it is a whole lot less complicated. I'll gladly take it over something like the GM 2.7.

Can't disagree. 275hp seems more reasonable for a 4 banger. That said, Honda, and others, push 2.0L 4 cylinders to over 300 hp, with good reliability. GM should be able to do the same.

 

[Cujet]

Can't disagree. 275hp seems more reasonable for a 4 banger. That said, Honda, and others, push 2.0L 4 cylinders to over 300 hp, with good reliability. GM should be able to do the same.

Pushing a car with a turbo 4 really is different than a 4x4 full sized pickup. There is a reason the cars get 30mpg and the pickups get 17mpg at the same speeds.

Clearly it can be done. I'd like to see more robust parts, but what do I know...

GM made a big deal about using spun nodular iron cylinder liners, they have a rough outer surface which grips the aluminum as they cast in place into the aluminum block. Ugh. Will this be a problem in the future given the massive difference in expansion rates?

The good news is that nodular iron is known to be wear resistant.

Ford's Compacted graphite iron (CGI haha) block used in their 2.7L turbo is considerably stronger than GM's spun nodular iron liners, offering more than 50% better toughness (tensile strength) along with much better fatigue resistance (resistance to micro and macro cracking) and has better heat transfer. This means it can handle more boost. GCI is amazingly wear resistant with it's oil retention properties. It is also about 30% lighter than typical cast iron blocks.

Put another way, CGI is the common material for modern diesel engine blocks. Tough, lighter, wear resistant, structurally stable.

I'd love to say each method has advantages, but that's just not so. Ford's CGI block is superior, and not just by a little.

 

[IndyIan]

So did this poor engine just eat too much dirt(eroded inlet vanes as evidence), or the turbo bearings failed, and then it cascaded from there? Or just a bad bearing(maybe the missing big end rod bearing) started the whole mess? Every bearing seemed to be almost equally messed up?

 

[Cujet]

So did this poor engine just eat too much dirt(eroded inlet vanes as evidence), or the turbo bearings failed, and then it cascaded from there? Or just a bad bearing(maybe the missing big end rod bearing) started the whole mess? Every bearing seemed to be almost equally messed up?

It is unlikely that a failed turbocharger took down the engine. The inverse is much more likely. What's more interesting is how terrible the overall condition is.