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Baby LS motor


mutantZ

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I would have to disagree, partially. Dohc engines (at least 4 cyls and I6) generally last longer than push rod engines. I've seen honda and nissan motors with well over 200k.

 

Pushrod v8's are still chain driven, and (obviously) have a pushrod that actuates a rocker- more parts to fail. A OHC or DOHC motor that has the cam act directly on the cam bucket would have less parts. Chains in street cars rarely break, so having two of them isn't really much of an issue...

 

That said I do see the merit of the push rod v8. In fact the ls motors are pretty sweet IMO- they get very good gas mileage for their displacement, and are constantly being refined.

 

For the record though, you should note that very few LS motors ever have issues with reliability regarding the head, or anything else relating to the fact it's a pushrod design. And the LS motor CAN reach 300k like most other modern engines. The LS is not a SBC in the slightest, even when it comes to durability.

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  • 2 months later...

Ok so i work on Corvettes for a living. I can cuss Garbage Motors all day long for a slew of things. I really cant say a bad thing about the LS motor. Pushrods or not it's a really well built engine. The only time we go into a engine is to gain more power, not fix a failure.

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  • 1 month later...

Latest state of the art Corvette cylinder heads are VERY if not more efficient than any other cylinder head on the market by any manufacturer. Displacement for displacement, blown or Un-blown, the pushrod engines makes the same or more power and just as or more efficient than the overhead cam engines with LESS PARTS to fail.

 

Why are some of the most complicated car engines statistically the most reliable then? Maybe the number of parts isn't as relevant as the design and materials.

 

What are the VE numbers for the best corvette engines?

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Where do the statistics come from for the more complicated engines? The number of parts IS RELEVANT to failure rate. Don't know the VE numbers for the corvette engines yet GM engineers use CFD software to design intake and exhaust ports. Just know that HP and TQ numbers are very good for a pushrod V8 engine.

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  • 2 weeks later...

Number of parts doesn't change failure rate. VE doesn't change failure rate. I've seen complicated hondas go 300k with nothing but routine maintenance. I've also seen pushrod V8s go well past 300k, which many people don't see as possible.

 

I think aspects like tolerance, combined tolerance, part wear, part friction, and subjected load are far more important factors to reliability than how many valves an engine has.

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All other factors being the same between the engines, the one with more parts Will Have a Greater Failure Rate.

 

See that's what I'm saying though, you're just not seeing the whole picture because you're looking at it with a telescope, not a microscope.

 

If "all things were equal" then the wear factor and stress would be the same. If you have twice as many parts under equal strain/load then the load on each part would be half. If you have twice as many parts and all is equal, then the wear on each part would be half as well, meaning tolerance would go out half as fast on each part, except the whole would be the same still, in order to make all things equal.

 

Just because a 1UZFE has twice as many cylinders as a 4AGE doesn't mean it's going to break parts in half the time. Does it mean it has more parts to fail? Yes. But you also have to remember that the output per liter usually isn't as high in big displacement motors and thus they're subject to less stress as a standalone engine, thus tend to be able to reach very high durability/low failure rates.

 

Motorcycle engines are lucky to go 1/5th most car engines ever will, and that's being generous. You can't argue an engine put under more weight/load strain will make it break sooner because that's exactly opposite in motorcycles. Motorcycles wear fast because they're reaching extreme operating conditions requiring exacting tolerances to run properly and subjecting parts to fairly high stress/load. An example of this would be the piston rings which are asked to reach very high mean piston speeds, all while operating in a large temperature range.

 

To go further into this muddy topic, just look into some of the testing processes companies use for new engines. The #1 casting prototype block for the new Ford Coyote 5.0 V8 reached well over a million miles without failure. That motor wasn't babied either. They're subjected to absurd loads that not just wouldn't happen in real life, but down right couldn't. Going full load at full RPM for hours on end, changing physical temps from hotter than any desert to colder than the arctic. They'll literally pour ice water into the cooling system to make sure the block and heads can withstand the radical temperature changes. I'd not hesitate to state that if properly maintained, that permitting there weren't electrical deterioration factors, or other time based deterioration factors like road vibration causing connections to crack and such, these new Coyote V8's would last a 750k miles between rebuilds, maybe more.

 

So many times common failures are due to things outside of what goes on inside of an engine. So often an engine can receive a bad rep because of their turbo's tendency to burn oil and owners that don't know how to check oil levels... You simply can't argue to me that more parts = less reliability. You also can't argue to me that old tech = less reliability. I've lived in both camps and I've seen what breaks motors on every side of the pool. More than 9 times out of 10, nay, I'd say 99 times out of 100 an engine failure can be traced back to how the vehicle was maintained, NOT how it was ENGINEERED!!! laugh.gif

 

P.S. Chevy advertised the Bel Air Taxi Cabs to go 500k between engine overhauls... I've never met anyone who go that out of a typical SBC. The beauty of automotive engineering is in the contrast.

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Gollum:

 

For equivalent technology and quality between a Ford Coyote and SBC engine, the Coyote will have more parts than the SBC and have a greater failure rate. Using the same casting techniques and equivalent quality parts internally, both the Coyote and SBC will last the same and likely the SBC will outlast the Coyote till death of either engine. The point is to use equivalent technology and quality parts. Metallurgy being the same among parts being used in both engines.

 

Where is the test of the Ford Coyote documented such that I can see the results even though there may be some non-truth in what is presented as fact. With the advent of Electronic Fuel Injection (EFI) and Synthetic Oils the longevity of engines is much different. EFI is so much better than carbs there is light years difference. EFI does not wash down the oil in the cylinders on start-up or gas pedal mashing. With EFI the cylinder lubrication is much better for better longevity. Add to that using Synthetic Oil which does not break down at higher temperatures and the longevity goes up exponentially. Likely this is the way that Ford ran the Coyote engine and it is no wonder that it ran so long without fail. The same holds true with a SBC equipped the same way. Typically the Detroit manufacturers do not design the engines to last a million miles at 100% rated power as this is not the way they will be used in service.

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I already know all of these things, is that not apparent?

 

More parts doesn't equal failure rate! What I CAN agree with, which you might be mis-communicating well is that more parts WILL equal a higher total WEAR rate.

 

A good example of this is that when you need to lap the valves you'll most likely have twice as many to lap. This doesn't equal failure, it equals wear which is completely different. When the rings or bearings are falling out of spec you'll have twice as many to replace if there's twice as many total. This doesn't make the engine twice as likely to break down on you.

 

The modern LS motors are extremely high tech, and I think they're the best pushrod V8 every made. That said I've seen plenty of them fail, some of which for very stupid reasons.

 

The point of why I'm arguing with you, is that what actually breaks in an engine, leading to total engine failure, is RARELY related to an engine having more or less parts. What we're really arguing about more than anything else is valve design and count. Are they directly or indirectly actuated? Are there 2, 3, or 4 per cylinder. How many times has anyone here actually seen an engine fail due to a valve, valve spring, rocker, camshaft, etc? The ONLY times I've seen engines fail BECAUSE of anything valve related is when a PUSHROD engines decides to throw a pushrod through the valve cover. I've NEVER seen a OHC engine lose contact between cam and valve due to a bad rocker or such.

 

I love pushrod motors, I'm not trying to knock them at all. I'm simply stating that the "all other factors being equal" are a way bigger factor than the number of parts.

 

Also, though I don't have the data I'm willing to bet the LSx series motors undergo similar testing to the ford coyote motors. I have no doubt that a LSx could reach 500+k miles as well. I think the required maintenance will be very different than the coyote, but it's still THAT engine's requirements to keep correct tolerances.

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  • 2 weeks later...

I just pulled a cts-v LSA engine and it had four bent pushrods and two bent connecting rods.

 

The car had an automatic transmission.

 

Must have been because it's parts weren't as "all things equal" as a 1UZFE when it comes to metallurgy...rolleyes.gif

 

I have to ask though, any clue as to the bend con rods? That takes some serious work!

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Gollum:

 

The fact still remains that the more moving parts in an engine, the greater the chance of part failure. This is based on "all things being equal" wherein same materials and same quality used in the piece parts to build the engine. As for the modern LS engines, they are not that high tech. GM went back to the rectangular intake ports in the heads after using the cathedral intake ports design. The rectangular intake port design has been around for MANY years. Gen I, Gen II, GenIII engines with the same (all) specs for displacement, cam specs, cylinder head flow number and fuel injection yield nearly the same results.

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Must have been because it's parts weren't as "all things equal" as a 1UZFE when it comes to metallurgy...rolleyes.gif

 

I have to ask though, any clue as to the bend con rods? That takes some serious work!

 

 

It was a LSA cadillac CTS-v with a V650 hennessey kit.

 

The owner somehow got it to downshift (automatic) into a gear that should normally be off limits due to the rpm at the time.

 

I'm not sure if they modified the transmission shift algorithms but most all stock algorithms usually don't allow a shift that would put the engine in an overrev situation.

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I would have to disagree, partially. Dohc engines (at least 4 cyls and I6) generally last longer than push rod engines. I've seen honda and nissan motors with well over 200k.

 

 

C'mon dude! That's such a BS statement. How many 400K Chevy and Ford pickup truck engines can I find in a quick Internet search? How long a particular engine lasts has much much more to do with how its cared for over its life then the basic design. I know of three 1900's hot air engines that have over 500,000 hours of continuous operation in oil fields near Taft California. Geez man...

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