Has anyone had a "built motor" last?

Lets hear some personal experiences, has anyone had a "built motor" last 100k miles +? 

Depends on what level of build your talking.  I've seen several modestly built Rovers go well over 100,000 miles, but that may be in part due to the fact that the stock ones were so underbuilt.  I've also seen overbuilt ones last less than 1000 miles.  Chasing 300 HP in one is a recipe for problems.  Thats why I'm getting into the LS game now.  I'm hoping for 500 reliable HP out of my LS3. 

Yea, it depends a lot on the build. High stung engines will have a shorter lifespan, but most never plan to run them a lot of miles anyways. So for 100K+ mile lifespan, probably need to be on the conservative side with the build.

To tr8todd, that should be an easy goal for an LS3. While they are 426 net hp, on a dyno (gross horsepower) they usually are 480+ hp and 470+ on the torque side. So you are just a cam swap away from your goal.

Most people with"built" motors also have "not very well tuned" engine management and "heavy right feet" so engine life is poor regardless.

I have over 50k on a 208whp (Mustang) nonturbo 13B, which is like more power than an FD engine and about the same lifespan.

People who build motors also tend to run them hard, which is why they’re built. Why would you build a motor for your commuter?

Some rebuilt engines don’t last long because the kid rebuilding doesn’t take good measurements, and uses cheap chinese eBay rebuild kits. 

THEN he decides to add power to it...

By definition, rebuilding an engine to be used  in a higher power output band, and then actually using it for that application, is going to shorten the life of the engine.

I see two main areas at play.  First is the stress-strain cycle. You put a stress ( force) on a part and it is going to strain ( stretch). When you run a modified engine for its intended purpose, you increase the stress and the strain. Plus, by operating at higher rpm, you increase the number of cycles per second.  That takes a toll.

The other parameter to consider is friction. All your friction surfaces were designed with a given load. Bearings and rings expect certain forces at certain rpm and the oil specified is based on these known loads. As the person modifying the engine, are you going to the effort to re-engineer all of these frictional forces and mitigate for increased loads as needed?

Pete

What does "last" mean?  I'm reminded of the diesel engine builders back in the '90's who, after coming up with a recipe for extracting 1500 hp out of a 60 Series Detroit, contacted Penske engineering to determine if it could last a "season" of a newly sanctioned roundy round big rig racing series.  Penske engineering evidently didn't fully understand the question because the response was something akin to: "are you folks nuts?  You build our engine like that and you'll be lucky to get 50,000 miles out of it."  Sadly, that series never really got off the ground but it wasn't due to the lack of reliable engines.

I don't know too many people running around with highly modified cars they have put 100k miles onto since modifications.

In my experience, most engine builders can't put the motor together as well as the factory can.  So, no, "built" motors don't last better than factory.

i only had about 20k on my 306 when it broke the ring in the number 5 cylinder (nitrous). But a friend of mine had a 327 in an s10 that seen a few thousand 11-12 second passes and around 40k miles over 6 years. it finally cracked a cylinder while being dyno tuned.

I remember when I used to have 4g63 cars. The forums were full of guys who wanted "500hp daily drivers". A lot of them spent thousands on getting the motor built and would drive them until they broke in a few thousand miles or sold them. 

Two things that always ended them were, tune or improper assembly. They also never thought about how 500hp turbo 4cyl felt in a 90s Mitsubishi. E36 M3ty shaky and loud!

The guys with more conservative goals cars lasted longer. My friend built motor evo x has almost 100k on it with just a hair under 400awhp.

My anecdotal built engine experience:

My buddy raced Honda Challenge in the early-mid ‘00s.  He ran an unopened D16Z6 that was bought from a junkyard with 16k miles to two championships.  Car got bent at an enduro and he built a new car.  During build 2 he commissioned a high dollar engine from a very reputable race engine supplier, but within the rule set.

That engine failed spectacularly after a couple events and was swapped back to the JY engine at the track.  Pro built engine #2 commissioned...same

That JY engine has been in and out of car more times than I can count and is now powering our Lemons car.  It’s ready for retirement after THOUSANDS of miles on track after the block was damaged due to corrosion and a broken boss.  It still has good compression and looks like new inside.

If you need something close to stock, a built engine is a liability.  If you need something radical, you pay your money and take your chances.

You know that feeling of low-grade disappointment any time you hire out work you are capable of doing yourself and see the finished product?  I imagine that’s the quality of work you get when you buy a ‘built’ engine: somebody else’s ‘another day on the job’ best-effort.

docwyte said:

In my experience, most engine builders can't put the motor together as well as the factory can.  So, no, "built" motors don't last better than factory.

Sure they do -- for their intended application.  The engine I built might not do 200K miles of commuting, but a factory Miata motor would be lucky to last 5 minutes at 25 psi of boost. :)

I built a 347 stroker small block for my wife's 90 Mustang LX. I bought a good quality rotating assembly, Edelbrock heads, and a bunch of Ford Motorsport top end stuff for it. It went about 120k more miles before she sold the car. I used good parts and didn't cut corners. She drove it reasonably. I beat that car like it owed me money.  No problems with it ever, but I wouldn't want to openly admit to the honest money outlay for what the engine cost.

In reply to codrus :

And the built motor lasts ten minutes?

docwyte said:

In my experience, most engine builders can't put the motor together as well as the factory can.  So, no, "built" motors don't last better than factory.

Agreed. My experience is quite limited, long time racers will have a larger repertoire, but it goes something like one high school buddy and his friend tried to rebuild an SBC who knows how and it never ran. Bought a ton of parts based on the phone rep's recommendations, and after spending all the money, the thing still wasn't exactly fast. "Hand built" has its advantages, but so does factory machining like million dollar equipment and machines that torque all head bolts simultaneously, etc. A hand built engine will take far longer and be far more expensive (not necessarily) in order to outperform a factory built engine, but this is only a subset of engine builders and customers willing to pay for that. It's kind of rude to say most people can't build an engine, even "builders," so maybe a better way to phrase it is to say that the modern robotic factory machines are quite good at it. This is even a bit of a niche scenario because it isn't all that complicated for the most part. 4 cylinder engines are very simple and as long as you don't screw up measuring the bearings or install things backwards it's a no brainer. With V engines all the geometry changes and it's much more involved if you're doing machining and stuff. For some people going medium fast is very fun and they don't want some pain in the rear correcting them or whatever I get it.

I build my weekend toy engines with a 10,000 mi goal in mind. Beyond that i'm bored and looking forward to building the next version. Current one is a 9500rpm 355 that burns 91 octane pump gas and makes around 700hp on one kit (it has two). ~19mpg on the highway.

In reply to Keith Tanner :

Because I run hard on my commute and want to track my daily as well as commute it. 

Carbon said:

In reply to Keith Tanner :

Because I run hard on my commute and want to track my daily as well as commute it. 

At stock power, shorten the oil change interval, keep it cool, and drive it as hard as you care to...whatever it is.  If it blows, buy another low mileage engine and swap it.

Another nearly worthless anecdote, I had a junkyard single cam turbo Honda engine that I drove like a maniac and some friends also built a CRX with a turbo junkyard single cam Honda engine. I'm having trouble finding a picture but maybe someone remembers the "Jesus CRX" chump or lemons car from some years back. Not that anyone is asking for data points but along with Tyler H's experience I don't think it's any surprise how well some engines are built from the factory. You can confidently say they don't wear out, even in extreme racing or prolonged boost environments but probably not both. Built engine is part of the essence of racing meaning super high dollar entertainment where you might lose it all. Big time racers have money to burn that is just a fact which is why I like GRM. It feels totally out of place to fork over thousands of dollars to smiling faces of brand new everything racing company so I can watch them play with their brand new toys. I'm not jealous it's just foolish to pay into that from my pocketbook. Seeing the look on their face when they get whooped by a junkyard car with cherry bomb muffler is what it's all about to me.

docwyte said:

In reply to codrus :

And the built motor lasts ten minutes?

A dozen or more track days on it so far.  The car's had reliability problems, but they haven't been with the motor (brakes, transmission, etc).

It isn't that I built the engine better than the factory could, I just used higher-spec (and vastly more expensive) parts.  That's what the phrase "built motor" implies to me -- one that's been upgraded internally to handle more revs, more boost, etc.

Sure.

I have modified every engine in every car I've owned but one. My 300 bhp turbo Fiero lasted 20 years using 10 psi of boost, and my big block Chrysler motors seem to last forever as well.  Just build them for longevity rather than short term peak power.  It means spending a bunch of money on things that address potential weaknesses in the engine rather than adding power, but it is an investment in long term viability.

In reply to Carbon :

You need to define what a built motor is. 

^That.

I think many people have put different pistons or rods in a motor with the intent of running power levels that might crack the stock ones and then run the motor for 100k.  Now if they put forged goodies in and decided to crank the boost to 11 then I don't think they will see 100k out of it.