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Discussion Starter · #1 ·
IN THEORY, if I built a EJ255 motor with forged rods/pistons/Manley crank, King bearings etc. (doesn't have to be those parts exactly, just an example) and kept heads, compression, boost, turbo, injectors, intake, exhaust and tune STOCK....what would that do to the life of the motor if anything? This is purely a technical question, not looking for financial advice as I have no plans whatsoever to mod my motor for a long time (its the last thing I intend to mod). I would assume the forged pistons would help with the common ring land failures of the EJ series but what about the spun rod bearing issues? Are there any downsides to having forged internals without tuning the engine for an increase in HP/Tq (other than looser tolerances when engine is cold)?

 

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The life of the motor would be much less than OEM.

Usually around 60k miles.
 

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It's very rare that a built engine will make it past 60,000 miles. Most of them are pretty much worn out by 30,000 miles.. that is if they don't fail within the first 3,000 miles, which happens A LOT.


On the other hand, a factory built OEM engine from Subaru should last at least 200,000 miles if it isn't abused and has undergone proper maintenance. OEM engine failures are rare.
 

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If your stock engine doesn't last 200k miles

1. Never buy another Subaru.
2. Trash them online and in person to anyone that'll listen.

There is no such thing as a "built" motor. I believe it's a euphemism. Why "build" something to decrease longevity?...

A motor either uses authentic parts as intended or a combination of imitation (fake) parts with the remaining authentic parts.

The best Subaru engines globally are made by Subaru. Nobody else has comparable experience or infrastructure.
 

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Discussion Starter · #5 ·
Couldn't you say that has more to do with the aggressive tuning and horsepower increase that typically comes with 'built' engines?

It's very rare that a built engine will make it past 60,000 miles. Most of them are pretty much worn out by 30,000 miles.. that is if they don't fail within the first 3,000 miles, which happens A LOT.


On the other hand, a factory built OEM engine from Subaru should last at least 200,000 miles if it isn't abused and has undergone proper maintenance. OEM engine failures are rare.
 

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Discussion Starter · #6 ·
I get that built motors typically don't last nearly as long as OEM strictly from a mileage point of view, but isn't that mostly due to tuning the engine to achieve HP numbers it was never designed for?

The life of the motor would be much less than OEM.

Usually around 60k miles.
 

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No, it entirely has to do with the clearences and materials.

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Makes sense, thanks.
Simply put to answer your first post question. A forged piston will be more durable. However because it's not hypereutectic cast like the factory piston it will have ptw clearences that cause piston slap and in some cases notable blowby when coupled with rings with larger gaps. It's less likely to fail under stress but they can beat the cylinder wall to death if not perfect.

Bearings are completely down to maintenance and abuse. People abuse their car and don't maintain it. No oil+ doughnuts=spun bearings

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Discussion Starter · #10 ·
So even though the OEM pistons have been known to have ring land failures, they are still the preferred choice when keeping the engine in stock form?

Simply put to answer your first post question. A forged piston will be more durable. However because it's not hypereutectic cast like the factory piston it will have ptw clearences that cause piston slap and in some cases notable blowby when coupled with rings with larger gaps. It's less likely to fail under stress but they can beat the cylinder wall to death if not perfect.

Bearings are completely down to maintenance and abuse. People abuse their car and don't maintain it. No oil+ doughnuts=spun bearings

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Subaru makes better Subarus than anyone else. There really is no escape from this.
 

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When Subaru designs an engine they have 2 basic goals, make X amount of power and last. When we build engine for performance we build them to not blow a head off or a rod through the block at numbers 2-3 times what the basic engine design was engineered to handle.

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is it that these aftermarket engine makers just dont have the budget to make it perfect? not a big enough market so they build it down to a price?

also is this 100% true for every single aftermarket engine maker or just all the ones that make Subaru engines? i remember when i was planning on getting an explorer sport. i found a company out of Detroit called Livernois Motorsports, they do everything from tuning to full engine builds. they have a very big shop, with an R&D department and a close relationship with ford(so they claim). so even with their resources would it be fair to assume even their engines wont last as long as OEM?
 

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It's any aftermarket "built" engine. The clearences have to be different because of expansion differences in the materials, or increased temperatures and pressures.

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Easy question to answer. Ask the company directly.

Ford warrants their engines for what? 60K? 100K? Something like that, right? Full support for let's say 5 years and 60K miles.

What support is offered by the expert builders (I used the term leniently)?

If it's comparable to the works warranty, then I'd shop almost solely on price (not quite though, because there are more Ford dealers than there are shops owned by whomever we are discussing that is not Ford -- but you get the idea).
 

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Discussion Starter · #17 ·
My 2013 WRX came with a standard 36,000 mile powertrain warranty. Hennessy's 600 HP F-150 Velociraptor has a 36,000 mile powertrain warranty.....

I think its safe to say that the OEMs aren't the end all/be all in terms of build quality/performance. Keep in mind that the non-luxury OEMs are building their cars in an extremely competitive market with often razor thin profit margins. I think it's safe to say that there are some cost cutting that takes place in design and production to help the bottom line.

Aftermarket companies don't have to live with such restrictions to innovation/design nor do they manufacture parts by the millions or tens of millions.

Just a thought.
 

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My 2013 WRX came with a standard 36,000 mile powertrain warranty. Hennessy's 600 HP F-150 Velociraptor has a 36,000 mile powertrain warranty.....

I think its safe to say that the OEMs aren't the end all/be all in terms of build quality/performance. Keep in mind that the non-luxury OEMs are building their cars in an extremely competitive market with often razor thin profit margins. I think it's safe to say that there are some cost cutting that takes place in design and production to help the bottom line.

Aftermarket companies don't have to live with such restrictions to innovation/design nor do they manufacture parts by the millions or tens of millions.

Just a thought.
I assure you working in the industry as a manufacturer, the standards expected are unreal. Every single thing we produce goes through insane research and development as well as rides a Dyno of some sort for months and months on end just to ensure it works. I can promise you 3rd parties do not have the expendable cash to afford that.

I'll give you a prime example. We have probably 300 sets of coil springs for your car right now in the spring Dyno. It has been going for 6 months non stop, if a spring begins to lose its tension or softens the run is pulled and redesigned either by material change or design.

Hennessey is a joke. The guy is a scam artist and it isn't unheard of for him to take money and not deliver.



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Aftermarket companies don't have to live with such restrictions to innovation/design nor do they manufacture parts by the millions or tens of millions.

Just a thought.
Companies that make imitation parts have neither the resources nor the infrastructure to compete in quality. I also question the intellectual reserves present in their HR, since it's simply a numbers game -- the company with more people is thus likely to have more talented people.

Consider this: Cars are meaningless, they don't matter. I've worked in an industry that makes products that matter, and the statements I've made above certainly hold true for that industry. I believe they are general rules-of-thumb concerning modern manufacturing. Resources in terms of money, materiel, and personnel matter and a lone alchemist working in his lair isn't going to overcome all that.
 
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