I recall in a spiel today by an experienced Subaru engine re-builder that a boxer engine, by design, has more of its crank enclosed inside the block, compared to a "V" or an inline engine, resulting in a stronger bottom end and therefore, greater ability to handle stress in forced induction applications.
How do you figure?
SSATB said:I recall in a spiel today by an experienced Subaru engine re-builder that a boxer engine, by design, has more of its crank enclosed inside the block, compared to a "V" or an inline engine, resulting in a stronger bottom end and therefore, greater ability to handle stress in forced induction applications.
How do you figure?
I am not an expert, but I doubt this for two reasons:
The GM gen III and IV engines have a deep enough skirt that the crank is basically shrouded entirely in the same way.
Very few blocks break at the crank caps when they break.
Basically, if the rods bend/break, if the pistons break, the crank breaks, etc, then it doesn't matter.
I'm not really sure I can think of an automotive engine who's crank is not (supposed to be) fully enclosed.
Worth noting that newish inlines and V's usually have some sort of support on the "bottom" of the main caps. And that you can buy a plethora of girdles for older engines that don't have one factory.
Subarus usually fail at rods and piston, less so with cranks. Could be due to boxer or just weak pistons and rods with crappy tunes with BOOST.
tuna55 said:SSATB said:I recall in a spiel today by an experienced Subaru engine re-builder that a boxer engine, by design, has more of its crank enclosed inside the block, compared to a "V" or an inline engine, resulting in a stronger bottom end and therefore, greater ability to handle stress in forced induction applications.
How do you figure?
I am not an expert, but I doubt this for two reasons:
The GM gen III and IV engines have a deep enough skirt that the crank is basically shrouded entirely in the same way.
Very few blocks break at the crank caps when they break.
Basically, if the rods bend/break, if the pistons break, the crank breaks, etc, then it doesn't matter.
Ford 5.0 engines and Turbo Buick engine blocks split in half leaving you two separate banks of cylinders, Mopar RB and Chevy small block engines blow the main webs down.
The boxer engine nicety is that the engine, if done right, is through bolted together. This does not stop high powered Subarus from hammering the mains saddles out, so new bearings will have excessive clearance unless you have the block cut and line bored/line honed.
FI = Forced Induction or Fuel Injection?
Flat engines have oiling issues that V or inline engines do not. Flat engines allow oil to pool in the heads even easier in high G turns. This can lead to oiling issues due to loss of suction and low sump level. They also have more startup wear especially if you have leaky fuel injectors.
Does it really matter if you still have to change head gaskets every 30k miles?
And yet, Subaru engines shred themselves with regularity. Fanboi comparison of engine longevity to Mitsubishi doesn't help the argument...
Maybe just trying to say ONE nice thing about a Subaru engine?
Thinking about every type of engine I have tuned the boxers are probably the lowest hp on the list before various failures.
Stampie said:Does it really matter if you still have to change head gaskets every 30k miles?
Is that like the Chevy engines that need the valvetrain rebuilt every 20k?
Aspen said:Subarus usually fail at rods and piston, less so with cranks. Could be due to boxer or just weak pistons and rods with crappy tunes with BOOST.
And those rods and pistons will only fail after you've gone through a few sets of head gaskets...regardless of the theoretical strength of boxer engines, which I don't know the truth of, in practice I definitely wouldn't give any preference to a Subie boxer for a boosted application considering their laundry-list of weak points when boosted. Check out this video where MotoIQ builds a totally reliable boosted boxer...by hitting it with a tsunami of cash for most every high-end part/coating/block & head prep procedure imaginable:
In reply to Pete. (l33t FS) :
Excuse me sir but that's way off topic. Let's stick with the OP's choice of engine. 
Maybe we take a Porsche engine as the example of a boosted boxer done well.
The Subaru engines I've been inside destroyed themselves without any help from boost :)
Paul_VR6 (Forum Supporter) said:Maybe just trying to say ONE nice thing about a Subaru engine?
Thinking about every type of engine I have tuned the boxers are probably the lowest hp on the list before various failures.
They are very light for their displacement. I could easily carry an EJ20 engine + turbo/exhaust manifolds.
Stampie said:In reply to Pete. (l33t FS) :
Excuse me sir but that's way off topic. Let's stick with the OP's choice of engine.
Fine fine
The only Subaru head gaskets I have done were on EJ253s with 180k+ and had external oil leaks. And one EJ255 that did not cotton to running without coolant in it.
I have probably done more Chevy 2.2 head gaskets with external water leaks, that would get noticeable around 50k. We would wait until they actually had liquid coolant streaming out before doing them.
Thanks for the replies everyone. Case closed!
Every enthusiast seems to have their own hypothesis of why what they like is best.
I once had a Honda fanboy tell me that the reason B18's made more power than other engines of the same displacement was because they turned counter clockwise. 
Trent said:Every enthusiast seems to have their own hypothesis of why what they like is best.
I once had a Honda fanboy tell me that the reason B18's made more power than other engines of the same displacement was because they turned counter clockwise.
It has to do with the rotation of the earth. Surprised you didn't know that.
Robbie (Forum Supporter) said:Trent said:Every enthusiast seems to have their own hypothesis of why what they like is best.
I once had a Honda fanboy tell me that the reason B18's made more power than other engines of the same displacement was because they turned counter clockwise.
It has to do with the rotation of the earth. Surprised you didn't know that.
That's why they make less power in Australia.
APEowner said:Robbie (Forum Supporter) said:Trent said:Every enthusiast seems to have their own hypothesis of why what they like is best.
I once had a Honda fanboy tell me that the reason B18's made more power than other engines of the same displacement was because they turned counter clockwise.
It has to do with the rotation of the earth. Surprised you didn't know that.
That's why they make less power in Australia.
I see, I see... is that also why Australian quarter mile and ET seem to be kind of incongruous? Like cars running 14.8 at 105mph, or maybe 13.0 at 95, I forget which way they are off.
I think what they're getting at is that a boxer has a greater percentage of the crankshaft supported by main bearings than V or inline engines. Consider that boxer and inline have twice as many main bearings per cylinder as V, while boxer and V have a crankshaft half the length for a given number of cylinders as inline. So it would be easy to think that the crankshaft has the best of both worlds between rigidity and support of the crankshaft
If only it were that simple.
V and in-line engines are also easier to assemble. I still want a WRX or WRX STI for my next rallycross car anyway.
In reply to Driven5 :
I was thinking along the same lines - it's a logical explanation. I know that Cummins claims their inline 6 is stronger than a V8 because of the number of main bearings, and of course the short crank could be viewed as a plus. I guess we can say that lack of crank support is not a problem with turbo Subaru engines. That does not mean they are problem free, just that crank support is not a concern for anyone.
In reply to AnthonyGS (Forum Supporter) :
Depends on the layout. EJ and EA engines had you assemble the bottom end, then assemble the crank into the crankcase, then pop the pistons in and fish the wristpins through an access hole. FA/FB engines assemble the short block in a more traditional manner, crankcase goes over the crank and the piston/rod assemblies go in after. The cylinder heads are much more complicated, but they also remind me a lot of a Toyota GR V6 (except no external oil pipes) so this is not strictly a boxer related issue, they just felt like making the cylinder head with a separate camshaft tray.
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