NOHOME said:
Not saying the Subaru Kludge is a BAD engine, but it is a silly thing if you stop and think of it from an elegant desigh standpoint.
4 cyls so lets go with 4 cams. yeah good idea why not.
4 cyls so yeah, lets use two cylinder heads... yeah good idea. And two head gaskets, just in case one does not fail
DOHC...lets use rockers, cause that adds more parts. I know, technically they are followers, but are they really needed?
How about we double up on them cam phasor timing things, cause yeah that adds more stuff to fail
Just in case..lets really get em rolling in the aisles...Wait for it...TWO fuel injection systems! Ironically, and I assume unexpectedly, this does have the benefit of saving this engine from the DI dirty valve syndrome. Put that down to serendipity.
Then...while they are laughing, lets make spark plug changes an engine out job!!!!
And lets make it sound like a flatulent platipus!
Toyota really needs to cut Subaru out of the picture on this chassis and put a real engine in the car. Figure a nice 2.5l straight four would do the job just fine.
Practically all engines have variable cam timing on every individual camshaft. This is nothing new. Cams without phasers is about like a points distributor on the off-the-back scale.
You do not need to have the engine out to change spark plugs.
Almost everyone is using followers now instead of buckets. You can get a lot more valve acceleration with a rocker (follower) than a bucket, which is limited by the bucket diameter and the fact that it is fixed at a 1:1 lobe lift/valve lift ratio. You also drop idle friction with a roller, and separate followers/HLAs makes the cylinder head design a lot simpler, as well as making assembly easier. At a guess, it also will either increase RPM capability or reduce required valve spring tension (or both!), since the HLA is "unsprung weight" and all that is moving is half of the follower, which is a lot lighter than a bucket, all of which which means reduced friction, and weaker spring required means less beating up of the seat so the valves stay sealed longer, and you can use a thinner valve stem, which means more flow and ultimately more power.
Toyota/Subaru are not the only people to run dual fuel injection, either, and I predict we will see a lot more of it as manufacturers work harder to eke every bit of out engines. Search this very forum for the words alfadriver has to say about some of the emissions difficulties that direct injection has (NOx and soot, IIRC) and why adding a couple rails and some injectors gives you the best of both worlds for very little expense.
Historically, Subaru's choice of a boxer is a good one, chassis-dynamics wise. They were always in front engined front wheel drive vehicles, and a boxer layout allowed them to place the transmission's mass behind the axle centerline, leading to a lower polar moment of inertia. They later exploited this to start making 4WD and AWD vehicles using largely the same components, and the polar moment got even better compared to transverse AWD layouts. As far as how it works out for Toyota... IIRC the FR-S/BR-Z chassis is largely a Subaru affair anyway. Subaru chassis, Subaru engine. I think the only "Toyota" part is the transmission, which is an Aisin unit anyway. I think the main reason why they worked it out with Toyota is to increase production levels. Notice that the BR-Z had a production cap AND had the "better" chassis tuning.
