i know porsche has used it for years, and the current WRX has it. what's the reasoning for laying the cylinders horizontal?

 

A flat engine doesnt produces as severe 2nd Order Vibrations onto the crank. The subaru has whats known asa 'boxer' engine layout.

Vertical 4 cylinder engines create a lot of 2nd order vibrations, this is why Hondas bigger 4 cylinder engines have balancer shafts to absorb these vibrations.

 

Not sure other than that they claim it reduces vibration because of the opposing force of each pair or cylinders balances out.....

meh.

edit: damn OTT, beat me to it

 

-Flat oppossed engine allows a lower hood line..
-No counter weights needed on crankshaft
-Seems to have a lower center of gravity

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PnX-R &raquo;</TD></TR><TR><TD CLASS="quote">-No counter weights needed on crankshaft</TD></TR></TABLE>


Counterweights definitely ARE needed. Just look at a subie crank or ask any oldskool bug or porsche guy.

IMHO it's because of 1) low cg, and 2) packaging.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">Counterweights definitely ARE needed...</TD></TR></TABLE>YES they are.

Counterweights are needed for first-order vibrations. They don't do any good for 2nd-order. But with a boxer, the 2nd-order are mostly canceled out by the other opposing piston. So why aren't subies perfectly smooth?? I don't know... Maybe a 12-cylinder boxer would be perfect. Anybody have a 512BB that I can use??? (just strictly for educational purposes...)

 

did the older imprezas have flat opposed engines, like a 97 2.5 RS for example?




Modified by The Machine at 11:28 AM 8/11/2004

 

yes

 

when they are opposed doesnt it make more torque or somethin?...i cant remember where i heard that

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99hatch &raquo;</TD></TR><TR><TD CLASS="quote">when they are opposed doesnt it make more torque or somethin?...i cant remember where i heard that</TD></TR></TABLE>

No, it's a misconception. Torque is all about airflow.

 

that and they use huge pistons too...

 

The low center of gravity is a big advantage for superior handling.

 

In light of all these benefits of a horizontally-opposed layout, my question is: why don't more companies (especially Honda) use them? Is there some drawback to them?

 

also, since the IM is on the top and the exhaust is on the bottom it kinda keeps the heat where it can be cooled and it doesn't heats up the IM.

I'm not too sure, but i think the boxers engines are more expensive to build since they are kinda bigger.

Windage was also a problem, since oil didn't have the incline to go back to the oil pan, off course, this is not MAJOR flaw, just a flaw, also, a piston would push air at the other one and that is not too good at high RPM.
just naming the things.

They are better, and they are worse, every engine design has its ups and downs, it all depends what do you want to do with it.

To me, every engine is awesome in some way, may it be rotary, opposed, diesel, in line, V.

BTW: i would love to get my hands on one of those Flat 12 engines, and jimblake, if you get your hands on one, don't hesitate and call me, i want to play with it too....lol

 

bah you guys can keep the horizontal 12

I want a F1 car or maybe the engine, tranny, witring harness and ecu and all controls so I can have a mad nasty NSX.... ::evil laugh::

 

does it cost most to fix these motors (parts & labor), like it is with rotaries?

 

yup, try "swaping out" a cam in one of those things.....see ya in a few days. I got very well aqauinted with flat fours in 96 or so because my friend went on an air cooled VW kick. Nice design, nice enginering for 1920 or wahtever it was but if you needed to do something with the rotating assembly have fun. Although it did get to a point the two of us could pull an engine, do a complete rebuild down to the crank and have it in a be braking in the new engine by that night

 

If the pistons lay flat it doesn't have to fight gravity when in motion.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Converted &raquo;</TD></TR><TR><TD CLASS="quote">yup, try "swaping out" a cam in one of those things.....see ya in a few days. I got very well aqauinted with flat fours in 96 or so because my friend went on an air cooled VW kick. Nice design, nice enginering for 1920 or wahtever it was but if you needed to do something with the rotating assembly have fun. Although it did get to a point the two of us could pull an engine, do a complete rebuild down to the crank and have it in a be braking in the new engine by that night</TD></TR></TABLE>

The old air cooled VW's are so simple to work on its pathetic. in 45 minutes I can have the whole drive train laying on the ground behind the car.

 

Boxer engines are not better. They're the result of trying to get a better weight distribution. The engine is actually compromised a great deal, and that is why they don't make much power per liter. You have to turbocharge them. Seperating the exhaust ports like that on a four cylinder makes for shitty scavenging. So Honda doesn't use them because Honda likes to get a lot of power out of a little engine without turbocharging it. Honda and Subaru engine design philosophys are practically polar opposites.

Just make an Inline four and mount it low and lean it at the correct angle. Or better yet, squeeze in a small aluminum inline six. Inline six is a smooth and very balanced engine. But mounting it for FF makes for quite a wide engine bay.

 

One of the main problems with making a flat-4 with a FWD system is how to position it witin the bay while still keep weight distribution even. That'd be a hard one to tackle... Flat-4's are great for lowering most of the cars weight down low, aswell as the signiture low rumble sound. I'm not sure the speculation on any forum would grasp how/why something actually works (except for the earlier comment on torque being directly related to airflow)

Personally, I love my WRX. Its what keeps me from going insane when a spirit driving sension is in order. The turbo kicks in, and its just fun to drive no matter what conditions are outside. The best attribute of the turbo'd subis are the HUGE selection of parts available and how Europe and Japan have already made it into a favorite. Parts, knowledge, and anything you wanna do you can. I love my Subi for a few reasons... but I love Hondas for others.

The one attribute about them is that you can swap any motor into any chasis (altho no special mounts required) will little more than the engine, harness, new subframe, and a few odd things here and there (although my knowledge is somewhat limited since I have not done a Honda swap from start to finish).

Im sure the bashing can go both ways, I just hope that everyone can remember that certain cars are made for certain reasons and that each one is better/worse than the next.

Rich

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Machine &raquo;</TD></TR><TR><TD CLASS="quote">does it cost most to fix these motors (parts & labor), like it is with rotaries?

</TD></TR></TABLE>

once you have the car, parts are cheap. Crate engines with twin-scroll and AVCS (subi vtech) are $4k (stock 280HP), turbo upgrades are $600, and there are as many choices and interchangable parts as Honda has.

Rich

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by egcivic80 &raquo;</TD></TR><TR><TD CLASS="quote">If the pistons lay flat it doesn't have to fight gravity when in motion.</TD></TR></TABLE>

I don't think that makes any difference.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by shaundrake &raquo;</TD></TR><TR><TD CLASS="quote">Boxer engines are not better. They're the result of trying to get a better weight distribution. The engine is actually compromised a great deal, and that is why they don't make much power per liter. You have to turbocharge them. Seperating the exhaust ports like that on a four cylinder makes for shitty scavenging.</TD></TR></TABLE>

Ok, thanks for clearing that up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Just make an Inline four and mount it low and lean it at the correct angle. Or better yet, squeeze in a small aluminum inline six. Inline six is a smooth and very balanced engine. But mounting it for FF makes for quite a wide engine bay.</TD></TR></TABLE>

How about a VR6 like Volkswagen uses? It only has a 15 degree angle between the cylinders, so it only has one cylinder head like an inline, but isn't as wide.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JCushing &raquo;</TD></TR><TR><TD CLASS="quote">that and they use huge pistons too...</TD></TR></TABLE>

"Huge" pistons and cylinders are the means for more airflow and pressure....