What makes the Boxer engine so special

[SubieNate]

I'm amazed at the stamina of some of the non-owners (and not planning to be owners) on this forum. I don't have the time or energy to hang around arguing with people about a car I have nothing invested in. Why is is that this car threatens so many people?

Originally Posted by fatoni

i just said that a boxer engine does not mean lower cog for the car.

Assuming the crankshaft of a boxer engine and an inline or V are on the same axis, then yes that's exactly what it means. And assuming the engineers behind the car have even the smallest amount of technical ability and understanding, there is nothing about the boxer that keeps that axis from being just as low as any other format. Some compromises may have to be made elsewhere (i.e. no double A front suspension) but that's what design is. Finding the best set of compromises to solve your problem. There is no perfect solution.

In this particular car, the CG would most definitely be higher with an inline. Assuming the driveline is a constant, installing an inline engine would raise the CG of the engine and therefore, raise the CG of the car. Done. That argument is pointless. The car was designed for and built around the boxer motor. Any comparison will prove that the CG is indeed very, very low for a car sold in 2012 with crash regulations. The fact that it's in the same area as Lotus's and Porsches and costs $25k is in and of itself groundbreaking. That kind of design detail usually doesn't happen at this pricepoint. Does it guarantee perfect uber OMG so amazing handling? No. But it helps.

The Miata is a wonderful little roadster that with the right modifications, can hand much more pricy and more powerful cars their asses. The twins happen to be in the same category. That doesn't take anything away from the Miata, and the fact that the Miata is a great car doesn't take away from the accomplishments of the 86 team.

If you like the Miata better, drive it. Done. Arguing that there aren't any merits to the boxer design is stupid. There are merits to every design or they would cease to exist in favor of a design that does have merits. Engineers don't get to blindly pick, "I like this one the bestest!" and stick with it forever and ever. This was a Toyota/Subaru joint project with a Toyota engineer leading the team. If they had felt that an inline 4 would have served best, it would have had an inline four. End of story.

Nathan

[fatoni]

Originally Posted by DarkSunrise

The inline-4 car you brought out as an example (NA/NB Miata) actually has a higher CG than the BRZ/FR-S once you adjust for ground clearance. It also isn't built to conform to modern day crash standards.

To compare apples to apples, the current NC Miata is built to conform to modern day crash standards. Also comes with an inline-4. Its CG height happens to be 1" higher than the BRZ/FR-S. Coincidence you say?

What car with an inline-4 do you think would have the lowest CG height? Probably a Lotus Elise, designed from the ground up to handle well (expensive, lightweight, mid-engine, track-focused). CG height on the Elise? 470 mm, or about a 1/2 inch higher than the FR-S/BRZ.

I can't think of any modern cars with an inline-4 that have a lower CG height than the BRZ/FR-S. You can't tell me that none of that has to do with the fact that the single heaviest component on the FR-S/BRZ (boxer engine) happens to have a lower CG height than a comparable inline-4...

i think im coming off like a **** because of a little miscommunitation. im not saying that the frs doesnt benefit from having a boxer motor. im just saying that the benefits arent inherent and they still have to be worked for just like anything else. the boxer motor isnt special. i failed to bring an apple to apple comparison because i was only trying to show that center of gravity isnt something that has even been mentioned historically but now all of a sudden its a big deal. if the boxer motor achieved that so well i think porsche or subaru would have mentioned it by now.
i would be curious to see how the types of motors compare across the generations. a 90 miata vs 911 for example. or current cars at different price brackets like the sti vs evo or cayman/911 vs vette.
i wouldnt use the lotus as an example because its midengined so the motor sits basically on top of the tranny.

Originally Posted by SubieNate

I'm amazed at the stamina of some of the non-owners (and not planning to be owners) on this forum. I don't have the time or energy to hang around arguing with people about a car I have nothing invested in. Why is is that this car threatens so many people?



Assuming the crankshaft of a boxer engine and an inline or V are on the same axis, then yes that's exactly what it means. And assuming the engineers behind the car have even the smallest amount of technical ability and understanding, there is nothing about the boxer that keeps that axis from being just as low as any other format. Some compromises may have to be made elsewhere (i.e. no double A front suspension) but that's what design is. Finding the best set of compromises to solve your problem. There is no perfect solution.

In this particular car, the CG would most definitely be higher with an inline. Assuming the driveline is a constant, installing an inline engine would raise the CG of the engine and therefore, raise the CG of the car. Done. That argument is pointless. The car was designed for and built around the boxer motor. Any comparison will prove that the CG is indeed very, very low for a car sold in 2012 with crash regulations. The fact that it's in the same area as Lotus's and Porsches and costs $25k is in and of itself groundbreaking. That kind of design detail usually doesn't happen at this pricepoint. Does it guarantee perfect uber OMG so amazing handling? No. But it helps.

The Miata is a wonderful little roadster that with the right modifications, can hand much more pricy and more powerful cars their asses. The twins happen to be in the same category. That doesn't take anything away from the Miata, and the fact that the Miata is a great car doesn't take away from the accomplishments of the 86 team.

If you like the Miata better, drive it. Done. Arguing that there aren't any merits to the boxer design is stupid. There are merits to every design or they would cease to exist in favor of a design that does have merits. Engineers don't get to blindly pick, "I like this one the bestest!" and stick with it forever and ever. This was a Toyota/Subaru joint project with a Toyota engineer leading the team. If they had felt that an inline 4 would have served best, it would have had an inline four. End of story.

Nathan

saying that you can mount the flat motor in the space of a v or i is a big assumption to make. once you make that assumption then sure. you can almost always take any type of engine out of a car (boxer to v or inline or vice versa) and swap another type and the cog will go up.
i would love to think that engineers pick what serves the car best but they dont. if they did and the boxer was the solution, they would have been in many more cars. i think its a matter of cost and convenience, they pick what meets the standards the cheapest.
also, look at the stuff i said above. i know i sound like an ass or i hate the thing or that im threatened or whatever but its not the case. the reason i dont have one of these things is that its the first production year. its the only new car that appeals to me but thats because of the whole and not any particular parts.

[SubieNate]

I'll give you the benefit of the doubt. But Subaru has been bragging about the boxer's affect on the CG since forever.

[DeeezNuuuts83]

Originally Posted by fatoni

i failed to bring an apple to apple comparison because i was only trying to show that center of gravity isnt something that has even been mentioned historically but now all of a sudden its a big deal. if the boxer motor achieved that so well i think porsche or subaru would have mentioned it by now.
i would be curious to see how the types of motors compare across the generations. a 90 miata vs 911 for example. or current cars at different price brackets like the sti vs evo or cayman/911 vs vette.

Actually, the lower center of gravity has been in past marketing materials of Subaru. The original spiral-bound brochure for the 2004 STi touched on it briefly in a few diagrams with another car's silhouette, likely the Evo's, but it didn't provide much beyond just showing that it the center of gravity was lower. But I don't think it was more than a sidebar on one page, from what I remember.

Despite that, the STi didn't end up outhandling the Evo, as reflected in almost every comparison between the two of them. Anyone who had seat time in both cars can also confirm that. I was surprised myself, as I remember expecting the STi to murder the Evo when they were first released stateside based on the differences along with the benefits that the STi had over the Evo at that time (i.e. lower center of gravity, engine output difference, front LSD, better center differential).

[Embarrassed]

Anyone with an engineering degree and a reasonable familiarity with cars can tell you that the twins with the boxer engine will have a cog ~.25 below an otherwise identical car with an upright inline. If you think that you can feel that difference with your handling butt dyno, think again. In fact, you would have a hard time telling the difference with careufully and automatically taken measurements.

The assumption that the crank height can be the same is only really true if you are also assuming the engine must have a full depth oil pan. I and V engines typically can somewhat lower installed heights with dry sumps as the boxer is effectively limited by the need for exhaust manifold routing.

Similarly, the boxer engine is not much shorter in height, owing to the need for intake manifold routing on the top. Where the boxer is much much superior, is the combination of the somewhat lower height and much shorter length allows for a steeply raked hood. That said, it looks like there is enough room for a different desgin. Isn't there a guy who put a V8 in one?

O

[Bristecom]

Advantages:

- Lower center of gravity (most of the weight is lower down but the oil pan and exhaust can prevent it from being lower vs. a V engine with dry-sump lubrication)

- Better balance which means no balance shafts or as many balancing weights on the crank which means more efficiency and smoother feel (good primary balance and natural firing order for a 4 cylinder but it still has some secondary imbalances as a 4 cylinder - this is a bigger advantage over 2.0L as inline 4 engines really start to suffer without a balance shaft)

- Shorter than inline engines so you can mount it longitudinally in an all wheel drive vehicle without much overhang in front of the axle

- More room above it for a lower hood or a top mount intercooler if desired (which results in less turbo lag)

- Better self cooling ability since it's more open/spread out

Disadvantages:

- Wide (less room for double wishbone suspension or other components and may be limited on stroke)

- Cannot be placed as far back in front as an inline engine with the FR layout because it gets in the way of the steering rack which means less than ideal front/rear chassis balance (for grip)

- 2 sets of cams and timing chains kind of offsets the lack of balancing weights vs. inline engine (this is less of a drawback/waste for 6 cylinder boxers)

- Not as easy to replace spark plugs vs. an inline engine

Overall though, I prefer boxer engines and think it makes the 86/FR-S/BRZ that much more special.

[fatoni]

Originally Posted by SubieNate

I'll give you the benefit of the doubt. But Subaru has been bragging about the boxer's affect on the CG since forever.

sorry, i meant objectively. its one thing to say that the boxer gives you lower cog. i just figured that if that actually played out, they would show you what the sti cog was next to the evo. as far as i know, they never did. also, im pretty sure thats because using the boxer motor isnt that impressive when you need to raise the engine in order to run the drive shaft to the front tires (not really sure on this since i dont really follow what subaru does with their cars).

i do see things like this which show what can happen conceptually but really provide zero information

http://www.subaru.com/content/media/...static_960.jpg

[BoostedWrbBrz]

Originally Posted by clevrname

I'd rather have the 2GR if you're looking at Toyota V6s.


http://25.media.tumblr.com/tumblr_m5...brxbo1_500.gif

My last car was powered by a 2GR. 2010 Camry. Very good torquey engine with lots of pep

[Accurate Race Shop]

I like the history behind the Boxermotor brought into the world in 1896 by Karl Benz. It has come a long way sense then but before the harmonic dampener engines had to be balanced. It has origins from the very beginning of gasoline powered cars any earlier than this they where using steam.

[DEnd]

Originally Posted by fatoni

also, im pretty sure thats because using the boxer motor isnt that impressive when you need to raise the engine in order to run the drive shaft to the front tires (not really sure on this since i dont really follow what subaru does with their cars).

Typically Subaru uses a front transaxle, much like what mid engine cars use, except with a rear output. This leads to the Subaru engine being placed in front of the front axle.

[SubieNate]

DEnd is correct. The motor can sit very low for an AWD system because the front axles come directly out of the transmission. All part of the "symmetrical" thing. Because of this, both front axles are exactly the same length so next to no torque steer.

I like to think of it as a backwards version of the AWD 911's. I think it's also similar to how Audi's Quattro system works on their longitudinal engine cars.

The big disadvantage of this is weight distribution (As evidenced by all of these cars), the front:rear bias is greatly affected by being forced to hang the entire engine completely in front of the front axles. Tradeoffs are a part of every design. The reduced weight of the transmission directly over the front wheels (most transverse AWD systems have much of the transmission fore of the axles, whereas much of a Subaru AWD transmission is back in the tunnel like a RWD car) tends to balance things out when compared to other AWD cars. There are very few transverse cars that can claim great weight distribution, AWD or FWD. Some MR cars are transverse (MR2) and they may do better but I'm not sure.

Nathan

[uspspro]

Not going to read all 5 pages, but here is another factor.

When you think of CoG, you have to think of the whole system. The boxer engine is really short, regardless of how high/low it is mounted. Sure the CoG difference between it and an I-4 may not be not an enormous difference, BUT it does allow for the hood to be extremely low, this allows the seats to be lower, which lowers the relative CoG further when considering the driver (and potentially passengers).

The low hood facilitates both a lower seating position and a good amount of headroom as well.

[SubieNate]

I forgot to mention that the boxer is uniquely suited to Subaru's brand of AWD because it makes the engine shorter front to back than an I-4. This is a very good thing when you're hanging an engine out completely in front of the front wheels. Keeps the bulk of the mass farther back, reducing the negative effects. Also shorter overhangs.

Nathan

[cf6mech]

Originally Posted by SubieNate

I'll give you the benefit of the doubt. But Subaru has been bragging about the boxer's affect on the CG since forever.

THIS ^