3.6 benefits over 2.5 Four cylinders??

86,035

Asked by Mark May 15, 2016 at 11:16 AM about the 2015 Subaru Outback

Question type: General

What are the major benefits or demerits ( poorer handling ?) of the H6 engine.
Is the extra two seconds or less of acceleration really worth the fuel cost.  
And, how much EXTRA passing power do you have ..  

Outside of speedier acceleration or passing on the open road in some cases a
compelling reason for purchasing it.. It also costs more to maintain.  

The 2.5 Four CVT transmission is pretty peppy for its size and once you're up to
speed it's a very efficient power plant.

What do you think??

21 Answers

48,040

The NEWER H6 (3.6L) is 1.5x the 2.5LH4, so operates more smoothly. The additional original cost is not worth it, in my opinion. Its mass adds extra weight, which further compromises the handling of the too-tall OB, but it's a nice addition to the Legacy Sedan. (Still, I'd rather have a G37x for an A4/328/C300 beater.) Because the new H6 required a beefier CVT the preceding 5EAT severely compromised fuel eco by comparison. So I'd NEVER buy the H6 5EAT as it's a real pig. Yet the H6 with a CVT may be playing with fire. Efficient? Sure, but at these prices the G37x is just far more reliable chariot, for example. Back to the OB: yes, the H4 is underpowered, but as fuel prices recover it will be seen as the only prudent choice. The previous 3.0L H6 was made from the smaller 2.0L H4 from the Imps, and was barely torquier than the '06+ 2.5H4, and thus, especially with the EAT, was really a fuelish choice...although owners liked the quieter operation. New car shoppers would be wise to avoid the 3.6H6 in an OB because of substandard handling because of high CoG. I'm not even sure I can accept the lighter 2015+ H4 Limited (importantly with 18" wheels), as the 2013-2014 handle better. Need more coffee....

8 people found this helpful.
86,035

Ernie, you have raised some interesting points. So, the 3.6 , 5EAT is a pig?? I guess it's not optimized as well as the CVT?? I suppose that the. 2.5 H4 with the CVT is more responsive and better fuel economy? One article I read said it takes a "few beats" for the H6 to get going.. Do you really think that the 2.5 H4 is that underpowered?? I don't think it's bad around town at all and once cruising on the highway, seems to keep up fine... Maybe only when I'm pulling the trailer uphill do I really feel it's underpowered. At least with the 2.5 H4, the handling is better than the H6 engine, with the lighter front end. It seems as though your BIGGEST concern about the CVT transmission is with the H6? How does the larger 18 inch wheels afect the acceleration on the H4? Seems like the extra high profile would diminish acceleration performance? Is that true? Let me know, please... Thanks, --Mark

4 people found this helpful.
530

Interesting... Full disclosure, I've had two 2.5 Outbacks, a 2.5 turbo Legacy, a 3.6 Tribeca and now a 3.6 Legacy. I'll never go back to a 2.5 after having the H6 3.6. I used to get 25mpg solid in the 2.5, surprisingly I'm getting 27mpg in the H6. You don't have to beat the H6 to accelerate nicely in traffic like you do a 2.5. The engine is butter smooth and way more responsive than the 2.5. There's a reason all the employees at the dealerships also drive the H6 as their personal cars.

13 people found this helpful.
530

How do the H6 3.6 and H4 2.5 have a different center of gravity by the way? They are the same height.

3 people found this helpful.

The 3.6 will be more front heavy. The high center of gravity in the Outback is due to ride height.

1 people found this helpful.
530

Honestly, the whole argument about the 3.6 handling worse seems rather speculative. The 3.6 car has a heavier spring rate and bigger brakes. Have you driven both? I have and I don't notice a difference in the handling at all. What is the weight difference between a 2.5 motor and a 3.6 motor? Does adding a sunroof or the Harmon Kardon system negatively affect handling then from the extra weight?

9 people found this helpful.
48,040

The "turn in" from being too front-heavy is slower than the 2.5i. Going to V-rated tires and keeping front tire pressure very high helps...as well to use a stiffer rear anti-sway bar to keep the rear in time to reduce the inevitable understeer.

3 people found this helpful.
530

In 2017 the 2.5i Touring is 3633 lbs. In 2017 the comparable 3.6 is 3810 lbs. That additional 177 lbs (that's all it is), is engine, bigger brakes, heavier springs, a dual exhaust, etc. Having driven both (a lot) there is no difference in "turn in" in my opinion. And that additional 81hp and 73ft lbs of torque more than make up for it if there is. How much heavier do you think the 3.6 engine is?

7 people found this helpful.
48,040

Further, neither power nor torque affect "turn in", which a function of suspension, geometry, tire/wheel and momentum.

2 people found this helpful.

People that drive at sedate speeds on straight roads probably won't notice the diff. but those that drive a lot of curves are going to feel that extra weight.

530

It is nowhere near comparable to someone sitting on the hood. That 177lbs is also in the brakes (larger on the 3.6), the piping for dual exhaust (the 2.5i has single), heavier springs, etc. What does that leave for the engine? Furthermore, whatever weight is left is perched on the crossmember, which is much different than high up on the hood. I've driven both, a lot, there is no difference in handling. The biggest handling complaint is the tires that come on the car, they have a lot of sidewall flex, which screws up handling. I don't drive at sedate speeds on straight roads, I've done autocross, karting endurance events and my '05 Legacy GT has 373hp/455 ft lbs of torque dynoed at the wheels. Granted I haven't autocrossed an Outback and anyone that does probably should find a more suitable car. I get the impression that posters in this thread have never driven both cars. If that's the case it's doing a big disservice to anyone looking at the thread, debating the 2.5 over the 3.6. It's ok to love your 2.5 if that's what you bought, the 2.5 is a great car (I've had two), but don't rag on another great car just because you feel the need to justify your purchase. Go drive the 3.6 and then come back here and post, otherwise it's all conjecture.

11 people found this helpful.
48,040

Scott, it's pretty simple. The 3.6R simply has a F/R weight distribution that increases understeer and reduces turn-in feel. Stiffening the springs (and especially the tire sidewalls, as you mention), helps, but there's simply much more weight over the front end...ala Audi, if you will. Yes, it's low center of gravity is gratifying, but it's just not as flingable as the 2.5i. I too have driven many of them (actually thousands of 2.5i and maybe a couple dozen 3.6R), and almost bought a nice '15 Leg Ltd at auction yesterday until I say the thirsty 3.6. Nobody's ragging on the 3.6R except for being a bit hefty and thirsty, as indeed it's been very reliable. We'll see if the new 2.4T offers significant improvements without reducing durability. If I'm willing to take the eco penalty of a 6 cyl I much prefer what I call the "Super Subaru": a 2009-2013 G37x with thicker rear anti-swaybar (from the G37 Coupe). They are seriously better built than any Subaru, with lots of aluminum, bigger brakes, etc. But this old-style 3.7L does suck gas...like the Subie 3.6,

4 people found this helpful.
48,040

Scott, you reference the 2017, so I'll have to assume that modifications to the 2015+ body/chassis were made to accommodate the 3.6R. I'll admit that I've only driven 3.6 models in the prior (up to 2014) Legacy/OB body. Given the huge difference in cog between the L and OB, I can imagine that the Legacy can much more easily tuned to satisfaction. The raised OB body mass clearly doesn't handle the 3.6's extra mass very well. I've been installing the Sti 20mm rear stabilizer (ant-sway) bar on all 2010-2012 and 2015+ OBs to remedy poor body control. Do you know if the 3.6 models use stiffer bar(s) to reduce sway, yaw and roll? I'll have to drive a 2015+ Legacy 3.6R to get a good sense of any improvements, but certainly the raised 2015+ OB needs remediation...with ANY motor. Ha! Tell me more about your sense of the 2015+ Leg 3.6R. If it's REALLY that finely honed I might grab a '16 for my wife and sell her '13 G37xS...the last of the fine Infiniti G's.

530

Sorry, didn't get the notification you responded. I really like the G37x, that's a hard car to beat. I was bummed when they were discontinued. In new cars, for the pricepoint I couldn't find anything currently in the new car range that could compete with Subaru for the options, power, AWD and price. Personally I think the 2017 3.6 Legacy handles far better than my 2005 Legacy GT. I haven't looked into if it has bigger sway bars (or even looked at them), but I assume it must. It's a nice handling car. But then again I'm surprised at how well the Outback handles for as big of a car that it is. If you are going for Eyesight do some research, I *think* 2017 was the first year for Gen3 Eyesight. I've heard 2018 has a buggy Infotainment system. I bought 2017 basically just for the Eyesight. The Eyesight overall is good, I use it for cruise control in highway driving and even as cruise control in stop and go traffic where I've found it's really nice. A couple of small gripes. It disables in bright head-on sunlight. You get a warning on the dash, but that's about it, a little nerve-wracking when you didn't realize it was off. The accident avoidance leaves some to be desired, but I've heard that from every manufacturer. For example, say I'm approaching a car turning right, I know he'll turn right before I even get to him, I've had several times where I get a warning on the dash and the car cuts the throttle and hits the brakes. I swear I've almost been rearended because of it. I've contacted Subaru about it and I've heard the same gripes from friends with other brands of cars, the logic needs some refining. I'm also not thrilled with the wind noise on the 2017. For 2018 Subaru laminated the small windows and I guess they are quieter. The dealer told me the 2015- 2016 were "really bad" for wind noise. That said, it's subjective, my friend with a top of the line F-150 rode along and thought I had "new car syndrome" as he had much more wind noise than me. Lastly, check the CVT revisions for 2015 and beyond, I think there have been some. The 2017 CVT is pretty flawless so far and Subaru has done a lot to make it feel "normal" such as static shift points and such. I do worry about its longevity long-term.

Subaru still sells the 3.6 H6 Outback and Legacy.

1 people found this helpful.
48,040

No. The new 2.4T is a joint development between Subaru's boxer expertise and Toyota's direct injection folks. Let's hope someone amongst the teams can make it can handle a turbo. Poor fuel eco very clearly doomed the reliable H6.

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