Compare these petrol and diesel engines (Subaru Forester)

[chacka]

G'day campers.

I've been mulling over getting a 2009 - 2012 Forester for a while now and think I'm pretty decided on it. Now just down to petrol or diesel. Both turbo.

Point of the car is for a comfortable, quality daily drive with a little off-road ability under the belt for some camping. I know the Forster isn't a "proper" 4WD and won't be doing anything extreme with it but for moderate trails I think it's the right mix.

Back to the engine... I've test driven the 2.5l turbo petty on the road and it's perfect for that. Plenty of pickup, comfy and all the rest. The 2.0l turbo diesel doesn't press you back into your seat but that's expected.

These are the figures for the engines/gearbox.

petrol-vs-diesel.gif (8.65 KiB) Viewed 11832 times

What I'm trying to work out is if it's worth going the diesel for the extra low down it gives that could come in handy off road, but obviously no one will let you test drive their car down a rough track to find out so I'm stuck with using my imagination at the moment.

To sum up the benefit of the diesel, with the extra torque lower in the rev range and the 6spd gearbox it's going to be better for challenging uphill take-offs, or if taking off against something pressed to the wheels like if you crept up to a small log to climb over.

Right?

The petrol is so much better on the road which is the majority of where I'll be, so I'm trying to work out if it's worth the trade off and how much better it is in the off-road regard with a diesel.

[Gwion]

ANother benefit of a diesel is longevity, but that won't really come into it as a daily driver as you'll likely upgrade before you see the benefit.

Both our cars are diesel but in you situation i'd go the petrol. For the "soft road" work you're likely to do, the extra torque isn't going to be that much use. If you plan on a lot of hilly terrain at low speed or will be towing something (pretty light at that sized engine) then the torque might help.

My wife's Peugeot is a 2L diesel and driven right (or wrong) it can definitely press you back into the seat. Not all diesel engines are pussy cats.

[Supporter]

My wife's Peugeot is a 2L diesel and driven right (or wrong) it can definitely press you back into the seat. Not all diesel engines are pussy cats.

The forester is probably 300kg - 400kg more than your average Peugeot though I'm sure.

Not knocking either, just keeping it apples to apples

[Rocker]

For the "soft road" work you're likely to do, the extra torque isn't going to be that much use. If you plan on a lot of hilly terrain at low speed or will be towing something (pretty light at that sized engine) then the torque might help.

+1 for this.

It's not a serious 4X4 as you said and the terrain you're tackling won't have anything in it that would really benefit. If it's a modest enough log/bump/hill that you're doing it in a Forester petrol will do it.

I'd take the petrol for the better road experience from what you've described.

[zobster]

I have a petrol forester and absolutely love it! With diesel boxer engines, you don't see many of them around and there have been some bad reviews going around regarding some "particle trap" in the "engine??" that make the engine stall at red lights.

I don't have any complaints with mine, does everything I want it to do and I use it on forestry tracks no dramas

[YoungBuck]

I'm in a similar situation, my xr6t falcon just isn't suited to off-road. Am currently keeping an eye on the price of Subaru XVs for some light off road action, though I am struggling to come to terms with the lack of power they have (less than 1/3 of what my falcon currently has ).

[bigfellascott]

My mate's got the diesel version and he's had it chipped from memory and man that thing pulls like a V8 on Steroids! 510nm of torque and halls his caravan up hills past everyone, gets around 8ltr per 100 from memory (that might be with the caravan on can't remember now) but he was very happy with the performance from it.

They are a beautiful car to ride in, I'd happily buy one no worries at all, its got all the bells and whistles.

He's a subaru nut by the way, had quite a few over the years.

[Wes]

My mate's got the diesel version and he's had it chipped from memory and man that thing pulls like a V8 on Steroids! 510nm of torque

Extra 160nm torque from just a chip?

[bigfellascott]

My mate's got the diesel version and he's had it chipped from memory and man that thing pulls like a V8 on Steroids! 510nm of torque

Extra 160nm torque from just a chip?

Yeah not sure if he's done anything else to it or not ( just remember him mentioning he got it chipped or ECU Tuned - can't remember now) all I know is it pulls like a V8 - farking awesome performance), I got my ECU remapped on my BT and it went from I think 380nm to 510nm $1000 well spent I reckon - heaps better to drive now - oh I also put a 3" TBE on it too which made it breath a lot better and she screams up hills now.

[Gwion]

My Hilux could use some of that magic chip action!

[bigfellascott]

My Hilux could use some of that magic chip action!

This is the fella that did my ECU Remap - he travels all over Aus doing em and does everything from Seadoos to trucks, race vehicles etc etc, very very pleased with my ECU Remap (turned it from a dangerous vehicle to one that's now capable of overtaking safely and without fuss, pulls like a train now instead of an asthmatic 90yr old.

https://www.youtube.com/user/lolergramCCCP

[juststarting]

Chaka, we go to the snow quite a bit, so, so this was our reason behind getting one, it has pretty good smarts for traction control. Regarding 'proper' 4x4, I took one from the dealer (XT 2015, not raping mine) to the 4x4 proving ground... Main functional, realistic difference is the ground clearance. If you are cool with not being able to do crazy tracks, it will go anywhere a 'proper' 4x4 will go. Possibly further in some conditions.

Re: diesel engine, if you don't do regular highway drives, go with petrol, IMHO.

[BBJ]

Extra 160nm torque from just a chip?

Sounded like a lot to me too but looks like it's right.

Did some Googling and found the MRT kits. There 'XA' kit which is just a tune is 15kw & 25% more torque.

About spot on 160nm on the Forester.

The they also do exhaust and more in higher kits.

60kw & 40% more torque in the top kit

Not bad for a compact SUV with 4 cylinders

[bigfellascott]

Extra 160nm torque from just a chip?

Sounded like a lot to me too but looks like it's right.

Did some Googling and found the MRT kits. There 'XA' kit which is just a tune is 15kw & 25% more torque.

About spot on 160nm on the Forester.

The they also do exhaust and more in higher kits.

60kw & 40% more torque in the top kit

Not bad for a compact SUV with 4 cylinders

Yep its amazing what you can get out of em with a bit of tuning, I reckon the ECU is the way to go (from what I've seen you can get more out of em and they are way more tuneable than just a straight chip set type thing ( I had my gearbox parameters changed too) mainly when the torque converter locks up and when the gears change type thing - all I know is its a hell of a lot more fun to drive now compared to the way it came out of the factory. I can still get more out of mine but need to install a EGT etc and bigger cooler - I haven't decided whether I want to go that way but if I do it would give me around 55%-60% torque increase over standard

[Bourt]

That's amazing for just a tune. I'm sure there is some reason but it seems ridiculous to me it wouldn't come tuned like that from the factory

Petrol sounds like the best option to me to for you.

[NuZo]

I have a 2003 Forester X - 2.5L N/A Manual.

If you're going to be towing anything, get the diesel.
If you're going to be going on long range trips, get the diesel.
If you want speed/handling, get the petrol.

I wish i had the diesel. I tow things maybe once a month and i go on long trips regularly. The fuel consumption of the turbo petrol models is very high, the diesel models is actually pretty good. My N/A 2.5 isn't bad either.

Your call, get the car that fits your needs best.

Cheers,

Nuzo

[Vati]

The fuel consumption of the turbo petrol models is very high, the diesel models is actually pretty good.

Depends on how you drive really.

The turbo's fully spooled in the Subaru's around 3,500 - 4,000 rpm I think, which is about where you'd change gear in 'normal' driving.

But yeah, if you're constantly pushing it up to 5,500 - 6000 all the time for the 'push you into the seat thrill' style of driving it really drinks it fast.

For towing or hauling a lot of weight around turbo diesel definitely the best option, hands down.

[Harper]

I have a petrol forester and absolutely love it! With diesel boxer engines, you don't see many of them around and there have been some bad reviews going around regarding some "particle trap" in the "engine??" that make the engine stall at red lights.

That's more likely the result of the wrong style of driving than a problem with the cars.

Copy and paste from the Subaru website is best explanation for you, here

However, a diesel engine also produces significantly more particulate emission (black soot) under certain operating conditions such as cold start, acceleration, high load and when driven at less that full operating temperature. These soot particles are microscopically small (0.09mm) which the human respiratory system is unable able to filter so they can enter the lungs and pose a serious health hazard.

This is why the modern diesel engine uses a special filter to capture 95% of these soot particles. This filter known as a Diesel Particulate Filter (DPF) automatically cleans itself by burning the captured soot particles. To be able to do this, however, its temperature needs to be in the region of 550 to 700 oC. Urban driving at light throttle results in exhaust temperatures typically in the range of 150 to 200 oC and so with this type of continual driving the DPF is unable to clean itself and it can become blocked. To help alleviate this situation the DPF is subjected to computer controlled regenerative processes that raise the combustion temperature to force drive the DPF burning process. However, these regenerative processes also require an engine operating temperature that is not sustainable in a continued urban driving environment.

When this situation occurs the driver is warned via a warning light to drive the vehicle at a higher speed & load to raise the exhaust temperature so the DPF can burn the soot particles. Failure to do so will ultimately result in the DPF becoming blocked. If this happens it will possibly be necessary to replace the DPF at a significant cost (thousands of dollars).

So again it is clear that a diesel engine vehicle requires a driving style and method of use that is only suitable for longer distances and higher loads! If this is your particular method of use and you travel high kilometres then a diesel engine vehicle is particularly suitable due to the fuel efficiency and environmental performance. But if you normally travel short distances then a petrol engine is a better choice.

Back to the original question for Chacka, the guys voting for petrol make sense but I wouldn't write off the diesel just yet. At least go and test drive one.

As is the way with diesels power drops off at the top of the rev range which you'll immediately notice compared to a petrol. You have to shift a earlier and a bit more often. Man do they pull in the low range though! Getting up to 60-70 km/h is definitely not slow. Going a petrol for monster power at the redline isn't really that useful as you can't drive on the road like that. The diesel has plenty in the normal driving range where it counts.

[bigfellascott]

You get those Diesels tuned right and they can deadset pull like a V8 - bloody amazing performance from a 2lt size diesel motor.

[Sender]

Amazing what a little boost can do

[bigfellascott]

Amazing what a little boost can do

Yeah I don't know what they did to my mates subbie, my BT didn't really have the boost altered much at all if at all, it was more altering of the parameters of when the boost happened and also changed the torque settings on the auto so the torque cut in earlier type thing, all I can say its a big improvement on how it was to what it is now and no real increase in fuel consumption either which is great.

ECU tune and 3" TBE really made it come alive instead of that asthmatic example it was (smashed a V8 Landcruiser going up a mountain the other day, he was trying but had nothing on the BT

[sbd3927]

My mate's got the diesel version and he's had it chipped from memory and man that thing pulls like a V8 on Steroids!

Did that cure the shocking lag from hitting the accelerator to actually moving?

I looked at them in 2007 and decided the lag made them too dangerous to drive. I checked both 4 & 6 cylinder, it was part of their drive by wire nonsense. It was reminiscent of a 1.2litre corolla I had in the late 80's, making the car gutless and unresponsive, just what you don't need when a semi comes around the corner after you already started pulling out of a side street.

[bigfellascott]

My mate's got the diesel version and he's had it chipped from memory and man that thing pulls like a V8 on Steroids!

Did that cure the shocking lag from hitting the accelerator to actually moving?

I looked at them in 2007 and decided the lag made them too dangerous to drive. I checked both 4 & 6 cylinder, it was part of their drive by wire nonsense. It was reminiscent of a 1.2litre corolla I had in the late 80's, making the car gutless and unresponsive, just what you don't need when a semi comes around the corner after you already started pulling out of a side street.

Nope she's still got serious lag issues I reckon if he had the ECU tuned it could be removed or improved. Other than that lag issue its a beautiful car to drive, they go seriously hard when tuned and bigger exhaust to let em breath.

[ebr love]

Hmmm... I had a 2009 I think it was forester as a loan car and the throttle response was pretty good.

Wonder if you guys got issues or if I got the lucky one?

[bigfellascott]

Hard to say mate, all I know is if you stomped on the accelerator it would take a few seconds to really respond, but when it did man did it come on hard and strong (V8 like performance).

[headspace]

Unless you're willing to spend the extra on putting a chip in the diesel, I'd go for the petrol motor and leave it standard. Diesels are great, I have one in my Pajero, but you have to be careful with service costs. They can get a bit steep. I'm not sure who makes the diesel engine in the Subaru though, as far as I know they have never been involved in diesels.
JD

[sbd3927]

It was a deal breaker for me, bought the missus a 6cyl Mitsubishi Outlander instead.
My opinion is a delay in acceleration is nearly as bad as a delay in braking, when the unexpected happens you want it to work instantly.
Seemed to be plenty of grunt in the 6cyl subaru I test drove as mentioned above, but without an actual throttle cable.. bleh. There were different modes in various models from memory, maybe one of the full sports tunings would have behaved better.

[AusC]

I'm not sure who makes the diesel engine in the Subaru though, as far as I know they have never been involved in diesels.

I thought they made their own, but they're a recent foray for them. I think it was about 2008 they added diesel engine options to a few of their line-ups?

In general Subaru seem to make a pretty good engine, and the diesel should be no different. A few years to see how they last over the long haul will tell.