Renault considers killing off diesel engines

"bhtooefr" (bhtooefr) 09/06/2016 at 23:54 • Filed to: diesel, emissions, euro 7, dieselgate

1

26

Looks like Euro 7 emissions standards may make it financially unsustainable for Renault to produce diesels for Europe altogether:

!!! UNKNOWN CONTENT TYPE !!!

Honestly... given the NOx-driven smog problems that European cities are experiencing right now, that’s not a bad thing, IMO. And, fundamentally, it’s not practical to limit NOx on a diesel to the levels that a stoichiometric-combustion gasoline engine produces, in my opinion - you end up having to have multiple aftertreatment systems (the best diesels right now have two EGR systems, an oxidation catalyst, a lean NOx trap, a selective catalytic reduction system, and a hydrogen sulfide trap), and that’s just not sustainable on anything that isn’t in the premium market.

That said, AFAIK, Renault’s current approach is downsized and turbocharged direct injected gasoline engines, which isn’t the answer either, IMO - particulate emissions are a huge problem there, and particulate traps aren’t the answer to that problem (they’re very effective while they work, at least on diesels... but when they fail, they’re often very expensive to fix, and often they’re illegally removed). Unfortunately, the current downsize and turbocharge trend is also producing automotive platforms that are dependent on small displacement engines, and we may all be in for a few years of pain before platforms start either supporting heavy hybridization or larger engines.

The Crazy Kanuck; RIP Oppositelock > bhtooefr 09/07/2016 at 00:05

1

My Juke has the same engine as the Renaultsport Clio (1.6L Dig-T). The engine is really damn good. Loves to rev, once on boost (starts around 2500rpm, hear it around 3000rpm) it is like a hyperactive toddler.

AMC/Renauledge > bhtooefr 09/07/2016 at 00:25

0

Luckily Renault has been out in front on electric vehicle production. My guess is that that’s also a factor in second-guessing the prospect of investing in Euro 7 diesel compliance.

bhtooefr > The Crazy Kanuck; RIP Oppositelock 09/07/2016 at 00:30

0

I’m not saying that they drive badly by any means - the modern wave of downsized and turbocharged gasoline engines has brought low-end torque that Americans haven’t really seen since the days of large displacement V6 and V8 pushrod engines in family cars, and they do drive well - but that the same emissions laws that are making diesels impractical even in Europe, will also make downsized turbocharged gas engines impractical.

Another factor is fuel efficiency - the current European test cycle is very, very lax, and avoids these engines getting into boost. Once they do get into boost, though, they start running rich - this is where particulate emissions go through the roof, and real-world fuel efficiency goes to crap. There’s a couple of new test cycles being introduced, however, that will be more representative of real-world driving (one of them actually being real-world driving with an emissions tester strapped to the back of the car), and are closing a lot of loopholes in the current regulations. Also, here in the US (which Canadian regulations are usually based on), the test standards are slowly being tweaked to close loopholes, and the EPA is doing random real-world testing to check for defeat devices.

I’m personally of the opinion that Mazda’s at least close to the right strategy for the medium term with the SkyActiv-G engines - good thermal efficiency, wide authority VVT set up to retard the intake cam under light load to improve part-load thermal efficiency (the same thing that a turbo’s trying to do, but with less need to enrichen the mixture under full load). They’re running rather high static compression, which requires direct injection, though, but they’re close to the right answer IMO. (However, their platform strategy isn’t considering hybridization, which I think is also a major component of the right medium-term strategy.) It’s also worth noting that Toyota’s actually licensed their engine tech, and has started deploying it in the VVT-iW engines (some of which are downsized and turbocharged, but not all).

bhtooefr > AMC/Renauledge 09/07/2016 at 00:31

1

Absolutely - and their relationship with Nissan helps, too. Nissan has a few hybrid products that can share engineering with Renault, which can help if downsize and turbocharge fails, and the platforms aren’t ready for larger engines.

The Crazy Kanuck; RIP Oppositelock > bhtooefr 09/07/2016 at 00:33

0

A medium size N/A in-line 4 would for sure help fuel economy. By the time I’m doing hwy speeds (115kph - 120kph) I’m turning 3000rpm.

bhtooefr > The Crazy Kanuck; RIP Oppositelock 09/07/2016 at 01:16

0

Yeah, I’d say something like the 2.5 liter Mazda SA-G would probably be a good engine for that application. Similar power, similar torque (although a bit higher in the rev range), more efficient when you’re accelerating, and maybe a bit less efficient when you’re gentle on it.

The Crazy Kanuck; RIP Oppositelock > bhtooefr 09/07/2016 at 01:26

0

They could use their own QR25DE, 2.5L 175hp/180tq.

bhtooefr > The Crazy Kanuck; RIP Oppositelock 09/07/2016 at 01:37

0

The reason I don’t mention the QR25DE is that it doesn’t have any special methods of reducing pumping losses at partial load.

There’s five main ways of doing that (which can be combined), the first two being independent of the engine itself:

Reduce engine speed through gearing (can hurt responsiveness badly)

Hybridize (so you can run the engine at full load, then shut it down and run on electric, and repeat once the battery’s depleted, if your power demand is lower than the engine’s minimum efficient power)

Cylinder deactivation (hurts NVH, can hurt responsiveness if done badly)

Downsizing the engine (reducing the power made when at naturally aspirated wide open throttle, increasing efficiency at that low power figure) and turbocharging it (making up for the lost power, but with a serious fuel economy and emissions impact at high load)

Variable valve actuation strategies to reduce cylinder charge, instead of using a throttle plate (late intake valve closing (easiest), early intake valve closing (Fiat MultiAir can do this), some variable valve lift strategies (BMW Valvetronic, Toyota Valvematic, Nissan VVEL, and Fiat MultiAir can do this))

Arguably, cylinder deactivation is a form of variable valve lift that alternates between zero lift and full lift.

As far as I’m aware, the QR25DE doesn’t have cylinder deactivation, and any VVT hardware it has isn’t set up to retard the intake cam significantly at low load.

The Crazy Kanuck; RIP Oppositelock > bhtooefr 09/07/2016 at 01:56

0

I think so, but Nissan would want to use their own engine. Most Juke buyers would not car what powers it anyways.

bhtooefr > The Crazy Kanuck; RIP Oppositelock 09/07/2016 at 01:59

0

Right - ultimately, Nissan would need to add VVEL (for their current suite of technologies) to the QR25, I think, to get similar results.

FSI - alcohol enthusiast with a car problem > bhtooefr 09/07/2016 at 03:07

0

When the EU finally decides to completely kill of the tax advantage for diesel fuel nothing will happen. And like you said and I always say, smallish displacement direct injected gasoline engines have a high nox emission, particle filters will probably (hopefully) mandatory within the next three years.

Personal opinion: the automotive industry lobby in the EU do a good job to keep the diesel engines alive.

bhtooefr > FSI - alcohol enthusiast with a car problem 09/07/2016 at 03:29

1

As I understand, the NOx emissions aren’t really the bad part about the downsize/turbocharge DI engines, it’s the particulates - and a lot of the problem there is the microfine particulates - and the real-world fuel efficiency. The NOx emissions being higher would only be due to poor mixing between air and fuel, and local hot spots on the edge of fuel droplets, with excess air around the droplet.

Upsize and Atkinsonize, IMO (especially with variable Atkinsonization as in Mazda’s SkyActiv-G engines and Toyota’s VVT-iW engines, so that power can be maintained), is the way to go.

Mazda’s claiming 40% thermal efficiency out of the SkyActiv-G engines (and my guess is that that’s at part load, low RPM, due to how they work), the latest version of the Toyota 2ZR-FXE is at 40% efficiency as well (AFAIK this is at high load, low RPM - low load doesn’t actually matter, because the hybrid system it’s attached to prevents it from running at low load), and Toyota has the 1NR-FKE at 38% efficiency in full Atkinson operation, making 98 hp out of a 1.3. Oh, and that 40% efficient 2ZR-FXE and 38% efficient 1NR-FKE are port injection.

bhtooefr > bhtooefr 09/07/2016 at 03:30

0

Oh, I forgot one thing - EGR. That can be used to replace intake air while reducing pumping losses, and also reduce cylinder temperatures if it’s properly cooled. (Interestingly, through exhaust cam timing, it can also be used to accelerate warm-up, by sucking hot exhaust gases back into the cylinder during the intake stroke.)

FSI - alcohol enthusiast with a car problem > bhtooefr 09/07/2016 at 04:13

0

VW increased the displacement of their 1.4 tsi engines to 1.5l, no big difference but the trend goes towards upsizing. I still think that particulate filters for gas engines will come though, Mercedes will offer them in the upcoming S-Class refresh.

Cé hé sin > FSI - alcohol enthusiast with a car problem 09/07/2016 at 04:57

0

Particulate filters for petrol engines are already here, or coming - VW are going to start fitting them and they won’t be the only ones.

Here

Cé hé sin > bhtooefr 09/07/2016 at 05:01

0

Interestingly, Toyota are doing the same. They’re switching to BMW diesels in the short term rather than developing their own because they don’t think small diesels have along term future.

Meanwhile Ford have just introduced a new 2.0 diesel, the Eco Blue

FSI - alcohol enthusiast with a car problem > Cé hé sin 09/07/2016 at 05:12

0

About time. I wonder if there will be any incentives like with diesel particulate filters from a few years back like in Germany.

bhtooefr > FSI - alcohol enthusiast with a car problem 09/07/2016 at 09:11

0

Yeah, I don’t mean upsizing a 1.4 TSI to a 1.5 TSI (although they did also Atkinsonize, nice touch).

I mean upsizing a 1.4 or 1.5 TSI to a 1.8 or 2.0 FSI.

FSI - alcohol enthusiast with a car problem > bhtooefr 09/07/2016 at 10:28

0

I’m not too sure if turbochargers will fade away anytime soon but I really like Mazda’s approach with N/A engines.

Mercedes Streeter > bhtooefr 09/07/2016 at 13:17

0

I was curious as to why the Renault/smart alliance didn’t have an answer to the “why no diesel” question for the new Twingo/smart fortwo/forfour, and I guess here is our answer!

bhtooefr > Mercedes Streeter 09/07/2016 at 13:48

0

Also, the turbo engines being used likely get near-diesel NEDC results anyway, for less money, although real world won’t be the same.

Mercedes Streeter > bhtooefr 09/07/2016 at 14:55

0

Indeed! The W451 smart cdi engine sipped tiny amounts of diesel, barely puffed out any emissions, and achieved an insane level of fuel economy.

The engines currently residing in the new Twingos, forfours, and fortwos are more of an evolution of the old W451 petrol engine than anything remotely like the old diesel...which is to say, is heartbreaking. Gone are the days of 80+ US MPG and records for incredibly low emissions. For all of the awesome things that came out of the smart (Daimler)/Nissan/Renault partnership, the new engines aren’t the hottest things ever.

bhtooefr > Mercedes Streeter 09/07/2016 at 15:31

1

Well, it depends on what you define as low emissions.

The OM660 had very low CO2 emissions... but that just means that it had low fuel consumption, really.

The versions used in W451s probably had pretty low particulate emissions, they had DPFs after all. But, there’s the durability problem with DPFs...

However, as far as nitrogen oxide emissions, the OM660 was almost certainly dreadful. No form of aftertreatment that I’m aware of, just EGR and a diesel oxidation cat, means that you’re going to spew NOx. And, that’s the problem with any lean burn engine, really, and diesels have to be lean burn, essentially.

Mercedes Streeter > bhtooefr 09/07/2016 at 15:41

0

Despite being an encyclopedia on smarts, the diesel engines were something I still didn’t know much about (due to smart USA’s aversion to bringing the diesels here, much less acknowledge their existence), but now I do! Thanks! :D

So, what you’re effectively saying is that the new turbo engines should be about as “efficient” as a diesel would have been, but with the minor trade off of lower economy?

bhtooefr > Mercedes Streeter 09/07/2016 at 17:38

1

To the contrary.

I suspect that the new turbo engines have pretty dreadful thermal efficiency at high load, because they’re having to enrichen the mixture to avoid detonation.

However, on the European fuel economy tests, which are extremely gentle on the throttle (because they were designed so a 1970s European city car could actually pass the test without failing due to insufficient acceleration) and therefore will never get into boost, they’ll do nearly as well as diesels (especially when looking at CO2 emissions, as diesel emits about 12-14% more CO2 per gallon/liter/whatever (it also has 12-14% more energy per gallon/liter/whatever)), for far less money than an emissions-compliant diesel. In the real world, they won’t get anywhere near that efficiency, and the current US fuel economy test cycle is far more aggressive too. And, European fuel economy tests are being redesigned to be more aggressive (and if a car is too slow to pass the test, it gets a slower portion of the test repeated instead, so extremely slow cars can still be made, without compromising the test for normal or fast cars).

(Mind you, there are ways to get near-diesel efficiency out of a gasoline engine in the real world, but they don’t involve turbocharging, IMO.)

Mercedes Streeter > bhtooefr 09/07/2016 at 22:49

0

Ugh...none of that sounds great. :(

Hopefully these new engines will be more reliable than the old Mitsubishi plants?