Friday 5th September 2008

Oil burner Impreza makes debut

Subaru equips the Impreza with it's horizontally-opposed diesel engine

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Subaru Impreza's new oil burner model is to be unveiled at the Paris Motor Show next month. That's when the firm will also show off its Boxer diesel engine, which is also going into its new Forester model.

Car fans at the show will also get to see a Subaru Impreza WRX2008 replica plus the Subaru R1e and G4e electric cars. There will also be a 50th Anniversary Display showcasing the original Subaru 360 minicar.

As for the Impreza and Forester, they will feature Subaru’s new 2.0 litre motor which is the world’s first horizontally-opposed diesel engine for a passenger car. It first appeared in the Legacy and Outback earlier this year.

The new Forester Boxer Diesel goes on sale in the UK later this month and the Impreza Boxer Diesel in January 2009.

[ScoobieWRX]

I just want Subaru to manufacture a 250/260bhp 4pot oil burner motor, shoehorn it into a WRX with with 320-340lb/ft torque available from 1200rpm, with proper brakes and suspension, and a 6spd paddleshift transmission for an easy crawlling in traffic.

Then i'll buy one even if it is uglier than my Bugeye wagon!!

[Richiefly]

A Subaru dealership told me a few months ago that they were indeed planning a 300BHP diesel variant to introduce to the WRX, replacing the petrol line altogether. He even suggested that the rev/torque band would be something approaching the petrol version too (i.e. 7k ish of usable rev range in a diesel!) Whether true or not, it works on paper and the torque potential would be huge! My 2.0TD Volvo S40 has 136bhp with something like 250lbs/ft torque - which is more than my WRX running 265bhp had! It pulls like a train and manages 0-62 in 8 secs. Imagine what the diesel WRX could do with 300bhp and something like 400lbs/ft torque!

[3doorPete]

Wonder what it will sound like? Will it still have the off beat noise, albeit with a diesel clatter as well?

[ScoobieWRX]

My mouth is watering at the prospect of 300bhp and mountain pulling torque

Just what i need as a tow car when i retire my wagon to track/sprint it. Yes please!!

[megab]

http://www.autocar.co.uk/CarReviews/FirstDrives/Su...

Autocar's review of Subaru's first diesel boxer; sounds pretty good!

[ChrisD]

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

[Richiefly]

ChrisD said:

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

hey, don't shoot the messenger!

[cowellsj]

3doorPete said:

Wonder what it will sound like? Will it still have the off beat noise, albeit with a diesel clatter as well?

You ever heard a Scania V8 Diesel with a straight through pipe? Few clips on youtube. If there is ever evidence that diesels can sound as good as petrols this is it for me. They make a great sound under load just as a big petrol V8 does.

So a derv flat 4 could and should sound half decent with the right pipe on it.

Edited by cowellsj on Friday 5th September 15:19

[Jenny Tills]

I always thought the problem with diesel engines is that they were heavy being (cast iron?) to cope with the higher compression ratios. I admit this ones horizontally opposed so the CofG is lower but isnt that going to mess up the handling? I wonder if theyll get around it by putting the battery in the boot!

[Welshbeef]

ChrisD said:

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

Latest 330d released this month 245bhp one revs to 5,400rpm.. it wasnt that long ago that the 204bhp 330d would rev to 4,500rpm only.

Given time + R&D diesels will get bigger rev ranges however that totally takes away the point of a diesel they are high torque engines at low revs therefore ideal for very high gearing thus low fuel consumption & its also a much more efficient "burn".

[megab]

According to autocar, the engine is smaller than the 2l petrol and has the same weight.

[rovermorris999]

''I always thought the problem with diesel engines is that they were heavy being (cast iron?) ''

All alloy. Have a look here:
http://www.subaru.co.uk/Subaru_co_uk/ViewMenu.qed?...

[tomTVR]

Im sure i read a review of this engine a couple of months ago and it was a bit naff. I would like the legacy saloon if they put a flat 6 derv in it.

[rovermorris999]

That's funny, I read a review and it said it was good!

[ChrisD]

Well, I guess the problem is not to get the engines running that fast - with adequate materials and decent construction obviously a diesel engine is just as able to withstand 6 or 7k rpm as, say, a beefy turbo petrol engine or a pushrod V8. However, the problem of engine efficiency remains. In every petrol engine your ECU fires the sparks earlier with increasing engine speed to compensate for the smaller amount of time there is to combust. In a diesel engine, you just can't do that, as you have virtually no control over the ignition timing. So you lose efficiency and ultimately power, as the fuel combustion takes place later and later in the combustion circle - until it ultimately brakes the movement of the piston on the upward (exhaust) stroke more than it accelerates it on the downward combustion one - sounds painful, doesn't it?

All the nice improvements of the diesel engine made so far fall short of providing a flexible way to control ignition timing - but I would love to get corrected on that!

Chris

Edited by ChrisD on Saturday 6th September 01:23

[sniff diesel]

Welshbeef said:

ChrisD said:

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

Latest 330d released this month 245bhp one revs to 5,400rpm.. it wasnt that long ago that the 204bhp 330d would rev to 4,500rpm only.

Given time + R&D diesels will get bigger rev ranges however that totally takes away the point of a diesel they are high torque engines at low revs therefore ideal for very high gearing thus low fuel consumption & its also a much more efficient "burn".

My 1997 325 tds will rev to 5k freely.

[Fire99]

sniff diesel said:

Welshbeef said:

ChrisD said:

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

Latest 330d released this month 245bhp one revs to 5,400rpm.. it wasnt that long ago that the 204bhp 330d would rev to 4,500rpm only.

Given time + R&D diesels will get bigger rev ranges however that totally takes away the point of a diesel they are high torque engines at low revs therefore ideal for very high gearing thus low fuel consumption & its also a much more efficient "burn".

My 1997 325 tds will rev to 5k freely.

i find that one strange.. I've driven many diesels since the mid 90's and most of them would rev to 5k.. admittedly with varying degrees of smoothness.

[morgrp]

Fire99 said:

sniff diesel said:

Welshbeef said:

ChrisD said:

Hmm, I sort of doubt the above statement of 7k revs in a Diesel. After all, at that speed the (self-)ignition delay of the diesel fuel is too long to warrant efficient combustion. Or were you being sarcastic?

Chris

Latest 330d released this month 245bhp one revs to 5,400rpm.. it wasnt that long ago that the 204bhp 330d would rev to 4,500rpm only.

Given time + R&D diesels will get bigger rev ranges however that totally takes away the point of a diesel they are high torque engines at low revs therefore ideal for very high gearing thus low fuel consumption & its also a much more efficient "burn".

My 1997 325 tds will rev to 5k freely.

i find that one strange.. I've driven many diesels since the mid 90's and most of them would rev to 5k.. admittedly with varying degrees of smoothness.

My Audi 1.9 TDI revs to just under 5k but I get barely anymore performance at those revs than if I only rev to about 4k

[rovermorris999]

I think a contributing factor is the speed at which diesel burns, it's much slower than petrol, so really high revs achieve little as there isn't sufficient time for the fuel to burn efficiently.
Out of interest, does anyone know what revs the Le Mans-winning Audi diesels pull?

[ScoobieWRX]

Le Mans Diesels are 4,500rpm i believe. Please correct me if i'm wrong