14:1 is the magic number!

Tea 1000

Interesting article.

http://www.autocar.co.uk/blogs/anythinggoes/archive/2011/08/31/mazda-maps-out-its-future-with-cx-5.aspx

by managing to give both the 2.2-litre diesel engine and 2.0-litre petrol engine the same compression ratio – just 14:1 – the company can produce both engines on the same production line

I don't really understand this to be honest, surely the line would still need to be fully flushed before manufacture of the petrol engine stops and the diesel commences?

SouperComputer

RoverJames wrote: »

by managing to give both the 2.2-litre diesel engine and 2.0-litre petrol engine the same compression ratio – just 14:1 – the company can produce both engines on the same production line

I don't really understand this to be honest, surely the line would still need to be fully flushed before manufacture of the petrol engine stops and the diesel commences?

Flushed of what exactly? There's no fuel involved in the motor assembly process.

Mazda are a way underrated car company IMO. They should put their prices up so they can sell more!

VolvoMan

Mazda are definitely one of Japan's most underrated car manufacturers.

Honda have lost the plot and I don't think there is any place for them in the world anymore.

pajo1981

Often smaller companies are more agile and innovative. Nothing unusual about this.

Using the skyactiv thing to kill two birds was very neat all the same.

Matt Simis

LIGHTNING wrote: »

Its stuff like this that really that really shows how Mazda is different type of car company. They have no problem trying out new technologies or bucking the trend by forcing the designers to make the new models lighter than the old ones. I would doubt that they have an enormous research budget like BMW/Mercedes have.

I think thats an optimistic way of looking at it. The way I see it they have stretched and fudged 2 "opposed" engines and made one core block to save on production. Its the move VW or BMW would not make as clearly a 14:1 Compression ratio in a Diesel is kinda crap and in a petrol will put huge strain in ignition systems and preclude low quality (sub 95octane anyhow) fuel entirely.

Its a great example of cutting corners.

MetzgerMeister

Or maybe Mazda thought of this and engineered a solution? They did that with the 13B Renesis engine, why can't they do it with a piston engine?

Anan1

Matt Simis wrote: »

Its the move VW or BMW would not make as clearly a 14:1 Compression ratio in a Diesel is kinda crap

I think it might be ok in a turbocharged diesel engine. I do share your concern that, as a solution, it seems to favour cost at the expense of engineering integrity, though.

Matt Simis

einheisserschre wrote: »

Or maybe Mazda thought of this and engineered a solution? They did that with the 13B Renesis engine, why can't they do it with a piston engine?

Oh jesus not that again! Let stick to piston engines and not tangent into the is the great or not wankel talk. Even if you buy into Rotary, the science behind that doesnt in any manner help a completely different set of Mazda engineers make a decent diesel engine.

Anan1 wrote: »

I think it might be ok in a turbocharged diesel engine. I do share your concern that, as a solution, it seems to favour cost at the expense of engineering integrity, though.

A turbo on a diesel doesnt change its compression ratio design per say, as diesels dont have detonation.
http://en.wikipedia.org/wiki/List_of_Volkswagen_Group_diesel_engines

Most (turbo)diesels are 20-25:1. Compression ratio = efficiency.
Making a 14:1 Ratio diesel is simply going the wrong way, its basically the major advantage diesel has over Otto engines near completely removed.

This is a solution for accountants, not drivers people!?


PS: The 12year old Audi 2.7t engine block was rumoured to be a diesel design converted to high PSI (ie RS4) boosted petrol. In Audi's case they took advantage of the high compression (note that the engine was way lower compression but boosted) offered by an iron diesel like block to make a great petrol engine. So if anything this was already done better over a decade ago.
Regardless, in Mazda's case, it appears they crippled a diesel to work at low compression and fine tuned a petrol to work at high compression.

SouperComputer

SouperComputer wrote: »

Flushed of what exactly? There's no fuel involved in the motor assembly process............

I wasn't on about fuel. The petrol blocks and the diesel blocks will require different ancillaries, not to mention heads etc to be added, I can't see how it's hugely advantageous making the blocks on the same line and then transferring them to the petrol engine and diesel engine lines. They are hardly making the engines on the same line without some sort of line flush in between batches of petrol and diesel engines. Admittedly they are saving on tooling and that sort of stuff for the manufacture of the blocks but it doesn't seem hugely advantageous considering the different applications the blocks are then used in.

Defo seems a Lean technique, many companies are going the Lean route now, and it's biting many in the arse soon after.

Anan1

I'm not really sure I can see the advantage here at all. Engines can share the same block and still have different compression ratios - all it takes is a different crankshaft, or even cylinder head, no?

bijapos

RoverJames wrote: »

I wasn't on about fuel. The petrol blocks and the diesel blocks will require different ancillaries, not to mention heads etc to be added,.

It saves on a lot of things such as factory space and makes the system more flexible, they can simply up the amount of petrol engine production without moving people from line to line. Its the done thing in car manufacturing, putting different ancilliaries on to the engine is easily done, after all every car that goes down a production line gets different paint colour, different extras, interior trim etc., its just taking the whole process a step further.

I knew an engineer in Munich about 15 years ago who worked in R&D for BMW, they had something like 84 different rear diff combinations across all models, their job was to reduce this to 17. They had 10 years to do it.

Same goes for platforms, know how many cars are built on the VW groups A5 platform? 20. That means huge savings long term.

• Audi A3 Mk2 (8P)
• Audi TT Mk2 (8J)
• Volkswagen Touran (1T)
• Volkswagen Caddy (2K)
• SEAT Altea (5P)
• Volkswagen Golf Mk5 / GTI / R32 / Rabbit Mk5 (1K)
• Škoda Octavia Mk2 (1Z)
• Volkswagen Golf Plus (5M)
• SEAT Toledo Mk3 (5P)
• Volkswagen Jetta Mk5 (1K)
• SEAT León Mk2 (1P)
• Volkswagen Eos (1F)
• Volkswagen Tiguan (5N)
• Volkswagen Scirocco (13)
• Volkswagen Golf Mk6 (5K)
• Škoda Yeti (5J)
• Škoda Superb (3T)
• Audi Q3
• Volkswagen Jetta Mk6 (NCS)
• Volkswagen Beetle (2011-)

challengemaster

mazda are crazy in terms of the stuff they'll do to save weight - shaving the smallest of pieces off every single part in the car, using new metals to save weight...

there was a video I saw about the mazda 2 that detailed everything they did to save weight.... can't find it now though

Hiace.

Any pics / vids of this common platform ?

shamwari

Matt Simis wrote: »

Most (turbo)diesels are 20-25:1. Compression ratio = efficiency.
Making a 14:1 Ratio diesel is simply going the wrong way

Not necessarily if you you are using a blower. A lower compression engine will accept forced induction much easier...

Matt Simis

shamwari wrote: »

Not necessarily if you you are using a blower. A lower compression engine will accept forced induction much easier...

Agreed, but we are talking about diesels.. that logic is not really relevant.
I already linked to a list of turbo diesels which shows the "norm" for compression ratio.
For the sake of clarity we assume all diesels are blown turbo diesels. Since detonation/knock isnt a problem on diesels, they historically have both high compression and high boost, which isnt possible on petrol.

Anan1

Matt Simis wrote: »

Agreed, but we are talking about diesels.. that logic is not really relevant.
I already linked to a list of turbo diesels which shows the "norm" for compression ratio.
For the sake of clarity we assume all diesels are blown turbo diesels. Since detonation/knock isnt a problem on diesels, they historically have both high compression and high boost, which isnt possible on petrol.

I didn't read through the entire link you posted, but here is one interesting extract:

2.0 R4 16v TDI CR 81-132kWidentification
parts code prefix: 03L, ID codes: CAGA, CAGC, CAHA, CBAA, CBAB, CBBB, CBDB, CBDC, CEGA, CFCA, CJAA
engine configuration & engine displacement
inline four cylinder (R4/I4) Turbocharged Direct Injection (TDI) turbodiesel; 1,968 cubic centimetres (120.1 cu in); bore x stroke: 81.0 by 95.5 millimetres (3.19 in × 3.76 in), stroke ratio: 0.85:1 - undersquare/long-stroke, 492.1 cc per cylinder, compression ratio: 18:1 (103 kW), 16.5:1 (125 kW)

It seems that the more powerful version has a lower CR. I'm not an engineer, but are you sure that this isn't to allow higher boost pressures?

Matt Simis

Anan1 wrote: »

It seems that the more powerful version has a lower CR. I'm not an engineer, but are you sure that this isn't to allow higher boost pressures?

Possibly, could also be they reduced the weight in the block too and had to scale compression back a notch. Or any number of things!
FWIW: The V10TDI 5.0 is 18:1 and the V12TDI 6.0 is 16:1.
So if the mega diesels still achieve higher than 14:1 compression, what are Mazda at? Oh thats right, making their assembly line marginally cheaper to run. :pac:

I think people are somehow thinking that making lower compression is a good thing.. its not at all.

VolvoMan

bijapos wrote: »

Same goes for platforms, know how many cars are built on the VW groups A5 platform? 20. That means huge savings long term.

It's also stretched to underpin the Passat and Superb.

VW are truly the masters of platform sharing.

challengemaster wrote: »

there was a video I saw about the mazda 2 that detailed everything they did to save weight.... can't find it now though

I think it's currently their advertising campaign on some channels.

Hiace.

Hiace. wrote: »

Any pics / vids of this common platform ?

It's a floor pan, google is your friend for that.

Anan1

Matt Simis wrote: »

Possibly, could also be they reduced the weight in the block too and had to scale compression back a notch. Or any number of things!
FWIW: The V10TDI 5.0 is 18:1 and the V12TDI 6.0 is 16:1.
So if the mega diesels still achieve higher than 14:1 compression, what are Mazda at? Oh thats right, making their assembly line marginally cheaper to run. :pac:

I think people are somehow thinking that making lower compression is a good thing.. its not at all.

I'm suspicious myself, but i'm wondering whether it's possible to just scale up boost to compensate for a lower 'mechanical' compression ratio?

Bearcat

To think Mazda were producing the 787b race car 21yrs ago which was a marvel of wankel technology..."..the same car today leaves me gob smacked and weak too with that glorious engine noise.

I agree with a lot of posters here, Mazda engineers are some of the finest brains around.

Bearcat

There's an older vid on u tube of a 787b warming up with a crowd around it. Just listen to the jap engineer rev her to a crescendo.....big crowd applause. Sounds even better with a glass of wine on board and headphones on!

Fishtits

If you do the maths on this you'll find that 14:1 won't ignite diesel, ie it wouldn't start. There's summat else to this that we're not being told...

172 BHP from a 2.2 litre is not exactly earth shattering when compared to its peers, although its far from a laggard either. Anyone have the emissions?

I'm not really a fan of many boring Mazda cars but I do admire their seemingly engineers ahead of beancounters mentality for some offerings.

Good luck to them I say.

SouperComputer

I think a lot of posters here are overly focussed on static or "mechanical" CR's and not so much on dynamic/effective ones which are especially relevant on a boosted engine.

Of course that raises the question of how they plan start the diesel engine, but I seriously doubt they would make an announcement if they were on the fence as to how they would get it fired up. Maybe it uses compressed air from a resovoir or a collosal amount of heat from glow plugs, or some sort of compression varyance system. 14:1 is right on the borderline for diesel self-ignition so it mightn't take much to give it that extra shove to ignite.

Pdfile

LIGHTNING wrote: »

Its stuff like this that really that really shows how Mazda is different type of car company. They have no problem trying out new technologies or bucking the trend by forcing the designers to make the new models lighter than the old ones. I would doubt that they have an enormous research budget like BMW/Mercedes have.

they had fords support and afaik they have a big stake still ??

whatever mazda does ford will surely re badge in a few years time ?

tobsey

Compression Ratio ≠ Pressure

Tea 1000

I think a lot of posters here are overly critical of Mazda. Possibly the same ones who'd applaud BMW or Audi for doing something similar.
I think Mazda are very innovative, and I've no doubt they'll make this work quite well. How well remains to be seen, but fair play to any company for trying.
And as for bashing them for saving money, sure isn't that what they all do? Every single manufacturer does that. Every car is compromised to some degree to save money.
It also seems that the better the diesel engine, the lower the compression ratio. Newer and better engines mostly seem to have lower CR than previous ones. I'm not an engineer obviously, but maybe there is merit to Mazda's methods.
I for one are firmly in the pro- camp until I see evidence to prove otherwise.

Anan1

Tea 1000 wrote: »

I for one are firmly in the pro- camp until I see evidence to prove otherwise.

Surely that's as bad as being in the 'anti' camp without evidence?;) Me, i'd like more information!

tobsey

Tea 1000 wrote: »

It also seems that the better the diesel engine, the lower the compression ratio. Newer and better engines mostly seem to have lower CR than previous ones. I'm not an engineer obviously, but maybe there is merit to Mazda's methods.

Exactly. Isn't the whole idea of CR diesels that they inject the fuel at a much higher pressure therefore less compression is required for ignition. It's also why the old PD engines can burn chip fat and pretty much any other liquid that will ignite.

Tea 1000

Anan1 wrote: »

Surely that's as bad as being in the 'anti' camp without evidence?;) Me, i'd like more information!

Maybe you're right, but at least we have camps! You stay out there in your "nothing"!