New Mazda petrol engine - 86 mpg!

Leonard Hofstadter

And it's not a hybrid, a compromised two or three cylinder or even turbocharged!

Apparently the new Mazda Skyactiv-G engine is good for no less than 86 mpg, but this is in the Japanese fuel consumption tests, and I have no idea how this compares with the EU ones.

Still, for a naturally aspirated four cylinder petrol engine, 86 mpg is an extraordinary result, especially for something that is still reasonably powerful for the engine size (1.3 litres, 84 bhp), it is a big achievement.

Even if it only did say 70 mpg in the EU test, it would still be a big advance on the Fiat TwinAir engine, as that also does 70 mpg, but is a 900cc two cylinder turbocharged yoke whereas the Mazda is a 1.3 four cylinder naturally aspirated engine.

It has a compression ratio of 14:1, amazingly high for a petrol engine, so no wonder it's good on juice!

I just hope Mazda will make it as reliable as their other petrols - it would be a real shame if what seems like a seriously impressive engine was spoiled by unreliability similar to that of their in house diesel disaster.

http://www.worldcarfans.com/111051933522/mazda-introduces-new-13-liter-skyactiv-g-engine---70-mpgs

Anan1

That's a new one, quoting mpg figures for an engine.:D

pajo1981

break it down for us captainspeed. how does it work?

langdang

http://www.mazda.com/mazdaspirit/skyactiv/engine/skyactiv-g.html

Shows some funky flow and piston stuff to achieve 14:1compression without savage knocking. Still dubious whether it will work outside of super high RON Jap petrol!

Joe 90

As far as I know, in Japan they can get decent 100 octane petrol. Would make a worthwhile gain over Europe where 95 is as good as you can hope to get in a lot of places.
Edit to add: Just looked at the link, compression ratio 14 to 1 so would seem to need decent fuel.

opinion guy

Anan1 wrote: »

That's a new one, quoting mpg figures for an engine.:D

Its alot lighter without the car around it :P

Mr Benevolent

It does seem like they're quoting for the engine. I smell bullshit coming from Mazda.

Shows some funky flow and piston stuff to achieve 14:1compression without savage knocking. Still dubious whether it will work outside of super high RON Jap petrol!

Same thing happened with the Mitsubishi GDI engines, they ended up being a disaster in non 100 RON countries.

si_guru

Even if it only did say 70 mpg in the EU test, it would still be a big advance on the Fiat TwinAir engine, as that also does 70 mpg, but is a 900cc two cylinder turbocharged yoke whereas the Mazda is a 1.3 four cylinder naturally aspirated engine.

How is that an advance?

Joe 90

si_guru wrote: »

How is that an advance?

I would suspect that the bigger N/A engine might be easier (cheaper) to live with in the long term. Probably cheaper to produce and possibly lighter as well.

Leonard Hofstadter

si_guru wrote: »

How is that an advance?

I would have thought that was obvious.

A 1.3 litre four cylinder engine that is as economical as a 900 cc two cylinder engine, and is less complex to boot (no turbo).

I am well aware of the disaster that was the Mitsubishi GDI engine, and to be honest I'm not keen on technology for technology's sake - God be with the days when diesels had single mass flywheels and we never heard of DPFs, but a lot of technology in modern car engines is very good - twin cam, multi-valve engines, variable valve timing, Valvetronic/Valvematic etc are all things that make a car faster and more fuel efficient and they don't give any more trouble than eight valve pushrod engines gave.

People talk about the 14.0:1 compression ratio as something to get worried about.

I take the point that perhaps it is optimised for the ultra high octane ratings of Japan, which I why I have to admit I am sceptical that it will actually get 86 mpg in Europe, but even 70 mpg is brilliant for a petrol, and besides we now use E5 petrol (or at least we're supposed to) and that is 99 RON to the best of my knowledge, which is only marginally less than 101 RON used in Japan and is higher than "Super Unleaded", which direct injection petrols need to work to their best.

It could turn out to be every bit as bad as the Mazda MZ-CD diesel or as problematic as the rotary engines, but the reliability of Mazda engines is generally second to none, and I presume that Mazda is like Toyota or any other Japanese maker in that they don't make the same mistakes with engine design twice.

pajo1981

This thing runs at higher compression ratios without the need for high RON fuels.

That's the whole point. :rolleyes:

ed: As for reliability, I don't think that will be an issue.
Look at all of the systems in the doc - they're all passive.

Daegerty

Will it run on E85 too? even though the bastards Fianna Fail forced it off the market

Joe 90

The thing though about the fuels containing alcohol is that they have less calorific value than 'pure' gasoline so although they may be a higher RON equivalent they will contain less energy in the first place.

ShadowHearth

Big improvement on theyr last 1.3 engine which is doing 18 mpg

Jokes aside it's good news. If it's not bull**** then it's more then impressive!

Realistically if 1.3 petrol engine can do solid 55 mpg then they got a winner already. 80? Well that would be just plain awesome, but I would not turn off my bull**** meter just yet...