Smaller engines

Goudy

People tend to forget/ignore that small turbo engines may be as thirsty as larger, non turbo engines at times.
Increase the air entering the cylinders means increasing the fuel injected.

On boost your 1 litre turbo is forcing in the sort of air a 1.6 or bigger non turbo engine would suck in, so will inject fuel for all that air.

There have been more than a few complaints regarding some bigger bodied cars with smaller turbo engines returning really poor mpg as they inevitably have to run harder,  "on boost" to move them. Hence all the references to lots of gear changes.

Mazda have taken a different approach with the Skyactiv engines.
They have tended to stick with larger petrol engines but refined and engineered them to run really efficiently. By increasing compression, improving exhaust scavenging and with the newer ones, using compression ignition they tend to return great mpg and with them having less parts, like turbos tend to be really reliable.

They have also used the same philosophy on their diesel engines and used some clever engineering to solve some emission problems.

tiger135

i like that idea by mazda. when did they start doing that and on which models?
my friend has just got a fiesta 1l ecoboost so will be interesting how he gets on.
im not a fan of turbos, dont need the performance. having the extra valves is enough for me, the power is there if you need it higher in the rev range. 

saker75

Yes, I’m looking at the Mazda 2.2l engines which are Euro 6. I don’t think I can trust the smaller engines.

Goudy

Mazda have been at it a good few years.
They call there engines Skyactiv or Skyactiv-D (diesel) and over the years have been improving on it.

I had a Mazda CX3 with a 2.0 litre Skyactiv G petrol engine on a long term loan a few years ago and it ran lovely.
It rarely dropped below 46-48 mpg and on a decent motorway cruise would hit 52 mpg easily.

It wasn't blessed with lots of grunt, it had enough but it was super smooth and quite refine

I seem to remember a version of the 2.2L Skyactiv-D was used in motorsport in the USA.
It was in a "GX" or alternative fuel class in their 2013 Sports Car series ran in places like Daytona, Indianapolis, COTA and Laguna Seca and I think it won it's class.

saker75

Thanks Goudy. I’m considering the CX5 which I think also has a 2.2l. 

Stubod

I test drove a Mazda 2.0 litre (cx5 I think), lovelly car but being non turbo it did seem to lack the "grunt" associated with a larger engine.

Nebulous2

Cars with small turbo engines are odd to drive coming from something bigger, and although they have the power they do have different characteristics. Slowing to a crawl at a junction requires a move to 1st gear to avoid stalling, where a bigger engine is happy to continue in 2nd. Part of that is a smaller flywheel with less momentum. 

I had a sub-1 litre petrol Dacia Logan, and towed 1000 kilos of caravan for thousands of miles, including over some mountain passes in the South of France. It did need revving, but it did the job. 

I've now got a diesel Renault Trafic turbo, towing 1600 kilos of caravan, and get better mpg in a much heavier outfit than I did with the Dacia. Even it is only a 1600 engine. 

Goudy

Stubod said:

I test drove a Mazda 2.0 litre (cx5 I think), lovelly car but being non turbo it did seem to lack the "grunt" associated with a larger engine.

Yes, their actual capacity is 2 litre but they have engineered them to run as clean and efficient as smaller engine cars, so they don't feel like 2 litres.
I reckon the CX3 I had felt like a 1.6.

They have downsized emissions and improved mpg without downsizing capacity.

I don't really know much about the diesel versions, but I think they have reduced compression ratios and used a variable lift exhaust cam which can open on the intake stroke.
This will reduce some pump losses but it also increases air temp in the combustion chambers which help with a cleaner burn of the fuel.

I gather Mazda keep a lot of what they have done under wraps, but it all seems to work well and appears quite reliable.

jimbo6977

We switched to a 1l Skoda Octavia estate recently and find it's very smooth, quiet and has plenty of get up and go if you want/need although it's built for economy, which it's very good at when driven smoothly.

We also test drove the Hyundai i30 tourer with an equivalent 1l engine, which sounded rough, harsh and overworked in comparison. So like with most things I guess there are better and worse in all categories. 

Toyota have been pumping out 1.8 hybrids for years, returning impressive economy, so maybe that's an interesting middle ground. 

zzzt

I live in a very hilly area. In my previous car I was struggling to get up hills, often having to move down a gear or even go up them in first gear. If I had to stop it was disastrous and I would be incapable of getting any momentum again and have to crawl up at 10mph or less.

It was for this reason that I bought a new car, but I didn't go for a much bigger engine, just a 1.2L petrol hatchback which has 110PS. I'm finding it to be fine on the hills, there was no need for a more polluting or uneconomical engine. With the turbo you can feel it has more acceleration and I can go up hills in a higher gear and if I have to stop, I can accelerate and build up speed again on the hill.

Try taking the car on a test drive on a steep hill and bring people with you to see how it performs under load, that's what I did.

Of course, if you want to be absolutely sure you have the power then just go for the bigger engine and pay more tax.