Interesting to read the 5* rating that the 1.5 SE Estate writup in Auto Express today.  I placed an order for a 1.4 DSG SE L Estate last month.  I seriously considered a 1.5 at only £300 more, but the improved MPG figures are only marginal and in any case, who believes published MPG figures?  What finally put me off a 1.5 was that the PCP Guaranteed Future Value (GFV) was actually £800 LESS than the 1.4!  What do the actuaries who calculate GFVs know that perhaps buyers don’t?  With the possible exception of company car drivers who may gain significantly from a more favourable benefit in kind allowance, I struggle to see the advantages of a ‘less proven’ 1.5 over a ‘tried and tested’ 1.4 which has exactly the same power and toque output.

The 1.5 I have driven was so smooth and effortlessly went from running from 4 cylinders to 2 then back again. 

It is really refined and feels nippy.

If I had to choose I’d be going for the 1.5 everyday of the week. 

I'd be concerned about the effect on the crankshaft and engine bearings etc. with switching between 4 and 2 cylinder operation. The vibration modes must be different.

I'd a 3 cylinder K75 BMW motorcycle that was basically a cut down version of the 4 cylinder K100. However the K75 had a chain driven balancer system to dampen out the different vibrations.

Just a gut feeling.

And if the 2 cylinder operation does not produce any "real world" improvement in mpg, then what's the point? Is it the emissions caper all over again?

Didn't Fiat produce a 2 cylinder version of the current 500 which could get worse mpg than the 4 cylinder version?

1 hour ago, Tim1631 said:

The 1.5 I have driven was so smooth and effortlessly went from running from 4 cylinders to 2 then back again. 

It is really refined and feels nippy.

If I had to choose I’d be going for the 1.5 everyday of the week. 

But did you a try a 1.4 too?  I have a Yeti with the 150 BHP 1.4 and would say the same about its refinement and nippyness.  There was no 1.5 available for me to test and compare with though, which was a pity.

Edited 18 October, 20178 yr by Falmouthboy

How different is the 1.4 compared to the 1.5 mechanically? 

Is it not just bored out slightly?

Slightly longer stroke?

Would the VAG develop a complete new engine 100cc bigger?

I am waiting for my 1.4 DSG SEL Executive Superb Hatch to arrive.

13 hours ago, vfrvrs said:

How different is the 1.4 compared to the 1.5 mechanically?

The biggest difference is that the 1.5 has ACT (Active Cylinder Technology) which will run on only 2 cylinders under light loads, so the camshafts are completely different and the engine ECU is different too.

Plus its a VGT, Variable Geometry Turbo.

 

 

VGT and variable compression ratio can reduce lag and improve efficiency, but they add complexity and reliability of the new 1.5 is unproven. One well-respected review site failed to complete their 1.5TSI test because the new engine failed and stuck within limp-mode.

 

If you only intend keeping the car for 3-years or less then there is not too much to worry about due to warranty. After 3-years it'll be higher risk than the 1.4. 

Edited 19 October, 20178 yr by Orville

15 minutes ago, Orville said:

One well-respected review site failed to complete their 1.5TSI test because the new engine failed and stuck within limp-mode.

 

 

Why don't you name your source? Then we can decide for ourselves if it's well respected.  

I think there have been versions of the 1.4 with ACT.....In the Superb unless I'm very much mistaken, so the 1.5 is more evolution than revolution.    

Plus the Miller combustion cycle. Whether that helps the emissions or the mpg, who knows. The Miller cycle has been used in various vehicles,  without obvious day to day gains.

1 hour ago, juan27 said:

 

Why don't you name your source? Then we can decide for ourselves if it's well respected.  

Carwow. I think it's now the biggest UK Car review channel by views. The car was a Seat Ibiza, but same VAG 1.5 TSI engine. It's pretty rare to find any (non-supercar) engine failures during new car tests. 

1.5 TSI Engine Fault

 

Edited 19 October, 20178 yr by Orville

45 minutes ago, Orville said:

Carwow. I think it's now the biggest UK Car review channel by views. The car was a Seat Ibiza, but same VAG 1.5 TSI engine. It's pretty rare to find any (non-supercar) engine failures during new car tests. 

1.5 TSI Engine Fault

 

 

Thanks for sharing, I wonder if the engine had been left in transport/delivery mode?. Whilst embarrassing for SEAT I'm not sure its evidence of widespread problems with the new engine.  

 

Edited 19 October, 20178 yr by juan27

I found a quoted VW press release, stating that the theoretical emissions and power improvements of the Miller cycle do not appear under test conditions. But the improvements are apparent when driving.

Oh really? Homeopathic snake oil ..

8 minutes ago, gregoir said:

I found a quoted VW press release, stating that the theoretical emissions and power improvements of the Miller cycle do not appear under test conditions. But the improvements are apparent when driving.

Oh really? Homeopathic snake oil ..

 

The press seem quite keen on the 1.5 so maybe a grain of truth.

 

I thought a true Miller Cycle engine needed a mechanically driven supercharger to provide boost at low revs so I was quite surprised the Evo is a Miller Cycle engine.

3 hours ago, juan27 said:

I think there have been versions of the 1.4 with ACT.....In the Superb unless I'm very much mistaken, so the 1.5 is more evolution than revolution.    

I am sure the 1.4 is ACT as I looked it up in the brochure when I was deciding. 

Are these cycles just delayed/longer valve open times?

I think engine tuners have been messing about with this for decades? 

Edited 19 October, 20178 yr by vfrvrs

The interesting bits on the 1.5 are variable geometry turbo and extremely high compression ratios.

15 minutes ago, vfrvrs said:

I am sure the 1.4 is ACT as I looked it up in the brochure when I was deciding. 

Try looking at the top of the 1.4 engine in an Octavia (easy enough as Skoda don't fit a cover like VW or Audi do) - you won't see the solenoids that deactivate 2 of the cylinders, they're definitely not there on my 2015 1.4TSI.

I haven't got the car yet, two weeks away but here is the brochure picture.

 

That’s a Superb brochure though...

Bearing in mind that VAG no longer adequately test and develop at prototype stage, I would be letting other folk be the guinea pigs for the 1.5. In a couple of years we will know what the score is.

The 1.4tsi engines fitted to the Octavia mk3 have never had ACT functionality, however the ACT versions are fitted to the Superb mk3.

Neither versions have had major widespread issues reported in theses forums and even minor issues are rare.

My own experiences with a manual 2013 1.4tsi Octavia are all positive. Good performance and easily able to achieve the claimed official consumption figures if driven sensibly.

Unsurprisingly if driven hard the figures are less and if driven with care, or ideal conditions then the official figures can be improved upon.

 

My 1.4tsi is to Euro 5 standards, and the increasing government pressures to achieve even greater efficiency and improved environmental performance require a lift in engineering.

I suspect the increase in volume from 1.4 to 1.5L is as much to do with marketing as engineering as the new engine represents a technological leap providing the base for the next generation of engines.

The variable turbo fitted is only the second in a production petrol engine (Porsche the first), ACT is proven tech in the current 1.4, and the other technical bits mentioned by others show how advanced the engine really is. 

The old 1.4 was designed with the previous consumption and environmental tests and the new 1.5 for the new formats and requirements, so I believe there should be real improvement in both with the new engine especially since it offers no real output or performance improvements on the older design.

Since the max torque is still 250NM the DSG box fitted is the old (if updated) 7 speed dry box. There was some confusion in early reports/reviews of using a 'wet' box, probably because the journalists thought the new 7 speed 'wet' DSG fitted to higher output units had been fitted.

 

The new 1.5tsi unit is not available in Australia and I think it may be due to the current high Sulpher content of our fuels.

 

 

A poster on here Headinawayofski is fairly certain that the 1.5TSi engine has the wet clutch DSG.

 

Getting mine in a week or so so I will let you know if someone can help me find out by looking.

 

Search for thread:-   Newbie- give me some reassurance!

Edited 23 October, 20178 yr by YMe