Yeti no4 ordered

[g6zru]

I'm wondering if the hatched etching (honing) reduced the bore glazing phenomenon of seemingly many decades ago.

Was that not a product of the oils in use at the time?

 

Fred

[Ryeman]

Was that not a product of the oils in use at the time?

 

Fred

I guess so Fred, at least a factor.

My old PRV V6 in my 604 still had them after 400K (kms) and no lip on the bores either .....the liners were boron composite, pity about the nightmare involved in working on it though.

[Sad555]

I thought the honing effect was due to the honing of the bores when the bores/sleeves were honed to a finish size of the Pistons/rings and honing also produces a perfectly round bore to a specific size after the initial maching of the bores,which also reduces the flow of oil past the rings.years ago when new Pistons were fitted in rebored engines they were obtainable in a couple of plus sizes to fit where engines were bored out to remove ware/damage.

[Ryeman]

Sorry for the OT diversion

I thought it was to reduce the potential for glazing and to trap a film of lubricant as a bonus.

[Jimrod]

Just as a quick follow up to the points I'd been making about running in, I did a test yesterday, purely anecdotal and not on a scientific basis due to all the variables but as close as I could get in the "real world". 

 

My friend with exactly the same spec car (L&K 150tdi DSG) works once a week at my office so we both did the 15 mile trip back to hers at the same time, same roads. I'm still trying to get some decent economy so stuck to 70 on the dual-carriageway section (about 2/3 of the trip) while she's impatient and went 80 or just above. She ran her car in as I'd suggested, warming it up when new and taking about 20 mins to put it in "Sport" mode and drive up and down the dual-carriageway accelerating hard and then coasting back down to 50 or so, rinse-repeat (was very late at night so hardly any cars on the road). Mine was run-in for the first 100 miles religiously carefully by the jobsworth driver who didn't want to listen to my suggestions...  :p

 

 

With 550 miles on the clock she averaged 41mpg over that trip, 2/3rds at 80mph, the rest "urban".

 

With 350 miles on the clock I averaged 38mpg over the same trip, 2/3rds at 70mph (I've checked and my figures definitely drop further still at 80mph).

 

 

So while this can never be 100% conclusive I'm just putting the info out there for any who may or may not be interested. Everyone has their opinions but as back up to this running-in theory it seems to bear out in the real world, my friend's car is definitely noticeably more economical than mine all things considered, I don't know if it drives better or worse power-wise but she has no complaints, certainly no harm seems to have been done by this harder running-in process and after-all mine's the one now saying it needs an oil-service! 

Edited 11 December, 2015 by Jimrod

[VAGCF]

As you say we all have differing opinions.

But as well as my earlier comment about running in using the giving it some stick method not being viable due to the synthetic oil being used from manufacture (and mentioned in that link to running in) I also think that the much higher compression of diesels means that the piston rings are pushed hard against the bores anyway.

As you say interesting but as we know two identical cars off the production line can produce different results. And as stated there are too many variables e.g. was everything drawing electrical power used exactly the same in both cars?

I have a 21 mile commute and I only have to alter my driving style slightly and it can easily make a 3 MPG difference.

Edited 11 December, 2015 by VAGCF

[Jimrod]

I'll try to do a like for like test next week just out of curiosity, I can get between 35 and 40 mpg on my daily commute but 40mpg involves a lot of coasting - I've no idea how she can get 41 mpg going 80mph all the way if the cars are identical because that drops me to low 30's! I don't have aircon on and she uses her heated seats too! :\ She does have ESSO diesel in hers and I've no idea what was put in my first tank though, also mine came with Pirelli P7 Cinturato's and hers Goodyear Efficientgrip... As we said, lots of variables...

 

 

*Edit: Even just went to check my tyres in-case they're a bit low - 36psi all round   Now they're 33psi and the ride's a little more comfy at least. 

Edited 11 December, 2015 by Jimrod

[Paul52]

 mine came with Pirelli P7 Cinturato's and hers Goodyear Efficientgrip.

 

Could it be as simple as tyre choice? I recently fitted Michelin Cross Country tyres to replace the supplied Conti Premium Contact 2s fitted at the factory. From my records based on brim-to-brim fills I'm consistently getting 2-3mpg better consumption on the new tyres for the same journeys and as far as I'm aware no change in driving style. the only difference, and this is subjective, is that the car "feels" as though it rolls better on the new tyres.

 

If you neighbour was willing you could repeat your test with each driving the other's car. If the figures stay the same it can't be down to driving style, if her car drops and your car goes up driving style could be a factor.

 

And like VAGCF and Ryeman, my Yeti was cosseted from the day it arrived with a very light foot for the first few hundred miles and after two and half years, a first service at around 16,000 miles and nearly 25,000 miles not a drop of oil used. 

Edited 11 December, 2015 by Paul52

[RickT]

Honing cylinders removes any ovalness and high spots, it also creates a surface (the hatched etching) that retains oil for lubrication and cooling that's perfect for pistons and rings.

 

Running in is basically removing initial high spots on components that create localised high temps and possible seizures and polishing surfaces to reduce friction and premature wear.

 

I had a Moto X bike and the instructions in the manual said; start engine, warm up to running temperature and then allow to fully cool (do this twice) then ride as normal for 10 minutes at no more than half throttle. Your machine is now ready to race. The bikes that were run in like this were always fastest. Then after 40 hours you were expected to rebuild the motor.   

[Nightowl]

Your still not losing as much as you "used" to lose in the old  "because its a skoda" days.

[Ryeman]

Numerous fill-to-fills are needed just to get a reasonable figure for one car.

Comparing 2 on one fill(?) and drawing conclusions about comparative consumption is unrealistic.

[fuzzybunny]

I 'used' to do fill to fill and record on Fuelly and my 170 TDI does 41-42 mpg and my previous 140 TDI did 42-43mpg.

I do lots of motorway and exceed the 70mph more than I ought too!!

I might have gone for third yeti but put off by the rather drab front end of the new model and fancy a change so have been looking elsewhere.

Seriously thinking of a petrol this time after the VW dieselgate issues.

What sort of mpg are folks getting out of the 1.4 petrol.

Edited 18 December, 2015 by fuzzybunny

[Ryeman]

A bit confused fuzzy,

A hatchback / sedan with 1.4TSI?.

Or

Another Yeti TSI?.

[fuzzybunny]

well I was thinking of another yeti TBH, I'm not totally convinced its the way to go but I'm impressed by wakev's loyalty to the marque and I do like the yeti having bought two of them.

So I should consider a petrol yeti but the only 1.4 option is the L&K from what I see on the Skoda website. just wondering what the real world mpg is.

Cheers

[VAGCF]

As I said the front end grows on you (post #66) and as usual colour makes a difference. To go elsewhere because of that could be a mistake.

 

This is my first Yeti and love it, I just can't think, even now, of anything I'd rather have gone for unless spending a lot more money. And then it would be a completely different vehicle.

Edited 19 December, 2015 by VAGCF