Turbo lifespan

[shineydave]

this is probably the wrong place to be asking about turbo failure, there's so much info on boost leaks, warm-up, cool-down routines etc that we probably baby ours so much a failure would be the exception rather than the norm.

try asking on Max-Power or www.ithrashthenutsofthebitchfromcold and i bet the responses would be a world apart from ours.

i guess paranoia is our friend

[Marshy]

54k miles, regular 5w/40w synthetic oil changes, drive it like a girl rarely above 3k rpm,,expect Ko3's to last forever!

You see, that's how I drove mine for a few days after getting it. However, after a suitable period of time gaining confidence in the thing, it all went straight out of the window...

...along with seeing 28mpg consumption

[GrahamS4]

Booked in for that remap yet Marshy?

[tdiquattro]

One of the K03s went pop at about 60k, (exhaust side, no smoke, just boost was zero and sounded like a siren!)

The car was chipped and miltek cat backed by QST early in it's life ( theirs is the 3rd stamp in the service book and I assume that is when the work was done), so the K03s had been on a high bost most of their life, I suspect their had beek a boost leak for some time even though it had samco tbb and F-hose, it just didn't feel right.

Now on K04s, got a boost guage and APR bi-pipe and everything is rock solid, boost is always predictable and I am on very regular oil changes.

[QuantumJohn]

Didn't Leon's K03's go for an early bath?

John
(now got 19,320 miles on my K03's and not worried for one moment!)

[MarkB]

I've given up worrying, they seem to go when they please.

I'm on just over 95K with original turbo's. Been remapped for about 20K and still going strong.

The car was on long life servicing in its early years and I now do an oil change every 5K ish. Only time will tell how long they last...

[DavidT]

I still think following all the guidelines (inc not running silly boost) will ensure they do good mileage, say 150k.

Perhaps we should have a 'Why did your K03's fail' poll thread?

[MCB]

Go on then...

[Marshy]

DavidT: define "silly boost"

[Nodds]

43K ON K03's all seems good (Just a slight whistling).
Having done a search it seems that warm up should be until the oil temp reaches 80deg and water around 90 deg keeping the revs below 3k. Cool down, gentle off boost driving for the last couple of miles then a 30 sec to 1min at idle.
It's going in for a service soon, is there anything i should specify for checking with regards to turbo health !

Thanks

Nodds

[ajsl]

Good question, what is "silly boost" for K03s?

[Dippy]

Don't think peak boost, think boost map. The K03 is a compressor, and as such it has a safe operating envelope. Try to get it to create too high a pressure differential at a high air flow and the poor little bugger will get overstressed. Remember that overstressing might not mean instant failure, but reduced longevity instead.

So whilst absolute peak boost is relevant, probably more relevent is how quickly the maximum boots falls off as engine revs (and thus turbine revs) increase.

Now Audi made the B5 S4 with peak boost about 0.8 bar above atmospheric. Don't know what this falls to at the redline but lets say it is probably about 0.4 bar.

A typical stage 1 remap will change that to between 1.1 and 1.3 bar, falling to around * bar at the redline.

(* I really haven't a clue here because I've never paid much attention to what my boost is at the redline even though my guage is on the windscreen. I ought to find out one of these days).

Now by definition, this increase in boost map has reduced the statistical lifespan of the turbos. Or put another way, by increasing boost, the risk of failure has increased too. Without going into detail, there are plenty of other factors which affect turbo life more than boost, which is why someone with a stage 1 car might stay on the same turbos longer than someone with a stock car.

Now since increasing boost reduces turbo life (statistically), it is impossible to define a 'safe' level of boost increase, as long as it remains within the safe operating envelope of the K03 compressor. We have to then get subjective about it, relying on the expertise and judgement of those who provide remaps.

As I noted, most maps raise the boost to no more than 1.3 bar. I know a tuner who will provide one that gives 1.5 bar. As I stated, the peak is not so important as the way the pressure map changes as revs increase, so per se 1.5 peak is not categorically a bad idea, but I guess most people would agree with me that it is "silly boost".

There should be plenty of people who can advise what might constitute "silly boost" at the redline.

[ajsl]

Interesting, thanks for that. I'm at 1.2bar peak, but I have no idea how fast that falls off.

[GrahamS4]

For ref. boost - my MRC custom map:

Call it peak 1.2 tailing to 0.8 bar.

[img]modules/pnCPG/Coppermine/albums/userpics/16089/WheelBHPvsBoost.JPG[/img]

[Marshy]

Also for ref, a 3rd gear run in mine - totally stock (main bulk of the RPM curve) followed by (I think) changes up through the box but slowing down.

This shows actual boost of .8 early on, dropping off to .55 or so as the revs rise. What's interesting, to me, is the lag between actual and requested boost, and the slight spike when I came off the throttle.

Normal? Who knows...