What revs the turbo??

[Solo Man]

Can someone tell met what the revs of the turbo will be approx if i travel at 120kph steady speed on a level road and the engine revs are 2100. Would very much like to know because i cannot believe that the turbo will be running at more than 20 - 30,000 at that speed, maybe even less. Trying to determine/prove that a turbo will last much longer at steady speeds doing long distances than city driving spooling up/down every time you pull away/stop. OK, i know that it is simple common sense that it is true, but how much longer will it last (how long is a piece of string?)? Am i making sense?

 

[Peter@AEW]

Funnily enough you are.You are equally sawing saw dust.
The longest life you would get from a machine would be if you started it and never stopped it again (if that could be possible) and keep it at a constant work rate with constant temperature.

Most wear occurs on start up and most wear and tear on hard short burst of increased engine revs with varying loads.

Hope I am making sense.

btw In a diesel turbo application (in SA)changing your fuel filter very regularly is even more critical than doing oil changes.

 

[P1000]

btw In a diesel turbo application (in SA)changing your fuel filter very regularly is even more critical than doing oil changes.

Not sure how accurate that is - I'm only on my third or fourth diesel filter at 290 000km (but on original turbo).

Now back to the original question - it depends on engine load as well as RPM. generally, the turbo would be idling at very low - say 10000rpm when driving at 120kph in a 3l diesel, providing no boost (boost is usually between 110 000rpm and 180 000rpm depending on the turbo size etc). In a 2l, this will be significantly higher, since the engine is under a much higher % load to maintain this speed. Now, keeping in mind that you need 30-40kW to maintain 120kph in a sedan, you can probably work out the NA power curve for your engine and work back how much boost you will require to deliver that power at 2100rpm. Or you could just listen, you can usually hear when the turbo spools up. In my car just driving at 130kph on a level road I know the turbo is just freewheeling, but as soon as you get to a steep incline, I can hear as it spools up.

 

[Philip Foglar]

Yep, scary speeds!!! :dizzy:

Well, it's kind of like the light bulb analogy - one left on permanently will no doubt last longer than one turned on and off...

But in general, I reckon with just about any engine, you are going to get more life out of it if you are more moderate with the way it is being used, and as such, driving long distances where you are able to keep the car moving at a more constant pace means little to no wear and tear compared to driving in town at low speeds pulling off and stopping often! :thumbs:

 

[netercol]

i dont think that you will be able to even measure the difference , since its not spool-up spool-down that wears a turbo, its startup-shutdown...

once the oil under pressure reaches the bearing, the shaft lifts and rides on a wedge of oil.. from there on, no metal to metal contact takes place, thus no wear (well virtually none)
so it is the amount of times a turbo starts dry and stops that ultimitely determines its life, same as an engine.. (excluding all the other factors, services, oil quality, heat yada yada)

 

[Raybimmer]

An American test years ago on a V8 run at high revs showed it had virtually no wear after a time , yet another that went through a hot/cold , start/stop cycle showed wear .
The turbo speed if 15 000 or 50000 should not influence the life . The cycles it goes through will have an effect . Maybe an electric oil pump activating as the key is inserted in the ignition will help get oil pressure up quicker .

 

[P1000]

i dont think that you will be able to even measure the difference , since its not spool-up spool-down that wears a turbo, its startup-shutdown...

once the oil under pressure reaches the bearing, the shaft lifts and rides on a wedge of oil.. from there on, no metal to metal contact takes place, thus no wear (well virtually none)
so it is the amount of times a turbo starts dry and stops that ultimitely determines its life, same as an engine.. (excluding all the other factors, services, oil quality, heat yada yada)

Spool-up-spool-down cycles cause metal fatigue in the impellers, which is what kills many E39 turbos...

 

[netercol]

i dont think that you will be able to even measure the difference , since its not spool-up spool-down that wears a turbo, its startup-shutdown...

once the oil under pressure reaches the bearing, the shaft lifts and rides on a wedge of oil.. from there on, no metal to metal contact takes place, thus no wear (well virtually none)
so it is the amount of times a turbo starts dry and stops that ultimitely determines its life, same as an engine.. (excluding all the other factors, services, oil quality, heat yada yada)

Spool-up-spool-down cycles cause metal fatigue in the impellers, which is what kills many E39 turbos...

not conviced NORMAL spool-up-spool-down cycles will cause fatigue failure before bearing failure occurs..

what garrett says :

"OVERSPEED AND EXCESSIVE TEMPERATURE
Turbo damage caused by working beyond its designed parameters or outside the vehicle manufacturer’s specification. Maintenance problems, engine malfuction or unauthorized performance upgrades can push turbo rotating speeds beyond its operating limits, causing fatigue failure of compressor and turbine wheels"

would be interesting to see how many fatique failures occur on remapped cars, with higher egt's..

 

[Rolf]

In my hometown in Germany the KKK turbo manufacturers (now Borg - Warner) have their test and dyno facilities and I've been there many many times

I have seen "white glowing" turbos and revs of 200.000rpm + on these dynos with turbos running under load for days!

It is indeed the particles in the oil that kill turbos and the way you care when you run in your motor; that's when 90% of all metal particals are washed into your engine oil!

Later on its less important as much less particles (from moving parts) occure!
As long as lubrication stays in tact ALL is fine :thumbs:

 

[Sabretooth tiger]

I just learned a lot. Great topc. Thanks guys.

 

[Solo Man]

Was worrying about the slight whisteling noise the turbo on my E39 is making especially when cold and up to normal working temp. Was even considering replacement with new turbo but then again read the comment i got from one of the turbo suppliers after i mentioned the whisteling noise and my wish to replace the turbowho said that: "If the turbocharger is not audibly loud or smoking – its clear that you have serviced your vehicle regularly. If there was something wrong with the turbo, it will definitely let you know." and "The only time blades break off is due to cyclic overspeed – chip tuning! My advise would be to leave sleeping dogs lie."
Car has done 228k km and is nine years old, E39 3,o d auto. Am driving it like Mr Daizy!

 

[Rolf]

....and "The only time blades break off is due to cyclic overspeed – chip tuning! My advise would be to leave sleeping dogs lie."
Car has done 228k km and is nine years old, E39 3,o d auto. Am driving it like Mr Daizy!

Sorry but I don't agree with the overspeed or chiptuning part

The rest is spot on! :idea:

 

[Naruto]

Rolf, so chiptuning the car wouldn't push the turbo to produce more than it is required to by the Manufacturer?

 

[Funky Toyz]

Rolf, so chiptuning the car wouldn't push the turbo to produce more than it is required to by the Manufacturer?

Interesting Question this.

Lots of guys have been doing software, with great results. Are there however any negative effects one should be aware of? More load on the turbo etc?

 

[netercol]

Rolf, so chiptuning the car wouldn't push the turbo to produce more than it is required to by the Manufacturer?

Interesting Question this.

Lots of guys have been doing software, with great results. Are there however any negative effects one should be aware of? More load on the turbo etc?

remap will cause higher EGT's which will negatively affect the turbo.. decat will help lower the heatload on the turbo again..