Turbo performance?

[haydes55]

Do turbos gain pressure from the air being heated up as it passes the hot turbo as well as the fan forcing more air in? Or would it be ideal to have the turbo cold (If it could be done) so the air passing through it is still cool?

If heating and cooling the air plays no part in the building of air pressure then developing a cool turbo of sorts could eliminate the need for an intercooler, so lighter weight.

(Random late night engineering ideas)

[schrodingers cat]

Do turbos gain pressure from the air being heated up as it passes the hot turbo as well as the fan forcing more air in? Or would it be ideal to have the turbo cold (If it could be done) so the air passing through it is still cool?

If heating and cooling the air plays no part in the building of air pressure then developing a cool turbo of sorts could eliminate the need for an intercooler, so lighter weight.



Do some reading about thermodynamics.

While you're at it can you also circumvent the laws of physics so I can ride as fast as I like without consequences?

[2Seat_Terror]

Simply: More pressure = higher air density = more boom.
More heat = lower density = less boom. This is why the intercooler is used (that and other heat-related problems like detonation).

[Woodman]

Cooler air is more dense of oxygen. Oxygen plus fuel is what makes fire.

[haydes55]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?

[quickbuck]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?
EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

[scumdog]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?


I see where you're coming from - a long shaft between the exhaust impeller and the intake impeller?

Unfortunately as mentioned by quickbuck, the very act of compressing air will make it hot - just feel what the temp the pump on an air compressor can get to...

[FJRider]

Simply ... Variations abound.

The exaust gasses are directed through a turbine, this turbine is on the same shaft as a fan which forces air into the cylinders (Through the carbs). The increased fuel/air mixture (in the same space as normal) makes a bigger bang. More revs ... more fuel/air in ... more power. Most turbo are lower compression engines (to compensate for the larger fuel air mixture and higher compression that bigger bang makes) ... that rely on the turbo to get power. So at low rev's ... they are a dog.

[FJRider]

Cooler air is more dense of oxygen. Oxygen plus fuel is what makes fire.

But fuel would burn better in warm air ... wouldn't it ... ???

[haydes55]

EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

That explains it thanks :sunny:

[FJRider]

EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

Not to mention the heat from the (usually) ceramic bearings ... as the RPM of the turbo shaft is spinning mind-blowing fast. (makes the red line figure of a 4 cylinder 250 seem slow by comparison)

[quickbuck]

Not to mention the heat from the (usually) ceramic bearings ... as the RPM of the turbo shaft is spinning mind-blowing fast. (makes the red line figure of a 4 cylinder 250 seem slow by comparison)
True that.
The Bell 47 uses a VERY large Turbo... and it spins at over 40000 RPM.
100000 isn't too far fetched for some of the smaller turbos out there.

[superman]

But fuel would burn better in warm air ... wouldn't it ... ???

All that would do is increase the risk of self detonation and reduce the oxygen content.

[2Seat_Terror]

You could skip the whole air compression thing and gear the turbo to the crankshaft! Turbo-compound engines on the last big propliners did this. :cool:

[FJRider]

You could skip the whole air compression thing and gear the turbo to the crankshaft! Turbo-compound engines on the last big propliners did this. :cool:

Then it would be supercharged. A similar principal ... with different characteristics in the final result.

Turbo's usually have a "lag" between throttle movement ... and response from the engine.(due usually because of distance from cylinders, through the exaust to the turbo)... Supercharging is (by comparision) instant .... as the "turbo" is driven directly off the engine.

[2Seat_Terror]

Yes, I understand superchargers. I still mean a turbo, but it drives the engine, not the engine driving a supercharger.
http://en.wikipedia.org/wiki/Turbo-compound_engine

[paturoa]

Hot air isn't as good as cool air, which is why inter-coolers are used.

As the air is "compressed" it gets hotter and expands, and will have less mass than colder air of the same volume (volume of the piston swept volume is the important part).

The fuel air ratio for burning gas optimally is for all intents constant (not true but for this you can take it to be).

So cooler air for same swept volume, will have more mass, and hence more oxygen, for which you need more gogo juice = bigger bang!

[Laava]

I just like the noise the pull-off valve makes. Can I install one on my V Strom? Pfffishhhhh!

[Monsterbishi]

True that.
The Bell 47 uses a VERY large Turbo... and it spins at over 40000 RPM.
100000 isn't too far fetched for some of the smaller turbos out there.

100,000rpm is nothing for a turbocharger, the small-ish turbo's that sit on V6 Mitsi motors can go past 250,000rpm!

[haydes55]

I just like the noise the pull-off valve makes. Can I install one on my V Strom? Pfffishhhhh!

Just let all the air out of your tyres haha. Or always carry an air tank on the pillion and rig up the release valve to the clutch lever. :lol:

[quickbuck]

100,000rpm is nothing for a turbocharger, the small-ish turbo's that sit on V6 Mitsi motors can go past 250,000rpm!

Yes, there are those too.... It is amazingly fast when you think about it.

[haydes55]

Screw using the turbo to blow air into the engine, use those revs to power the drive shaft haha Near no torque but imagine the hp

[Monsterbishi]

Yes, there are those too.... It is amazingly fast when you think about it.

Yup, with a 4cm wheel you're looking at 1872kph on the tips when the shaft is turning 250,000rpm!

[ducatilover]

You want hot air going through the exhaust side, hot = gas velocity.
You want to keep the intake charge cool as everyone said.

There are better benefits in water cooled barrels than cooling the housing (has been done)
If you're wanting the nicest performance go variable vane (Holset make them and they're not the newest idea either) and make sure the A/R is right for your needs on both ex/intake side.

[Big Dave]

I just like the noise the pull-off valve makes. Can I install one on my V Strom? Pfffishhhhh!


Sure can.

http://www.traskperformance.com/

[avgas]

Screw using the turbo to blow air into the engine, use those revs to power the drive shaft haha Near no torque but imagine the hp
I think you will find the HP to be quite low..........HP = watts = energy.......in this case waste energy (i.e. energy not being used to more the motor parts around).

[baffa]

Wow some people really need to read up on how turbos work.
And yes, it isnt just the kinetic energy of the exhaust gases, the thermal energy also contributes to the turbo's usage.

[FJRider]

Screw using the turbo to blow air into the engine, use those revs to power the drive shaft haha Near no torque but imagine the hp

If you connected anything else to the turbo shaft ... all you would have is another silencer in your exaust system.

And a dog of a bike.

[scumdog]

I just like the noise the pull-off valve makes. Can I install one on my V Strom? Pfffishhhhh!

I was gutted when I found out my XN85 didn't have one.





Yeah right...

[Motu]

Wow some people really need to read up on how turbos work.
And yes, it isnt just the kinetic energy of the exhaust gases, the thermal energy also contributes to the turbo's usage.

Yes, the waste energy is in the form of heat, it's the heat that wasn't used to push the piston down...or what went into the cooling system or over coming friction. Blowing cold air into a turbo isn't going to produce boost, but the waste heat that's still expanding, that will do it.

[ducatilover]

I was gutted when I found out my XN85 didn't have one.





Yeah right...
You know it needed wank factor to match your tracto...Harley!

[paturoa]

There are better benefits in water cooled barrels than cooling the housing (has been done) If you're wanting the nicest performance go variable vane (Holset make them and they're not the newest idea either) and make sure the A/R is right for your needs on both ex/intake side.

How about cold water injection directly into the intake air stream?

I can't remember much about how it works other than cooling the intake air temp after the turbo / super for the same result, colder = more mass for same volume = more oxygen = MORE POWER!!!:cool:

I have a vauge recollection about WW2 aero engines using water injection concurrently with increasing the wastegate pressure. Something about not only did the water cool the intake gas temp, but also converting the water into steam enabled much higher compression ratios. Not sure so happy to be "educated" by KB experts.....

[ducatilover]

How about cold water injection directly into the intake air stream?

I can't remember much about how it works other than cooling the intake air temp after the turbo / super for the same result, colder = more mass for same volume = more oxygen = MORE POWER!!!:cool:

I have a vauge recollection about WW2 aero engines using water injection concurrently with increasing the wastegate pressure. Something about not only did the water cool the intake gas temp, but also converting the water into steam enabled much higher compression ratios. Not sure so happy to be "educated" by KB experts.....
A lot of people still run water/meth injection, have seen a few set ups myself. Very good way of reducing the risk of detonation :yes:

I think you'd be correct on the WW2 planes, with water injection you can run higher boost and not crack or melt pistons

On a related note, I've been pulling down a Z18 in a Datsun 720 that's given itself a nice dose of water injection on cyl.4...:rolleyes:

[paturoa]

Blowing cold air into a turbo isn't going to produce boost, but the waste heat that's still expanding, that will do it.

Not sure I understand your point re blowing cold air into a turbo. I though it was a function of the exhust gass pressure (pushing on the zorst size of the turbo) and the size of the hole on the intake that are to the limiting factors.

Also the exhaust gas will only slowly expand after it leaves the engine port before the turbo as there is no additional heat being added (PV=nRT) and it wouldn't flow otherwise. But it will expand quite a lot as it passes through the turbo and / or reduce temp and / or pressure; as energy is transferred to the other side of the turbo.

[paturoa]

A lot of people still run water/meth injection, have seen a few set ups myself. Very good way of reducing the risk of detonation :yes:

I think you'd be correct on the WW2 planes, with water injection you can run higher boost and not crack or melt pistons

On a related note, I've been pulling down a Z18 in a Datsun 720 that's given itself a nice dose of water injection on cyl.4...:rolleyes:


Will goggle / pootube that as may find some interesting stuff.

720 - Dads got one that sufferring from body cancer but the engine is simply stunning for starting. Does your involve a head gasket issue? He bought his new in 85, the hand brake style 4wd selector was brilliant, never worked out why others didn't copy it.

[ducatilover]

Will goggle / pootube that as may find some interesting stuff.

720 - Dads got one that sufferring from body cancer but the engine is simply stunning for starting. Does your involve a head gasket issue? He bought his new in 85, the hand brake style 4wd selector was brilliant, never worked out why others didn't copy it.

That's the way to go.

This blew the gasket on the intake side at the back on number 4.
It's a horrible thing to work on (it's on big rubber and I'm only 5ft7 so I have some reaching issues :facepalm:
There's a small amount of cancer, but it's actually not a bad rig to drive.
The auto locking hubs are rather nice and it rides well for an old ute.
It's not mine though, although I do like it.

[paturoa]

Nice read here - old school! Merlins etc

http://www.enginehistory.org/Convention/2005/Presentations/LawPete/ADI.pdf

[paturoa]

The auto locking hubs are rather nice and it rides well for an old ute.
It's not mine though, although I do like it.

The old toymotors / hilux get all of the press, particularly after the Top Gear thing, but the 720, other then the rust was a much better bus.

[FJRider]

For those that don't know that much about turbo's ...

http://en.wikipedia.org/wiki/Turbocharger

And water injection ...

http://en.wikipedia.org/wiki/Water_injection_(engines)

[ducatilover]

The old toymotors / hilux get all of the press, particularly after the Top Gear thing, but the 720, other then the rust was a much better bus.
I have to agree, the Z18 lump pulls a lot better than the Toyota 2Y lump.
The Toyota Y series engines are very, very easy to work on, camn knock a headgasket job out on one in just over 2 hours.
I'm pulling the donk out the 720 soon, need to check the bottom end. :(

[onearmedbandit]

Had a guy on the yard one day tell me if you had a turbo timer you didn't need an intercooler. I didn't bother explaining to him the difference, I just simply drew him a little picture of what they each did, and then asked him to explain what he said again.

[ducatilover]

Had a guy on the yard one day tell me if you had a turbo timer you didn't need an intercooler. I didn't bother explaining to him the difference, I just simply drew him a little picture of what they each did, and then asked him to explain what he said again.
:clap::clap::lol::rolleyes:

[Woodman]

used to work with a guy that had detonation problems in his turbo rally car so he set up a crude water injection system using a winow washer pump some hose and a button under the accelerator pedal so when he put his foot to the floor it pushed the button and squirted water into the inlet stream via the washer pump.. Worked a treat.

[avgas]

Had a guy on the yard one day tell me if you had a turbo timer you didn't need an intercooler. I didn't bother explaining to him the difference, I just simply drew him a little picture of what they each did, and then asked him to explain what he said again.

I always liked the fact that people paid $200 for a glorified APEXI egg timer. Had one guy tell me it calculated the time on his car that the turbo needed to spool down. Asked him very politely where it plugged into the computer on his carb'd mitsi.

Laughed at the ford dealership the other day. Turns out heaps of people (such as myself) had complained about the overpressure+lag of the turbo on the TDCi.........so ford came out with a 'hot fix patch'.
Nope wasn't a computer download or a tune..........there is a tiny blow off valve installed now lol
At first I thought my clutch was doing something funky........too me a while to realise what it was.
So now its half boy racer and half tractor.

[ducatilover]

Asked him very politely where it plugged into the computer on his carb'd mitsi.


They just "calculate" it by the running time of the car. Pointless contraptions.

[onearmedbandit]

Yup when someone complains that the car they are looking at hasn't got a turbo timer, I ask them to name a turbo car that has one fitted from factory. I don't know if there actually is or not, but if there is I've yet to met someone on the yard who can name one.

[ducatilover]

Yup when someone complains that the car they are looking at hasn't got a turbo timer, I ask them to name a turbo car that has one fitted from factory. I don't know if there actually is or not, but if there is I've yet to met someone on the yard who can name one.
Was an option on the S13 and some Toyotas, the SW20 had dealer installed ones, not sure about factory fitments. Do I get a cookie?

[onearmedbandit]

Was an option on the S13 and some Toyotas, the SW20 had dealer installed ones, not sure about factory fitments. Do I get a cookie?

Driven a few SW20's and none of them have had them. I don't think the turbo ones were sold NZ New, and the Japanese ones I've driven didn't have them. Maybe still just an option?

[ducatilover]

Driven a few SW20's and none of them have had them. I don't think the turbo ones were sold NZ New, and the Japanese ones I've driven didn't have them. Maybe still just an option?
Was a dealer fitted option. So I'm not sure if you'd consider it factory or not?
I've been in a revision 5 SW20 GTS with a dealer fitted turbo timer. Not NZ new though.

They're the only two examples I can think of and neither were a standard option and are very rare. Probably because there's no need for a turbo timer

[onearmedbandit]

Probably because there's no need for a turbo timer

Exactly!!!!

[ducatilover]

Exactly!!!!

I've heard some ridiculous arguments about the need for them...
One being cooling the oil to the shaft. Bullshit.
Slows the turbo down and cools. Bullshit.

Have yet to hear someone come up with a good excuse other than wank factor :rolleyes:

[2Seat_Terror]

It was pointed out to me once that they may in fact be dangerous, if you had a serious accident and turning off the key didn't stop the engine from running (or pumping fuel into the hot part of the wreck?).

[ducatilover]

It was pointed out to me once that they may in fact be dangerous, if you had a serious accident and turning off the key didn't stop the engine from running (or pumping fuel into the hot part of the wreck?).

Could be a bit of a problem couldn't it? :(

[Fast Eddie]

I thought the theory of the turbo timer was mainly to give the engine oil time to circulate and cool down a little bit if you had just been driving vigorously and the oil was very hot and then turned engine straight off. So that there wasn't some sort of carbon deposits or something happening to the oil in the hot turbo or something building up in the turbo? doesn't really make much sense though since the oil is only really going to start cooling down after the engine is stopped anyway?

meh.. there was no turbo timer fitted to my turbo bike anyway..

[Woodman]

The theory of a turbo timer is that when the engine stops so does the oil pump therefore not pumping oil to the turbine bearings which because the turbine is not mechanically connected to anything can still be spinning.

[jonbuoy]

used to work with a guy that had detonation problems in his turbo rally car so he set up a crude water injection system using a winow washer pump some hose and a button under the accelerator pedal so when he put his foot to the floor it pushed the button and squirted water into the inlet stream via the washer pump.. Worked a treat.

Neat methanol based windscreen washer fluid works even better than water you can buy kits online. RE Turbo timers - I thought it was mainly to protect the turbo bearings - pull off the road straight away and switch the engine off and the turbo will still be spinning faster than an engine that has been idling, as soon as the engine stops you loose oil pressure and the turbo bearings loose their supply of fresh oil. Pretty sure in the last turbo car owners manual I read it said if you stop straight after a motorway run let the engine idle for a few moments until the turbo has slowed down a little.

2. After highway driving or high-load driving, Subaru recommends allowing the engine to cool by idling for at least 30 seconds before shutting off.

[dangerous]

Wow some people really need to read up on how turbos work.yeah aye, im trying to bite my tounge but but... ohhh shit



100,000rpm is nothing for a turbocharger, the small-ish turbo's that sit on V6 Mitsi motors can go past 250,000rpm!Like my CX500 17psi and 250,000rpm :drool: early lasers etc were a massive 7psi try 150psi http://www.youtube.com/watch?v=XAIHPzuqSc4&feature=fvsr



Screw using the turbo to blow air into the engine, use those revs to power the drive shaft haha Near no torque but imagine the hpHUH... turbos use wast energy to produce power.



I was gutted when I found out my XN85 didn't have one.It did, does, LOL but I ducted the wast back into the exhaust... I just figgered a aging oll boy with his fingerless gloves, tassels, potty hat with a externally vented pull off (love that term) valve just wouldent seem right.


Ohh and timers, well yeah maybe with the 1st of the turbos due to the material used as seals, now days ceramics and all that, na anyways by the time ya pull up the drive stick er in neutral enough cooler oil has passed through.

[Mooch]

It was pointed out to me once that they may in fact be dangerous, if you had a serious accident and turning off the key didn't stop the engine from running (or pumping fuel into the hot part of the wreck?).

In an accident most fuel injected cars have an inertia switch that switches off the fuel pump. If anyone has been dumb enough to bypass it then they should be in the darwin awards list.

[scumdog]

It was pointed out to me once that they may in fact be dangerous, if you had a serious accident and turning off the key didn't stop the engine from running (or pumping fuel into the hot part of the wreck?).


Meh, a naturally aspirated V8 will do that easily if it's still fitted with the factory mechanical fuel pump.

I've been standing there at the gas station, keys in my hand and the motor still running...

Too high an idle speed is enough to get that going.

[SMOKEU]

It was pointed out to me once that they may in fact be dangerous, if you had a serious accident and turning off the key didn't stop the engine from running (or pumping fuel into the hot part of the wreck?).

I've owned a car with a turbo timer and all I had to do to bypass it was put the handbrake up and down and the engine would shut off immediately.

[onearmedbandit]

The theory of a turbo timer is that when the engine stops so does the oil pump therefore not pumping oil to the turbine bearings which because the turbine is not mechanically connected to anything can still be spinning.


RE Turbo timers - I thought it was mainly to protect the turbo bearings - pull off the road straight away and switch the engine off and the turbo will still be spinning faster than an engine that has been idling, as soon as the engine stops you loose oil pressure and the turbo bearings loose their supply of fresh oil. Pretty sure in the last turbo car owners manual I read it said if you stop straight after a motorway run let the engine idle for a few moments until the turbo has slowed down a little.

2. After highway driving or high-load driving, Subaru recommends allowing the engine to cool by idling for at least 30 seconds before shutting off.

That's the reason that has been put to me every time. My reply is, who actually boosts their car hard then turns it off immediately? Do you nail it up your driveway? When you pull into your park at work is that at speed? Into a service station?

Two reasons I've heard of not to use them, and one happened to a guy I knew. His tt failed and left his car idling for over 2hrs while he was at the movies. The second is that they can be a link to your ignition system for car thieves. Don't know how likely that one is though.

[jonbuoy]

That's the reason that has been put to me every time. My reply is, who actually boosts their car hard then turns it off immediately? Do you nail it up your driveway? When you pull into your park at work is that at speed? Into a service station?

Two reasons I've heard of not to use them, and one happened to a guy I knew. His tt failed and left his car idling for over 2hrs while he was at the movies. The second is that they can be a link to your ignition system for car thieves. Don't know how likely that one is though.

No idea, I don´t know if they are concerned about temperatures or speeds. These guys say its more about temperature. Looks like Porchse and Audi have electric cooling pumps for their turbos that stay on after engine shut down.

http://www.mrtrally.com.au/performance/whytimer.htm

[ducatilover]

The theory of a turbo timer is that when the engine stops so does the oil pump therefore not pumping oil to the turbine bearings which because the turbine is not mechanically connected to anything can still be spinning.
It's still spinning at idle, which is when you shut it off anyway, as OAB pointed out, who is on boost right before turning the car off? Regardless of how you do it, the oil will still be subjected to heat soak when you shut the engine off and running it at idle is not really going to give you a dramatic decrease in oil temp at the turbo.

No idea, I don´t know if they are concerned about temperatures or speeds. These guys say its more about temperature. Looks like Porchse and Audi have electric cooling pumps for their turbos that stay on after engine shut down.

It's a pointless device. You oil temp after a hard run is going to drop temp slower when you run it for an extra 3 min without air flow past the turbo housing, sump or oil cooler.

http://www.mrtrally.com.au/performance/whytimer.htm
It'd work better too as you'd be cooling the oil as it soaks the heat from the block. Not running oil that isn't cooled to the turbo and pretending it's helping.

[jonbuoy]

Uncooled oil will still be cooler than the bearings even at idle/stationary.

[ducatilover]

Uncooled oil will still be cooler than the bearings even at idle/stationary.

Even so, by how much? And will you run the engine until you are certain that the bearings are at oil temp? Either way, neither are going to cool down at such different rates for the shaft do warp/crack as the heat transfers. Oil is going to be sitting around at +90c anyway...

It's a gimmick, a well built turbo and well kept lube system does a better job.

[jonbuoy]

Even so, by how much? And will you run the engine until you are certain that the bearings are at oil temp? Either way, neither are going to cool down at such different rates for the shaft do warp/crack as the heat transfers. Oil is going to be sitting around at +90c anyway...

It's a gimmick, a well built turbo and well kept lube system does a better job.

Well if a turbo can get hot enough to glow cherry red and even if you´ve got a high oil temperature of 150 c thats a pretty big difference in temperature and a lot of cooling. Google turbocharger hot shutdown failure. I can see the advantages of a turbo timer. I run a supercharger so its not an issue for me but I can see the merit of having one.

I know marine generators have set cooldown timers before shutting down.

Pretty common to see boy racers "boosting" up the road before pulling into a servo or driveway.

[schrodingers cat]

The problem is the heat soak 'burning' the oil and causing carbon buildup which reduces the clearances. Something spinning at thses speeds needs to be pretty right. Too much build up leads to reduced lubrication and then some riding on the bus.

Just as an observation - this is a frightenly uninformed post. Everyone has an oprinion but seemingly no-one has the time to do any research

[scumdog]

Pretty common to see boy racers "boosting" up the road before pulling into a servo or driveway.

How much 'boost' are they really making at a time like that?

And how much work is the turbo REALLY doing?

A 4 to 6 second burst isn't really giving the turbo a hard work-out.

[jonbuoy]

How much 'boost' are they really making at a time like that?

And how much work is the turbo REALLY doing?

A 4 to 6 second burst isn't really giving the turbo a hard work-out.

No idea mate, next time you do a late night stop on a boi racer ask them to pop the bonnett and take a peek at the turbo for us!

[ducatilover]

Well if a turbo can get hot enough to glow cherry red and even if you´ve got a high oil temperature of 150 c thats a pretty big difference in temperature and a lot of cooling. Google turbocharger hot shutdown failure. I can see the advantages of a turbo timer. I run a supercharger so its not an issue for me but I can see the merit of having one.

I know marine generators have set cooldown timers before shutting down.

Pretty common to see boy racers "boosting" up the road before pulling into a servo or driveway.
How often are people running the turbo in their Evo/etc that hot?
I still think there is no advantage running the engine on for 1-3min to "cool" the oil. It's not going to cool much and it's still pumping hot oil to the turbo.

I can understand if you're getting the turbo red hot just before stopping (shouldn't really be an issue on the road...) as that's an extreme.
But, otherwise letting your engine idle is not really helping anything.

In my opinion.

[FJRider]

How much 'boost' are they really making at a time like that?

And how much work is the turbo REALLY doing?

A 4 to 6 second burst isn't really giving the turbo a hard work-out.

and how many (other than the owner) will care if the turbo shits itself earlier than it should ... ???

[onearmedbandit]

I've never seen a turbo glow 'cherry red hot' under normal use, including thrashing the nuts off turbo cars. And if they were so critical, how come virtually no turbo cars from factory come with them?

[Fast Eddie]

yea, although I noticed some big turbo diesel machinery I operated over summer holidays all had big stickers saying run engine for a minute or so after use before shutting down.. wonder if that was for the turbo.

They were grunty, big loaders n shit

[Fast Eddie]

.. still not fitted with a timer tho hehe.. a sticker would suffice

[FJRider]

yea, although I noticed some big turbo diesel machinery I operated over summer holidays all had big stickers saying run engine for a minute or so after use before shutting down.. wonder if that was for the turbo.

They were grunty, big loaders n shit

Most diesel manufacturers reccommend an idle-down period before shutdown.

[Mooch]

To turbo timer or not comes down to the use of the vechile. If your running a standard boost and you've allowed turbo to spool down then you dont need one. If your running extra boost or using for comp. use then a minute or two gives the housing and manifold a chance to drop below the point of cooking up the remaining oil from the oil feed. It takes a while for it to return via the drain feed back into your sump. I'll be running one on my club car for this reason

Check out this vid , and think about how long the manifold is taking to drop down from being red hot.

http://www.youtube.com/watch?v=Yfom9ybsFbc&NR=1&feature=endscreen

[jonbuoy]

I've never seen a turbo glow 'cherry red hot' under normal use, including thrashing the nuts off turbo cars. And if they were so critical, how come virtually no turbo cars from factory come with them?

I'm guessing because In a lot of places its illegal to leave a car running unatended not to mention safety issues if the car was left in a locked garage. Your car your turbo your money, if you look on all the turbo repairers and manufacturers websites they all mention the dangers of hot shutdowns. Its not that hard to get a dull cherry red glow on an unturboed engine, how often have you looked at night?

[jonbuoy]

How often are people running the turbo in their Evo/etc that hot?
I still think there is no advantage running the engine on for 1-3min to "cool" the oil. It's not going to cool much and it's still pumping hot oil to the turbo.

I can understand if you're getting the turbo red hot just before stopping (shouldn't really be an issue on the road...) as that's an extreme.
But, otherwise letting your engine idle is not really helping anything.

In my opinion.

Not sure what your saying, the oil is cooling the turbo bearings the oil won't get cooler it will get hotter taking heat away from the turbo.

[avgas]

Most diesel manufacturers reccommend an idle-down period before shutdown.
Actually anything with 2 foot throw on a piston recommends "idle-down" times.
Hell its even on the old David Brown 885.

I can answer the "why is not factory ttimer?" question. There is on 'few' cars. But there has to be a need for it. And most only have about 2-5 seconds........not the bad old 1-2 minutes.
Not to mention that the turbo's of today from what they were in the 80's. I felt like a complete noob recently when I found out a TD04/05 Hybrid has nothing on the new standard turbos.

[avgas]

I'm guessing because In a lot of places its illegal to leave a car running unatended not to mention safety issues if the car was left in a locked garage. Your car your turbo your money, if you look on all the turbo repairers and manufacturers websites they all mention the dangers of hot shutdowns. Its not that hard to get a dull cherry red glow on an unturboed engine, how often have you looked at night?
Yeah/Nah.......sometimes its good and sometimes its crap advice.

As mentioned earlier - sometimes a new 'hot fix update' comes out for a vehicle............I suspect if Mitsubishi blew up a decent amount of turbos, factory fitted turbo timers would be high on their list.
Instead it seems that a carbon fibre roof is more important :scratch:

I actually think they should be factory fitted (on all vehicles), but then again I am an engineer who dreams of utopia and never gets the budget.

[jonbuoy]

Timers are illegal here even so I would probably just go with an egt gauge. Lets face it car manufacturers arent interested in long term reliability of your car, after 7 years they want you to buy a new one.

[ducatilover]

Not sure what your saying, the oil is cooling the turbo bearings the oil won't get cooler it will get hotter taking heat away from the turbo.
Was typing too fast for my d\slow brain methinks. (Happens a lot, I own a Kawasaki)
The oil in the turbo is getting as hot, if not hotter than the block.
So how is a turbo timer going to help that? Agreed, in extreme situations, it may help, but why do you need a turbo timer at the track? No-one is stealing your car and the time the engine spends at idle is more important than your turbo cooling isn't it? You have far lower oil pressure at idle, the turbo is only heating the oil if it's red hot unless you idle your engine for a significant amount of time (Loner than 1-3min).

So, why bother? Your turbo is going to be hotter than the block temp, regardless, so it's only heating the oil. In a road application.

(Disclaimer; In my opinion.)

I have seen many vehicles with turbo timers have "early" turbo failure, as well with vehicles without. I personally think it comes down to the design of the turbo, for example, a lower friction shaft will last well, whereas an older design with solid bearings will not last as well. Same goes for a turbo set up with a decent wastegate and blowoff valve, without the compressor stall/surge you'll have a much happier turbo.

[ducatilover]

Instead it seems that a carbon fibre roof is more important :scratch:

Have you seen how many roofs on 90's Mitsis rust? CM/CD5A etc etc etc all pull the spot welds int he roof because the glue in them is shiiiiiiiiiite? I think they should have looked at that long before turbo problems... :laugh:

[jonbuoy]

Was typing too fast for my d\slow brain methinks. (Happens a lot, I own a Kawasaki)
The oil in the turbo is getting as hot, if not hotter than the block.
So how is a turbo timer going to help that? Agreed, in extreme situations, it may help, but why do you need a turbo timer at the track? No-one is stealing your car and the time the engine spends at idle is more important than your turbo cooling isn't it? You have far lower oil pressure at idle, the turbo is only heating the oil if it's red hot unless you idle your engine for a significant amount of time (Loner than 1-3min).

So, why bother? Your turbo is going to be hotter than the block temp, regardless, so it's only heating the oil. In a road application.

(Disclaimer; In my opinion.)

I have seen many vehicles with turbo timers have "early" turbo failure, as well with vehicles without. I personally think it comes down to the design of the turbo, for example, a lower friction shaft will last well, whereas an older design with solid bearings will not last as well. Same goes for a turbo set up with a decent wastegate and blowoff valve, without the compressor stall/surge you'll have a much happier turbo.

No I'm still not getting it, if the turbo is hotter than the oil that flows through the bearings (which it will be if its got 400 degree gasses passing through) the turbo will be cooled by the oil. As long as there is oil flowing what has the pressure got to do with it? Even at idle your exhaust gets pretty toasty, I can put my hand on the engine block after a hard run for a few seconds, I wouldn't try touching a turbo or exhaust manifold. So yeah the block, cooling water and oil will soak up the heat from the hotter turbo. You dont think passing oil through it can cool it?

[Kickaha]

..I suspect if Mitsubishi blew up a decent amount of turbos, factory fitted turbo timers would be high on their list..

The Mitusubishi Tredia/Cordia had a window sticker advising to let it idle for a minute or two before shutting down or it could cause turbo "problems"

[ducatilover]

No I'm still not getting it, if the turbo is hotter than the oil that flows through the bearings (which it will be if its got 400 degree gasses passing through) the turbo will be cooled by the oil. As long as there is oil flowing what has the pressure got to do with it? Even at idle your exhaust gets pretty toasty, I can put my hand on the engine block after a hard run for a few seconds, I wouldn't try touching a turbo or exhaust manifold. So yeah the block, cooling water and oil will soak up the heat from the hotter turbo. You dont think passing oil through it can cool it?

I just don't think it's making a huge difference if you idle it for 1-3min, that's not exactly a long period of time and the turbo is still accumulating heat during idle. As OAB said, why were there not more fitted from factory?

I could be completely wrong though, highly possible :laugh:

[pete376403]

I have seen many vehicles with turbo timers have "early" turbo failure, as well with vehicles without. I personally think it comes down to the design of the turbo, for example, a lower friction shaft will last well, whereas an older design with solid bearings will not last as well. Same goes for a turbo set up with a decent wastegate and blowoff valve, without the compressor stall/surge you'll have a much happier turbo.

Most of my turbo experience was Cat earthmovers, but these ALL used floating bush type bearings (ie what you describe as solid bearings) - the oil film seperates the shaft from the bushing (bearing), AND the bushing from the housing. These turbos had uptimes of thousands of hours, most of which was under full load, red hot exhast housing conditions. The turbo was correctly sized at the factory (not much aftermarket hotrod stuff for D8s ), no wastegate or blowoff, and provided they were fed a steady diet of clean oil and clean air would last more or less indefinitly. An extended (15 minute or more ) pre-shutdown idle was mandatory.

This book http://www.amazon.com/Turbochargers-Hugh-MacInnes/dp/0912656492 gives a LOT of good info (MacInnes designed a lot of the Rajay turbos)and the engine pictured on the cover is niiice

[ducatilover]

Most of my turbo experience was Cat earthmovers, but these ALL used floating bush type bearings (ie what you describe as solid bearings) - the oil film seperates the shaft from the bushing (bearing), AND the bushing from the housing. These turbos had uptimes of thousands of hours, most of which was under full load, red hot exhast housing conditions. The turbo was correctly sized at the factory (not much aftermarket hotrod stuff for D8s ), no wastegate or blowoff, and provided they were fed a steady diet of clean oil and clean air would last more or less indefinitly. An extended (15 minute or more ) pre-shutdown idle was mandatory.

This book http://www.amazon.com/Turbochargers-Hugh-MacInnes/dp/0912656492 gives a LOT of good info (MacInnes designed a lot of the Rajay turbos)and the engine pictured on the cover is niiice
Very good info, thanks :yes:

[scumdog]

I just don't think it's making a huge difference if you idle it for 1-3min, that's not exactly a long period of time and the turbo is still accumulating heat during idle.

My take of this is: the turbo is NOT 'accumulating' heat during idle to the extent it did during a high-load fang, it would only be as hot as a regular exhaust manifold if just left at idle - but during the high-load fang it creates heat, lots of it after that the temp drops as the load drops.

The oil flowing through the turbo while the motor is idling (whether with a timer or otherwise) will keep the bearings lubed as (I may be wrong - again!) shutting down after 'giving it heaps' the oil-pressure drops to zilch - but the turbo-shaft will still be spinning a bit.

And a steady flow of oil through the turbo will cool it as the oil will be way cooler than the turbo housing.

[imdying]

The problem is the heat soak 'burning' the oil and causing carbon buildup which reduces the clearances. Something spinning at thses speeds needs to be pretty right. Too much build up leads to reduced lubrication and then some riding on the bus.And here was me thinking we'd go the entire thread without hearing from somebody who knows.

The OEM doesn't fit them because most people never run them WOT then switch them off straight away... and they tell you not to do that in the handbook. As a result, it's cheaper to replace the odd turbo than it is the equip every car with one. Every manufacturer has entire departments dedicated to calculating risks like that, and those people get just as much say as the engineers.

[ducatilover]

My take of this is: the turbo is NOT 'accumulating' heat during idle to the extent it did during a high-load fang, it would only be as hot as a regular exhaust manifold if just left at idle - but during the high-load fang it creates heat, lots of it after that the temp drops as the load drops.

The oil flowing through the turbo while the motor is idling (whether with a timer or otherwise) will keep the bearings lubed as (I may be wrong - again!) shutting down after 'giving it heaps' the oil-pressure drops to zilch - but the turbo-shaft will still be spinning a bit.

And a steady flow of oil through the turbo will cool it as the oil will be way cooler than the turbo housing.
After a mental fang I can see why you'd cool it down, but I'm talking about Joe Boyracer in his Starlet GT.
Or do people really thrash their cars that hard and just turn 'em off?

[pete376403]

After a mental fang I can see why you'd cool it down, but I'm talking about Joe Boyracer in his Starlet GT.
Or do people really thrash their cars that hard and just turn 'em off?

Most modern cars have watercooled turbo bearing housings anyway, don't they?

Also the problem with hot turbo/no oil flow (ie motor turned off) is not that the shaft keeps spinning unlubricated as much as the oil that is in the bearings becomng burned, turning to bits of carbon and clogging passages, scoring shafts and so on .

[Mooch]

So from a performance point of view what would be the best turbo combo ?

My thoughts would be shot of NOS to spin up a Turbo nto it's working range , on demand methonal injection to stop detonation on full boost (rather than backing off ignition timing). Water to air intercooler and a air ram cold air box.

[ducatilover]

Most modern cars have watercooled turbo bearing housings anyway, don't they?

Also the problem with hot turbo/no oil flow (ie motor turned off) is not that the shaft keeps spinning unlubricated as much as the oil that is in the bearings becomng burned, turning to bits of carbon and clogging passages, scoring shafts and so on .
Water cooling seems to be uber common, kind of annoying when looking for the right turbo for the bike too as I'd like ball bearings and small, already a limited choice and don't really want to run water pipes.

That makes sense to me.


So from a performance point of view what would be the best turbo combo ?

My thoughts would be shot of NOS to spin up a Turbo nto it's working range , on demand methonal injection to stop detonation on full boost (rather than backing off ignition timing). Water to air intercooler and a air ramp cold air box.
Sounds like a good plan :yes:
Variable vale timing and lift helps a shit load too, along with a variable vane turbo :2thumbsup

[dangerous]

hehehe... ok my turn, you lot going on about turbo's still spinning after an engine is shut down, well think about it, it only spins due to exhaust gasses flowing through it, stop the gasses and the turbo stops... if the turbo was still to spin after an engine was shut down then were would the air its compresing go? cant go in the engine cos its not going simple as there is only one way in and one way out for the gasses as soon as they stop flowing the turbo stops spinning.

Thus why we use homo fluff off valves (actually common oem fitments mostely with diesels but quite due to them being vented into the exhaust or manifold)
When the engine revs drop during a gear change so does the turbo, it then needs to spool up again this causing a drop in power... so a blow off valves releses the presure going into it allowing it to spin freely and maintaing reves till the next gear is selected and the engine revs raise.

If a blow off was to open when a engine is shut down the yes the turbo would keep spinning.
Cos the turbo does stop spinning any oil in it would fry on the spot, hence the need to do a few revolitions to allow cooler oil through it that has just come from the oil cooler.

daa daaa... how'd I do

[ducatilover]

So in that case, every time you shut the engine off you stall the compressor? I think maybe we should never shut our motors off :bleh:

[Monsterbishi]

hehehe... ok my turn, you lot going on about turbo's still spinning after an engine is shut down, well think about it, it only spins due to exhaust gasses flowing through it, stop the gasses and the turbo stops... if the turbo was still to spin after an engine was shut down then were would the air its compresing go? cant go in the engine cos its not going simple as there is only one way in and one way out for the gasses as soon as they stop flowing the turbo stops spinning.
.
.
.
daa daaa... how'd I do

Not so well, you forgot about inertia...

I've seen turbo's happily spin for some time after a car has been shut off on a Dyno before.

[scumdog]

Not so well, you forgot about inertia...

I've seen turbo's happily spin for some time after a car has been shut off on a Dyno before.

So:nya:Dangerous!!!

[Monsterbishi]

Like I tell my kids, look with your eyes, not with your hands :-)

[TimeOut]

Had a guy on the yard one day tell me if you had a turbo timer you didn't need an intercooler. I didn't bother explaining to him the difference, I just simply drew him a little picture of what they each did, and then asked him to explain what he said again.

When I bought the Triton I had the salesman try to tell me you didn't need to cool the turbo because the intercooler did that, had to get one of his mechanics in to set him straight.

The handbook even states that the engine should be idled after heavy load to cool the turbo, it doesn't say how long though.

[dangerous]

So:nya:Dangerous!!!hehe, yeah was trying to get the thread alive again, but alas its on its way out no fishing to be had :woohoo:



When I bought the Triton
The handbook even states that the engine should be idled after heavy load to cool the turbo, it doesn't say how long though.yeah but LOL its a Mitsi :facepalm:

[jonbuoy]

Not so well, you forgot about inertia...

I've seen turbo's happily spin for some time after a car has been shut off on a Dyno before.

Yeah I had a rumbling turbo issue in the past, you could hear it spinning for a surprisingly long time after shutting down the motor.

[ducatilover]

The handbook even states that the engine should be idled after heavy load to cool the turbo, it doesn't say how long though.
As Dangerous said...
That'd be to cover their asses in the case of "premature turbo failure".
Premature failure of anything is a Mitsi trait :bleh: <_<

[actungbaby]

As Dangerous said...
That'd be to cover their asses in the case of "premature turbo failure".
Premature failure of anything is a Mitsi trait :bleh: <_<

premuture hmmm not good hehe oh your taliign cars okay i knew that

Oh just there automatics just ask lincon friends whould cost over 2000 but was covered under

warrenty

[actungbaby]

Most modern cars have watercooled turbo bearing housings anyway, don't they?

Also the problem with hot turbo/no oil flow (ie motor turned off) is not that the shaft keeps spinning unlubricated as much as the oil that is in the bearings becomng burned, turning to bits of carbon and clogging passages, scoring shafts and so on .

Thats why have turbo timers problem solved easy . whould seem bit wried walking away car still running

[actungbaby]

Do turbos gain pressure from the air being heated up as it passes the hot turbo as well as the fan forcing more air in? Or would it be ideal to have the turbo cold (If it could be done) so the air passing through it is still cool?

If heating and cooling the air plays no part in the building of air pressure then developing a cool turbo of sorts could eliminate the need for an intercooler, so lighter weight.

(Random late night engineering ideas)

Only problem is the turbo is spun with exhust gas which can never be cold so nice try no way to achive this

In supercharger yes

[haydes55]

Only problem is the turbo is spun with exhust gas which can never be cold so nice try no way to achive this

In supercharger yes

:facepalm:

You didn't read any of this thread did you?

[TimeOut]

Thats why have turbo timers problem solved easy . whould seem bit wried walking away car still running

It would but Mitsi dealer said if one was put on it could void the warranty, interfering with the engine management system

[avgas]

When I bought the Triton I had the salesman try to tell me you didn't need to cool the turbo because the intercooler did that, had to get one of his mechanics in to set him straight.

The handbook even states that the engine should be idled after heavy load to cool the turbo, it doesn't say how long though.
You only need to do it for about 5 seconds (or less) at idle from full speed.
I've "e-stopped" a few of the work hacks (SR5 Hilux's, Tritons, Focus etc) - spool down time for the turbo's in these from max rev's is only about 10-15 or so seconds. So from idle would be less than 5.

The old SR5's and Safari's etc would take 30 or so seconds at idle because they were old tech.

[baffa]

Still bickering about this?
My (the correct) understanding:
A turbo is driven by the kinetic and thermal energy of an exhaust, driving the turbine to compress air, allowing more air and fuel into the cylinders. Compressed air becomes much warmer, so to maximise the effects of a turbo, an intercooler or water injection (or nos) is preferable.
Intercoolers dont cool the turbo itself. It relies on the oil that lubricates it to help cool it, and in some cases, water cooling as well.
Unless you turn off the engine when you are revving the engine, the turbo doesnt need time to "spin down".

The reason it needs time to idle, is because of the massive heat generated by the turbo. Engines tend to operate at 80-100 degrees. A turbo can reach 800-1000 degrees, so idling helps the turbo cool down. I have personally seen plenty of turbo vehicles with glowing hot turbos after a decent thrash. Especially motors like the 300zx, with two turbos crammed in a cramped engine bay and forced to share space with a large V6.

The second reason is that when the oil supply suddenly stops, oil stops circulating, and small amounts can coke/burn in the turbo. Combined with irregular oil changes (turbos need fresh oil), and you are asking for trouble.
Most turb cars and utes (surf etc) need rebuilding after 150k, but ive seen them blow in less than half of that. It all comes down to how well you look after them.

So turbo timers arent essential, but unless you are happy to sit in the car and idle it for a couple of minutes every time you fang it, theyre not a bad idea either.