As title

 

good question!! as i havn't a clue what a turbo is??

 

Its a complex chain of events that leads to it as a result, however, the most well known form of damaging turbo surge is very very common..

You know that so called "Wastegate chatter " that you all love so damn much?


Thats compressor surge

 

err.....mine chatters really really loud!!! that mean its fooking something up??

 

ooooooo
wot duz it mean when it gets REALLY NOISY then ??

 

i'm worried now!! as mine chatters its nuts off

 

same here thing is tho its a brand new t34 ( less than 2000 miles )

 

mines a T3 thats about 600 miles old!!

 

Do you have to remove the factory fit re-circ dump valve in order to get turbo surge. Because does the dump valve not equalise the pressure on either side of the turbo.???

Or am I talking complete nonsense??

 

took the factory d/v off...got chatter....

put k&n on.......got CHATTER!!!!!!!!!!!!!!!!!!!!

 

tis a good sound tho innit

 

its a load of turkey's under the bonnet

 

the bollocks mate!!!!

 

I think i have the whole farm under my bonnet then.....GOBBLE GOBBLE

 

ive never even thought of chatter as surge

 

you might have picked em up @ armadillos

 

sell em to bernard mathews

 

I *think* Stu meant chatter and surge can both be related to the same thing: turbo stall.

 

OH I'M LOST!!!!!

all i know is that it'll keep chattering like a bag of turkeys ready to be introduced to mr butcher on a certain day in december!!!

 

keith
ur as mad as a bag o badgers

 

Surley "Turbostall" (the chatter you hear) is caused by "surge" (the turbo is creating more air than the engine can consume). Basically "chatter" as everyone calls it may sound good if your into that kind of thing, but it isn't actually doing the turbo anygood Bloody fashion victims

 

Surge causes turbo to stall (an event) - this makes a sound = chatter - that's the relationship.

 

So we could say relationship leads to chatter?

Wasnt until i looked up the word surge in an english-swedish dictionary i understood how bad it is, my father used to be a jet pilot and surge is last thing you want on a jet engine (although the blades in the t34 probably withstands it better)

 

Mine used to chatter like a flock of pigeons!!! until i fitted my dump valve! now it hardly chatters! only here it slightly but nothing compared to what it was!

 

Ok,
Im feelin a bit low tonight and need summat to pass the time away, so maybe a small essay will help?

Brief explanation:
Surge is caused by stall, which is worsened by surge, its a vicious circle...

Imagine the way our turbocharger's compressor is driven, right back to basics: The turbine wheel is spun by exhaust gas, utilising also the energy stored in the exhaust gas as latent heat.

This force on the turbine shaft generates torque at the compressor end as they are physically connected. Remember that part as its the key element, Torque

Ok,
Now lets imagine our turbocharger compressing air, forcing it into the engine, the engine is utilising it.. what happens then? Ok, The engine expells it, and our turbine housing pressure goes up accordingly, the torque applied at the turbine wheel increases, increasing the spin speed and compressor efficiency at the other end. Great chain of events!
End Result? boost is climbing nicely.

Ok,
Now imagine this scenario:
The turbo begins to spin, as above, but the compressor wheel is generating more air than we can move and the torque required to spin that huge compressor is not being met? Remember that unless the air is processed by the engine, and expelled as hot, rapidly moving air into the turbine housing, our turbine shaft torque will not increase to spin the compressor faster, and it may well diminish.. our compressor is slowing, braked massively by the compressed air its trying to overcome and increase.....

Result? Compressor starts to slow a little.. (beginings of a compressor stall)

Ok,
So now what?
The engine is still rotating and consuming air, but the turbo has stopped producing an excess, so our engine has now had chance to consume what excess was available and the inlet pressure is now diminishing, the turbine torque is now increasing again...

VERY IMPORTANT:
Remember also that at same time, compressor resistance to spin has also dropped due to housing no longer being as pressurised and as a result, the torque required to spin it has dropped massively..

Boom.. Suddenly the Turbine wheels torque massively exceeds the compressors resistance and the turbo spins to speed in an instant!! Sounds great, rapid boost climb!! The compressors acceerating at over 2G

BUT:
We just hit the same problem again, our huge compressor has made so much boost, so fast, and is trying so hard to push the massive volume or air, that our YB cant use it.... so we start to slow again........

So we went: Fast, slow, fast, slow, or in other words: The turbo is Surging.
As you can imagine, it continues this cycle until it hits the revs your engine consumes all the air.. then your away!!

Downsides to this surge are pretty obvious:
We can have serious bearing wear, due to the excessive loads imparted on the shaft supports.

Compressors have been known to simply explode!!

Worst case scenario, the compressor being slowed rapidly with a turbine still trying to accelerate it can simply do as expected, part company.

Hope this helps to explain in as simple terms as i can put it, the phenomena known as "Turbo Surge."

 

nice one Stu

 

I couldnt find the words stu... I know what it is... but thats very well put!


alex

 

Ive just re-written some of it to make a bit more sense.. sorry, my heads not with it tonight at all..

 

What did I start with my post aye Stu,

good reading, its given me something to think about while i'm trying to sleep!!

 

Yeah.. so much for my quick reply on your post to keep it simple!!

 

Bloody hell Stu. Are you going to publish a hard back with all these essays you have been writing.

You explain things well though. Definatly better than that Visard fella.

 

Ive written a lot of essays over the last few years, but sadly, theyve nearly all been lost as most were on the RsBB

I dont really have the heart to write them anymore, i dont know why?

Glad you find the ones i do write of use though, its the making it easy for everyone to understand thats hard for me, and takes the time, using technical terms would make it simple, and id do more of them, but that wouldnt benefit many folks at all, as they wouldnt understand..

 

its the laymans terms that IS the skill with you though stu! impressive to say the least.

what happens at the other end of the scale? i.e. the engine wants more than the turbo supplies? does that occur like over speeding or something?

 

Boost just tails off... think T3 peaking at 30psi.... holding about 15 or less by the redline and spinning its tits off.. LOL

 

@ the new improved 'laymans' terms!!

 

"Tits" can be used to describe any thing, to any man!!

 

Nice one Stu.....


Dont think you've cured that Turkey Keith G666 though

 

I just answered the topics direct question.. lol

 

had to read it 3 times , but thanks stu

the actuator controlls boost, should it not also control surge??

 

No, as surge always ocurs below peak boost.