Some Turbo Related Advice Needed

[pugpete1108 62 1 Cars]

i hsve just fitted a cone filter to my rover turbo (daily drive) , and have noticed a 'chatter' when i take my foot off the throttle.

bearing in mind that i have no idea about turbo'd cars and this is my fist, is this sound ok and will it hurt my engine?

 

i have heard about wastegate chatter is this what it is?

 

sorry for sounding so thick but it does sound good and would like to keep it

[danpug 1]

Iirc its not actually the wastegate but the turbine stalling. It will have always been there but fitting the induction kit allows the sound to vent easier.

[pugpete1108 62 1 Cars]

Iirc its not actually the wastegate but the turbine stalling. It will have always been there but fitting the induction kit allows the sound to vent easier.

 

a i see , surely this can't be healthy for the engine? or performance ? is there no way of improving it?

[Big_Jimbob 0]

To prevent wastegate chatter (turbine stalling) you need a good quality dumpvalve....

 

the stalling of the turbine is due to the butterfly on the throttle body slamming shut fast when you take your foot off the throttle...

 

the gas pressure builds up and stalls the turbine.... this can cause damage to the turbine blades....

 

the best bet is to fit a dumpvalve and as you shut the throttle the spare pressurised gas is expelled through this making the woosh noise associated with chavs!!

 

Jim

[sonofsam 5]

a i see , surely this can't be healthy for the engine? or performance ? is there no way of improving it?

 

Depends how much boost your running really? Been without dumpvalve running 0.6bar on my 2.0T for over a year now and it's fine

I would however personally fit a dump valve if getting over a 1bar of though.

 

Much prefer the sound of the stall though

[McDude 33]

Danpug is right - the sound will always have been there, just that the production airbox will have been tuned so that you can't hear it. It is stalling of the air on the compressor/inlet side.

 

The pressure ratio is too high versus the volume flow and the flow can no longer adhere to the compressor blades on the suction side . The air flow is momentarily reversed until a stable flow/pressure is reached but then the pressure builds up again in a repetitive cycle. This creates the noise/chattering sound. It is sometimes known as surging. It is damaging if the car runs like this continuously (eg if you'd wound the boost up without considering the flow requirements), but not during off throttle moments.

 

You could get round it with a dump valve, but remember two things. One: Your car has been doing this for years, was signed off with this in mind so is nothing to worry about; Two: Dump Valves sound chavvy as you pssssssssttttchhhhffff through the gears.

 

The wastegate is on the turbine/outlet side - they do chatter, but if you've not heard it before, you probably won't now.

[bales 1]

The wastegate is on the turbine/outlet side - they do chatter, but if you've not heard it before, you probably won't now.

 

No they don't chatter thats a myth, its just a bypass for excess gas when the correct boost level has been reached. The only time you would hear the wastegate is if you had an external one that vented to atmosphere i.e a screamer pipe, but even that is just feckin loud as its only like having an unsilenced exhaust - there's nothing to chatter.

 

This seems to come from rally cars as it is said about them a lot but the squeaking noise they make is the anti-lag systems, nowt to do with the wastegate.

 

To the original qs I have run mine now for 8 months without a dump valve and it is fine, though I would probably get a recirculating one if I turn up the boost to a bar. Pug put a "diverter valve" as the VAG boys like to call them or a re-circ DV on some of the xu10cj2te models and not on others so probably wasnt too much of an issue for at least a large majority of the cars life.

 

Sounds way better than a DV anyway - though I do find that mine doesn't pick up too well between gears unless you have full throttle as it does take a little while to spool up again.

 

Alex

[Henry Yorke 269 3 Cars]

Mine used to do it until I fitted a dumpvalve

http://www.pughosting.co.uk/photopost/show.../cat/575/page/2

[McPikie 0]

Dumpvalves are for men who like other men, and kids at maccies.

 

They are just gay.

 

I actually found my cossie ran better without

[welshpug 1,678]

Dump valves are there to preserve the Turbo, you can get re-circulating units that don't make the massive "PTSHHHHHH!!!" noise, there may actually be some sort of dump valve fitted from the factory, but they are never as effective as aftermarket units it seems.

[pugpete1108 62 1 Cars]

just finished fitting my boost gauge this morning and it appears i am only running 9psi of boost?. i have a adjuster valve to fit so i can wind it up a bit but now face the decision : do i leave it with the lovely noise and risk damage when i wind up the boost or fit a recirculating dv (quiet one of course!) and loose the noise and preserve the turbo.

 

what psi would be reccomended? given the engine is std apart from the filter (its only a 20k engine btw).

 

i am kind of getting the hang of this turbo lark now

[welshpug 1,678]

Petrol turbo engines don't generally run that much boost, a standard Skyline only runs about 7psi.

 

what you need to find out is what the injectors+fuel pump are capable of, too much boost will run dangerously lean.

[bales 1]

Also you need to know if it is MAP controlled rather than MAF as it won't fuel for the extra boost otehrwise unless you play with the fuel pressure with a FPR but then you will be rich off boost and run a bit rougher probably.

 

Mine only runs 7psi standard, 1 bar is actually quite a lot of boost for factory spec cars to run.

[McDude 33]

Mine only runs 7psi standard, 1 bar is actually quite a lot of boost for factory spec cars to run.

Agreed, 1 bar is a hell of a lot of boost.

 

Could it be that that is 1 bar gauge rather than absolute (or the other way round - I always confuse myself on that one!)? In other words, you are reading off boost and just seeing atmospheric pressure?

 

Just a thought.

[bales 1]

Agreed, 1 bar is a hell of a lot of boost.

 

Could it be that that is 1 bar gauge rather than absolute (or the other way round - I always confuse myself on that one!)? In other words, you are reading off boost and just seeing atmospheric pressure?

 

Just a thought.

 

All gauges read in Barg (which is why they have a negative pressure side), so 7 psi is actually 21.7psi absolute but there isn't much point in measuring atmospheric unless you are trying to measure pressure drop in an induction system.

 

Thats why MAP sensors come in 3,4,5 bar as they need to be turbo presssure + atmospheric pressure.

 

My car will be running 1 bar soon and it is quite a bit of boost but not anything major, think the quicker evo's (standard) run up to about 1.2-1.4 which is usually the limit factories tend to go to.

 

Though when you see tractor pulling and realise some of the top modified diesel (well methanol actually) compression ignition engines run upto 60 bar!! thats bar not PSI! thats starting to be quite a bit of boost!!

 

But then they do get 3000bhp from an 8l cummins diesel designed to run about 80bhp

[McDude 33]

Hang on - 9psi is only 0.6bar, not 1 bar

 

0.6 bar is still a fair bit of boost but not crazy for a stock engine

 

Anyway, this is getting slightly off tangent. Winding up the boost further should not be taken lightly and could easily lead to problems:

 

Boost = heat and could cause detonation problems

Boost = pressure and could cause detonation problems!

You may go off the island of efficiency (turbo compressor map), melt the blades, over spin the turbo...

 

Hell, there is an endless list of problems that one could face.

 

I'd suggest going to an equally nerdy forum for Rover owners and see what people are getting away with. But on your daily drive vehicle you might want to keep it reliable.

 

Is this a Rover K-series engine? Wouldn't you be better off saving your money for when the head gasket fails

[welshpug 1,678]

tomcat turbo engines are 2.0 T series IIRC, as in T16 amusingly enough

[cybernck 403 1 Cars]

405 T16's run 1.1-1.3 bars of boost as standard so there IS a need for a dump valve.

 

they even come with full preparation for either a recirculating or a vent to atmosphere dump valve!

 

i guess they haven't actually fitted one as OE Bosch ones are only good for about 0.5-0.6 bars .

[Mikey S 29 1 Cars]

i wouldnt go winding the boost up on a rover t16! they have a very nasty habit of bending the rods as there s*ite!

 

save up for some forged h pattern rods and the upgraded headgasket before you fit a bleed screw.

[sorr 0]

I know you hear that compressor stall kills turbos, but my old Saab managed 165K miles on the original turbo which stalled quiet nicely. Much better noise than an external dump valve .