Compressor surging ?

[Wolf_Tm250]

Hello Mates,

after 22 months of HARD job, finally my car was ready.

I made it mapped, last Tuesday, by Motec's australian engineer Dave Rowe.

On the dyno, numbers were fantastic, over anyone's expectations.... btw, having done ALL the job by myself, I was already happy when I switched it on for the first time and all sounded ok !!!

BTW... let me describe my... "problem" ?!?

Especially in longer gears, 4th or 5th gear, I push WOT on the pedal from low rpm ( 2500 rpm ), around 3500 rpm the boost jumps up, the engine has some hesitations and the boost gauge start to vibrate up & down !

Dave Rowe told me to decrease the plugs' gap: I tooke them from 0.70mm to 0.60mm, but the problem is still there...

Could it be compressor surging ?

Could it be that, given that I connected pressure line for the BOV and for the EBC togheter, so when the ebc is starting to control the boost, and releasing some air in the atmo, the boost is able to force the BOV spring and makes it flutter ?

Any idea or advice ?

Thank you !

[Akane]

Without telling us ANY of your mods, it's impossible to say.

[vvega]

have you got a compressor map for your turbo ??
thats the eazy way to tell

it would be un usually for it to surge at low rpm and not high but anyhting is posible

start with the compresor map and well go from there

v

[Wolf_Tm250]

Unfortunately I don't have the comp map, it's an unrestrictored version of the WRC turbo, and I don't really know what kind of turbo is...

So I was asking what the surging is like, to understand if it is...

I even have another idea...

At the same pipe coming from the plenum, with a 4 holes joint, I attached 3 pipes:

- BOV pipe
- pressure line for ext. HKS wg ( set at 1.15 bar )
- pressure line for Blitz EBC ( set at 2.00 bar )

Could it be that the boost's variations in the 4-holes-joint is making the wg to flutter ?

Or could it be due to the too much differenze between waste gate opening pressure ( 1.15 ) and my boost setting ( 2.00 ), so when the max setted boost is reached, the wg valve opens too fastly ( for the poor preload ) and makes the boost to fall to rapidly ?

Thank you very much.

[vvega]

if your running a steel ct20b (st205wrc) turbo i doubt you are getting surge

you t juntion could could casing a issue

what bov are you runnning ??

[Wolf_Tm250]

if your running a steel ct20b (st205wrc) turbo i doubt you are getting surge

you t juntion could could casing a issue

what bov are you runnning ??

Hi vvega,

no it's not the ST205wrc turbo, it's an unrestrictored TTE-WRC turbo... it seems to be an hybrid T3...

I'm using Greddy Type R bov with softer spring...

[vvega]

if your running a steel ct20b (st205wrc) turbo i doubt you are getting surge

you t juntion could could casing a issue

what bov are you runnning ??

Hi vvega,

no it's not the ST205wrc turbo, it's an unrestrictored TTE-WRC turbo... it seems to be an hybrid T3...

I'm using Greddy Type R bov with softer spring...

was it bought in nz
if so i will know the man that built it and could probably get some info on it for you
from my understanding it will be a hybrid ct20b
though ill check on that

even then a genuine tte item designed for your car will not be surging
it wouldnt win many races like that now would it

id seperate the wastegate and bov lines for a start
they should alway have there own dedicated line to the manifold

surging has a very distingtive sound as its bassically cavataing the turbo
is there a noise assosiated with the issue
do the intake temps rise drematiclly ??

cheers
v

[vvega]

Or could it be due to the too much differenze between waste gate opening pressure ( 1.15 ) and my boost setting ( 2.00 ), so when the max setted boost is reached, the wg valve opens too fastly ( for the poor preload ) and makes the boost to fall to rapidly ?

Thank you very much.

if this was the issue with teh wastegate spring tension you would find that the boost would spike and then it woudl struggle to drop down to the proper tension as it woudl be unable to clamp on the turbine pressure

sure way to check is unplug the boost controller in its intiruty and see what happens


so its all a bit disjointed
you have put forward many good sugestions and im just tring to give thme all consideration before answering with something that explanes what i think rather than just a flat answer

v

[Wolf_Tm250]

was it bought in nz
if so i will know the man that built it and could probably get some info on it for you
from my understanding it will be a hybrid ct20b

I bought it in Germany, from the Toyota F1 motorsport - ex-TTE, and believe me, it's TOTALLY different from a CT20 !



http://img516.imageshack.us/my.php?imag ... g014jz.jpg

id seperate the wastegate and bov lines for a start
they should alway have there own dedicated line to the manifold

Ok !

surging has a very distingtive sound as its bassically cavataing the turbo
is there a noise assosiated with the issue

Yes, an hesitation like misfire, and you hear the WG, through the screamer pipe, that opens and closes many times in a second !

do the intake temps rise drematiclly ??

I'll check the logs !

Thank you !

[vvega]

i want a better pic of that turbo please
id liek to see compressor side pics ans wastegate side pics
i sure you would have taken a few befor you put it on the car

v

[Wolf_Tm250]

if this was the issue with teh wastegate spring tension you would find that the boost would spike and then it woudl struggle to drop down to the proper tension as it woudl be unable to clamp on the turbine pressure

Boost is really bouncing up and down on my Greddy boost gauge, and even the waste gate opens and closes many many times in a second...

at the beginning the FOO FOO FOO sound from the screamer pipe is rapid and short, many times in a second... but gradually the FOO becomes longer ( and decrease the frequency per second ) till it become stable...

how can I explain...


" FOO FOO FOO FOO FOOO FOOO FOOO FOOOOOO FOOOOOO FOOOOOOOO FOOOOOOOOOOOOOOOOOOO-stable boost "


Maybe I'll really to adjust wg spring tension... I'll try...

so its all a bit disjointed
you have put forward many good sugestions and im just tring to give thme all consideration before answering with something that explanes what i think rather than just a flat answer

v

I'm doing my best, and you're doing your best ! Thank you !

[Wolf_Tm250]

i want a better pic of that turbo please
id liek to see compressor side pics ans wastegate side pics
i sure you would have taken a few befor you put it on the car

v

Yes I had.... before my HD went for strawberries....

[vvega]

just a thought if it is a tte tubo you could well be running it under its effencancy range
from my understanding there desided to run at 2 bar

what ignition system are you running and what static compression are you running

v

[Adydas]

mmm 2 bar, thats a figure worth a beer

[fivebob]

Good to here you finally got it mapped, after all those hassles.

Could it be that, given that I connected pressure line for the BOV and for the EBC togheter, so when the ebc is starting to control the boost, and releasing some air in the atmo, the boost is able to force the BOV spring and makes it flutter ?!

Yes it could be that. When the shuttle valve opens you lose pressure on the diaphragm and that means the pressure on the turbo side of the BOV is greater and could force the valve open.

From this distance the turbo looks like it could be a CT34 or possibly a CT44/ST hard to tell without a close up photo.

[Wolf_Tm250]

vvega, fivebob...

first of all, thank you for your help...

I'll post asap an in-car video of the trouble, so to see, first, what is the problem...

Good to here you finally got it mapped, after all those hassles.

Yes ! And thank you for the help you gave me to make it mapped for a good running-in !

Could it be that, given that I connected pressure line for the BOV and for the EBC togheter, so when the ebc is starting to control the boost, and releasing some air in the atmo, the boost is able to force the BOV spring and makes it flutter ?!

Yes it could be that. When the shuttle valve opens you lose pressure on the diaphragm and that means the pressure on the turbo side of the BOV is greater and could force the valve open.

I divided the pipes, but the problem is still there...

could it be due to low wg opening pressure ( 1.15 ) versus high ebc setup (2.0 bar) = too much difference ?

I'll try to increase the wg opening pressure to the max, around 1.4 bar...

Bye !

[fivebob]

Yes ! And thank you for the help you gave me to make it mapped for a good running-in !

No problem, long distance tuning was an interesting exercise, wonder if there's a market for web based real time tuning

could it be due to low wg opening pressure ( 1.15 ) versus high ebc setup (2.0 bar) = too much difference ?

I'll try to increase the wg opening pressure to the max, around 1.4 bar...

Not sure, I would've thought it wouldn't be an issue with proper control of the duty cycle you should be able to work with any pressure spring, to my way of thinking a lower pressure spring, with a lower duty cycle, but higher frequency may give better control.

Have you tried it without the EBC, just relying on the wastegate? I know it's lower boost that you want to run, but that may eliminate the wastegate as a cause and could point to compressor surge as the cause.

If you are getting surge, then can you make the engine flow any more freely than it already is?

[Wolf_Tm250]

Yes ! And thank you for the help you gave me to make it mapped for a good running-in !

No problem, long distance tuning was an interesting exercise, wonder if there's a market for web based real time tuning

Have you tried it without the EBC, just relying on the wastegate? I know it's lower boost that you want to run, but that may eliminate the wastegate as a cause and could point to compressor surge as the cause.

When I used it without the EBC, it seemed to me to be fine... I'll check again...

If you are getting surge, then can you make the engine flow any more freely than it already is?

Intake or exhaust ?

Intake I have 2.5" pipes compressor to ic - ic to butterfly, and 70mm butterfly...


Exhaust I have a full free 3" system with screamer pipe for the wg... even if I was going to put it back in the exhaust... it's impossible to use a street car with the screamer pipe !
BTW, in that case, I must reconsider: 3" + screamer is bigger than only 3" ...

PS: did anyone dyno'd the power loss turning the screamer pipe back in the exhaust ?

PS2: I dynoed 526 FWHP, and 588,2 NM ( yes rr dyno are crazy... ), do you think 3" exhaust could be small ?

TIA !

[fivebob]

If it is surge then you need to identify the most restrictive part of the engine.

588nm of torque is huge, even allowing for the FWHP "fudge factor", as torque is the best indictation of flow through the engine I think you may well need to increase the 3" system. But that's just a guess, first we need to determine the cause.

Can your EBC do RPM dependent boost control, restricting the max boost at the lower rpms might be a solution. Sounds like this turbo is making some serious boost down low which is the opposite of most 3S-GTE systems and probably why I've never come across surge before, even with huge turbos.

BTW have you got a dyno plot, or at least some more information about where peak torque occurs, and possibly a boost curve from you logs.

[Wolf_Tm250]

If it is surge then you need to identify the most restrictive part of the engine.

Ok...

588nm of torque is huge, even allowing for the FWHP "fudge factor", as torque is the best indictation of flow through the engine I think you may well need to increase the 3" system. But that's just a guess, first we need to determine the cause.

Ok.

Can your EBC do RPM dependent boost control, restricting the max boost at the lower rpms might be a solution.

Unfortunately not my id3...
what about the Motec boost controller ?

Sounds like this turbo is making some serious boost down low which is the opposite of most 3S-GTE systems and probably why I've never come across surge before, even with huge turbos.

The Motec's mapper told me to decrease the gap again and again, but now I'm already at 0.60... will try with 0.55mm ...

BTW have you got a dyno plot, or at least some more information about where peak torque occurs, and possibly a boost curve from you logs.

I have only a pic taken with my phone of the numbers I told you, because the mapper was still refining the maps... but after that we discovered WI pump was not working, so I have a final dyno plot at home at "only" 1.95 bar:

411.8 AWHP at 6.139 rpm
489.4 FWHP ( only 78.4 hp lost in trasmission ???? )
561.1 Nm at 4957rpm

Will show you the plot this night...

And even the loggings of today's trackday

Thank you, mate.