Something is telling your turbo to speed up and then it's not getting the air out fast enough and stalling the turbo. I have a 350bhp 200SX running 1.4 bar and if it sounded like that I wouldn't be driving it. I may be incorrect in my diagnosis but it just doesn't sound healthy.
Evo's been remapped, but...
- Thread starter ChrisD.
- Start date
I'd be interested to understand how the engine is not consuming enough air to allow the compressor to stay on the right hand side of the surge line.
You may need have an issue with cam timing or exhaust backpressure.
typical compressor map :
The red line is the line you don't want to cross, if you are making too much boost at a low mass flow then it is possible to cross it (from right to left) The right side is about compressor efficiency, the higher the efficiency the better (this obviously needs to be matched to the turbine on the turbo charger too)
From wiki:
Axi-symmetric stall, more commonly known as compressor surge; or pressure surge, is a complete breakdown in compression resulting in a reversal of flow and the violent expulsion of previously compressed air out through the engine intake, due to the compressor's inability to continue working against the already-compressed air behind it. The compressor either experiences conditions which exceed the limit of its pressure rise capabilities or is highly loaded such that it does not have the capacity to absorb a momentary disturbance, creating a rotational stall which can propagate in less than a second to include the entire compressor.
The compressor will recover to normal flow once the engine pressure ratio reduces to a level at which the compressor is capable of sustaining stable airflow. If, however, the conditions that induced the stall remain, the return of stable airflow will reproduce the conditions at the time of surge and the process will repeat.[1] Such a "locked-in" or self-reproducing stall is particularly dangerous, with very high levels of vibration causing accelerated engine wear and possible damage, even the total destruction of the engine.
You may need have an issue with cam timing or exhaust backpressure.
typical compressor map :
The red line is the line you don't want to cross, if you are making too much boost at a low mass flow then it is possible to cross it (from right to left) The right side is about compressor efficiency, the higher the efficiency the better (this obviously needs to be matched to the turbine on the turbo charger too)
From wiki:
Axi-symmetric stall, more commonly known as compressor surge; or pressure surge, is a complete breakdown in compression resulting in a reversal of flow and the violent expulsion of previously compressed air out through the engine intake, due to the compressor's inability to continue working against the already-compressed air behind it. The compressor either experiences conditions which exceed the limit of its pressure rise capabilities or is highly loaded such that it does not have the capacity to absorb a momentary disturbance, creating a rotational stall which can propagate in less than a second to include the entire compressor.
The compressor will recover to normal flow once the engine pressure ratio reduces to a level at which the compressor is capable of sustaining stable airflow. If, however, the conditions that induced the stall remain, the return of stable airflow will reproduce the conditions at the time of surge and the process will repeat.[1] Such a "locked-in" or self-reproducing stall is particularly dangerous, with very high levels of vibration causing accelerated engine wear and possible damage, even the total destruction of the engine.
Man of Honour
- Joined
- 13 Nov 2009
- Posts
- 11,674
- Location
- Northampton
Boost doesn't necessarily equal horsepower though.
A big turbo at 7psi will be flowing more air than a small turbo at 7psi.
Soldato
- Joined
- 19 Oct 2002
- Posts
- 18,243
- Location
- Shakespeare’s County
Boost is just an engines inability to consume air. It means little in the grand scheme of things.
Soldato
- Joined
- 11 Dec 2005
- Posts
- 11,364
- Location
- Cheshire
Soldato
- Joined
- 19 Oct 2002
- Posts
- 18,243
- Location
- Shakespeare’s County
Well yeah you're right, its loads.
1.6 bar on a supra gives you effective engine size of 7.8 litre.
The FQ360 boost control may well be mapped to avoid compressor surge at low rpm as its a very high factory bhp/litre so the turbo will be sized 'suitably'...... hence it didnt do it before!
Man of Honour
- Joined
- 13 Nov 2009
- Posts
- 11,674
- Location
- Northampton
Pretty sure the stock turbos are good upto about 2bar on the eco viii and ix after doing some research as my dad will be buying one later in the year.
I've also been told that a 9 can take up to 2 bar if mapped well but day to day above 1.8 is not recommended. I chose the tuner wisely and I am sure he knows what he is talking about. I would appreciate less 'zomg too much boost/poor map' comments without anything else as they add nothing to this thread.
Thanks to the guys who have posted decent replies, it is good info.
Ant mailed me again, he says it is completely normal for a remapped Evo to make this noise and it is the solenoid releasing the boost rather than compressor surge.
Thanks to the guys who have posted decent replies, it is good info.
Ant mailed me again, he says it is completely normal for a remapped Evo to make this noise and it is the solenoid releasing the boost rather than compressor surge.
If it is stalling the turbo then why do I get no drop in PSI (I have a pod) and why does the power not drop?
Ok cheers. So what do I do? I don't know enough about turbos to make an informed decision my self. I know about K20's, and the H22. But not turbo's. On one side I see some pretty well written posts in here by people who to me seem to know what they are talking about. On the other I have the tuner saying it's normal, a tuner who I researched and have seen good feedback, very good feedback in fact. I don't want to pay someone else now, for something I have already spent money on.
Give the RacingLine a ring, just tell them the symptons, don't name any names and see what they suggest.
When I had the X they will regarded as the masters of tuning them and seemed very respectable to the point they did not want to take my money as my car was running so well on the stock map.
Is TheRacingLine or Powerstation at all local to you?
No idea, and I'm still not 100% convinced that it's a 'bad map'.
Not using TRL mate.
Powerstation is 20 minutes up the road. But I don't want to pay for another remap or second opinion.
I don't really want to post anything as it will end up in a tuner ****ging thread.
I have been searching, some posts similar to my 'noise'.
http://lancerregister.com/showthread.php?t=375885&highlight=boost+solenoid+noise
http://lancerregister.com/showthread.php?t=280268&highlight=boost+solenoid+noise
Few more threads on MLR saying that 3 ports are noisy.
Soldato
- Joined
- 27 Aug 2003
- Posts
- 9,831
- Location
- West Midlands
I have to say, this also to me sounds like compressor surge. However I am not an expert.
Does the boost gauge not move at all during this noise?
I've had compressor surge on mine before, and I also have a 3 port solenoid...
Does the boost gauge not move at all during this noise?
I've had compressor surge on mine before, and I also have a 3 port solenoid...
Soldato
- Joined
- 27 Aug 2003
- Posts
- 9,831
- Location
- West Midlands
Wastegate flutter would be the wastegate opening and closing trying to keep the boost at that level. You would (IMO) see the boost gauge fluttering at least a bit? For either scenario..