Evo's been remapped, but...

Gibbo · 15 Jul 2013 at 15:30

Chris one thing I would say is your 27psi seems very high, though I can't be 100% sure as its being a few years since I had my EVO but 11psi rings a bell to me. At 10-11psi it made stock 354BHP.

I never touched the boost or ECU, just decatted the exhaust from turbo back and fitted a larger intercooler. Resulting in 400BHP, of course what the boost PSI changed too if it did I cannot remember but I had no strange sounds or anything.

ChrisD. · 15 Jul 2013 at 15:33

Standard is 23psi I think mate, well on a 9 anyway. A X wouldn't be running 10-11.

Gibbo · 15 Jul 2013 at 15:39

MilanoChris said:
Standard is 23psi I think mate, well on a 9 anyway. A X wouldn't be running 10-11.

Its being a long time since I had mine so can't remember.

To simply rule it out, why not just turn down the boost to around 22psi and see if the noise goes away? Or get Ant to modify your map to a lower PSI and email it you to try out.

ChrisD. · 15 Jul 2013 at 15:43

That's the thing, Ant doesn't think that it is a problem.

Jonnycoupe · 15 Jul 2013 at 15:55

Why is a solenoid that should be PWM modulated to hold a set 'leak rate' to give boost higher than actuator pressure producing any sort of fluttering noise?

The leak rate back will be at a much higher frequency than what you can hear in the video. Its not good for have something controlling boost swinging around levels either.... hello boost spike.

Are you sure any sort of BOV is solid and not leaking aswell?

ChrisD. · 15 Jul 2013 at 16:03

Jonny, I'm not going to lie, I don't understand what you're saying.

I don't think there's any leaks, certainly didn't have 'problems' before the map.

Ant says it's peak boost at 1.75 bar.

Phil W · 15 Jul 2013 at 16:10

Any other owners experienced similar?

ChrisD. · 15 Jul 2013 at 16:14

There are a few threads on the MLR that match the search criteria of 'solenoid noise'. Will have a further look tonight.

Noxia · 15 Jul 2013 at 16:15

Hope it's nothing serious Chris. On a side note, my post times seem to be an hour behind.

LizardKing · 15 Jul 2013 at 16:17

I'd say your not accelerating enough to be spooling the turbo enough to create compressor surge.

ChrisD. · 15 Jul 2013 at 16:18

Heard back from another well regarded Evo tuner:

Yeah, that's just a bit of compressor surge, the nines do it a bit at low rpm at full throttle. Nothing to worry about, keep the boost under 1.9 bar and beware high overswings to keep your rods safe cheers!
Its a slightly too efficient turbo producing more air than the engine needs so causes that. All fine!

Jonnycoupe · 15 Jul 2013 at 16:37

MilanoChris said:
Heard back from another well regarded Evo tuner:

Yeah, that's just a bit of compressor surge, the nines do it a bit at low rpm at full throttle. Nothing to worry about, keep the boost under 1.9 bar and beware high overswings to keep your rods safe cheers!
Its a slightly too efficient turbo producing more air than the engine needs so causes that. All fine!

You know the bit i mentioned about boost spikes...

Thats the risk you run.

The solenoid is managing air much like a finely tuned valvetrain, many times a second, its nothing like a human hand controlling a stop **** so the flutter noise of compressor surge can't be the solenoid.

I would ask that the boost control map is turned down in the low rpm region based on that. The PWM - Pulse Width Modulation (like LEDs flashing and being picked up on film) shoudl be able to do that. You dont want compressor surge ever? So you get the noise and the fix is to back off the throttle ? I guess changing down a gear will mask it but thats what you do in VTEC Honda's not turbocharged engines.

Jonnycoupe · 15 Jul 2013 at 16:37

LizardKing said:
I'd say your not accelerating enough to be spooling the turbo enough to create compressor surge.

I'd say that was conjecture.

ChrisD. · 15 Jul 2013 at 16:42

Think it's worth getting a proper boost controller fitted?

LizardKing · 15 Jul 2013 at 16:44

Jonnycoupe said:
I'd say that was conjecture.

Welcome to the internet

It doesn't sound like any chatter I've heard before but then i've only experienced it when a garage failed to plumb my wastegate back in.

I've never heard a solenoid do that for sure though!

MartynB85 · 15 Jul 2013 at 17:34

I wouldn't run my car like that, it's not good for the turbo. If it was mine I would drop the boost a little, or get a decent boost controller and limit the boost at low rpm.

Pabl0 · 15 Jul 2013 at 17:57

MilanoChris said:
Think it's worth getting a proper boost controller fitted?

That's just masking a problem on the map surely? I'm not an evo expert in the slightest but in the 1.8t tuning its a big no no to run a boost controller parallel to another device (your solenoid) (might be very different for your engine though.

Do as Jonnycoupe and ask them to bring it down a little because quite frankly, why should you have to worry about surge when it can be mapped out.

Simon · 15 Jul 2013 at 18:17

I'm still see how a factory specified turbo on a pretty standard engine can surge. Increasing the boost via the ECU doesn't magicially reduce boost threshold, the engine will still need X rpm to get it to start driving the turbo and start making boost.

My theory (without reading on Evo specifically) is that the turbo could be right on the limit for surge from the factory and if your map is running too much ignition retard (for safety) it will have a nice 'anti lag' effect as the energy will end up in the turbo's turbine housing rather than the engine. The energy will then end up spinning the turbo faster than the standard map, producing more air than the engine can consume and hence the surge.

A lot of mappers target peak power and forget about drive ability unfortunately.

The peak level of boost is not the issue here, the issue is the excessive pressure ratio (y-axis) at low engine speed (x -axis mass flow).

ChrisD. · 15 Jul 2013 at 19:07

That's the thing, Ant isn't one about numbers. He won't push to impress the customer unlike some so called reputable Evo mappers. Ant is all about safety and mapping well within the limitations of current setup. But it does seem odd that the car does this.

Gaijin · 15 Jul 2013 at 20:03

Not particularly sure if its much use as mine has lots of bits different from a 9. but mine definitely doesn't do that.

In fact the only time I do get compressor surge is when I unexpectedly back off the throttle, usually up a hill. And even then it will usually last for about a second.

I don't think there is anything wrong with getting a second opinion.

What's the brand of solenoid? I think mines a Perrin. Not 100% sure though.

As you've mentioned, 1.4-1.8 Bar is commonly used on stock engines to achieve maximum power within the safety margin of the engine.