My Evo 9

Badly mapped rather than broken let's be fair.

If all my research on mapping over the last few days it should down to the waste gate duty cycle being wrong after you've had the 3 port solenoid fitted so you're effective requesting too much boost in the lower rev range.
 
Still think it's odd that the turbo is specced so that this can happen. In my day, the wastegate 'requested' all the boost, all the time, and surge didn't happen. I suppose you can't argue with 400hp capability with quick spool on 2l though.
 
Clarkey said:
Still think it's odd that the turbo is specced so that this can happen. In my day, the wastegate 'requested' all the boost, all the time, and surge didn't happen. I suppose you can't argue with 400hp capability with quick spool on 2l though.
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Wastegate pressure on turbos on cars that rely on the ecu to control boost is less than they actually run Iirc.

Example an impreza wrx is about half a bar iirc purely on Wastegate pressure but just shy of a bar with the ecu controlling boost.
 
Some Americans said on YouTube that it's my wastegate spring not being stiff enough. I don't know much about turbo's though to be fair.
 
MilanoChris said:
God awful? Taken out of proportions I think, it's a worst a little bit of surge, you make it sound like it's broken.
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I didn't mean to offend!

It just sounds broken to me at the moment, and it's concerning to think it 'might' be damaging something.
 
MilanoChris said:
Some Americans said on YouTube that it's my wastegate spring not being stiff enough. I don't know much about turbo's though to be fair.
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Americans :rolleyes:

:D

Get that exhaust on there and the surge will probably go away anyway despite going in for a re-tune..
 
Clarkey said:
Still think it's odd that the turbo is specced so that this can happen. In my day, the wastegate 'requested' all the boost, all the time, and surge didn't happen. I suppose you can't argue with 400hp capability with quick spool on 2l though.
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"back in the day" turbos weren't that efficient.

If you want efficiency from a turbo then by default you run the risk of surge as that is at the very same point of highest efficiency
 
I don't profess to be an expert either but from after many many hours over the last week spent on rom raider forums and reading various open source mapping guides surging generally comes from requesting too much boost at low rpms or small throttle opening.
 
The way I see it (laymans terms) is you ask the turbo to supply more boost than the engine can swallow, so yes low rpm, too much boost is exactly that.

You end up with more pressure in the manifold than the turbo is actually producing, that air wants to get out so it goes back through the turbo instead of into the cylinders.
 
Fuzz said:
The way I see it (laymans terms) is you ask the turbo to supply more boost than the engine can swallow, so yes low rpm, too much boost is exactly that.

You end up with more pressure in the manifold than the turbo is actually producing, that air wants to get out so it goes back through the turbo instead of into the cylinders.
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That's what I read on MLR, the turbo is basically consuming more boost than the engine can consume.
 
MilanoChris said:
So Fuzz you think it will be sorted tomorrow?
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I think simply fitting the exhaust will sort it as it will be a more free flowing system, either way you're having it mapped as well by the sounds of it so if the exhaust doesn't fix it, the mapper will..

(lower the boost a tad at point it surges, it's simple enough.)
 
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