What are the symptoms of compressor surge, I understand the cause (to much air in/around the compressor wheel causing it to slow down).

 

Just really what it says its like the boost comming in and out if that makes sense, feels like pressing the throttle peddle on and off when driving, i get it now and again on very cold mornings.

 

If you have a boost gauge you will notice the neddle fluttering like mad.

 

Compressor surge is a badly matched inlet or turbo spec to engine.

It's an audible "fluttering" or "oscillating" sound as stated above, easily seen by a boost gauge normally at peak boost on a twinscroll.

It's not good and should be avoided.

 

If it was the inlet would it not be apparent before a turbo change?
And what about the mapping?

 

It will sound like dump valve delete. Loudness depends on the turbo type. Blocked/faulty recirc valve can cause this issue.

 

sounds like a pigeon cooing, so often referred to as a "pigeon mod".

 

If you have the same inlet pipes and filter than before the turbo swap and it never surged then, then it won't be your inlet. If all you've changed is the turbo, it points towards your turbo being the issue.

Not sure what you're referring to when you ask about the mapping?

 

Could the map of the car be a factor which would cause comp surge?

 

Usually high gear low rpm so can be mapped out especially if it is possible to control the boost independant of gear like megarom for example.

If its a noise the I wouldnt worry, if the physcially shakes then it needs looking into further.

Some setups are prone to it. The vf turbos very often surge in a high gear.

Simon

 

As Simon says... it can be mapped out, but imo that's a crap solution to a problem that lies elsewhere and should be sorted at that source.

 

Cheers Simon

 

What do you suggest?

 

My Spec C on its mental 1.7 bar peak map from Powerstation would surge in 3rd gear and above when accelearatig from low revs. I adjusted my driving style to make sure I was in the right gear and not too high a gear.

 

Dont totally agree with you Shaun as in Rickys example thats a map issue as if it were mapped to a slightly lower peak boost at low rpm it would be just as mental only he could use full throttle from low rpm.

Although yes sometimes surge is not map related.

If its just a noise it fine but if the car bucks and bolts or the boost pings then I would worry

 

It's not a noise it's as Ricky described, what about the housing would that be an issue it's a standard IHI twinscroll housing?

So it looks like it needs a map adjustment

 

The vf twin scroll can be prone to it, not sure exactly what turbo you are running now.

Assuming boost is sensible and inlet pipe is normal one then it shouldnt really be surging unless turbo issue or mapping issue

Simon