HX35 Compressor Surge

[1stGenTSi]

Ok, so I'm getting compressor surge under two different situations with my HX35 in .55 ar housing. First off I hear it when slightly accelerating (enough to build a few psi) and then letting off the gas slightly but not all the way. Like going from ~30% throttle down to ~10%. This happens to me often when speeding up and slowing down on the highway. I have to let all the way off the gas quickly in order for it not to surge under this condition. I assume this can be fixed by adjusting the bov (Greddy RS) but I haven't had much luck.

The second situation is if I hold it at around half throttle for a little while, like trying to accelerate from 60 to 80 or so on the highway. When this happens the boost gauge will flutter back and fourth rapidly from about like 10-15psi. I believe the turbo must be putting out more air than the motor can ingest at this point. You can feel the engine stuttering a little bit as the boost fluctuates.

So what's the deal, can I just like never go part throttle any more? Isn't the ported cover supposed to prevent this? I'm almost ready to put my evo 3 16g back on. I never had any of these issues with it.

Turbo is 8 blade hx35 in .55ar housing. Running external 38mm off o2 housing. Both these problems happened with both 1g BOV and Greddy type RS. Any help is greatly appreciated. Thanks.

 

[JusMX141]

I don't see cams listed on your profile....I believe that may be where your problem lies.

 

[jeff24680]

.............

The second situation is if I hold it at around half throttle for a little while, like trying to accelerate from 60 to 80 or so on the highway. When this happens the boost gauge will flutter back and fourth rapidly from about like 10-15psi. I believe the turbo must be putting out more air than the motor can ingest at this point. You can feel the engine stuttering a little bit as the boost fluctuates.

So what's the deal, can I just like never go part throttle any more? Isn't the ported cover supposed to prevent this? I'm almost ready to put my evo 3 16g back on. I never had any of these issues with it.
..................

This sounds similiar to a problem I had before. What are you using as a boost controller?

Im going to try and explain this as clear as possible

EVO III Internal wastegate spring = 12 lbs on my 14B turbo(thanks jusmx)

AEM Wideband set to start send boost to waste gate at 11.5 lbs.

Therefor once my boost hit 11.5 the wastegate would start receiving pressure and bleed some off, however under light load what this was causing it to do would bleed to quick and drop below 11.5(close wastegate), raise above 11.5(open wastegate, drop below 11.5(close wastegate), as you can see boost would fluctuate from 13-10.5 at half throttle.

To fix this I need to adjust my boost controller settings based on what I know. Which is only that my wastegate actuator stock opens at 12psi.

I raised my boost controller setting to allow more flow through while adjusting the spring crack setting(the setting which tell the BC when to send pressure to wastegate) and doing some testing. I settled with a duty cycle of 50% low setting and 65% high, which a spring crack setting of 11 psi.

Hope this makes sense...

 

[1stGenTSi]

Hmm... so you think some 272's would help out? I thought a lot of people were running the hx35 with stock cams. You think the turbo can hold up okay to this low boost compressor surge? It runs great at WOT.

This sounds similiar to a problem I had before. What are you using as a boost controller?

Im going to try and explain this as clear as possible

EVO III Internal wastegate spring = 12 lbs on my 14B turbo(thanks jusmx)

AEM Wideband set to start send boost to waste gate at 11.5 lbs.

Therefor once my boost hit 11.5 the wastegate would start receiving pressure and bleed some off, however under light load what this was causing it to do would bleed to quick and drop below 11.5(close wastegate), raise above 11.5(open wastegate, drop below 11.5(close wastegate), as you can see boost would fluctuate from 13-10.5 at half throttle.

To fix this I need to adjust my boost controller settings based on what I know. Which is only that my wastegate actuator stock opens at 12psi.

I raised my boost controller setting to allow more flow through while adjusting the spring crack setting(the setting which tell the BC when to send pressure to wastegate) and doing some testing. I settled with a duty cycle of 50% low setting and 65% high, which a spring crack setting of 11 psi.

Hope this makes sense...

I had thought about the wastegate opening and closing over and over causing the half throttle surge/flutter issue, but I have a 1 bar spring in my wastegate and a MBC set at 22psi so the wastegate shouldn't be opening at all during the 10-15psi that this is occurring at. Thanks for the reply.

 

[black_gst]

+1 cams and soften your BOV

 

[1stGenTSi]

+1 cams and soften your BOV

I've got it all the way soft. I think there's two springs inside, should I take one out? Thanks.

 

[black_gst]

yes take a spring out

 

[doesitonall4rs]

2 questions,
1: Why do you have 2 springs inside you greddy RS?

2: Doesn't the HX35 have an anti surge housing cover on it to prevent compressor surge? I have been running a crushed 1G BOV and never have heard my holset surge ever

 

[1stGenTSi]

2 questions,
1: Why do you have 2 springs inside you greddy RS?

2: Doesn't the HX35 have an anti surge housing cover on it to prevent compressor surge? I have been running a crushed 1G BOV and never have heard my holset surge ever

It comes with 2 springs in it. Yes the hx35 has an anti surge cover, I don't think it prevents compressor surge but just lessens the damage from surge by allowing the backed up air to go around the comp wheel rather than back through it.