I just installed a BBK Full and am a bit surprised to be getting compressor surge. I am running a 3-port and hitting 26 psi at around 3700 rpm. Unless I turn it down to the very low 20s in that RPM region, I get the tell-tale ch-ch-ch-ch-ch-ch from the turbo. It's not the BOV and it happens only at WOT. I think it may be the combination of my large BF 272 cams and a small turbo. I'm not sure if the best approach to resolving it is to go with smaller cams (thinking GSC S2s) or getting the FP antisurge cover. I'm assuming that this doesn't happen with the S2s since so many people have them. I really would rather not get the cover, though it would be way cheaper than changing cams ($700+ with labor). I just removed a Black and really like the fact that this turbo is so much quieter. Could there be a solution other than slowing down the spool of the turbo with the 3-port (which I can do, but it largely defeats the purpose of getting the BBK in the first place).

Thanks,
Rich

 

Isn't compressor surge primarily a function of the basic characteristics of the turbo compressor itself and the amount of air the engine can ingest at a given RPM level?

 

I think the turbine side also comes into play, but yes. I suspect that the surge I'm getting is from the fact that the large cams can't take so much boost so early. I would assume that a stock turbo would do the same thing.

 

Difficult to say if different cams would help with the surging. Personally I doubt it. You could try a set of adjustable cam gears to move your powerband into a higher RPM range. Does it surge in all gears, or just in the higher gears?

l8r)

 

drive out of efficiency of turbo and that will happen. try advancing the exh cam and retarding intake to optimize 6000+rpm

 

FP antisurge cover - you answered your own Q.

 

I personally would ask CBRD about it, and how to stop it seeing as they designed these turbo's.

But yes i'd have to agree with C6C6CH3vo, retard the intake cam and/or advance the exhaust cam to move the power band to the right.
The intake will have more affect than the exhaust changes.

 

Rich,

this is not a common complaint we've had at all over the past 2 or so years with our turbo....

Let's get on the phone and chat about your setup and go from there

cb

 

I ran the BBK Full with Kelford 280/272 with zero surge issues. Call Chad

 

My BBK (30-33psi) would surge on the street if I started my pull around 3k rpm. If I started my pull at ~4k rpm everything was happy. Try and downshift? It doesn't happen on the dyno, I assume because the load is different or something.

 

Isn't the issue more likely that I'm driving out of the efficiency range of the engine, not the turbo? I actually would think that moving the powerband down (to the left) would better enable it to accept the boost that the BBK is making down low. My powerband already tends way to the right with the long duration cams and ported head.

I didn't mean for this to come across as a complaint about the turbo. I know that the BBK is more than proven. I think this is really just an issue of parts combination and/or tuning, or both. I didn't call you right off because I bought the turbo from a 3rd party (who had it as a spare and never used it).

If it helps, here's a more complete mod list of relevant parts:

Buschur Racing 2.0
BR ported head
BR 272 cams
BR 65mm TB
BR ported exhaust and intake manifolds
BR 3" intake
BR Race FMIC w/BR piping
DSM 1G BOV w/Dejon Tool leak stop kit
3" TBE

I think my next step is to play around with AFR and timing to see if I can slow the spool down with tuning. Chad, I'll try to give you a call during the day, but I'm so busy at work it might not happen soon. Please PM me if you have any ideas.

Thanks!

 

I used to have wicked surge with the FPWhite. I loosened up the WGA 1.5 turns and BAAM, no more surge! Like, never.

I have the standard wastegate on there but it was not opening enough and with the quick spool of these smaller turbo's, it makes sense.

Give that a shot first Rich, can't hurt any and I did not see any difference in spool up.

 

Just giving my input here ut have you tried to change or check your spark plugs? My car was acting up not to long ago (seemed like surge) and I checked my plugs (as recommeded to me) and they were bad. Now I run E85 and thats why they were bad (common problem with E85), so I figure maybe your gapping might need to be changed or they might be going bad. If I'm wrong about the plugs then sorry for waisting your time and sending you on a wild goose chase. I just like to start small and cheap with trouoble shooting.

 

Compressor surge happens when you operate below the efficiency range of the turbo - specifically the compressor side. It happens when you're trying to move too much air too soon. If you look at a compressor map, it generally occurs when you land on the left of the surge line. Head porting, types of cams, intake, etc. all play into VE - usually for the better. Larger cams generally have lower VE at low RPM and improve VE up top - hence the suggestion from several people to use adjustable cam gears to move the powerband (i.e., where they improve VE) of your cams. I had surging issues on a 3071 that I ran a number of years ago, and it was nothing like BOV related surge. No friendly tsh, tsh, tsh sound. The whole car would start bucking pretty badly when it started to surge. So I wouldn't count out the BOV or wastegate yet.

I would suggest talking to Chad, especially if you have log files to share with him.

l8r)

 

Oh ok, thanks^