I am getting heavy surging at around 4000 rpm as boost is passing through the 22-23 psi range on my FP Black at WOT. This is not just a sound I hear. The car bucks hard and momentarily stops accelerating. In 4th it is bad enough that I have to lift off. In 3rd, it happens for just an instant, and doesn't happen at all when my cutout is closed (in 3rd).

I didn't have this issue with my old stock cover FP Red until I got a BR head, cams and bottom end. BOV was the same before and after. Boost control was an EBC before and after. When I swapped to an FP Black the problem continued. When I switched to ECU boost control, it didn't make a difference either, though I can tune out the issue by lowering WGDC in the problem range (at the heavy expense of spoolup and low end torque).

Is this really compressor surge?

Could it be a BOV problem at WOT?

I have a 1G BOV (recirc'd) with the Dejon Tool leak stop kit and it will hold boost up top no problem. At BR, the car made 464whp on 93 with the Red, but it did surge badly on the way there.

I'd hate to spend the money on another BOV set up only to have it not help, particularly when the part throttle characteristics of this one are so nice. I'm running SD so I'd probably get a Tial Q VTA if I were to change.

Any advice would be appreciated.

Thx.

 

I would look at the BOV. I have yet to see any FP really truly surge and I have tried to make them. Definitely not a Black.

Aaron

 

I blocked off the BOV and the problem is still there. Here's an example of what the log looks like when it happens. Notice the boost struggling despite the steady WGDC. It should be going smoothly to 27-28 psi. But for this issue, I think it would hit 27 psi by 4000 rpm. This is fourth gear. The problem isn't there in 1st and 2nd and there is just a touch in 3rd. Haven't revved it this high in 5th yet.

TPS RPM MPH LoadCalc Timing WBO2 MDP WGDC


100 3688 53 270 8 11.5 20 49
100 3781 58 282 8 11.3 16 49
100 3750 58 308 7 11.1 21 47.5
100 3938 58 318 6 11.1 19 47
100 4000 58 278 9 11.2 18 47
100 4219 63 255 10 11.2 21 47
100 4250 63 252 10 11 23 47
100 4344 63 252 10 10.8 23 47
100 4531 63 327 9 10.9 27 47
100 4500 70 326 9 11.1 26 47
100 4719 70 315 11 11.3 27 47
100 4750 70 311 11 11.5 26 47

p.s. Knock is zero throughout.

 

That's weird.

 

One thing I should mention is that I have an 18 psi actuator rather than the usual 25 psi actuator that comes on the Black. I wonder if that could be the problem?

 

Double check the way the leak stop kit is piped, I know you can run into problems at or around 15 PSI where the LSK kicks in but what you describe sounds different. By the way I found a way around the 15 PSI issue by stretching out the spring under the white cap by about 5MM.

 

Since the problem persisted when the BOV was blocked off (put a piece of sheet aluminum between the valve and flange), is there any way that the BOV could be a factor at all?

 

My stock turbo does it (did it a lot more with the TiAl, now use Synchronic), only at part throttle, 40%-60%. In my case, I think it's too much boost with too much restriction in the flow path (throttle butterfly).

Can you tune your boost on throttle position at all?

 

That sounds like typical stock turbo compressor surge. I could turn down boost in the problem area, but I shouldn't have to with the Black.

 

I'm having the same problem with mine. built 2.0 .5mm oversize valves and mild porting, ported IM, FP Black, stand alone. I haven't spent a ton of time on drivability because I've been tracking down other issues with the build, but that really should not be a drivability issue since it happens at WOT.

One thing I'm wondering is I have a stock throttle body, is yours ported? I know with everything else done besides that it may be a slight choke point

 

I have a 65mm throttle body. You are the first person to report a similar problem. What are you using for boost control and which actuator spring do you have?

 

if the bov is not working right I think it would be just like not having one installed.

 

25psi fp actuator, boost control via pro efi

speed density and Tial Q bov (vta)

what do you have for cams and exhaust?

 

I have BF272 cams. Exhaust is straight through 3" with a Magnaflow 6" round muffler and a 4" resonator that doesn't neck down.

cfdfireman-- At WOT isn't the BOV supposed to be sealed shut?

 

There is another thread about this same issue, most of the guys solved their problem by getting their car retuned.