Compressor Surge

[SloS13]

KA-T with a .60/.63 Turbo w/ 360 degree thrust bearing.

I've heard that having the 360 degree thrust bearing makes compressor surge less harmful to the turbo. Any truth to this?

Running a Greddy Type-S. I've tried both recirulating and atmospheric. It ALWAYS surges for about .5 seconds before the BOV opens up. I forget exactly what source I'm tapping for the BOV signal but IIRC I've tried a couple vac lines and they all meet with the same result.

Any idears? Is that BOV to small of an opening for my turbo?

[nissanfanatic]

My car does the same thing. You can solve the problem by hooking up a boost only line to the bottom port of the BOV. I find that it always leaks tho so you may wanna run recirculated when you try it.

[SloS13]

Best ET: 13.404 (2.097 60') open diff-205 street tiresBest Trap Speed: 107.4MPH

Thanks for the tip. I'll try that out tomorrow. BTW - Our best times are like identical except for my 60' was more like 2.2

[Craving4Boost]

so where does your boost source come from? off the IC pipe?

[klattr1]

how much have you played with spring pressure adjustment on top of the unit?

that made the difference for me (loosening it up some)

[DRIFTEADOR]

^ yeah did you try that? does it still do it when loosened all the way? have you tried a bigger line, like the brake booster, as the source?

[SloS13]

I don't think i've let it out "all the way" but will give that a shot. I've entertained the idea of trying the brake booster line but havent given that a shot yet. The Vaccum manifold I bought doesnt have in/out big enough for the booster line. I need a better one.

[nissanfanatic]

Acutally I had my boost only source from one of the hoses below the Throttle body. But I did away with it because of the leaking.

[Craving4Boost]

i also have a greddy type S BOV and i was wondering what thing do you turn on top to loosen it up? because i have compressor surge as well. i thought it was that little nut laying on top but i doubt thats it. do you get a hex key and turn the WHOLE head?

[DRIFTEADOR]

loosen nut, adjust allen screw, tighten nut

[Craving4Boost]

oooohhhhh...i didnt know that big screw actually spins.. noob

[Fenvy]

careful

the cap of greddy type s bov is made out of alumnum and when you adjust it a few times, the thread will strip

[SloS13]

Holy crap. I hooked up the second nipple to a boost only source and it TOTALLY irradicated the problem. Thanks man!

[nissanfanatic]

No problem. Just mind that boost does leak through that port. IDK why it has to be gay like that, but if you are recirculating, it shouldn't be a problem.

[Craving4Boost]

so you didnt try if adjusting the sensitivity worked? i think im going to go ahead and try to hook up the boost only source on the BOV as well. did you also use the source from under the throttle body? i know mines are capped off and i can just use them

[nissanfanatic]

I did try that and I have it adjusted right now to where it sits ever so slighly open at idle. I still get surging, but not bad.

[SloS13]

I used the actual turbo as the boost source. Boost went up about 1psi as a result because my boost controller is T'd off there.

[Craving4Boost]

vacuum source is the same as boost source right? because eventually vacuum sources see boost?

[nissanfanatic]

No.

Boost only source would be a source of boost before the throttle body. If you hooked a vacuum/boost line to the bottom port, the BOV would not open when you let off the gas. It would have vacuum on both sides of the diaphram.

[sunnys14]

your BOV (and if you have an FMU) can use the same source (like brake booster line, thats what i used). your wastegate should have a line running into the turbo.

[nissanfanatic]

My wastegate line runs from the FPR line.

[Florida240sx]

I'm lost now... MY wastegate rns to a nipple on my hotpipe.And BOV runs to FPR line...Think mine is Greddy RS.