I have an Ebay special brass spring and ball manual boost controller, It spikes from 11 psi and settles at 8. I do have an issue with this at all, what I am concerned about is when I downshift from 5th to 3rd, I'll get a 14 psi spike. Is there any explaination to this besides the fact that I am running a shitty boost controller? Is the spring too soft inside it or what?

 

depends on your wastegate placement and manifold design

 

and wastegate size, but not really at that boost level.

What spring is in the wastegate?

 

im having this problem with my hallman mbc..ill hit 17psi then settle to 16psi or so...i called it loosing boost....

 

The wastegate is a Turbonetics Evo 38mm with a 6.5 psi spring placed right in the center of all 4 runners on my cast turbo mani. Perhaps the wastegate doesn't have enough time to open because I was rev matching from 5th to 3rd not allowing the turbo to spool down or the revs to drop.

 

hook the wastegate line closer to the turbo or right on compressor housing i bet my car it will fix problem!

 

No, it will not.

Try running your wastegate feed to intake manifold pressure.

- Derek

 

^^^ that is the best setup of a MBC if you want boost spike best way to resist boost spike is the way mentioned before ... wastegate to compressor the closer the better