Boost control issues....
 

So after realizing my Greddy EBC was ---- I threw it away in favor of one of the Alcon flow control MBCs that someone was selling here on HMT. I finally got off my lazy ass and instaled it and it doesn't really work as well as I expected. It will spool to 14 lbs or so where I like it then immediately fall off to 7.5 lbs (wastegate spring). I get a taste of 1 bar and then its gone >:( I had this same issue with my HomeDepot special MBC. So I am at my wits end, should I just buy a Hallman and be done with it or is there something else going on with my setup? FWIW here are some mild details of the thing:

9.8:1 GSR motor
HKS manifold with Greddy 18G, ported mani and wastegate hole w/2.5 inch downpipe (no cast iron elbow).

Any help or thoughts on the topic would be greatly appreciated.

Re: Boost control issues....
 

internal wastegate?

rule of thumb, internal gates pretty much suck past 10psi.

i'd stop blaming the boost controllers and look into external.

Re: Boost control issues....
 

My internally wastegate is adjustable and it works good set right up at 10psi. Doesnt spike at all or anything, do u have the wastegate vaccumm hooked to the itnake manifold or the turbo, cuase if its at the turbo then, its boostin what the turbo sees and not what the intake manifold sees

Re: Boost control issues....
 

I have an internally gated Volvo T3 and it's adjustable. I just don't know how much it adjusts. Any standard or ideas? Or should I go get a MBC?


JP

Re: Boost control issues....
 

your best bet is to not start a thread in a thread.

Re: Boost control issues....
 

Right I understand they suck, but does nobody with an internal WG have a proper functioning boost control? It does have a 34mm flapper and a Forge Motorsports actuator so it should be OK to 14 psi or so. At any rate, I think it has something to do with the spring rate of the spring in the MBC. If I tighten the actuator arm I can get it to creep to 14 PSI by redline but I just want it to spool and hold. I just ordered a Hallman, hopefully that solves the problem.

Re: Boost control issues....
 

well i dont really think that going from boost controller to boost controller is going to solve your problem

and to answer your question of doesnt anyone with internal wastegate have steady boost...yes they do, at low boost most times.

it is very very very very common for internals to be unsteady in higher applications (over 10psi)

34mm flapper? is there a 33mm hole under that flapper or the usual 20mm or so hole? the problem behind internal gates is the hole is smaller and they cant bleed pressure off fast enough.

Re: Boost control issues....
 

No, the hole is ported to 32mm, has a smoothed and radiused entry from the turbine inlet, and has a divorced wastegate dump. Obvously it should have plenty of flow for what I am trying to do. It pulls up to the boost level that I want then falls right off. If it couldn't flow enough, I would be getting boost creep, not dropping off boost as soon as it hits. The new Hallman comes with 2 springs, one is stiffer for (what they claim) running more than 5 lbs over stock boost level. That makes sense to me seeing as how i felt the spring rate was too low on the current MBC spring. Eh ---- it, I need to start shopping for a good manifold and a Tial WG.

Re: Boost control issues....
 

Well I got my Hallman MBC on Thrsday and it holds boost no problem. 15 lbs to redline with no spiking, creeping, or any other nonsense. I think the springs in those Alkon valves that people were selling on here weren't stiff enough for higher boost levels.