I have my 2 joe-p mbc's installed in the lines from the nipples on the turbo outlet to the wastegate and pre-spool actuators, the other nipple on the actuators is capped off.

My question is, will turning the screw on the mbc for the pre-spool cause more pre-spool (less primary boost and then a spike after transition) or less pre-spool (more primary but secondary never really kicks in). It seems like turning the screw will increase the pressure needed to open the valve, which would mean it would start pre-spooling earlier, but that doesn't seem to always be the case. Maybe I'm misunderstanding how the pre-spool mechanism works though.

Alternate version of the same question, if I'm seeing something like 12-11-8-12-11 any ideas how to tune the mbc's to keep a more solid 12?

My mods are intake, dp, cb, ic, and pfc.

 

I have that setup, and tightening the PC adjustment gives more primary boost and a later spool-up. However, the only effect that I notice is the increased primary boost.

On your 2nd question, I don't have an answer for that...

 

Some more info...

0 to 3,000 RPM
In this RPM range, boost is produced by the Primary Turbocharger only. At this time, most of the exhaust is directed to the Primary Turbo by the Turbo Control, and the Secondary Compressor is isolated from the Primary by the Charge Control. Boost pressure is mostly regulated by the Turbo Pre-Control.

3,000 to 4,500 RPM
In this RPM range the Turbo Pre-Control valve is almost fully opened and preliminary rotation of the Secondary Turbo has begun, any boost pressure from the Secondary Turbo is vented via the Charge Relief Valve to the air cleaner. Boost pressure is regulated by the Turbo Pre-Control and the Wastegate Control.

At 4,500 RPM
At this time, the Secondary Turbo is at full preliminary rotation speed, the Turbo Control is opening, Charge Relief closes causing the Secondary Turbo to surge for a short time. The Charge Control then allows Secondary boost to be added to the Primary boost.

The above is the way the stock system works.

Therefore, with a boost controller, lower primary boost means earlier pre-spool, and possibly more spike at transition.

Your 12-11-8-12-11 may be related to lag in the MBC's control, maybe due to line lag, the response of the MBC, itself, etc. I think the controllers are trying to control at 11, but they have a bit of lag, giving you the momentary 12 value. Having too long or small lines between the nipples on the turbo outlet and the controllers, or from the controllers to the actuators could cause that. I don't seem to see that. My boost is very steady (11-9-10).

 

Cool, thanks for the info. That helps explain whats going on with the controllers...

I had a perfect 10-9-10 using the joe-p's, then I upgraded my intercooler and installed the pfc. At this point I thought it would be easy to just turn up the mbc's to get a 12-10-12 pattern. However, its been all over the place. For a while I had 11-11-12-11, so I turned down the precontrol (screwed it in I think), and got to the 12-11-8-11-12 pattern. Which I guess makes sense since the primary went up a little and it didn't pre-spool as much.

There must be a happy medium in there somewhere...

 

Yea good post dave. Simplified things pretty well.

 

nice work dave, you basically answered it all for me, let me just chime in on some things:

hose diameter, make sure you use bigger diameter hose than what came with the controllers, that stuff is like 3 or 4 mm, ayou want to be using around 6mm stuff, this will help with boost controller response and range.

what gear are you testing in?

>>then I upgraded my intercooler and installed the pfc

you dont have the stock solenoids still in line with the mbc do you?

i think you should open the pre-control more, keep opening it untill you either see lower pri boost or you see to big a spike on the sec on transition. If you are able to open it all the way (pre control sees full signal all the time) and not get your primary to drop, then your flow has out grown the pre-control system.

 

>>and tightening the PC adjustment

by the way, make sure you guys are matching the setups, if the controllers are on the vent side of the actuators it will be different than if they are on the pressure source side of the actuators.

 

Damian, I want to thank you, again, for originally posting this method. You're the one who put it all together so the light went on and I began to understand how to consistently control my boost.

Thanks, again.

 

no prob Dave :-) glad to help.

 

I'm pretty sure I used 6mm stuff, it was big enough that the seal on the nipple wasn't tight until i zip-tied it.

>> what gear are you testing in?
The testing has been in 2, 3, and 4 throughout the rev range. Naturally I pay most attention in 3rd, since at the track the end of 4th is close to 140mph and my eyes are definetly not watching my boost gauge

>> you dont have the stock solenoids still in line with the mbc do you?
the stock solenoids are completely out of the loop, the line goes straight out of the nipple on the turbo outlet into the joe-p, then out of the joe-p into the actuator. The other end of the actuator is capped off.

>>i think you should open the pre-control more, keep opening it untill you either >>see lower pri boost or you see to big a spike on the sec on transition. If you >>are able to open it all the way (pre control sees full signal all the time) and not >>get your primary to drop, then your flow has out grown the pre-control system

I tried this accidentally when I forgot to tighten the locknut and the screw almost entirely backed out, primary was down to 6 or 7 and then it spiked up to 14psi before I realized something was wrong and backed-off. Are you saying to try it as an experiment or that a spike after transition is about as good as I'm likely to balance it?

Again, thanks for all the responses! I'm going to summit point on the 18th and hope to have most of this ironed out before then...

 

I essentially just replaced the lines with the pills in them with lines with the joe-p's in them (same nipples), then disconnected the line that returns into the engine bay somewhere and capped the nipple.

 

I believe Damian was saying to try this to see if the primary boost could be controlled, or if your modifications to the air flow path were so great that the controller wouldn't work. You have already proved that you CAN control the primary with your accidental experiment.