Boost Question

[NYTSKY]

Today i turned off my Profec B for the first time and let the wastegate set the boost level.But it seems as the revs rise so does the boost.It hits 7-8psi then as i go over 4500rpm it slowly climbs and has gone as high as 9.8psi.

Is this boost creep??

And would a HKS actuator fix it??

CHEERS

[tridentt150v]

I could be wrong here and want to understand why, but if you turn your profec off how is your actuator going to get a signal to open the wastegate.

Logic tells me that without a signal of any sort, your boost will just continue to build with revs.

[NYTSKY]

Even with the boost controller turned on the boost still rises with the revs.But just happens at a higher boost level.

Eg: Turned off- boost is at 7psi then rises with the revs to 9ish psi

Turned on- boost is at 12psi then rises with the revs to 13.7 psi

Does anyone know why this would happen???

[mad082]

do you still have the factory solenoid hooked up? if so, that is the problem.

[NYTSKY]

Profec B comes with its own solinoid.

[mad082]

yes i am aware of that, but when it was all hooked up was the factory solenoid left connect to the hose? if so it will be bleeding off about 2 psi over 4500rpm.

[NYTSKY]

Stock one is gone.

[joeyjoejoejuniorshabadoo]

i get a spike from 12 to 13ish at 5k+ if i hold it... should be safe if its just for a second or 2 every now and then

[Leadfoot]

Okay, I may be able to offer some assistance here.

I have just finished a HKS 2835 ProS (internal wastegate) turbo upgrade due to failure of stock turbo.

The car spent 3 hrs on X-speeds dyno and came back a setting of 55% duty cycle in manual mode.

I was quite happy with this setting however the initial boost pressure can be a bit inconsistant depending on the outside air temperature variation.

In the morning the turbo comes on hard at 16psi. In the middle of the day the boost comes on at 12 psi which I find a bit annoying.

So in the bid for a more consistent boost response I first tried playing a bit with the actuator rod length.

Initially I set the wastegate to be visibly opening at 10psi and be fully open by 12 psi using compressed air.

X-speed seemed happy with how the actuator was operating and used the controller to do the rest.

I, like yourself, thought I could a better result than the blitz-ibc using the actuator spring preload itself. How wrong I was.

After a fully day of experimentation I verfied this to be the optimum actuator rod length setting. If I make the actuator any stronger I end up over-boosting at around 6000rpm. Any less and the solenoid was having to do too much work.

To verify the effect of the actuator length changes just leave the EBC powered on and set the duty cycle to 0% (or fully open).

I found actuator-only control gives a steadily increasing boost pressure from 6 psi at 3500rpm to 12psi at 5500rpm and then drops back to 10psi by 7000rpm (boost creep).

So, contrary to car magazine theory it is not possible to obtain good boost control just through actuator adjustment only.

In fact, I found actuator only control to be very poor as it brought the turbo on too hard and too quickly over a narrow rpm range resulting in high knock.

This is something that X-speed warned me and they were correct.

Following some more highway tuning I think I now have a good setting which seems to give a more consistent result.

- Actuator opens at 10psi.

- Solenoid duty cycle 70% open for 0 - 3500rpm, 65% for 3500 - 4500rpm, 55% 4500 - 5500 rpm, 48% for 5500rpm - 7200rpm.

you need a 4 channel EBC to do this.

I know that the Blitz, E-Boost and the AVC-r potential have this capability in one way or another however I am not familiar with the Profec.

Using this downward sliding duty cycle boost commences much earlier at 3000rpm with 16psi and holds to 4500rpm and then steadily drops to 14psi at 7200rpm. This is a good overall setting since it spools the turbo quickly and then reduces chance of knock at high rpm.