Wastegate creep

[SimonR]

The spring rate on my external HKS wastegate appears to be about 1 bar - that's the max boost that I'm getting.

 

I've noticed that the wastegate starts to open (audible via the screamer pipe) at about .6 bar and then continues to open progressively (at least that what it sounds like) up to full boost.

 

Reading up on wastegate creep, it appears that this is a known phenomenon and is intentional (at least on manufacturers' production systems) with the purpose of making the onset of boost smoother. That’s all very well, but why would such a function be present on an after-market performance item?

 

I’m wondering whether this is actually a ham-fisted attempt at preventing boost spikes or possibly an intentional starting-point default behaviour which you are then expected to manipulate.

 

I’m now looking at ways of eliminating – or at least minimising – this effect. I’m not expecting the wastegate to go from fully closed to fully open in a millisecond but I’m sure that the current situation can be improved upon.

[Andy-No-Knee]

I think this can be removed by the duty cycle on the boost controller.

 

I have an Apexi AVCR, and after getting it worked on I found that the settings had been 'played' with! Thanks a bunch. And the waste gate opening like yours is at .6 bar which was not what I wanted. After playing with the duty cycle it now stays shut until 1 - 1.1 bar and is open fully at 1.2 - 1.4 depending on the setting.

 

It does however have slight spiking now which is prob down to my hamfistedness when setting it up rather than any inherant problem.

 

I will (hopefully) be getting the new pressure sensor fitted and then remapped and the boost controller reset up again.

 

(Saying that, I'm also thinking of getting water injection fitted at the same time if it will make a big difference).

[Alex]

A gated Boost controller would stop this.

 

A Gated BC slams open at the right boost pressure and so therefore does the wastegate. This maximises spool.

 

An example of a gated BC would be the eBoost2 from Turbosmart.

[SimonR]

I think this can be removed by the duty cycle on the boost controller.

 

I have an Apexi AVCR, and after getting it worked on I found that the settings had been 'played' with! Thanks a bunch. And the waste gate opening like yours is at .6 bar which was not what I wanted. After playing with the duty cycle it now stays shut until 1 - 1.1 bar and is open fully at 1.2 - 1.4 depending on the setting.

 

It does however have slight spiking now which is prob down to my hamfistedness when setting it up rather than any inherant problem.

 

I will (hopefully) be getting the new pressure sensor fitted and then remapped and the boost controller reset up again.

 

(Saying that, I'm also thinking of getting water injection fitted at the same time if it will make a big difference).

I believe that you are referring to the 'gain' function which is available on some EBCs. I have it on the Blitz D-SBC and it is one of the methods that I will be looking at.

[SimonR]

A gated Boost controller would stop this.

 

A Gated BC slams open at the right boost pressure and so therefore does the wastegate. This maximises spool.

 

An example of a gated BC would be the eBoost2 from Turbosmart.

What gain settings are you using? I assume that there's some commonality in the configuration of this function between EBCs?

[Alex]

Not all BC's are "Gated" ones.

 

Just keep upping the gain 5points at a time till you get good response WITHOUT a boost spike.