[Mark in Ireland]

Advice required on upgrading my wastegate actuator. I have a 2.3T Carlsson with gas flowed head, MBC valve, motosport recirc valve plus 3" JT exhaust, no cat. At the moment I'm hitting very high boost spikes and need these controlled better. In third from 40mph, WOT I spike at 1.7bar (no cut off) and then a couple of seconds later it held 1.0bar constant. As I want to hold a higher boost constant I tweaked the MBC valve which gave me a 2.1bar spike but quickly dropped to a steady 1.2bar.
What pressure actuator should I get, most people seem to go for 0.5bar.
I'm going to try and get one from Demon Tweeks (COLLINS PERFORMANCE Wastegate Actuators £55.00)as their prices seem reasonable.
http://www.demon-tweeks.co.uk/catalogue/...ACT&from=search

I cannot afford the prices from Saab specialists so your comments on this approach would be appreciated and what pressure should I go for.

 

[John Vaughan]

You may want to check with "Forge" They have some custom actuators available. I would think if your getting spikes like your describing that you may want to go with at least a 10# spring.
Good luck and let me know as this is one of the items I am looking to change on the Griffin

 

[Alex_S]

What sort of MBC are you using. If its a ball&spring type (Dawes Device etc) you could try drilling the small bleed hole out slightly and then lowering the boost from the spring adjuster. This will introduce slightly more wastegate creep and control the spikes. Also worth giving the valve a clean. If there is any oil present then the ball will stick in its seat which won't help with spikes.

 

[Mark in Ireland]

No its a Abbott valve with no moving parts, its a very basic bleed valve arrangement.

 

[Alex_S]

As that always allows some pressure to reach the wastegate and so there is always some wastegate creep there should be no overshoot at all.

Is the wastegate sticking shut?