Lawone

Morning People!

I've since had my boost turned up to 24psi using the DIYautotune EBC (https://www.diyautotune.com/product/...-solenoid-kit/)

all is well. But I'm getting Wastegate flutter noise.

Dimitris (MSLABS) has advised to play with the EBC frequency. which I'm going to have a little play with later. Thanks for the advise Dimitris

I understand this is normal due to the EBC working. But god does it sound ugly and i be great to reduce if not remove the flutter.

Just wondering if anyone has had similar experience and had a fix. (I'm hoping changing the frequency will. But thought I still see if anyone else had this issue)

Lawone

Little update.

It was the EBC. As it's a on / off motion. it was causing the EWG to flutter.

Changing the HZ slowed it down or made it faster depending on which way I went.

I'm going to fit a N75 valve as they run quite high HZ so much faster on/off motion to prevent the flutter.

For the time being I've gone back to a MBC which is working perfectly with zero problems or odd noises.

cwatson

Lawone,

Were you able to determine the maximum operating frequency and usable duty cycle range for the N75 valve? I have the same issue on a TD04HL with a log manifold and Tial 38mm using a 4 port EBC configuration. MAP is stable at 20hz+ because the intake system volume damps the pulses but the acceleration/deceleration of the turbine sounds horrible at even 40hz.

Thanks!

Lawone

I ended up just running a manual boost controller. Which was simple and worked for what I needed.

cwatson

Copy, thanks for the response and I'm glad you found something that worked. I tried a newer N75 (Peirberg EPW) but was able to eliminate the flutter and get the best control using a MAC 4 port and a combination of restrictors (pnuematic mufflers, you can get adjustable ones) and accumulators (cheap fuel filters, see image).

Constraints:

• Tial 38mm EWG with 7psi spring
• TD04HL 9 Blade Turbine
• Audible (bad) compressor wheel/wastegate fluttering up to at least 40Hz (at the EWG inlet/outlet)
• Desired closed-loop boost control range: ~7-30 psi (150-300 kPa)
• MAPdot equal to applying boost pressure to EWG close port with atmosphere on the EWG open port (spool time limited by spring and available boost pressure to keep EWG closed)

Random notes:

• Idle valves are readily available valves for PWM proportional flow control but would need custom manifold (e.g. GM needle type)
• Industrial 12vdc proportional valves are uncommon and expensive; OEMs: Clippard, Parker, etc
• 240cc fuel injector had quickest response time but not enough flow to control pressure
• Quickest OTS solenoid I found (but 24vdc): SX10, 2 Port High Speed Valve | SMC Corporation of America

cwatson

Update to this - my flutter problem was related to leaks at the wastegate mount and turbine to manifold that developed at high temperature. The wastegate action was audible because of the leak. I since welded these joints (in addition to large inconel fasteners) and no longer have the problem. The charts above are still valid for MAP vs EBC duty.