Turbo flutter on partial throttle

I noticed turbo flutter on partial throttle applications whilst on the track and i am not sure that the EFR turbo internal BOV is managing the boost levels well (21psi)

I asked DVS tuning and they said to check that i am actually getting a vacuum for the BOV, I didn't have a gauge so ordered one from eBay and it arrived last week. 

After getting the car up to idle i checked the pipe to which i have connected the BOV to at the throttle body and found it was reading about 18-19 in-hg which is pretty good (photo above is when it was cold). I also took the opportunity to check for common issues like worn rings, head gasket leaks, vacuum leaks and valve issues and following this guide it all seemed to check out OK.

I have the upgraded EFR cover and spring and have heard of the diaphragm cracking but upon opening and inspecting i cannot see any cracking

Any ideas on the cause?
Next would be replacing with the turbosmart bypass valve, but it i can save the money it would be good

Trackday Checklist (Tools and Equipment)

At my last trackday i had forgotten what i needed to take so spent half the day throwing stuff into the car. This is most of what i took, some is specific to my setup but a lot is general.
Would love input into what others are taking to there club days?

Fluids and Filters

• Oil and Filter
• Brake Fluid
• Brake Pads
• Radiator Fluid
• Radiator Fill Tool
• Fuel x 4 Jerry cans

Tools

• 8mm, 10mm, 12mm, 14mm, 17mm, 19mm Spanners x 2
• 8mm, 10mm, 12mm, 14mm, 17mm, 19mm Sockets
• Ratchet
• Shifter (adjustable wrench)
• Pliers - Needle Nose, Side Cut and General
• Allen Keys
• Phillips and Flat head screwdrivers

Parts/Equipment

• Electrical tape 
• Cloth Tape
• Fuel Line & Intercooler Clamps
• Battery Drill
• Drill Bits
• Phillips Head Bit
• Jump Starter Pack
• Cable ties

Equipment

• Laptop
• Serial Cable
• Compact flash card
• Compact flash card reader
• Ecu cable
• Battery Charger
• Helmet
• Cams licence
• Club Licence
• Racing Numbers
• Diffuser fins
• Jack Stands x 4
• Jack
• Tyre Gauge
• Multimeter
• Tyre Pyrometer
• Anemometer
• Pen and Trackday Setting Paper

Trailer Equipment

• Weight Distribution Hitch and handle with pins
• Trailer Straps (x 4 plus wheel straps x 4)
• Radiator Tow Strap
• Trailer Winch Handle
• Trailer lock and keys
• (Check trailer Tyre pressure)

Radiator Overflow Bottle & Mount Base

Picked up a radiator overflow bottle from supercheap for $23, it is a nice little bottle that will sit nicely in the car. I wanted to make up a neat bracket to hold it in as the way it was designed to mount wont work with where i want to put it.
Aluminium angle cut at 45deg

Welded up on the outside, i

Front Bar Blanking Plates - Foam Mold

I want to blank off both of the side ducts with a lightweight piece of fiberglass, a number of years ago i bought some 2 part foam from the fiberglass supply place and wanted to try it out in making a mold of the current side pod to then fiberglass over.

It is called Plastifoam and it is a 2 part foam.

Oil Cooler Duct - Part 3 - Finish

Removing the foam from the center of the duct was relatively easy to do, there was a fair bit of the masking tape that had to be removed from the duct.

Trial fitted the

Radiator & Intercooler Duct - Part 4 - Finish

Removing the fiberglass mold from the foam was a little difficult and i needed to melt the foam with some acetone.

Radiator & Intercooler Duct - Part 3 - Fiberglass Duct

I moved the paddle pop sticks to the inside of the duct so that they can stay on when i fiberglass

 Pulling down the new can of resin i had i found it was the same as the old opened can so i had to buy some new resin. Apparently

Oil Cooler Duct - Part 2

I changed the design around a bit after a bit of thought and decided to ditch the previous piece i made. The new design will slip over the original front bar and mount permanently to the oil cooler.

Using the foam i cut multiple pieces out and shaped them to get the desired shape then using some core flute, painters masking tape and the paddle pop sticks with a hot melt glue gun.

I had to do a fair bit of fitting and refitting to clear around the brake duct but below you can see the foam piece and using the paddle pop sticks to hold it into place on the bumper before taking the bumper off and masking up.

 Here is the oil

Oil Cooler Duct - Part 1

Tonight after putting the kids to bed i started to frame up how i want the oil cooler duct to work. I am going to block off the side duct and just have this oil cooler and brake duct. It is a bit of a compromise for aerodynamics but i want to make sure that i can do multiple laps at a time as the car is primarily used at track days.

If i want latter i can make a section up to temporarily block these off for those one lap dash's.

The photos are taken just as i am starting to wet out the first layer of fiberglass. The resin is now pretty much had it and i should have thrown it out but i thought i would give it another go, terrible to work with and i was pulling gelled globs out of the glass.

Silly thing is i have another 4ltrs of resin sitting on the shelf unopened.

I will add a few more layers with some fresh resin tomorrow and then work on using some foam to build out the shape of the duct from the oil cooler.

Radiator & Intercooler Duct - Part 2 - Foam Mould

I picked up some 30 mm foam board to use for the shape of the Radiator & Intercooler duct, it was pretty cheap at Bunning's for $12.50 a sheet but because some of the panels were marked and ends damaged i got them for $7ea. I purchased 3 sheets.

I then set about cutting and hot melt gluing the sheets together building up the shape i

Brake duct - checking the clearance & shaping the transition using stockings

After fiber glassing one side using a mix of paddle pop sticks and thin metal and leaving to dry overnight i checked the clearances over the oil cooler and they were good.

I then trimmed off the paddle pop sticks and extra fiberglass before cutting down the PVC pipe to ensure a smooth entry and angle into the pipe, i used a stocking to get the desired angle and

Radiator & Intercooler Duct - Part 1 - Headlight supports

I am looking at making some ducting for the radiator and intercooler from fiberglass, the first problem is the headlight supports, they are quiet wide and will block some of the airflow as well as make it difficult to place the fiberglass around.

Modify drivers side brake duct

I have to modify the drivers side brake duct to clear the oil cooler. A while ago i had moved the cooler back on that side to cut down on weight from extra lines and also so i can attach the ducting to the brakes.

Crimping

I had to move the wires around on the fuel pressure sensor which is a texas instruments (TI) sensor, i managed to find a wiring diagram online so saw i needed to swap the wires around as i had them wrong.

The connector is one that you cant pull the terminals

Intercooler Mounting Bracket

The intercooler was only attached

Radiator Clean and Flush

After using the aluminium cleaner the radiator had come up great

I used Tectaloy

Radiator locator broken

The locator pin at the bottom of the

Silicon Hose Cleaning

I cleaned the silicon hoses, simple warm

Radiator Clean

I dumped the coolant and pulled the radiator out thinking i would take it to a radiator place to get it flushed. There is a bit of black crud inside and what looks like calcification inside the cooler but also the outside is pretty dirty and needs a good clean.

From memory i brought the radiator and