Boost spike issue

[DougsfastZ]

Yes, I know this topic has been beat to death, but I've searched and searched with no luck on how to fix my boost spike issue.

First off the car has a stock downpipe with no modification to the flapper, stock wastegate rod, and mods listed in the sig. I have a RJC boost controller set to 17 psi. Problem is, at WOT, the boost spikes to 19, falls to 16 then creeps back to 17. On the 1-2, and 2-3 shifts the boost will flucuate but will level off at 17.

I'll include some pics to make sure that I installed the boost controller properly.

O2's look good and very little knock, I just want to control spike.

Thanks guys,

Doug D

 

[DougsfastZ]

Should I enlarge the puck opening on the stock down pipe, or just wait till I get the THDP 3". Does the THDP have the right size puck opening?

Thanks,

Doug D

 

[MaxVO2]

The THDP has a larger puck than the stock valve, but the opening itself is on the exhaust side of the turbo.

You will need to carefully mark the outline of the new puck with a marker, or some paint on the turbo itself where they meet. The puck simply seals the hole up. You need to open the hole up with a drill or Dremel tool, and a carbide burr, or grinding stone, etc.. The larger, newly ported hole allows more exhaust gas to be shunted away from the spinning turbo assembly, thus reducing boost creep, and boost. The mechanism itself is quite simple.

Boost creep can be caused by many things (fueling issues, backpressure, too big a turbo, etc..), but porting the hole bigger won't hurt anything as long as you are careful aligning everything so that the larger hole is still completely covered by the new and larger puck.

Since you plan on getting the THDP, I would wait to port anything as the stock puck does not leave much reserve for opening the wastegate hole. It will save you some time just to do it all at once since it has to come apart anyway.

Hope this helps some

Billy
Montgomery Village, MD