2.9 Whipple Boost Drop

[JustaGT5408]

Hey guys, I am trying to narrow my boost drop issue and was hoping to get some direction from people that have had similar issues. I have the car pullied for 24-25psi and it will peak that at gear change but bleed off to around 20-21 psi by the end of the gear. Here is a brief rundown on the car:

-8.5:1 Aluminator
-2.9 Whipple (4lb lower, 3.125" upper)
-E85
-Thump tensioner
-Gates Fleetrunner belt
-JLT RAI with brand new Amsoil filter

There is no belt dust so I dont believe belt slip is my issue, VHT on the belt had no effect either. I have redone most all the vacuum lines in the car as well. While it was running I sprayed brakleen around the gaskets and there was no change in idle so I dont think there is a gasket leak anywhere. I am starting to wonder if the boost bypass valve is my issue or if the valves have seen better days (doing leakdown test here soon to find out).

If you guys have any other ideas please share, I am all ears as I feel like I am chasing my tail with this. Thanks!

 

[mkb116]

Is this a new whipple? Has it ever run without that issue? With lower boost did it do the same thing or is this your first setup with it?

 

[JustaGT5408]

Is this a new whipple? Has it ever run without that issue? With lower boost did it do the same thing or is this your first setup with it?

It has just started doing it this season, I've run several different pulley combos in previous years with no issues as well as this combo last year. No changes over winter that would affect it either. Whipple is about 4 years old.

 

[roy_1031]

Did a line possibly pop off the back of the blower?


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[JustaGT5408]

Did a line possibly pop off the back of the blower?


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Not that I am aware of. I re-did 90% of the lines 2 weeks ago thinking one had a leak or a crappy connection but the issue still remains after changing them out.

 

[MG0h3]

Is it possible hot summer temps could cause this? Im only on 15psi right now but Ill lose a bit when I actually drive the car in the summer. Could be exponential with your higher boost level. I think that would have to mean your boost gauge is "bouncing" on the shift though. Of course if youve never seen this in similar conditions its ruled out.

 

[MalcolmV8]

I was going to guess belt slip but you said you ran this combo previously with no issues. When I ran 3.0/4 lb lower on my 2.9 I used a slotted pulley up top to dig in the belt. Prior to that running a 3.0/stock lower I'd see occasional belt slip where it would sort of pulse or jerk towards WOT as the belt slipped.