5 gen whipple vac leak

[dblcbra]

I have a boost leak somewhere and I can't for the life of me find it. My numbers on the dyno came back much lower than expected at 716hp with a 3.875 pulley. I finally got around to hooking up my boost gauge and found I'm only making 8 psi. The kit said it should be making 10-11 psi. I tried using some starter fluid around the lid of the s/c, both connections in the back of the s/c, the bypass actuator hose, TB, and cai. No revs happened at all. I also did a homemade smoke test and didn't find anything that way. I'm seeing 14-16 vacuum at idle which is a bit low compared to everyone I've talked to as well.

What should I try or check next? I'm doing runway pulls with some fast cars this coming weekend so I'm really hoping to get the car dialed in.

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[Torinate]

What should vacuum be at idle?

How is it running though?

 

[dblcbra]

What should vacuum be at idle?

How is it running though?

The other people I have talked to say theirs are 20-21 on vacuum. Overall it runs pretty good. There's a little blip at idle and when I do a pull it's not smooth power all the way, but not falling on it's face or anything.

 

[sabtaj1]

If your running longtube headers you will see 9-10lbs on 3.875. Breaths better. I’ll check my vacuum at idle in AM.

 

[dblcbra]

If your running longtube headers you will see 9-10lbs on 3.875. Breaths better. I’ll check my vacuum at idle in AM.

Totally stock exhaust. Only other engine mods are injectors and a catch can.

 

[engineermike]

Can you post your dyno graph?

 

[Vegas5OH]

First off look behind the bypass valve on the front of the blower. There is a 1/8 npt port there for boost reference that needs a plug if not in use and I could see somebody forgetting to install the plug if not being used, I think there might be one on the back of the blower too. If thats fine, check the orange gasket you have to install under the blower lid, make sure its seated correctly. If thats good, pull blower and check the green o ring gaskets and the bottom of the blower that seal to the head.

 

[engineermike]

A lot of folks put the bypass valve o-ring in the wrong place.

 

[dblcbra]

A lot of folks put the bypass valve o-ring in the wrong place.

Which one is the bypass valve o ring?

 

[Dominant1]

Who tuned the car? Start there..

 

[dblcbra]

Who tuned the car? Start there..

PBD did a remote tune

 

[5ohcoyote]

#99

 

[dblcbra]

#99

I have it sitting in the groove inside that cup.

I pulled the lid last night and everything looked good. Pulling the lower portion today to check those seals. I was thinking possibly one of the injector adaptors might have popped out from removing the injectors. Going to check that as well.

 

[Torinate]

Any progress?

 

[dblcbra]

Any progress?

I took the entire sc off, cleaned everything, put thread tape on every piece, put metal clamps on the tube coming from the bypass actuator, replaced the black seal around the base that seal the lid. I'm not seeing anymore than 8psi still, but my bypass actuator wasn't moving before and it is now.

I'm driving around trying to see if the OAPCT % comes down. The car is pulling hard but not sure how accurate my seat of the pants dyno is since I've been driving my EcoBoost the last couple of days.

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