Correct boost pressure?

[mr_mazda329]

I just dynoed my car last week on a Mustang Dyno. I have a Forge BPV w/blue spring and no shims and a Cobb SRI.

Put down 225hp and 248tq in a 4th gear pull

The thing is that boost spiked to 15.6 @3100 and averaged 12psi and then fell to 11 @5000-5500. Shouldn't it be holding more psi all the way to 5500? Like 14 or so?

 

[AutoEuphoria]

How were you measuring boost? Why not include the shims? Might have been leaking a bit through the BPV.

 

[mr_mazda329]

From direct on the BPV

 

[mr_mazda329]

Well I put the 2 shims in. I noticed boost cut in 2nd gear a lot more around 5000rpm. Does this sound right?

 

[mr_mazda329]

Bueller...Bueller...Bueller. Anyone?

 

[AutoEuphoria]

With the stock boost control setup you're hitting boost cut? That doesn't sound right at all.

 

[mr_mazda329]

Yea, only in 1st, 2nd and then 3rd pulls strong all the way to 5500 RPMs

 

[skubidoobie]

1st and 2nd? You don't say...

 

[mr_mazda329]

The point is...It's more noticable now that I put the two shims in.

 

[AutoEuphoria]

What is your definition of "boost cut"?...because I think we might be talking two different things.

 

[mr_mazda329]

When I accelerate, It's pretty stong up to 4500 and then afterwards its almost like someone tied the car up to a pole to keep it from accelerating as quick.

 

[GhostMercury]

i spike to 20-21 and settle at 15-16 past first and second with just a sri...hmmm

 

[Conso]

put the yellow spring in blue is for higher then stock boost lvls, and if that doesn't work check ur tubing and make sure everything is tight a small leak will cause boost pressure to drop

 

[mr_mazda329]

Thanks, I'll go check all the TMIC plumbing. I'm wondering if the readings were correct or not at the Dyno. Why does everyone here mostly run with the Blue +2 on theirs?

 

[AutoEuphoria]

That is not boost cut. Boost cut is a violent bucking of the car when you stray over 18psi for too long.