I stumbled across this thread while I was searching for something else but it precisely describes what I was planning to do to overcome a pretty abrupt drop in TQ that starts around 5k rpm which I think is due to the fact that I'm running a cat and an otherwise stock exhaust. As a result I am ending up with a lower HP number than I was expecting. Just wondering if anybody has any more specific experience to add...and maybe even a boost controller to recommend.

 

^ post turbo cats will drop power across the rpm range a fixed amount. You lose power everywhere. The graphs below show 200 cell cats and 100 cell cats in series in a dual 3" exhaust with the cats located midway back through the exhaust. When located immediately post-turbo, it was a 60-70 whp loss off the bat with just a single 200 cell cat behind each turbo across the rev range.

These dynographs may be helpful:

e85 maps with boost peaking at 24 psi and dropping to 20 psi at redline (max torque map).


Final e85 dyno curve with ramp up in boost from 17 psi to 25 psi at 6k rpms and up (to help with traction!):

 

Its hard to argue with those plots that you posted regarding the cats unless there is some other factor not being accounted for. The pressure drop across the cat should be proportional to the flow so I would expect the flow restriction to have more of an effect at high engine speeds.

I like your tq curve with the climbing boost. Thanks for sharing. Mine looks like a triangle.

 

so it looks like it is not your cat but something else that is causing the abrupt dip, balaguru.

 

I'm running the stage I BP kit with the only difference being that I'm running a high flow cat post turbo. Here's a dyno plot made from UpRev data.



I finally made a run on a chassis dyno and the shape of the tq curve was basically the same. The mustang dyno just showed higher numbers and a shift of the curve to the left.

 

raise your boost at 5000-redline rpms up another 5-10psi

Alot of GTR tuners are starting to tune like that. progressively increasing the boost to redline.

BUT, you can only do this if your turbo can flow enough at those rpms. RcDash and myself have more than enough turbo to do so.

 

I think I have enough turbo (Precision 6266E JB turbo) to do it but won't know till I try. In fact it looks like I get a little boost creep after 5k. I run a 7psi spring with the reference line hooked up right before the throttle body and my MAP sensor hooked up to the plenum and I quickly hit 7psi at 3600 and then slowly increase boost to about 9 psi at redline. Care to recommend a boost controller.

 

you just need a controller that can increase duty based on rpm.

http://tunertools.com/gizzmo-electro...st-levels.html

http://www.turbosmartusa.com/product/e-boost-2

pretty much any electronic boost controller will work since you have to define the duty cycle at given rpm increments. instead of keeping the duty cycle flat, keep raising it up at the point on yoru dyno when the torque starts to lay over.