More boost =less power " WHY"

[cobra0393]

I put my car on the dyno last thursday and the more boost the car made the more power it lost. At 5800 rpm with 15.6 psi the car made 532hp and at 6000rpm at 20.9psi the car made 444.3hp
the air fuel stayed from 11.1 - 11.4 across the chart. Can anyone help me on this.

JAMEY

 

[Red Turtle]

Belt slip? I would think this may be the problem being that it increased 5lbs of boost in 200rpm.

 

[LEE93COBRA]

Jamey,

Off topic....What type of fuel systm are you running on your car. (injector size, pump, etc..)

Recently put a d-1 on my car and it looks like I may make around 16psi on it. My fuel system consist of 42's, Univer, 255 in tank w/ a Kenne Bell BAP. I am afraid I am not going to have enough fuel since I am already seeing almost 80% duty cycle on the injectors at 5000 rpm (12 psi)

 

[93Cobra#2771]

Lee - the duty cycle parameter is off by just a tad. It is figured off pulsewidth, and the pulsewidth is off by about 1/2, if I remember correctly.

Throw a post up in the tweecer bbs and someone should chime in with the exact numbers, I forget them right off hand...

 

[93Cobra#2771]

I don't know which blower you are running, but it could be several things:
• overspinning the blower (loses it's efficiencey at a certain rpm)
• the extra boost horsepower power is being negated by the extra heat
• you may have reached the max flow of your inlet or exhaust system

Remember, boost is basically backpressure. Throw some monster heads/intakes/exhaust on there, keep it pullied the same, and your boost will drop, but you'll make more power.

 

[cobra0393]

Lee
Im running an aeromotive eliminator kit with 50 pd injectors

93cobra2771
I have a ys trim with ported twisted twedge heads and 3'' exhaust. There are alot of renegade cars running this blower at 25-28psi.
What size headers do you think i should be running. I have 13/4 macs.

 

[93Cobra#2771]

Doesn't sound like exhaust restrictions to me (since you gave me the specs on that). Blower isn't an issue, I don't believe.

Hate to say it, buy maybe you ought to look into something mechanical. Possibly a blown HG or a broke ring or something like that? My blower experience is pretty minimal, so maybe the blower guys can shed some light for you.

Almost 100 hp is a heck of a lot of power to lose, and it makes me a little worried...

 

[cobra0393]

The car doesnt smoke,miss,lose water, or run hot, But im with you a 100 hp is alot to be losing so im going to look into the motor. It gives me a good reason to put in a good block.

Thanks for the help

JAMEY