Reason for boost "bleed off" on pullied cars....

[MJ32V]

WOT in 4th gear, boost starts out at ~14psi at 3,500 RPM then gradually drops off to 12psi at 6,500 RPM. Boost drop off is gradual and linear... does not drop abruptly. I doubt its due to the boost dump solenoid opening because the drop in pressure would be abrupt, correct? Could some boost be bleeding off due to slight misadjustment in the boost dump valve set screw? Theories/opinions?
MJ

 

[46stang]

my car does it as well. mine goes up to 12ish lbs and drops down to 9ish lbs. I personally think we are just maxing out these blowers all ready, as several people have said theirs does this too. It may help to open up the throttle body and intake elbow and air filter assy. but I don't know that for sure!
Leon

 

[bender460]

Here's what I think and I think alot:shrug: The drop in boost could be the eficiency of the motor? Put the same blower(and blower RPM) on a motor half the size of a 4.6 and you will get way more boost. Put it on a 540ci big block with blue thunder heads you will get way less. But I am no expert. so I can't say I'm right. Just something to think about.

 

[mm49]

I used to Pull 13-14 #s on my 01 Lightning all day long and did not get any Boost bleed off. I ran 4 and 6 # lower Pulleys and pulled up to 5600 rpm.

Same Blower and slightly larger engine. I have several Lightning friends running 1.5# uppers and 8-10 # lowers and seeing 18-19 # total boost on stock blowers. I don't have a good reason for the Bleed off, but I don't think it is the blower running out of steam.

Those Higher Boost #s will build lots more heat but the blower will handle it. For how Long ???

Just my .02 worth

JL