First off, I am at 6000-7000 feet above sea level...


I am hitting 6.5 PSI logging boost pressure with Torque Pro Via OBD port.


I have LT Headers, and a 76MM pulley.


I have a lot of red dust around the EC SC pulley, checked shims = proper adjustment!


I was kind of shocked to only see 6.5 PSI, and maybe placebo affect since I just started logging bosst, but the card feels a lil sluggish. I also added a bigger HE and my IAT's are typically 15* above ambient, hitting 130-150 depending on the length of WOT with a 30 second recovery.


What are folks hitting with Pulley's at sea level? I see 10PSI stock is common. We have about 80% of the air you have at sea level, so maybe this is expected...


Stock Atmospheric Pressure 14.7
6000 ' Altitude Atmospheric Pressure = 11.7


If I expected 13 PSI at sea level, that is 24.7 atmospheres, or 1.88 * atmospheric.


At 6000', that is 1.88*11.7 = 21.996 atmospheres - 11.7 atmospheric = 10.3 PSI expected, less 1.5 PSI drop due to headers = 8.8 PSI expected.


Any thoughts?

 

I'd expect a lot more boost than that. I'll add info later, heading out the door.

 

I saw 10-11 PSI at 5000 feet above sea level all stock. Haven't checked it sea level.

Since you have LTH you're engine is breathing better and making more power less boost. Any belt slip?

 

When you go out next, only log boost. No other parameters. If you are pulling from the obd2 and have a few things up, the numbers will be all up **** creek.

 

Thanks will do. Hit 7.3 PSI at the track yday, 12.66 seconds. Im sure I have some belt slip, not sure how to verify that!

 

To start, do you have a BWK (belt wrap kit) ?

 

I do not have a BWK.

 

Did you end up figuring out what your issue was? I am currently suffering the same thing on my stock E55 @ 4200 feet seeing 6-7 psi at the most.

I guess it could be belt slip but I usually have ~6.5 psi steady and it creeps up to 7 at redline, very consistently, didn't really sound like belt slip to me. I previously had read that belt slip pressure would be jumpy.

I am also using the torque app to view pressure.

 

I suspect it is the torque app calculation. I am datalogging and no A/F spikes which would indicate slip.

I cannot for the life of me find the setting "boost calculation method" try changing that! Have to pull the blower tomorrow to install a new throttle body I might see if I can tap a nipple then and hook up a boost gauge. Let me know if you figure it out!

Are you running a pulley? What size? I did see an extra one PSI after adding an ice tank. Dynod at 460/590. Im going to build a belt wrap kit see if that helps, will let you know what I find.

 

I think you're probably right about it being the app. I'm on stock pulley, but I couldn't possibly see you hitting 460/590 on any dyno AT ALTITUDE with only 7psi.

I did find that if you go to your cars profile in torque, and show advanced settings, there is a boost pressure adjustment based on atmospheric pressure. I set mine to -0.034 because my local atm press is 14.734. I have a feeling this isn't going to make a difference, just adjust it linearly by .03, but I haven't re-tested to see if it made any difference yet.

 

I also reckon no ways you putting down that power with only 7psi at 6k-7k elevation..

I am running the same pulley 77mm upper with long tube headers and full exhaust and I see max 9psi boost at 5500ft altitude. You loose nearly 1 psi per 1000ft going up so your boost number seems about right for your altitude. The red dust though sounds like belt slip especially if you running a 77mm upper then recommend a BWK.

 

These cars need a fresh blower belt tensioner at this age.