I tried to search this but the results were overwhelming i couldnt find anything.

What is your boost gains going from the stg 2 pulley to nates 2.9?

My car only has 3500kms on it and right now without my 2.9 (its in the mail) iam getting anywhere from 13.05 to 15.2 psi from 1st to top of 3rd.

Also i think my boost is low because if i punch it in 1st or second iam only seeing around 13.5psi, top of 3rd iam getting around 15 though...

 

Right now with it cold out it hits about 16.25ish (tic past 15). I wouldn't even try to watch it in first, its way too short. I had mine on for a while, a trip to the track as well. Your elevation can play a roll in your boost too, plus the gauge isn't the most accurate in the world either. You should gain around 1 psi'ish over the stage 2 pulley.

 

Gain varies with elevation. At sea level it's about 1 PSI per .1 inch reduction in pulley size, assuming you don't change anything else. Where I live, at 5,000 feet, I only saw a 2.5 PSI increase instead of the full 3 PSI (I started at 10 PSI and Stage 2 bumped it up to 12.5). I'd vote for you getting a full PSI gain out of it if you're hitting 15 in third.

Oh, and first gear never attains full boost, my car is fine and it does the same thing. Something to do with the boost bypass valve I believe (not 100% sure, someone else who knows please verify).

 

In first you are probably not going to see full boost, the car is going to bleed it. In Second this stands true as well. The reason you don't see full boost in first and second is that the computer has TQ settings for the engine and transmission both. If either of them fall out of spec the car bleeds boost. The only way to get around this is to get your car tuned. Third and higher are really the only gears you are going to see full boost in. 15 psi with Stage 2 sounds about right. With a true 2.9 pulley you will probably see around 16.5 Psi.

Oh yeah! Elevation does play a part in it as well.

 

so the higher you are the less psi you get? iam around 2500 ft above sea level... sorry iam new the the whole boost thing...

 

Im at 1600ft in Saskatoon, and with Nates 2.9 I see depending on weather 16psi -16.5psi on my hpt. The gauge so far is accurate on mine showing about a needle over 110kpa ( about 112 ish)

 

Yes. There is a calculation - I believe it is something around you lose 1 psi for every 1500 to 2000 feet in elevation.

It is worth noting - I don't know how the gauges get their reading, but if it measures the psi based off ambient, then even at 2500 ft you should still read the same PSI as at 0 ft.

 

110kpa is that max? like top or 3rd or 2nd gr pull, also do you have stg 2?

 

The gauges do indeed get their reading from ambient pressure, but it measures in atmospheres, not in PSI per se, although one can be converted to the other if you know what ambient is. Up here in CO, ambient is 12.2 PSI, and the stage 2 pulley puts manifold pressure at just over two atmospheres. At sea level this translates to 15 lbs. boost, up here it translates to 12.5. Both scenarios will result in the gauge displaying the proper boost, but it does show the drop in pressure due to altitude.

Hope that helps

 

avg beteen 16.5-18

cold nights i have seen it spike to right at 20

 

That is because you have some restrictions.... I have a 2.85 and I generally see 17-18 PSI

 

Here in Calgary 3400 ft SL with a 2.85 I am seeing 15.5 to 16.5 psi on my mechanical boost. It also depends on temp and air density.

Where abouts in AB are you?

cheers

 

at higher elevations the air is thinner. which is why athletes do high elevation training. and is why helicoptors cannot fly that high. and sea level is where air the thickest. i can run 3miles in cali at about 19-20min and in idaho i run it in 20 to maybe 21

 

That is with my HPT tune. Makes no diff on stage 2 or not in third gear.