2003 HO boost?

[manganos]

What is the stock boost #. I just hooked up the boost bolt and I'm getting mid 20# 's Say 24-26 at WOT. Thanks PS I tried the search button

 

[bpenrod]

That sounds about right for stock. Mine hits about 34# but I have the EZ elbow installed along with the boxes / mods in my sig.

 

[CIverson]

Yup, 25lbs is max for me.

 

[CumminsBu]

The 600 is up in the 30#'s. I know I was :{ too. Time for a better turbo.

 

[Jeremiah]

Altitude factor

Altitude has to be taken into consideration in any boost discussion. There is so much difference between vehicles driven at various altitudes that trying to draw comparisons is useless.

 

[JRMora]

Just got back from Colorado. Ran 22psi WOT at 9000'. At home (~5200 ft above sea level) I have seen 24.



Juan

 

[manganos]

Yeah I'm only 400 to 600 ft above sea level here. Thanks guys!

 

[DLeno]

to confirm truck differences, I live at 2700 feet which is supposed to represent only 1 psi difference from sea level. I run 21-22 psi max when stock, and about 24 psi max with a fueling box.



keep in mind that there are variables over which we have no control:



1. the turbocharger itself, mfg tolerances, the efficiency of the wastegate valve, its set point and opening behavior.



2. altitude



3. exhaust mods. I've known boost to go down, but never up.



4. There is some debate about intake systems. some argue that the high flow intakes will raise boost, some say no.



5. tolerances in the production injectors, the fuel system calibration and actual performance, etc.

 

[Jeremiah]

No overboost here!

What I get out of this is that I will never have an overboost code set in my truck. I live at 9,000' and frequently drive over to Cripple Creek, which is just under 10,000'. My dealer in Colorado Springs is at 6,000'. Now if I can just get him to "not see" the EZ box taped to the battery ...

 

[DLeno]

get a 2nd fuse box lid. always take the box off when you go to the dealer. this is not a morality thing -- it messes with their diagnostics and you don't want that if you are in for service.



I always put on a fuse cover that has dust on the top and doesn't have velcro on it. thats not to deceive the dealer, its to simplilfy the service experience.



overboost code: you have two things going for you:



1. with an EZ, boost fooling occurs so you're right you will never see an overboost code. generally, a pressure box will limit boost to the 20 psi region, just below the figure where the ECM begins to de-fuel. the ECM sees 19-20 psi even though you may generate more than that.



2. the turbocharger's own wastegate, unless you put in the EZ elbow, will limit things depending on how much fueling you have. I get only 24 lbs max, which is beyond the stock wastegate but with aggressive fueling you can blow past that anyway.

 

[Jeremiah]

Originally posted by DLeno

get a 2nd fuse box lid. always take the box off when you go to the dealer. this is not a morality thing -- it messes with their diagnostics and you don't want that if you are in for service.



I always put on a fuse cover that has dust on the top and doesn't have velcro on it. thats not to deceive the dealer, its to simplilfy the service experience.



overboost code: you have two things going for you:



1. with an EZ, boost fooling occurs so you're right you will never see an overboost code. generally, a pressure box will limit boost to the 20 psi region, just below the figure where the ECM begins to de-fuel. the ECM sees 19-20 psi even though you may generate more than that.



2. the turbocharger's own wastegate, unless you put in the EZ elbow, will limit things depending on how much fueling you have. I get only 24 lbs max, which is beyond the stock wastegate but with aggressive fueling you can blow past that anyway.

I had the boost elbow installed. I think I remember seeing almost 30 psi once WOT climbing a steep hill coming out of Cripple Creek. I was honking along pretty good on a curve and trying to watch the gauge out of the corner of my eye. It went there momentarily and then dropped back down. But no codes were set. I even did the "switch on and off three times" trick to see if any codes showed up in the odometer. None did.

 

[DLeno]

sure. thats because the EZ itself performs "boost fooling". The ECM never sees that 30 psi -- if it did you would certainly defuel and/or set an overboost code. One major point about fueling boxes is that the extra fuel and the stock wastegate conspire to limit boost. change the wastegate (with the elbow) and add fuel and bingo you can hit 30 psi. So the EZ box has to lie to the ECM about boost.



now then, do NOT take your EZ off, leaving the boost elbow on. that might indeed set you up for an overboost code. not likely, especially at high altitudes, but possible. what will happen is that the turbocharger is now capable of acheiving higher boost pressures than stock. and if you pull the EZ itself off, then you will not have boost fooling anymore, so the ECM sees every bit of that boost.

 

[Jeremiah]

Making me a conspirator

Originally posted by DLeno

sure. thats because the EZ itself performs "boost fooling". The ECM never sees that 30 psi -- if it did you would certainly defuel and/or set an overboost code. One major point about fueling boxes is that the extra fuel and the stock wastegate conspire to limit boost. change the wastegate (with the elbow) and add fuel and bingo you can hit 30 psi. So the EZ box has to lie to the ECM about boost.



now then, do NOT take your EZ off, leaving the boost elbow on. that might indeed set you up for an overboost code. not likely, especially at high altitudes, but possible. what will happen is that the turbocharger is now capable of acheiving higher boost pressures than stock. and if you pull the EZ itself off, then you will not have boost fooling anymore, so the ECM sees every bit of that boost.

Fascinating how this works! I guess that makes me and EZ co-conspirators, huh? What we won't do for more power! Hey, thanks for the information. I knew I should remove the EZ if I took the truck in for service, but doubt that I'd have thought about removing the elbow too. I'll probably leave 'em both in place on the theory that, at 40,000 miles already, I won't need any warranty work. Truck runs perfectly, knock on wood.

 

[WPeschel]

I have the ez boost elbow and a 35psi guage. I bury the needle past 35psi I believe around 38 psi boost... .

 

[Jeremiah]

Your altitude

Originally posted by WPeschel

I have the ez boost elbow and a 35psi guage. I bury the needle past 35psi I believe around 38 psi boost... .

Could be. What's your altitude?