just wondering how much boost can you get out of a stock turbo without blowing it up. I have a 35 pound gauge and rap it around almost back to 0

 

i was hitting 45 when i had the stocker in.

 

i have hit 43 with my smarty and 45 when i had the hot juice

 

so i should be good for awhile but dont expect anymore

 

also the 04.5 and up make more from the start

 

On an 03-04 you DO NOT want to exceed 35psi of boost, going past that creates all kinds of ineffeciencies!

 

can you be more specific

 

Going past 35psi will create excess heat because the inlets and outlets are too small to accomodate higher boosts and airflo. You also get out of the drive-pressure range, unhealthy for the turbo and will cause excessive wear eventually.

 

so the air flow gets all screwd up in and out of the turbo in lamens terms

 

The turbo is trying to pull more air through than it can handle....

 

how much can i make before head problems occur im am going to put in studs soon

 

50psi is kinda the redline for boost till studs are needed.

 

Most claim that on 03-04.4 turbos, 35 psi boost measured at the intake manifold is the most "mass" of air that you can compress. After 35 psi, you are pushing the same "mass" of air but it is at higher temperature so the gauge will read 40 psi*.

*In lay man's terms: at 35 psi boost, you are pushing 52 lbs of air per minute at 200*F. At 40 psi boost, you are pushing 52 lbs of air per minute at 250*F. So in reality, no more air=oxygen to make more power, just more heat.

If you set the wastegate to open at 35 psi, you can still add more fuel and get a little more power because the wastegate is open and bypassing some of the choking exhaust. But temps will soar as your air/fuel ratio drops from an optimal 18:1 down to 15:1. When a diesel engine runs rich, it gets HOT!

If you keep the wastegate closed and let the boost hit 40 psi or more, you choke the engine on the exhaust side and power does not increase but exhaust temps soar even higher!

The 04.5-present 5.9 cummins have a bigger turbo. No one has tested enough to say definitively where maximum lbs of air is compressed, but we guess it to occur somewhere between 40 and 50 psi of boost measured at the intake manifold. Also the newer turbo: He351, from my research, is capable of compressing a little over 60 lbs of air per minute. This is not boost pressure, this is the weight or mass of air that it can compress.

Also interesting to note, the most HP that guys can get out of the HX 35: 94-02' or HY35: 01-early03' or He341: 03-04.4' is about 420 HP.

The most HP guys can get out of He351: 04.5-07'5.9 is about 510 HP.

510HP/420HP =1.214

And the HX35 totally maxed out=52#air/min.

52#/min x 1.214 = 63#air/min for He351.

And that makes sense, 54mm on HX vs 60mm on HE

 

Great write up Big Blue...Thanks for the info