Engine/Transmission (1998.5 - 2002) Boost vs. Altitude

[DrewGzy]

I have had lower boost than expected with the mods I have on my truck. There are no leaks in the system, I just can't build more than 28 PSI. I am driving daily from around 6,000 feet above sea level to 10,000 feet. I think the boost I am seeing is consistent with the altitude I am at. Does this sound about right, or should I see a little more? Thanks for the help, a B-1 is next on the list

 

[NIsaacs]

Drew,



Based on your mods, I think you are low on boost. I am running an Edge EZ with 275's and can pull 30#. This is with an 01, HO. I live at 5600 feet, and drive between 1500 and 8000 with very little difference. I have not seen much difference with high altitude changing max boost. However the lower elivation will spool the turbo quicker. There is a small difference in boost between a hot & dry day vs. a cool & humid day. The cool air will burn the fuel better and produce a little more boost. What are you running for EGT's? With low boost you might be on the hot side. With my mild mods and 30# of boost I just about never have to back out of it. Back to why the low boost on your truck, I am not sure, some others on here will probably know.





"IF IT AIN'T CUMMINS POWERED, IT AIN'T A TRUCK"





"NICK"

 

[Sticks]

Sounds like we both need to get together and find our problems. I could pull 37# with my stock injectors, but with my stage II's I can only max out at 30#.

 

[DrewGzy]

With my box on level 4 I have to back off in about 10 seconds otherwise EGT's are way to high. I can run on level 2 for a little while longer, but EGT's still climb fairly fast. Usually I will just run with the box off just so I don't have to worry about it too much. With the box off I really don't see much higher than 1300 EGT's, and no more than 23 PSI. I didn't run the truck very much with stock injectors and the box.

 

[Luke Warmwater]

I can push 31-32 in town with comp on 3x5. Have not tried it on 5x5 because stock clutch only begrudgingly holds 3x5. I'm planning on a KSB-1 and FE in the near future.

 

[BarryG]

Drew and Sticks:

Do not know why you dont get more but with just an ez and 275's I can hit 30+ psi at 10k going over Vail, Wolf Creek or the Tunnel. If you are sure you don't have a boost leak, check your wastegate (which you probably already have). My wastegate is hardlined so I have it turnbuckled with no spring. Aside from the boots is it possible the intercooler has a leaking seam, or pinhole in it? Just thinking out loud.

 

[Sticks]

Drew and Sticks:

Aside from the boots is it possible the intercooler has a leaking seam, or pinhole in it? Just thinking out loud.

I don't want to think about that. I lost my boost after I switched to the stage II injectors, which would point to a intake hat gasket problem, which I inspected... twice. I need to make a cap for the downpipe and hook up the ol' air compressor and pump the system up and start spraying some soapy water around.



It may also be the AIT sensor, MAP sensor, or the original place I had the boost line connected into the block forward of the MAP.

 

[DrewGzy]

I thought the original problem was a boost leak, I did have two small leaks on the intake, but they are fixed. I did replace my boots with piers boots, and I have checked that the inter-cooler holds pressure. Everything looks good. If I get really ambitious I will swap my stock injectors back in and see how they are.



Thanks for the information.