High altitude boost #s

[Luke Warmwater]

I'm at around 5000' and question the boost pressures I am seeing. The two setups I have tried both yielded numbers that seem a little low so. Just curious what other's experiences have been at higher elevations.



My first setup yielded 514hp with Mach4s and non-gated B1-2. I would see anywhere from 35-38 psi. I didn't get concerned because EGTs would stay under 1350 or so on 5x5.



Current un-dyno'ed setup with non-gated II regular 66 and Mach6s I have a hard time seeing 35psi and EGTs are up around 1500 on 5x5. So the big step up in fuel would explain higher exhaust temps but I figured I would see at least 40psi maybe 45. The guys at II have been great to deal with so nothing bad about them. Brett said he was seeing over 45 when they were out here in July for DieselFest and thinks maybe I have a boost leak. I'm going to crawl around tonight and see if I can see anything but just wondering if anyone else has seen similar low boost numbers when at 5000'+. Thx

 

[mgoncalves]

Not sure if it relates, but with my old setup I was getting right at 35 psi at 5000' with stock HX35, went down to about 1200' and hit 42psi. I was afraid I was going to blow up the turbo passing cars, but it would have been worth it .



Matt

 

[Rattlin_Ram]

Boost numbers sound low, but I'm no expert. I saw 28psi+ on my HY with just the EZ box. Boondock see's about 32 on his stock HX on his 12v'er with #10 plate. These numbers are here in the springs at 6000+. Down in the midwest at around 1500' I saw 32psi on mine.



If you have a boost leak I went to Lowes and harbor frieght and picked up the stuff to buld a cheap boost leak tester we put on the air intake hose on Boondock's truck to find a leak in one of his boots to the intercooler. Down by the AC lines going into the intercooler, where it wears a hole often on these trucks I guess.



Here's a pic of what I rigged together:

(oh and it doesn't show it in the pic, but I also picked up a tire inflator at HF, the ones you push the lever down on to air up the tires, and rigged it up with quick couplers to attach to the tester to easily start and stop the air pressure)

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[Luke Warmwater]

Thanks guys. I'm going to build one of those this weekend and see if I can find a leak.

 

[Luke Warmwater]

Built one of those dealies and tested for leaks. First, you can't put much pressure through the air cleaner hose without blowing it off lol. Second, I had a pretty big leak on the compressor discharge elbow o-ring. I'm thinking alright this will make a huge difference. Nope... went from 35-39psi. EGTs are the same for all practical purposes. Spool might have got a tad better but for as much air as it was leaking, the improvement was dissapointing. I'm going to check the boost gauge accurracy tomorrow against gauges on compressor and regulator. Maybe cooling Mach6s and a Comp at 5000' is asking a bit too much of a single lol. I think Industrial Injection is going to let me try some other configurations so we'll see what happens.

 

[Rattlin_Ram]

Built one of those dealies and tested for leaks. First, you can't put much pressure through the air cleaner hose without blowing it off lol. Second, I had a pretty big leak on the compressor discharge elbow o-ring. I'm thinking alright this will make a huge difference. Nope... went from 35-39psi. EGTs are the same for all practical purposes. Spool might have got a tad better but for as much air as it was leaking, the improvement was dissapointing. I'm going to check the boost gauge accurracy tomorrow against gauges on compressor and regulator. Maybe cooling Mach6s and a Comp at 5000' is asking a bit too much of a single lol. I think Industrial Injection is going to let me try some other configurations so we'll see what happens.

Yeah forgot to mention the part about not much pressure... LOL about 15psi or so is all I could do. Might be able to rig up something better with some imagination, and block off the intake into the engine, and just pressurize everything else... .

 

[Luke Warmwater]

I hooked up my compressor to my BD X-Mon gauge and it seems to be off. Both compressor gauge and regulator gauge are in sync and both read differently than X-Mon.



X-Mon / Compressor & Regulator gauges



35/38

38/45

46/46



So it would seem that when I see that 36-38 range I'm probably really seeing 42-45 range I would guess. That seems a lot more likey with my current setup. Turbo is still a bit laggy(1900 rpms) and hot(1500f 5x5/ 1375f 3x5) on top but is definitely drivable with Mach6s(6000')



I'm still thinking there might be a turbo config that will light sooner and not be any hotter on top...

 

[Hohn]

I'm still thinking there might be a turbo config that will light sooner and not be any hotter on top...

There is. Build some twins with a HX35/12 and a SPS66. Enough air for 650hp-- nearly instant spool. Should cool 6s and a Comp.