View Full Version : Boost Pressure
11-14-2002, 09:07 PM
OK guys now that I have my boost gauge installed what the heck is normal for my truck. Around town driving there is little or no pressure rise. <br><br>Romp on it and I can get up to 15psi max. As soon as I get off the throttle the boost drops to almost nothing. Is this normal?
11-15-2002, 12:09 AM
Yup....<br><br>The boost of the diesel is more like a load gauge... Around town you don't use much power and have low boost numbers.<br><br>Also at low RPM you will have lower boost than at higher RPM due to the amount of air the engine produces/requires and how the pump administers fuel vs speed/boost. Of course more fuel adjustments may help the cause a little. [laugh]<br><br>This truck stock was about 14 psi around 2200 rpm and up.<br><br>J-eh
11-15-2002, 02:03 AM
8)<br><br>Thanks Lil Dog. <br><br>I got concerned when I first hooked up the gauge and reved the engine in park. Zero boost regardless of rpm. I used my compressor and an air regulator to check the gauge and it was fine. It was only while driving that the boost pressure came up.
11-15-2002, 07:57 AM
I did the same thing. I feel kinda stupid after I found out that was normal.<br>my 94 runs 38psi and my 93 will hit 25 or 28 sometimes.
11-15-2002, 09:28 AM
i got 15psi out of mine with the 21cm housing and fuel turned up. i get 20psi now with the 16cm. with the 21 i rarely saw boost 'puttering' around, i see 2-3psi most of the time now with the 16, aside from when i let of the throttle of course
11-18-2002, 01:37 PM
How about a little more explanation. Why can't you spool the turbo boost up setting out of gear. Inquiring mind want to know??<br> JJ ???
11-18-2002, 06:11 PM
Exhaust drives the turbo, so the greater the load (thus more fueling) the greater the volume and velocity (and temp) of the expanding exhaust gasses...so the turbo spins faster, moving more air at a higher pressure. ;)
11-19-2002, 02:37 PM
Good explaination VinD...I was surprised also when I first connected a temporary boost gauge to mine and couldn't get any boost pressure in Neutral. The turbo is like a gas turbine and needs the waste heat energy from the exhaust to spool up fully and without a load on the engine it doesn't produce much wasted heat.
12-10-2002, 08:33 PM
I can make 18-20 lbs of boost just reving my motor in neutral.
12-11-2002, 07:13 PM
Ah Heck, 18-20 lbs. idling ain't real hard to acheive if you tweak the kanooter valve, but not to much to cause blow by of the muffler bearings, but if it does, that means that the high frequentcy ocilator will need to reconfigured to control the temperature of red tail light sparking oil, which if it goes above 1700* F, you'll melt down the muffler bearings, which in turn will lead to lost of the red tail light sparking oil.<br>But mine will only build 18 psi at WOT, 2-5 around town [laugh]
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