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General tips: Boost, Pyrometer, Transmission Temperature, Fuel Pressure, etc.

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– Be advised that upon initial start up, you will not register a boost “number.” It takes engine load to make exhaust flow; thus intake boost pressure. You will find the boost pressure will parallel the position of your accelerator pedal.

Typical 60 mph, half-throttle boost number is 8 – 10 psi.Rule of thumb: every psi of boost equals 10 horsepower (i.e. 10 psi means you’re using 100 horsepower to motor down the road). Full throttle equals full boost. ‘94 – ‘97 trucks have a maximum boost specification of 15 – 18 psi. The 215 hp, ‘96 – ‘98 trucks have a maximum boost specification of 21 – 23 psi. The ‘98 – ‘02, 24-valve engines have a maximum boost specification of 20 psi.


– As a guideline, do not exceed 1000˚ – 1050˚F with the pyrometer in a post turbo location such as the exhaust elbow or exhaust brake elbow. If you installed the pyrometer pre-turbo, in the exhaust manifold, do not exceed 1250˚ – 1300˚F. You will find the EGTs will parallel the position of your accelerator pedal. A typical 60 mph, half-throttle EGT number is 600˚ – 700˚F (probe location prior to the turbocharger). Readings are usually lower if the probe is located after the turbocharger. Be advised that the registered temperature reading will only be 250˚ – 350˚F (ambient air temperature and location of the sensor are the reasons for the variance) at initial start-up and idle. It takes engine load to make the EGT escalate.

Transmission Temperature

– The lower you can keep the temperature, the longer your transmission is likely to last. The oil viscosity starts to break down around 220˚F, and the transmission will be much happier below this point. Maximum oil temperature in the pan should not exceed 250˚F. If the temperature rises above this point, pull over and fast idle the engine in neutral for a few minutes to cool the transmission fluid.

Courtesy: http://www.genosgarage.com

Fuel Pressure


3 to 10 psi at injector pump


[*] 17-22PSI at idle

[*] 25-35PSI at 2500RPM NO LOAD

If your pressure drops below 25PSI at 2500RPM, it is time to diagnose why.


[*]14-15psi with light engine load

[*]2-3psi drop from normal under heavy loading

[*]10psi minimum. Less than that, you're asking for a wallet hemorrhage

[*]Overflow pressure bypass valve set to ~14psi

CP3 (stock lift pump)

[*]FP at idle 8-10PSI

[*]Hwy cruising, 6-8psi

[*]WOT acceleration, can drop to 1-2psi. (but would normally recover to about 3-4psi, if you stayed at WOT)

(Subject to change for corrections)

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The CR engines with the OEM fuel filter housing can handle about 60psi of lift pump pressure before the plastic lid will crack or the seal will leak. That's going off the "top of my head" from a post years ago by a fellow called "SuperDuty" on another forum. He was the fellow that pioneered the Walbro systems we see now. I'm guessing he cracked an OEM Dodge fuel filter housing cover!!! The CP3 will take what it needs and send the rest of the fuel back to the tank. I've been running the same Walbro for almost 6.5 years, and I normally see 24-25psi this time of year at idle.........she'll pull down to 23psi under a heavy foot. In the winter, with thicker fuel and 0 degree temps, my gauge will be pegged. That's 30+psi!!!! The Walbro not only supplies adequate pressure, it also meets volume also. Many pumps cannot do both. The CP3 can pump fuel on it's own without a lift pump, but it doesn' do it well under high fuel volume needs.................such as "BOMBED" trucks!!:smart:I normally drive by my boost gauge and my rail pressure gauge. I try to keep boost down (under 5psi empty if possible) and rail pressure high (17,000+psi if possible) for the most part. If I'm bucking a headwind, or quartering into a headwind; I just drive slower. There seems to be an "ideal spot" of boost and RP for all conditions........they may not be ideal conditions for you time-wise, but you'll max out your fuel dollars by doing so.:smart:See my "3 In a Row" thread in the 3rd gen section.:2cents:

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