Article - Detroit Diesel air box pressures at Barrington Diesel Club

Barrington Diesel club provides Detroit Diesel engine specs and technical Data

Air box pressures are discussed at Barrington Diesel Club. Air box pressures are a vital factor affecting all two stroke cycle engines, in that air box pressures that are too low translate into loss of power for the engine.

At Barrington diesel club bolt tightening torques and fuel consumption rates are also provided for many engines beginning with Detroit Diesel,Cummins, and ADE. Our Web Log provides a forum for discussing diesel engine features and problems. We also provide general technical data such as Standard Torques for bolts and nuts, Properties of materials like the melting and boiling points of metals, metric to imperial cross references, SAE Flywheel housing sizes, as well as providing articles of general interest like discussions on fuel consumption.

At Barrington diesel club bolt tightening torques and fuel consumption rates are provided for many engines beginning with Detroit Diesel,Cummins, and ADE. Our Web Log provides a forum for discussing diesel engine features and problems. We also provide general technical data such as Standard Torques for bolts and nuts, Properties of materials like the melting and boiling points of metals, metric to imperial cross references, SAE Flywheel housing sizes, as well as providing articles of general interest like discussions on fuel consumption and Detroit Diesel Air Box Pressures.

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Article by Steve Barrington

Air Box Pressure

Basically sufficient air box pressure is required for:

Combustion pressure - Power.
Scavenging burned gasses - Smoke.

If your engine has enough power and does not smoke excessively your air box pressures are probably within the normal ranges, or right.

Low Air Box Pressure

Insufficient air box pressure will cause:

Power problems - too little.
Smoke problems - too much black or grey.

Insufficient Air, low air box pressures are caused by:

High air inlet restriction
Incorrect blower clearances
Damaged blower rotors
Blown or leaking blower end plate gaskets
Air box leaks - bolts, washers, gaskets
Clogged blower screen
Intercooler or aftercooler clogged.
Faulty turbo

High Air Box Pressure

Too much air box pressure may indicate problems with:

Air box drains - Blocked or clogged - can cause problems with:
- Smoking - engine starts to burn waste materials
- Control becomes difficult and misfiring - burning waste material, severe cases can cause engine to run away.
- Overheating - air box, and exhaust temperatures rise.
Excessive crankcase pressure.
Blocked or clogged liner ports -(multiple possible sources)

Power and Smoke Problems

If you have power or smoke problems with your engine, some basic checks may reveal the problem(s) very easily:

Basic air box checks and inspection:

Check the air box drains are properly open or operating, clean or replace as required.
Remove air box covers, inspect for damaged rings and broken parts. Check gaskets, sealing washers, etc. - if all OK, reseal and replace as required. Run engine, if problem persists go to next step.
Remove air cleaner element, try engine without element for short run, if problem persists go to next step.
Check after and intercoolers. Clean or replace as required, if problem still persists, go to next step.
Inspect exhaust and silencer for clogging and restrictions. Clean or replace as required, if problem still persists, measure the air box pressure.

Full Load expected Air Box Pressures for Detroit Diesel engines
Indicated in inches and mm of mercury
rpm	1800	2000	2100
Naturally aspirated N engines	1", 25 mm	4", 100 mm	5", 125 mm
Turbo engines	22", 594 mm	28", 756 mm	30", 810 mm
TI engines	27", 686 mm	32", 864 mm	35", 945 mm
Notes: Measuring Air Box Pressure Connect a manometer to one air box drain. Measure pressure at fixed RPM's The above table gives an indication of what to expect, but air box pressures vary with altitude and from engine to engine, injector to injector, turbo to turbo; so take nothing as definitive. If your air box pressures are close to the values listed in the table there is normally no problem in this area. If you're at all concerned, contact the local agents with your model and serial number for further advice.