From: James Shanks (n1vbn@bit-net.com)
Date: Thu Dec 05 2002 - 20:03:26 PST
Tom is very knowledgeable about the fuel system compensator but
regarding the 1200F statement I would like to clarify it. 1200F Max is
correct BUT that reading can only be taken at one point only. The Pyrometer
thermocouple can and is used at only two points to accurately read exhaust
gas temperature, the 1200F max reading is only good if the thermocouple is
between the turbocharger and the engine. At that point only to you use the
1200F reading as a maximum normal operating temp reading. If you see the
thermocouple mounted AFTER the turbo ( the most commonly found mounting
point) The max operating temperature is 900F!! That's right, there is a
three hundred degree Fahrenheit difference and if you do have pyrometer
installed in any of your MV's check and see where the temp reading is
taken. Before the Turbo? 1200F Max, After the Turbo 900F Max. and by Max I
mean if you see it go over the max normal reading BACK OFF THE THROTTLE AND
DROP A GEAR TO REDUCE EXHAUST TEMP IMMEDIATELY to avoid overheating
expensive (surplus or not) parts!!!
Nice description Tom on the Compensator system.
Jim
n1vbn@bit-net.com
1998 IMZ 8.103
At 05:33 PM 12/2/02 -0500, tom-nooneofconsequence wrote:
>ok, several people wanted to know about the compensator and if it should
>
>be by-passed. first let me say a few things about the system. if you
>like adding gauges there are 4 that i think are justified - a clock,
>exhaust temp gauge, boost pressure gauge, and a 0 - 100 psi fuel
>pressure gauge plumbed to the bleeder on the final fuel filter. this
>last gauge will tell you some important information. fuel from the tank
>first goes through a booster pump on the side of the injection pump. at
>
>idle there should be around 35 psi and at full rpm around 70+ psi. if
>this reading is a lot lower it shows dirty fuel filters or weak booster
>pump. now this pressure is critical to the compensator working properly.
>
>the pressure is applied to a piston in the top of the comp. and tries to
>
>raise it. at the same time there is a calibrated bleed hole venting this
>
>pressure back to the tank. the thicker the fuel the higher the piston
>goes. on the bottom of the piston is a rod that raises a precision ramp,
>
>and this ramp limits the range of the fuel control rod. the position of
>this ramp is adjusted by the main fuel adjustment screw. if you bypass
>the compensator you are in effect leaving the ramp at its lowest
>position and giving the engine a lot more fuel. of course it will run a
>lot better, but it may also melt the pistons......... if you choose to
>by-pass be sure you check the exhaust temp. max 1200f on a hot day. the
>
>boost pressure gauge will also give you valuable information at this
>point. at full throttle and full load at 2300 rpm there should be 9 psi
>at the manifold. this is the factory setting and is in my opinion very
>conservative, but this will give you the factory performance.
>tom
>
>
>
>
>
>
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