Quote:
Originally Posted by 88tlc
Thanks dougal for the information and others. I have rechecked with my IP mechanic, Wally, and he confirms it needs boost pressure. here are some of his thoughts, that sound reasonable to me.
Altitude compensators - are only on naturally aspirated motors. this makes sense to me, as if there is less oxygen, it needs less fuel. this can be accomplished by reducing fuel, when reduced barometric pressure is measured (which by the way is the definition of a ANEROID - measures pressure, barometric pressure, without liquid).
Aneroid - this is for Turbo engines, and will compensate fuel delivery to match oxygen, and boost pressure. If the IP does not see the boost pressure, it will meter less fuel. when the IP sees boost pressure, it adds more fuel. the IP and turbo are synched up so to speak, providing power, not providing insane amounts of black smoke. Also note, that a Turbo engine, with boost, is not as affected by altitude, and 'thin air' , as it is getting compressed air.
I installed my IP pump, and I must say it was not an easy task. There has got to be a better way of getting the IP pump gear to stay put long enough for me to insert it back into the timing housing. 
But finally I hooked it all up, and I added boost pressure to whatever it is on the back. I just added a Tee to my boost pressure from the intake, and to the boost gage.
I can report that it now runs with significantly more power. great acceleration, smooth power, there is no black smoke, but now feels like a turbo boosted engine, with fuel to match. I do not have EGT gage, but I use a hand held point and shoot temp gage, getting exhaust temps in the 440 range. I have yet to run it up the hill yet, concerned still with varying opinions on the matter, and not having EGT protection!
I would like others thoughts. it seems that a IP needs some sort of signal from boost. |
Your mechanic is mistaken.
If that was a factory aneroid, it would have a factory boost line from the manifold above down to it. The factory boost lines are roughly three times larger than a line which will fit the nipple on the back of that compensator.
I would expect that port with the nipple is for charging the device with a certain air pressure to set the working range.
Altitude compensators are needed on turbo engines which are run hard at altitude, most manufacturers even list how much engines should be derated at different heights.
My engine smokes a little at 1000m but not at sealevel.
I have not yet seen a 4BD1T with this device attached to manifold pressure. Does that tell you anything?
Here's a photo from
Overview
My guess is by opening the device to boost pressure you have vented it which allows it to deliver more fuel before the turbo wakes up. But as the boost builds this will reduce rack travel as evidenced by your 440 deg EGT. That's very cold, these engines run up to 750 deg preturbo.
BTW the purpose of an aneroid is not to increase fuel on boost, it is to decrease fuel off-boost to prevent smoke. They are a pollution control device.
It does this by a pushrod that limits internal rack travel.
I have mentioned earlier that simply removing the device from the injection pump will allow it to deliver full fuel for tuning purposes.