Turbo boost pressure and gauges

Hi All.
Just recently finished plumbing the intercooler on the 200TDI Rangie engine into the Kogzbilt, previously had the pipe going from the outlet side of the turbo directly into the inlet manifold.
Now comes out of the turbo outlet. through the intercooler, back to the inlet manifold as per original but a slightly larger size. The good book is saying MAX boost pressure SHOULD be around the ONE BAR, which I recall being around 13-14 psi.
I put a low pressure gauge (20lb/inch) on the inlet manifold and seem to be getting very little pressure at idle. not enough to move the gauge. You can wet your finger and just feel the pressure (at idle),s0, I'm thinking either the new pipes/fittings leaking although couldn't find any, the turbo is not supplying enough boost at idle.
If you build the RPM up, nothing really happens pressure wise. Must point out that this is with the vehicle stationary so not really under any load.
Not sure whether I have the boost gauge in the right location, tapped into the inlet manifold itself.
Most people seem to think it should be fitted to a "tee" piece at the waste gate diaphragm. Just looking at that canister makes me think that it's a VACUUM canister, not a PRESSURE canister, bugger of a thing to get to at the moment.
There's a nylon line runs from this wastegate canister to what looks like a VACUUM diaphragm on top of the fuel pump body.
The workshop manual I have is sketchy at best, doesn't go into great detail about this area. so as I said, I'm unsure if it's simply not working hard enough (no load), have a bad leak I haven't found yet, or if the turbo itself is crook. I did start the engine when I had the pipe going direct from outlet of turbo to inlet manifold. Take the hose off and seems to be plenty of flow, both at idle and at higher RPM.
Any thoughts?? Thanks.
Dave_64

Hi Dave.

In my bus, the boost gauge is connected after the inter cooler. I also neeed a little canister in line to slow the pulses down. Ended up putting a plastic fuel filter in line to smooth it out.

You won't get boost at idle. The turbo has to spool up to get boost. If you really blip the throttle, there might be a little blip on the guage. Like just a little wiggle if you're lucky. Remember, the turbo will be spinning at about 175,000 - 200,000 rpm at full pelt.

jon_d wrote
"I also neeed a little canister in line to slow the pulses down. Ended up putting a plastic fuel filter in line to smooth it out."
jon, reading what you wrote there made think you have some sort of electronic boost pressure gauge??
My outlet for the mechanical gauge is in the inlet manifild, after the intercooler.
What you wrote probably why it's not registering on the gauge.
Dave

A Turbo won't produce much boost from blipping the throttle.

The engine needs to be working to get any real boost.

My Son's Mitsubishi Evo VIII has no boost at idle and when driven hard will show well over 20psi from about 2,500 rpm on.

If you like scary rides this is it. All 4 wheels spinning in second in the dry.

Dave,
Guess that Injection pump is a version of the Bosch VE, the line to the top of the pump is the fuel control, as boost goes up it supplies more fuel. It will be a pressure line.
Pic's are always good to be certain.
Cheers Steve

"I also neeed a little canister in line to slow the pulses down. Ended up putting a plastic fuel filter in line to smooth it out."
jon, reading what you wrote there made think you have some sort of electronic boost pressure gauge??
My outlet for the mechanical gauge is in the inlet manifild, after the intercooler.
What you wrote probably why it's not registering on the gauge.

No, it's mechanical. Engine is 6.5 litre, 6 cyl. The needle would flicker badly as the pots opened in sequence. The canister is buffering the flicker.

Jon,
Is that a universal gauge or designed for boost? I have a mechanical VDO boost gauge and no pulsing, think there is a restrictor built into the gauge. (5.9 L six)
The other trick for pulsing gauges is a small needle valve, just close it enough to dampen the pulsing.
Cheers Steve

Yes, think it is what they call the VE pump,
I have only had the top off it the once as I was told that after a while they tend to gunk up with oil, just wiped it out and put it back in. Diaphragm seemed to be in good nick

Zuffen wrote:

A Turbo won't produce much boost from blipping the throttle.

The engine needs to be working to get any real boost.

My Son's Mitsubishi Evo VIII has no boost at idle and when driven hard will show well over 20psi from about 2,500 rpm on.

If you like scary rides this is it. All 4 wheels spinning in second in the dry.

Everything Zuffen says is correct, no boost with no load, if you drive a truck out in the country type of running on undulating road as the truck speed stays constant as well as the accelerator pedal when going up and the rise the governor in your injector pump senses the motor is slowing and slides the rack open more, the injectors squirt an increased amount of diesel in and this continues until either the governor returns to the neutral position or the hill is climbed

The more fuel the more hot air comes out the exhaust

The more hot air spins the turbo quicker creating boost

Once the load drops off the governor senses the motor is over speeding and closes the rack, cutting the amount of fuel so theres no to little hot air so theres no boost

So when your motor isnt running and stop button is pushed in the injector pump has the rack fully open and once it fires it brings it back to the governed speed

Sorry Im getting off topic now

To the naughty corner


Paul

Not at all, bloke don't ask questions, gonna be a Dubbo all his life!
Read all recommendations and responses, much appreciated.
Dave_64