Thread: 300tdi's with boost gauge fitted

Finding out the pressure drop was going to be one of my over xmas projects.I was going to chamfer,polish,smooth out the system from the turbo to the manifold and see what the actual drop with two gauges was going to be.I wanted to replace the pipe with a mandrel bent piece and silicon hoses but I can't get it made in Kal.It would be interesting to drive around for a week and record the findings. Pat

Originally Posted by PAT303

Finding out the pressure drop was going to be one of my over xmas projects.I was going to chamfer,polish,smooth out the system from the turbo to the manifold and see what the actual drop with two gauges was going to be.I wanted to replace the pipe with a mandrel bent piece and silicon hoses but I can't get it made in Kal.It would be interesting to drive around for a week and record the findings. Pat

Hey Pat, check out ThermoGuard Instruments , Ian, a member here (leo109) has done some excellent research on this with his Tdi Disco...Makes great Pyro kits too!

JC

Originally Posted by Bush65

The boost compensator is fitted to the injection pump for environmental reasons. It's function is to reduce the fuel when the boost pressure is low (not enough air to burn fuel completely).

By connecting the line to the boost compensator from the manifold instead of the compressor outlet, you are fooling the compensator into thinking the boost pressure is lower.

So it should reduce the fuel, causing power to drop. Less energy in the exhaust gasses will reduce the performance of the turbo and boost pressure should drop ...

urmmm.....

putting the boost pressure sense on the turbo side of the intercooler tricks the boost compensator into thinking that its got more air to play with than it really has. This lets it inject more fuel which then raises the EGT's without giving you more boost.

its a lot more complicated balancing act than that but at the end of the day for optimal preformance and longevity the compensator needs to know whats going into the cylinders not whats coming out of the turbo..

Originally Posted by justinc

Hey Pat, check out ThermoGuard Instruments , Ian, a member here (leo109) has done some excellent research on this with his Tdi Disco...Makes great Pyro kits too!

JC

Mate that was what I was going to do.I want a MUD center dash and fit up one of Daveys coolant alarms,pyro,tacho etc and I have the money in my pocket but right at the time I was going to buy the dollar dropped through the floor!. Pat

Originally Posted by Blknight.aus

urmmm.....

putting the boost pressure sense on the turbo side of the intercooler tricks the boost compensator into thinking that its got more air to play with than it really has. This lets it inject more fuel which then raises the EGT's without giving you more boost.

its a lot more complicated balancing act than that but at the end of the day for optimal preformance and longevity the compensator needs to know whats going into the cylinders not whats coming out of the turbo..

2nd that one!

Originally Posted by justinc

There is a handy plug already in the manifold that you can unscrew and either substitute for a designated hose fitting, or just drill and Gas tap the plug.
JC

Hi, any pic of this?

The injector pump adds more fuel when the boost goes up to ensure the correct mixture, this is calibrated by land rover to change fuel dependant on boost pressure from the turbo, not the manifold pressure.
By changing the detection from turbo to manifold, due to the pressure drop across the intercooler the diaphragm will essentially sense a lower boost pressure therefore add less fuel and therefore a drop in performance.
I would leave the boost presure sensing from the manifold, by all means connect your boost gauge to the manifold to measure manifold preesure rather than turbo output pressure, two gauges would help you when upgrading the intecooler to understand the effect on pressure drop.

Nik

By switching your pickup for the boost gauge and compensator from turbo outlet to the manifold you will still get to your max boost pressure, as the turbo will keep pushing air and pressure right up to when the waste gate says no more and won't let it go over 15psi or where ever it is set to(the waste gate is connected to the boost compensator hose as well). The pressure drop over the intercooler relates to static and dynamic pressure, where static pressure is the drop in pressure from drag or resistance of the intercooler as the air passes through it and dynamic is the static pressure plus the drop in pressure from the reduction in temp of the intake charge(this is what gives you the efficiency of an intercooler). A cooler charge is more dense and so lower pressure for given volume. So by moving your pickup the gauge and boost compensator is reading the pressure entering the engine, which in my view is the better spot for it and you won't get a reduction in power.
Well that's my understanding of it anyhow.