Boost pressure plumbing

[bambamjj]

Does anyone know if it is true that you can drill a hole in the plenum chamber (assuming the part of engine next to rockers) on a 300TDI plum in a fitting with a barbed end and connect this directly to the injector pump, the fitting on the top that is connected to diaphram?
See link below

http://forums.lr4x4.com/index.php?showtopic=31

Has anyone done and got photo's

[Les Henson]

Plenum chamber is on a V8. Some boost guage kits come with the necessary plumbing to attach it in-line with the boost pipe (a T-piece). You cut the boost pipe, fit the T-piece in line, then run the boost pipe to the guage inside the cab.


Les.

[stageonesimmo]

Not strictly true - the plenum chamber is the intake manifold on a 300TDi as well, as it gives the cylinders a stable evenly pressurised volume of air to draw on which is in essance the definition of a plenum chamber in automotive engineering terms. 

Good news is that you dont need to drill it as there is a blanked off drilling already in place at the rear of the plenum nearest the bulkhead - I've moved the waste-gate actuator pipe to this position on mine already  - theres a thread on LRUK forum detailing it and the reasons why, but I can explain it all if you want........

[bambamjj]

stageonesimmo, can you explain, if it is the thread i think it is it has no pickies, i need pickies co i is stoopid.

waste gate actuator pipe, that runs from the outlet of the turbo, round back of engine into top of injector pump, right?  the one that looks all bent and about to split in my engine bay but is so solid would have to cut it off to make any changes about 8mm dia.

Your help is appreciated.

[stageonesimmo]

Bam,

Sorry mate - I cant do pictures here at work as the MoD wont let me!

Right - the main thing we are after is the boost pressure being sensed at the valves rather than the turbo outlet.  LR have thoughtfully left us a way to do this easily.  At the back of the plenum chamber is a drilling that is blanked off with a threaded plug, this is a standard sized metric pipe fitting and I used the fuel inlet banjo bolt and pipe from a pugeot 104 diesel which I had to hand - its a common size and easily slipped in you pocket at any scrappies yard.  Down at the turbo outlet there is a 'T' piece onto which 2 pipes connect - they are the FIP boost sensing pipe and the waste-gate actuator pipe.  All you need to do is simply fit the new connector (its a 'swan-neck' type banjo bolt that can accept a push on rubber pipe) with suitable copper washers (from whatever you steal the banjo and bolt off?) to the drilling at the plenum.  Then take the pipes off teh 'T' at the turbo , remove the T and get a suiable length of rubber hose to connect the threaded part of the T and the new banjo bolt together - simple as that.

This leaves you with a hole in teh turbo outlet that you can do 2 things with - either, plumb in a boost gauge so you can see your improved boost in action or blank it off and forget it - I used a nromal metric brake bleed nipple as a temporary measure until I could be boithered to fit my gauge.

there job done.

If you really need them, I can take some piccies at the weekend and post them up............

[stuartevans]

this may sound like a stupid question but im all new to this what does doing this achieve?

[Les Henson]

Depending on the type of guage you fit - it shows when the turbo is on boost/what the boost pressure is. Just a means on keeping an eye on what the engine is doing, much the same as fitting a volt meter, amp guage, oil pressure guage, etc.


Les.

[stageonesimmo]

this may sound like a stupid question but im all new to this what does doing this achieve?

In standard form the waste-gate actuator opens the waste-gate when it senses the correct boost pressure at its standard location - at the turbo outlet.  However, due to friction, bends the intercooler etc etc, some of that pressure is lost between the turbo outlet and the valves.  Moving the position that the waste-gate senses its pressure closer to the valves means that you over come these losses and have more chance of having full boost at the valves where you need it.  It may not seem like much but it made a hell of a difference to mine!  I was losing nigh on 0.25 bar through the pipes and cooler meaning that I could only ever expect to get 0.75 bar at the valves - now that the waste-gate opens when the correct pressure is reached at the valves I'm getting the full works all the time.

[chris.hunt22]

I have plumbed my gauge into a tapped fitting in the plenum chamber, my gauge at full toot is reading about 0.6 - 0.7 bar, I have read in my Haynes manual that 300 tdi will boost from 0.7 - 1.0 bar but where is this reading taken from, I don't want to crack the actuator up to 1 bar and get a loud bang one day!!!!

[Snake110]

I have plumbed my gauge into a tapped fitting in the plenum chamber, my gauge at full toot is reading about 0.6 - 0.7 bar, I have read in my Haynes manual that 300 tdi will boost from 0.7 - 1.0 bar but where is this reading taken from, I don't want to crack the actuator up to 1 bar and get a loud bang one day!!!!

Further to this would someone kindly confirm what peak boost should be for a 200Tdi on the standard intercooler so i can set mine for optimum without
melting pistons or blowing gaskets? i have been told 13psi but this seems like an odd figure to me..

[Porny]

I have plumbed my gauge into a tapped fitting in the plenum chamber, my gauge at full toot is reading about 0.6 - 0.7 bar, I have read in my Haynes manual that 300 tdi will boost from 0.7 - 1.0 bar but where is this reading taken from, I don't want to crack the actuator up to 1 bar and get a loud bang one day!!!!

Land Rove state 1 bar (14.7psi) at the actuator (i.e. Tee'd into the pipe from the compressor housing to the actuator) however, 1 bar at the inlet manifold will be fine. I've known 300Tdi's run 17-18psi without a problem

A 200Tdi as standard is 0.8bar at the actuator.... A 200Tdi will happily run 1 bar or 14.7psi all day long (and even a bit more if you want)

You will get a spike above what you actually want on both 200tdi and 300tdi (the actuator can not control the spike), it is the pressure that the actuator holds after the spike you are interested in.

Anything above about 17psi is not worthwhile as the turbo become inefficient.


Ian

[Snake110]

thanks for that porny just what i needed to know .. :clap:


right lads the head gaskets are on porny :lol: :lol: :lol:

[bilge rat]

am i getting this right , basicaly you take the t off at the turbo end  and the threaded part you have removed from the turbo you run a peice of pipe straight to the plenumn and then you block the hole in the turbo outlet ?. anyone got any pics or anything .cheers alan...

[smith335]

Any body got any pics of this mod?
and allso any pics of this blanked of threaded hole in the plenum ? cant find it!!

thanks in advanvce

[Range Rover Blues]

It may not seem like much but it made a hell of a difference to mine!  I was losing nigh on 0.25 bar through the pipes and cooler meaning that I could only ever expect to get 0.75 bar at the valves - now that the waste-gate opens when the correct pressure is reached at the valves I'm getting the full works all the time.

And you don't think the engine designers took this into account at any point?

The quoted pressure of 0.7 to 1 bar is at the turbo outlet, if you are registering a pressure difference at the plenum then effectively you have "wound the turbo up".

If the intercooler became blocked the pressure at the turbo will rise uncontrolably.

The only advantage I can see is the the fuel pump would not increase the fuel rate quite as quickly and you wouldn't get the puff of black smoke that will result.  However you could connect the fuel pump to the plenum and leave the turbo alone.  I'd considered doing this before our TDi took up residence in the bodyshop.

If you want an effective turbo tweak then fit a boost regulator, one big advantage is that they eliminate waste gate creep ie the waste gate stays fully shut until the set pressure is reached rather than opening progressively as the set pressure is near.  Again you are raising the boost above the "designed" level though but not altering the peak boost (unless you want to).