Max boost pressure

Hi.

Can someone provide me with quotable information about the maximum boost pressure (normal and peak) for the 2.5 DSE ?
I've been reading lots of threads, here and in other forums, but everything I've read so far is hearsay. RAVE has nothing on the subject (searched for every possibly related term, read every paragraph referring to bar, psi ou pressure). To make things even harder, I can't even find many references to the TD04-11G4 variant of this turbo.


Cheers,
Manuel

mcapinha said:

Hi.

Can someone provide me with quotable information about the maximum boost pressure (normal and peak) for the 2.5 DSE ?
I've been reading lots of threads, here and in other forums, but everything I've read so far is hearsay. RAVE has nothing on the subject (searched for every possibly related term, read every paragraph referring to bar, psi ou pressure). To make things even harder, I can't even find many references to the TD04-11G4 variant of this turbo.


Cheers,
Manuel

Click to expand...

Mitsubishi TD04-11G4 1.2 bar (1.26 kgf/cm, 18.0 lb/Sq.in)
__________________

Is that the bmw injun or the tdi? Eitherway if it made by LR it was probably overstressed when it let the factory.

wammers said:

Mitsubishi TD04-11G4 1.2 bar (1.26 kgf/cm, 18.0 lb/Sq.in)
__________________

Click to expand...

Not doubting your immense knowledge on this, but where does this information come from ?
I remember reading that the boost normal pressure is 1.1 bar and it peaks at 1.25 bar. I've also read there's a fail safe in the ECU that will send the engine into limp mode if the boost goes over 1.3 bar.

Main reason behind this question is that, according to the MAP sensor, my boost at full throttle is around 1.0 bar, and I'm curious if this is bellow standard or if it's OK (some time ago I had a pressure gauge fitted and its reading was the same as what I'm getting from the sensors now, ie, 1.0bar on full throttle).

mcapinha said:

Not doubting your immense knowledge on this, but where does this information come from ?
I remember reading that the boost normal pressure is 1.1 bar and it peaks at 1.25 bar. I've also read there's a fail safe in the ECU that will send the engine into limp mode if the boost goes over 1.3 bar.

Main reason behind this question is that, according to the MAP sensor, my boost at full throttle is around 1.0 bar, and I'm curious if this is bellow standard or if it's OK (some time ago I had a pressure gauge fitted and its reading was the same as what I'm getting from the sensors now, ie, 1.0bar on full throttle).

Click to expand...

You cannot check boost pressure on a static engine. You need a teed pipe into the cab connected to a pressure gauge. Drive the car up a long hill with the engine under load. 18 PSI i would think is the MAX boost pressure the turbo is capable of.

I checked the pressure just as you described, full throttle in 2nd, going up a big hill.
In the past I had installed a pressure gauge, in the cabin, connected to a T piece that intersected the pipe that goes to the MAP. In both cases the pressure was at 1.0 bar.

mcapinha said:

I checked the pressure just as you described, full throttle in 2nd, going up a big hill.
In the past I had installed a pressure gauge, in the cabin, connected to a T piece that intersected the pipe that goes to the MAP. In both cases the pressure was at 1.0 bar.

Click to expand...

That is 14.7 PSI, the turbo when new and has everything going for it produces 1.2 BAR or 17.64 PSI. So what you are getting is about right. How much did you expect?

If it aint broke dont try to fix it
if you car runs ok count yourself lucky and drive it, if your after up-ing the boost think carefully cos the auto box on diesels is already at its "safe" torque limit! thats why bmw de-tuned the engine

I was expecting to see something around 1.1 bar.
I've seen the results of piston meltdown from a M51 engine where the boost pressure was too high and they weren't nice at all..

I know the P38 is a big beast (and I love it) but it struggles to get into it's top speed (when tested in a private stretch of highway, off course). When I got, 3 years ago, it could get up to 170km/h easily and now it struggles to reach 160..

mcapinha said:

I was expecting to see something around 1.1 bar.
I've seen the results of piston meltdown from a M51 engine where the boost pressure was too high and they weren't nice at all..

I know the P38 is a big beast (and I love it) but it struggles to get into it's top speed (when tested in a private stretch of highway, off course). When I got, 3 years ago, it could get up to 170km/h easily and now it struggles to reach 160..

Click to expand...

170 KPH is 105 MPH. 160 KPH is 99.5 MPH what the hell do you want. How many miles has your engine done? Get the pump refurbished, get the injectors refurbished, take the head off and grind the valves fit new piston rings. If you think that is all worth 5 MPH do it. Other than that if you want to go faster buy a Porsche.

wammers said:

170 KPH is 105 MPH. 160 KPH is 99.5 MPH what the hell do you want. How many miles has your engine done? Get the pump refurbished, get the injectors refurbished, take the head off and grind the valves fit new piston rings. If you think that is all worth 5 MPH do it. Other than that if you want to go faster buy a Porsche.

Click to expand...

Hell my 4 ton box of a ford F350 4x4 boosts at 35psi and has a speed limiter set at 100MPH...........

Trying to solve an earlier problem of bad idle, I tested as many sensors on the engine as possible. One of these was the map sensor bolted onto the fuel filter. By connecting it to an airline the change in resistance across the terminals was measured. The change was tiny.

I disconnected the plug from the sensor, the vehicle showed a marked improvement in performance, a new sensor was purchased, and the vehicle performance was much improved again. I hadn't really noticed the slow loss of performance, in my case the sensor had failed.

My boost pressure gauge has never gone past 15 psi, and to be honest it's generally not pushed beyond 10 psi for preservation reasons. Didn't cure my bad idle, that turned out to be something else:

wammers said:

170 KPH is 105 MPH. 160 KPH is 99.5 MPH what the hell do you want. How many miles has your engine done? Get the pump refurbished, get the injectors refurbished, take the head off and grind the valves fit new piston rings. If you think that is all worth 5 MPH do it. Other than that if you want to go faster buy a Porsche.

Click to expand...

Pump is on the todo list, head is new, compression has been checked and injectores were refurbed a little while ago. Still, you forgot to add "check turbo pressure" to that list

I don't want to go fast in the P38. If I did, I wouldn't have chosen the oil burner version. Actually, driving a 2.5ton beast past 80mph makes me a little itchy.

But, economy worries me and I feel that the reduced top speed and low mpg are associated, so I'm looking into that. Low(er) turbo pressure seems like one of the culprits, so far. Mistimed pump (I have hot starting issues) may be the other one.

mcapinha said:

Pump is on the todo list, head is new, compression has been checked and injectores were refurbed a little while ago. Still, you forgot to add "check turbo pressure" to that list

I don't want to go fast in the P38. If I did, I wouldn't have chosen the oil burner version. Actually, driving a 2.5ton beast past 80mph makes me a little itchy.

But, economy worries me and I feel that the reduced top speed and low mpg are associated, so I'm looking into that. Low(er) turbo pressure seems like one of the culprits, so far. Mistimed pump (I have hot starting issues) may be the other one.

Click to expand...

The more turbo pressure the more fuel it will use. Your turbo pressure is fine. Tired injection pump will cause reduced MPG.