Boost on D4 3 litre

[discotwinturbo]

Picked up an OBDII port transmitter today and linked in to REV app on my iPhone. Gee that shows a whole lot of info!
One thing though, boost on full throttle gets to about 22 psi. This seems high to me, but may not be high for a modern diesel turbo engine.
Would this be about right from experience from others with the 3 litre ?
Brett....

[Dougal]

It sounds about right, but to be honest I was expecting a little higher, like almost 30psi.

A non turbo 3 litre diesel will put out in the low 200's for torque, to get 600Nm you need to cram in almost 3x as much air.

[400HPONGAS]

Wouldnt believe them IPHONES and their app , Ill put my Android Torque Plus and OBD2 bluetooth on !! (Me 2.7 does 18 Psi on full load)

[mowog]

I got around the same numbers with a Garmin EcoRoute on my GPS.

[discotwinturbo]

I just tried in on my V6 diesel Touareg......22psi too.

[baldivistribe]

Dunno how much it is but its enough to put a smile on my face and a slow down from the mrs when overtaking on the highway.
It just seems to get to a point that it takes off.
Im still impressed.
Cheers
Steve

[mowog]

Boost Highway and the Little Lady...

I use to own an XR6 Turbo ute... We were out and about one weekend and the little lady was driving... It was a wet day... She overtook a car and I felt a little side slip as she was passing... I warned her not to much peddle in the wet.

The next passing move... A caravan and a Truck she gave it a boot full..... the result lots of boost and a car sideways at 80k and accelerating.... :eek:

She actually got it straight again :o without backing off to much and finished the pass...

But now its not an issue she can sink the slipper in and no drifting will occur :)

[Dougal]

Just another reference point. BMW's 3 litre 600Nm diesel was running 42psi max boost.

[Graeme]

IIRC my TD5 had around 21 psi but I think that was at the turbo, ie before the IC.

[discotwinturbo]

Just another reference point. BMW's 3 litre 600Nm diesel was running 42psi max boost.

Bugger me. It must certainly be a strong motor to handle that.

Brett....

[Dougal]

Bugger me. It must certainly be a strong motor to handle that.

Brett....

Pretty low compression ratio to make up for that. In the 14's, which is very low for a diesel. I can't find compression ratio specs for the 3.0 V6.

[400HPONGAS]

And when you do Dougal, make sure sure its the "Dynamic Compression ratio" and not some irrelevant Static ratio as you have quoted (eg 14:1) This conclusion of all you do is increase the boost to increase the Torque is rubbish ,when even a basic understanding is you woud have to increase fuel first !

[Dougal]

And when you do Dougal, make sure sure its the "Dynamic Compression ratio" and not some irrelevant Static ratio as you have quoted (eg 14:1) This conclusion of all you do is increase the boost to increase the Torque is rubbish ,when even a basic understanding is you woud have to increase fuel first !

Eh?
Dynamic compression ratio can't be accurately measured, so it's a little hard to quote in engine specifications. Static at least is the ratio of volumes that physically exist.

I thought everyone understood that fuel followed boost?

[400HPONGAS]

Jeez,and here am I thinking that boost follows fuel ! (just how do you make boost without increasing fuel ?)Static means very lttle ,you need to look at the CAMSHAFT events to calculate/understand the role of any compression ratio .Your static comp is only the theoretical number calculated as if the valve were totally closed at BDC and stayed that way for all of the compression stroke .

[Dougal]

Jeez,and here am I thinking that boost follows fuel ! (just how do you make boost without increasing fuel ?)Static means very lttle ,you need to look at the CAMSHAFT events to calculate/understand the role of any compression ratio .Your static comp is only the theoretical number calculated as if the valve were totally closed at BDC and stayed that way for all of the compression stroke .

I'm unsure what your agenda is here, it's pretty clear you have one. Dynamic compression ratio is never listed in engine specficiations. Static is and is clearly defined.

EFI diesels limit fuel based on air mass flow. Boost needs to increase the air-flow before extra fuel can be injected. This is why fuel follows boost.
With small variable vane turbochargers they are producing boost long before the engine has reached the fuel limits that it would have without boost.

Basically, if they are being driven, they are producing boost. It's very different to a turbocharged petrol.

[discotwinturbo]

It's all over my head.

Brett.....