Thread: Boost on D4 3 litre

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 !

Originally Posted by 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 !

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?

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 .

Originally Posted by 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 .

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.