BMW Valvetronic and Audi FSI combined
BMW Valvetronic and Audi FSI combined
(OP)
Does anyone know - would it be possible to combine BMW's Valvetronic system with direct injection such as Audi's FSI, to give a double improvement in fuel economy and performance? Or are the two systems just different methods of achieving the same?
Dan
Dan





RE: BMW Valvetronic and Audi FSI combined
Mart
RE: BMW Valvetronic and Audi FSI combined
See (it's in French, but Google can translate it not too badly):
http://www.histomobile.com/histomob/tech.asp?id2=17&id1=3&lan=1
(Valvetronic, 2 pages)
http://www.histomobile.com/histomob/tech.asp?id2=17&id1=6&lan=1
(BMW V12)
http://www.histomobile.com/histomob/tech.asp?id2=2&id1=16&lan=1 (direct injection)
I don't think Valvetronic and charge stratification are compatible because Valvetronic is a throttling system – at the intake valve – while charge stratification works with no throttling, like in a Diesel engine. The Audi FSI and likes have a throttle butterfly, but it's used in the homogeneous mode only.
Cheers
Aorangi
RE: BMW Valvetronic and Audi FSI combined
Let's not forget that diesel engines also throttle flow at the intake valve - that's what the intake valves are there for, after all.
RE: BMW Valvetronic and Audi FSI combined
Did I misuse the word throttling? Do you mean throttling the reverse flow? Or are you joking since we are the 1st of April?
Cheers
Aorangi
RE: BMW Valvetronic and Audi FSI combined
RE: BMW Valvetronic and Audi FSI combined
Additionally, I don't think that throttling flow with a butterfly valve upstream of the intake has the same effect on pumping work that closing an intake valve earlier would have. Your previous statement seems to imply that you expect pumping losses to be the same (or similar) regardless of whether a butterfly valve is used, or early IVC. It does seem clear to me that using reduced lift (rather than reduced duration) to decrease air intake would have an effect similar to a standard throttle. To summarize, I think shorter intake duration is preferable to intake throttling, whether by intake valve or throttle valve, from the perspective of reducing pumping work.
RE: BMW Valvetronic and Audi FSI combined
RE: BMW Valvetronic and Audi FSI combined
Stratified charge engines could benefit from a Valvetronic system in most of their operating envelope… when they don't run in the stratified mode.
But Valvetronic equipped engines would hardly gain from a stratified charge because they use shorter inlet valve duration (and lower lift) at part and low load to limit the amount of charge admitted in the cylinder while the stratified charge principle works with a cylinder's full charge of air, without throttling.
Cheers
Aorangi
RE: BMW Valvetronic and Audi FSI combined
RE: BMW Valvetronic and Audi FSI combined
Cheers
Aorangi
RE: BMW Valvetronic and Audi FSI combined
http://www.histomobile.com/histomob/tech/2/123.htm
Cheers
Aorangi