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VWs new Budack-Cycle engine #4522745
09/22/17 12:37 AM
09/22/17 12:37 AM
Joined: Apr 2012
Posts: 9,384
Kendall, FL
wemay Offline OP
wemay  Offline OP
Joined: Apr 2012
Posts: 9,384
Kendall, FL


'18 KIA Sportage LX AWD: Mobil Super Synthetic 10w30
'13 Hyundai Santa Fe Sport 2.0T: EDGE 5w30
Re: VWs new Budack-Cycle engine [Re: wemay] #4522783
09/22/17 02:48 AM
09/22/17 02:48 AM
Joined: Mar 2013
Posts: 4,766
The Midwest
skyactiv Offline
skyactiv  Offline
Joined: Mar 2013
Posts: 4,766
The Midwest
I noticed the engine use port and direct injection.


Wife: 15' Audi A4 quattro 6 speed manual
Me: 13' VW GTI 3 door 6 speed manual
Re: VWs new Budack-Cycle engine [Re: wemay] #4522794
09/22/17 03:22 AM
09/22/17 03:22 AM
Joined: Dec 2002
Posts: 40,884
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 40,884
'Stralia
AAARRRGGGGHHHH

Quote:
The Budack Cycle—as Jason Fenske from Engineering Explained mentions in his video—uses the same concept, except it closes the intake valve early. Thus, as the piston goes down with the valve closed, the pressure inside the combustion chamber drops, and then rises during the compression stroke. Ultimately—like in a Miller Cycle—this yields a lower effective compression ratio, which makes it easier for the power stroke to turn energy from combustion into downward motion of the piston. Like in the Miller Cycle, the increased efficiency comes at the detriment of power output


I hate these hacks...

The closure of the valve early (or late) traps a smaller volume of air/fuel in the cylinder at the commencement of ACTUAL compression, effectively lowering the swept volume...that's what limits the power.

The effective compression ratio yes, is lowered, but doesn't do what the article explains...lowering the effective compression ratio lowers efficiency.

However, allowing the trapped gasses to expand to a larger volume increases the efficiency, as more work can be gained.

Re: VWs new Budack-Cycle engine [Re: wemay] #4522811
09/22/17 04:43 AM
09/22/17 04:43 AM
Joined: Sep 2017
Posts: 46
Outside U.S
Floydian Offline
Floydian  Offline
Joined: Sep 2017
Posts: 46
Outside U.S
Atkinson cycle?

Re: VWs new Budack-Cycle engine [Re: Floydian] #4522860
09/22/17 06:31 AM
09/22/17 06:31 AM
Joined: Dec 2011
Posts: 4,744
North Carolina
rooflessVW Offline
rooflessVW  Offline
Joined: Dec 2011
Posts: 4,744
North Carolina
Originally Posted By: Floydian
Atkinson cycle?

Yep its more or less an evolution of the Miller cycle, which was more or less the Atkinson cycle with a supercharger.


"Zed's dead baby, Zed's dead."
Re: VWs new Budack-Cycle engine [Re: wemay] #4523015
09/22/17 09:29 AM
09/22/17 09:29 AM
Joined: Mar 2011
Posts: 693
Ont Canada
Koz1 Offline
Koz1  Offline
Joined: Mar 2011
Posts: 693
Ont Canada
Id rather wait for the Mazda Compression gas engines.


Currently using, Fuchs TITAN GT1 PRO FLEX 5W-30, M1 5W-20 and Castrol Edge 0W-20 Gold B.
Re: VWs new Budack-Cycle engine [Re: wemay] #4523185
09/22/17 01:43 PM
09/22/17 01:43 PM
Joined: Aug 2010
Posts: 1,025
pa
benjy Offline
benjy  Offline
Joined: Aug 2010
Posts: 1,025
pa
those having paid $$$$ for valve cleanings should welcome the dual injection, BUT like anything new issues can arrive before things get sorted out. port injected older engines is all i want + will own for now!!!

Re: VWs new Budack-Cycle engine [Re: wemay] #4523206
09/22/17 02:14 PM
09/22/17 02:14 PM
Joined: Jun 2014
Posts: 1,773
Ca.
UncleDave Offline
UncleDave  Offline
Joined: Jun 2014
Posts: 1,773
Ca.
I see nothing new here, just a repackaging of old ideas.

A compromise in one place barely offsets a compromise somewhere else.



UD


Uncle Dave
Cat 3126/2 MB3500/Titan/RX400H/17 Ridgeline
700HP V10/ 725HP BBC/ Raptor 700/ KFX450/ YZ250/Onan 8K/ Cat3011C
Re: VWs new Budack-Cycle engine [Re: wemay] #4528902
09/28/17 10:05 PM
09/28/17 10:05 PM
Joined: Feb 2003
Posts: 7,427
Jupiter, Florida
Cujet Offline
Cujet  Offline
Joined: Feb 2003
Posts: 7,427
Jupiter, Florida
Closing the intake valve early, is much like a throttle limiting airflow.....


People who count on their fingers should maintain a discreet silence.
Re: VWs new Budack-Cycle engine [Re: wemay] #4528977
09/29/17 01:45 AM
09/29/17 01:45 AM
Joined: Aug 2002
Posts: 14,424
Silicon Valley
PandaBear Offline
PandaBear  Offline
Joined: Aug 2002
Posts: 14,424
Silicon Valley
So the "Atkinson" cycle in piston engine closes intake late to avoid too high of a compression, and this Budack cycle closes intake early to avoid too high of a compression. Seems like it is a matter of whether you pump out the excess of what you suck in vs close early so you pull on a loaded spring then release it back.

What is the pros and cons of each method? Which one has less pumping lost?


"You keep asking questions PandaBear and you'll end up a vegetarian like my wife" - Camu Mahubah
Re: VWs new Budack-Cycle engine [Re: PandaBear] #4529041
09/29/17 06:02 AM
09/29/17 06:02 AM
Joined: Feb 2003
Posts: 7,427
Jupiter, Florida
Cujet Offline
Cujet  Offline
Joined: Feb 2003
Posts: 7,427
Jupiter, Florida
Originally Posted By: PandaBear
So the "Atkinson" cycle in piston engine closes intake late to avoid too high of a compression, and this Budack cycle closes intake early to avoid too high of a compression. Seems like it is a matter of whether you pump out the excess of what you suck in vs close early so you pull on a loaded spring then release it back.

What is the pros and cons of each method? Which one has less pumping lost?


Here is my best guess:

Closing the intake valve very early really is akin to a partially open throttle. It increases pumping losses. As the cylinder never really fills.

Closing the intake valve very late also slightly increases pumping losses, as the cylinder is allowed to completely fill, then some volume of the gasses are pumped back out into the intake manifold. However, with the Atkinson cycle, the cylinder can be completely filled. The compression stroke starts upon valve close, and the compression ratio is adjusted to match this lower volume of air being compressed.

Last edited by Cujet; 09/29/17 06:03 AM.

People who count on their fingers should maintain a discreet silence.

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