This link: http://www.fordvehicles.com/suvs/esc...eatures/specs/

specifies a 12.3 to 1 compression ratio for the Ford Escape Hybrid. What other street legal--non-turbo engine-- vehicles have a higher compression ratio?

 

This is what I call misleading about the FEH and why I used the term final compression ratio in the FEH in my post about John and the SGII. You and John know that the intake valve in the Atkinson Cycle engine stays open during the compression stroke to reduce compression at the time the ignition fires a spark. Is the truth about Ethanol that important to ruin our economy for you? Maybe you don't understand compression ratios or maybe you do and support the big rip off of ethanol.

The link you provided does not give the FEH the 12.3 compression design in the Atkinson engine, but I know where you are trying to go with your post. Shame on you Billy!

GaryG

 

Gary, I think the reason you're so anti-ethanol is all the problems it caused for you to achieve and maintain this: "1st Place MPG Challenge".

I know it's a lot of work to get 1st place and I respect you for it, but I bet it would have been a lot easier if only E0 was available.

 

12.3 doesn't mean much without decent cylinder pressure tho. With all the bleed off, it's a good thing the engine has 12.3:1 or it would make even less power than it already does!

12.3:1 in an otto cycle would NEVER be able to run on even 93 octane super unleaded. Everyone would be running C12!! lol

 

FYI, the link does provide this information. Since most of us like to learn about our vehicle, please provide us information/reference with the compression ratio at "spark ignition".

 

Billy, I'm probably going to add 5 gallons of E70 (winter blend E85) in the next day or so. That'll get me 30% ethanol. Ethanol calculator.

 

The FEH does NOT use a 12.3 to 1 compression ratio.

The physical dimentions measure to 12.3 to 1, but not all the space is used.

The effective compression ratio is close to every other "average" car on the road. I forget the number, and I don't want to post a guess.

The FEH has no special ability to better use ethanol than any other traditional vehicle.

*However, with the eCVT myself and a few others bold enough to try ethanol have notice lower RPMs to maintain the same driving speed.

-John

 

The FEH has an expansion ratio of 12.3:1, which allows for greater thermodynamic efficiency. The 12.3:1 could be called the static compression ratio, an essentially meaningless term. Dynamic compression ratio, which is a function of SCR, ignition timing and valve timing, is somewhat helpful in determining detonation wrt fuel octane. Brake mean effective pressure is the most important parameter, but it is not easily understood by most and can not be readily determined from the physical properties of the engine. The effective DCR for the FEH is on the order of 7:1, much less than most OTTO engines.

 

There quite a few modern day N/A automotive engines that have a "true" (overall) compression ratio of 12:1 and even 13:1. With DFI the evaporation of the fuel as it is injected directly into the combustion chamber has a "cooling" effect and thereby allows the use of a compression ratio above the otherwise traditional ~10:1.

 

The FEH/MMH doesn't use the "otto" cycle. It uses the Atkinson cycle that was invented back in the late 1800's in an attempt to circumvent the "otto" cycle patents.