Efficiency of the LS1/LS6

[blykins]

Well, he wasn't asking about horsepower...he just asked if there was an engine made by Ford that came close in mpg...I was just putting in my $.02. I think 23 mpg is pretty good for a V8 and a 4.11 rearend.

I think Matt's missing out on one of the qualities of a Cobra though. It's not meant to be a Cadillac, where you just sit and recline with cup holders and 30 mpg...It's a muscle car for goodness sake. It's supposed to be mean, loud, shaky, and poor gas mileage. That's my opinion anyway.

I'd really like to see, however, an LS1-LS6 that got 28 mpg...I'm sure GM would like us to think that, but in ideal situations, I'm sure it's not up to that par. I have several friends with LS1 Z28's and T/A's....I haven't heard them speak of the LS1's great gas mileage yet. You usually buy a V8 for one reason...power...not fuel efficiency.

To answer the second part of Matt's first question...I'm sure a little bit of it could be contributed to gearing.

GM cars usually have a 3.42 rearend ratio...It that case it wouldn't be putting such a burden on the engine on street traffic...plus it would be high enough (especially with a 6th gear) to cruise on interstate at around 1200 rpm. That's probably how these cars can get any gas mileage at all. They're basically idling at 70 mph. On the flip side, most Mustangs have a 3.27 rearend and only 5 forward gears. To take an engine that makes all its power and torque high up in the powerband, it's pretty stupid to gear the rearend up that high. You wouldn't believe what a low gear does to these cars...So taking off in street traffic, you're faced with putting a pretty big load on the engine to take off and get up to speed...that's not too easy on gas mileage.

I don't know...there are probably several ways to look at it, but those are my opinions.