Jacksoncove

Hi all I have done a search and the concensus seems to be to go with the 4.10 set up. How does this set up do on the high way? I do a mixed bag of highway and around town and in the summer time I will be using the stang to go to work which is 100 miles a day of highway. Currently I have 3.55's and at 80 mph its turning about 2300-2400 rpm. What approx would it be with the 4.10's at the same speed? is there a drastic drop in MPG?
Thanks in advanced

stealth_GT

I have to drive about 100 miles as well over the weekends during the summer to get to the track and then back again. I have an auto and I am right at 2800 rpms@80mph, maybe more not sure. It feels kinda weird at first but you get used to it. I have open headers and its insanely loud on the freeway cruising. My MPGs surprisingly didn't change too much, but it was crappy to begin with (15mpgs)

Acceleration off the line is out of this world though.. with my Vortech, I could floor it from a dead stop and get it to 80mph with no effort at all.

alkemist

It's about 2800-2900 rmps @80mph for an auto, would be a little lower for a manual. I didn't see much of a decrease in fuel economy, but then mine was lower to begin with. I still get around 18mpg doing mixed driving and around 21mpg highway only. Cruise control FTW.

If you have 3.55, most recommend going to 4.10 since the change to 3.73 is minimal.

yank194

I do about 50/50 highway/in town driving and went from 3.31 (I think that is what they were) to 4.10s. My MPG did drop, but it wasn't anything drastic. The MPG go up when I am driving around town BC I am in 4th gear at 45 MPH. It takes a little getting used to, but definitely worth it. Also, I only have a CAI and Flows axlebacks as my only mods. The shop I take my car totold me to install 4.10s to make up for the power loss I will get in the lower gears (1st / 2nd) when I add the Kooks LT, catted H and FRPP cams.

stealth_GT

not sure about the manuals, but for the auto, I noticed that my top end wasn't all that great. Even with the blower, anything above 120mph it gets pretty slow up top. From 0-120 though, it pulls like a raped ape!

Nuke

Depending on your tire O.D., that will change slightly but, yeah, about 2800-2900 RPM's at 80 MPH.

The S197 GT's can get around 26 MPG if you can keep engine RPM's at or below 2000 RPM (at least I can). The fuel mileage will begin to suffer dramatically as you go beyond 2000 RPM. With my 3.55's, my mileage drops to about 17-18 MPG at asteady cruising speed of 85. IMO, 4.10's are NOT for you but driving at 80 MPH with these engines, no matter WHAT gear, and your fule mileage will suffer. Even with 3.31's you'll be turning around 2300 or more RPM at 80 MPH. But then, we didn't buy these cars for the economy, did we?

BTW, if you have an auto, be sure to get Bama to tune for new shift points, no matter WHAT gears you go with. It'll make a noticeable difference in performance.

iceguyb14

http://www.jekylhyderacing.com/spg.htm

try out that calculator

mikemc04gt

The extended highway driving puts you in a catch 22. There is no doubt that you will lose at least a mile or two per gallon above 55 mpg. On the other hand, I would not waste money on a 3.73 gear. I can tell you from experience with my 04 GT that the 3.73 is not much of an upgrade for the money it costs to install them. If you even have to think about fuel economy, the 4.10 may not be for you. I am lucky, my commute is mostly 55 mph roads so my fuel economy slightly increased with 4.10's because I use 5th gear more now. But when I want to have some fun...WOW, the 4.10's are amazing.

Jacksoncove

Thanks to all I appreciate all the responses
I am not concerned with just losing 2-3 miles per gallon, but definitly want to gain some performance, what are some other options if I were to keep the 3.55's?

Nuke

For performance, your first mod should be a CAI & custom tune combo. You'll need the handheld to adjust the PCM when you regear anyway.

AM is probably the better of the 2 if you're an auto. If you're manual, then it's a toss-up.