GEARS AND MPG? WHATS THE REAL DEAL?

[Allforspeed]

dear burnout brethren,
about to go through rear gear puberty and wondering what gear and engine combo is getting you guys what MPG on your cars? i live in San francisco and i'm in college so: mustang + 3 dollar a gallon gas sucks. but i'd rather claw out my eyes with a fork than buy a four cylinder honda
i've heard gears help gas mileage and have heard the exact opposite also?!?!
current combo:

OR x pipe
equal length short tubes
flowmaster cat back
under drive pulleys
GT body with some weight reduction
edelbrock performer intake
ram air setup
synthetic fluids
electric fan
adjustable FPR set to 40 psi

all else stock;(

so far sticking with mods that get horsepower and gas mileage, get around 26 on the freeway if i try and maybe 18 round town
so...........stuck between 3.55's or 3.27's now.........

how much improvemnet?
what do you reccomend and what gas mileage you guys getting on the highway and city?
any recomendations on mods to get better gas mileage?

THANKS!!

 

[HISSIN50]

you want better fuel economy? solution:
a 4 banger transplant.

with gears it depends upon how the car is driven. ive heard both arguments and understand what you are saying/asking. i might play with an RPM calculator and see what you will be turning at speed with each ratio. im not sure 3.27s would be worth it. you have to decide how much highway driving you do, etc.

good luck.

 

[Allforspeed]

thanks for babysitting the newbie yall

i've got two types of driving
1 wallet feling light drive like old woman
and
2 death wish with impending doom (only on the track) where MPG does not matter!

mostly wondering what MPG you guys are getting with your setup and gearing though, any gear change other than 2.73's mean worse gas mileage??
heard of people gaining MPG with AFR and other aluminum heads.....same for you?

 

[5spd GT]

I get between 18-20 mpg with my 373's...if your going to drive the car everyday go no bigger than 373's on a 5spd or auto for that matter...any steeper than that and you shift more in the city (can make you hate the 5spd pretty quick), more wear on the engine, and worse gas mileage...

I say get some 355's...

 

[Allforspeed]

great gear vs rpm chart

thought this rpm vs gear chart was real cool too

http://mr5oh.tripod.com/gears.html

 

[Allforspeed]

new vs old

did you get better gas mileage in the newer mustang or the old 5.0?

 

[Allforspeed]

fan?

OH by the way did you guys notice any better gas mileage when switching to an electric fan? the ads say yes but i didn't get any?

 

[5spd GT]

did you get better gas mileage in the newer mustang or the old 5.0?

The newer one...

I didnt' notice any loss of mpg when I did my h/c/i swap on my car (cam, AFR heads, Performer intake, with bigger fuel pump and bigger fuel injectors)...it might have went down just a tad...

 

[TheUser]

Not to be a jerk, but if you're griping about $3 a gallon for gas, you might as well forget AFR or other alluminum heads. They're not gonna increase your gas mileage, at least not enough to offset the $1200-1500 price tag.

Generally with a lower gear (numerically higher), you get less mpg because you're most likely gonna be running at a higher RPM...around town, you prob. wouldn't go fast enough to use up all 5 gears, though. Depends on your driving style really.

 

[Allforspeed]

well......... i'm not against spending money, just wasing it, and i'm just trying to see what the truth is here and what products increase MPG just cause i think other people would be interested to see also and the concepts of why something increases fuel efficiency is interesting.
Not going to buy some twisted wedge head just to get better gas mileage but if they drop my gas mileage a bunch than maybe i'd buy a nitrous kit set up instead or something else, just want to see what you guys are all getting
thought maybe the heads increase gas mileage due to the higher compression?
then when i finish up my masters degree, i'll buy a big block ford and feed it C16!!!

 

[OL' WHITEY]

I changed out my 2.73's for 3:73's a little over a year ago. I found that my city mileage actually went up from 18 to 20 mpg. My highway mileage went down from 22.5 to 20. It seems odd, but now I get the same mileage all the time, regardless of city or highway. Of course, if I really get on it a lot, mileage suffers some. All in all I'm not too dissappointed with losing two MPG on the highway withe the 3.73's. The goods outweigh the bads in my opinion. If you're looking for a gear to really increase gas mileage, you're going to be disappointed.

 

[FastDriver]

If you're doing a lot of city driving, there's nothing wrong with going larger than 3.73s, IMO. You won't use up fifth gear in and around town. Only on the highway does such a gear become bothersome for me. Guys say that you have to shift a lot, but I actually had to shift more in my Honda Accord with stock gears than I did in the mustang with 4.10s. Most 4 cylinders need short gearing to make up for lack of low end torque.

As for gas mileage, you won't notice a difference around town. My old H/C/I/4.10 combo got 20-22 mpg. I got 22 mpg on the highway, but I had to cruise at 65 to do it. It dropped down to 19-20 if I cruised at 80.

I think that if you're trying to buy something that will give you better gas mileage, you should look into cams. It seems to me that a good cam can both make more power than the stock cam, and make better gas mileage. But, I personally wouldn't spend a lot of money on aftermarket equipment just to save a few mpg. It just won't offset the cost without driving the hell out of your car.

 

[5spd GT]

Just go with the 3:55's so you can be happy with the better performance/mileage/driveability gear...it is a pretty happy medium of them all...

Even my 373's get tiresome having to shift out of first so quickly from a stop...most of the time I start off in second gear...and that is why I loved my 2000 Gt's gearing (327's) because first gear was "useful"...

Oh and did I mention I love the Mach 1's gearing (3:55)...maybe it was the third gear "bark" I got out of it that made me love the car or maybe it was just the shaker

 

[Allforspeed]

thanks guys

i know mods cost gas milage, not looking to gain gas mileage by buying parts just wondering what the effects are so i know of the hidden cost/compromises each mods has, i've bought the mods i have not to get better gas mileage, just thought i would stay away from those mods that destroy my mileage in the beginning.

i bought the car with an E303 cam andstock head that have a real quick clean up on them and didn't notice any loss in gas mileage compared to my stock LX and probably not any real power gain either with the stock heads thought, maybe a little more upper mid range.
looking to put on some old school 351W heads with big valves though and that should help in the power deparment, got a brand new set all fresh for 150$ from a freind of mine, light porting and all new with comp springs, that probably going to cost me a bit of gas mileage too though compression should be higher around 10:1

thanks for the input!

 

[Allforspeed]

think i'm going with the 3.55s

 

[ninety15.0]

i also went fromt eh stock gears to 3.73 and i was in the same boat as you. I was really considering the 3.55's and thats what i thought i was gonna get. but i went with the 3.73 b/c i wanted the car to pull like crazy in 3rd and 4th. Driving around town my mpg went up from like 12ish to about 16 because you can just start off in 2nd and just skip 3rd and go right to fourth. (thats if you dont wanna have any fun and you wanna save $$) however if you wanna launch like a mo-fo and pull like crazy in fourth go with the 3.73's. My mpg on the highway was were i suffered the most. I went from about 26mpg going 70-75 all the time to about 20-22 mpg doing 65-70. That part sucks. So basically its all about how u wanna drive the car. I live the city all the time and the only time im on the highway is going out to college twice a yaer. def dont go with 3.27's they ar e a waste of money!! giood luck man

 

[v8only]

your choice should be between 3.55's and 3.73's, 3.27's is not worth the dough for that kind of install.

anyone who tells you their gas milage went up does NOT drive their car very hard. Your gas mileage WILL go down, significantly, and this is for several reasons.

1. You wind up accelerating and gassing your car like a ****ing maniac because it is so fun now

2. your rpm band moves much, MUCH higher up

3. to keep up with freeway traffic, you're gonna have to drive 75-80 mph, which is around 2700 rpms for 3.73's, and that eats much more gas.

4. I do NOT like driving in 5th on the streets, too much of a pain in the ass to use 5th on the streets.

not calling anyone out, but you're gonna have to work REAL hard to get better gas milage, and that includes driving in 5th on the streets constantly, and keeping it under 65 mph on the freeway, which is 2100k rpm's or lower.

my .02

also, if you have to ask about gas mileage, perhaps you can't afford to do this swap.

 

[ninety15.0]

your choice should be between 3.55's and 3.73's, 3.27's is not worth the dough for that kind of install.

anyone who tells you their gas milage went up does NOT drive their car very hard. Your gas mileage WILL go down, significantly, and this is for several reasons.

1. You wind up accelerating and gassing your car like a ****ing maniac because it is so fun now

2. your rpm band moves much, MUCH higher up

3. to keep up with freeway traffic, you're gonna have to drive 75-80 mph, which is around 2700 rpms for 3.73's, and that eats much more gas.

4. I do NOT like driving in 5th on the streets, too much of a pain in the ass to use 5th on the streets.

OK buddy.....I actually did the friggen calculations at the pump before and after the gear swap...how are you going to sit there and tell me that the MPG didnt go up. If you read some of the posts and didnt just blindly say what you felt like saying you'd be a little better off and you wouldnt get people like me to say $hit like this to you. Secondly your gas milage around the city WILL MOST DEFINATELY go up if you drive and shift just like you did with the old gears. Its all about torque multiplication, and you can accelerate through the gears without using nearly as much throttle with 3.73's. And im very sorry if you dont like using 5th gear, but the engineers at ford put it there for a reason. It saves on gas and engine wear b/c your turning significantly lower rpm's. 5.0's have a ton of torque and you can just throw it in 5th whenever your cruising and it will most certainly handle it with 3.73's, and very well might i add. Another thing...."people that say their mpg went up does NOT drive their car very hard." what a ***got!! i dont have time for your bull**** reasoning...its not always about revin it to 6k and flooring it everytime in every gear. Thats how little ***gots with mustangs get in big trouble and get absolutely no respect from anyone else. People like you are the problem with kids owning mustangs. Only little ricer ***gots race from every stop light to stop light. grow up!! whatever

 

[notchman90]

 

[HISSIN50]

the bottom line is that there are too many intangibles (mods, tune, and perhaps most importantly, how one drives and the conditions one drives in) for there to be 'one gear is best'.

i hate to see bickering start because i think you all have valid points - the end results are different for everyone.