25 mpg and 350 h.p. - how to do it?

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tjnavyblue

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Feb 21, 2007

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Apr 11, 2007

#1

• Apr 11, 2007

• #1

Well... that's the question assuming I'm starting with a 87 - 93 5.0 with MAF and stock internals and a T5. What are your ideas?

 

S

Sicarius428

Active Member

Jan 6, 2004

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Apr 11, 2007

#2

• Apr 11, 2007

• #2

I get about 20mpg. See sig. Full weight with full options. Also have the stock 2.87 gears in the back too. Not the mach 1 BTW, that gets about 7mpg on a good day.
Kevin

 

wythors

Get off my lawn!!!

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May 17, 2000

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C Addle

Apr 11, 2007

#3

• Apr 11, 2007

• #3

Check my mod list. The one road trip that I've made since doing it, I got 22 mpg with an automatic. I was pretty jazzed. I'd think that after I do my T5 swap, it ought to be near 25 mpg on the highway.

 

Woodrow

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May 19, 2002

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Apr 12, 2007

#4

• Apr 12, 2007

• #4

Buy a corvette....

 

Foxbody1993

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Apr 12, 2007

#5

• Apr 12, 2007

• #5

Woodrow said:

Buy a corvette....

Click to expand...

LOL Silly boy vettes dont really get that kind of MPG!



Honestly, Keep your foot out of it.

 

jrichker

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Apr 12, 2007

#6

• Apr 12, 2007

• #6

EFI and pressurized induction - Turbo or small supercharger, good tune, 3.55 gears. Keep your foot out of the boost and the engine will run at stock power levels and get great gas mileage.

 

HISSIN50

"How long does it take to get help in here?

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Nov 29, 1999

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Apr 12, 2007

#7

• Apr 12, 2007

• #7

Trailer the car to the top of a mountain and coast down.

Seriously, the caveat is that while folks do get close to doing what your propose, you have to leave your berries at home in order to accomplish the mileage portion. Folks generally build powerful stangs to have fun with them.

The new cylinder-on-demand stuff is pretty neat and help the future of big motors which otherwise are slow to see tech advances IMHO.

 

302RollinHard

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Sep 26, 2005

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Columbus, OH

Apr 12, 2007

#8

• Apr 12, 2007

• #8

I would say a small turbo would be the key in terms of efficiency. Other than that a gerbil generated auxillary power pack would be my second choice. Just don't let those little buggers loose in your car. They will F you up in short order.

 

M

mackey

Active Member

Jan 25, 2003

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Apr 12, 2007

#9

• Apr 12, 2007

• #9

Put a LS1 in it!

I would look into cleaning the entire system out. Fuel/ carbon off pistons and see how much you get stock. Also stick with 19lb injectors and don't put your foot down ever.

 

millhouse

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Apr 12, 2007

#10

• Apr 12, 2007

• #10

jrichker said:

EFI and pressurized induction - Turbo or small supercharger, good tune, 3.55 gears. Keep your foot out of the boost and the engine will run at stock power levels and get great gas mileage.

Click to expand...

Drop those down to 3.27's and you'd fare even better!

Seriously though…the biggest thing that has help me in those regards is being able to to the low load portions of my VE table to be a bit lean. Stock AFR's typically hang around stoich (14.7:1) while I tune to around 15.5:1. I get around 24mpg and I'd estimate my horsepower to be around 500 at the wheels with my current combo. Of course…of you can't stay off the happy pedal then no amount of tuning is going to help you achieve your goals.

 

B

Boss 351

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Jul 13, 2003

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Apr 12, 2007

#11

• Apr 12, 2007

• #11

I got 27 on the highway, stock 5.0, T5, car weighs around 2800lbs and stock 2:73 gear but driving a little BELOW the speed limit. In town no matter how granny-like I drive I can't get better than 13mpg... that's shifting at 2500rpm max. I have 3:55's that need to be installed, I'll get better mpg in town and little less on the highway.

 

85_SS_302_Coupe

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#12

• Apr 12, 2007

• #12

tjnavyblue said:

Well... that's the question assuming I'm starting with a 87 - 93 5.0 with MAF and stock internals and a T5. What are your ideas?

Click to expand...

Maybe not with the T5, but i bet if you stuck with 3.08 gears in the back and switched to a T56, and then turboed it...you'd make gobs of power and still get pretty good mileage. That's assuming that your car EVER got 25mpg though.

 

Dean85GT

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Thorold, Ontario, Canada

Apr 12, 2007

#13

• Apr 12, 2007

• #13

I can only get 16.5mpg at best around town with a holley DP carb and 4.10 gears. Im super happy with that too

 

B

Boss 351

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Jul 13, 2003

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Apr 12, 2007

#14

• Apr 12, 2007

• #14

I wonder what kind of MPG those fox bodies with mod motors do?

 

ninety15.0

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#15

• Apr 12, 2007

• #15

I consistently get 25 MPG on the highway with my current setup. I run 3.73's and 24# injectors. Its all about your driving style and speed control. To get the best mileage you DONT need to drive slow. I average between 75 and 85 with current gears and still get 25 MPG. I also have a vac gauge and watch it like a hawk. I tend to go 75 up hills because at 2500 rpm my car barely loads up going up hills. When i come down hills i generally go about 85 and the pedal is just barely cracked open (ie. injectors are basically shut off). When i drive 65 or 70 i only get about 22 MPG. Good mileage can be obtained you just need to relearn how to drive.

The car weighs 3150 with the cage and gas but without me.

 

ninety15.0

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Apr 12, 2007

#16

• Apr 12, 2007

• #16

Boss 351 said:

I wonder what kind of MPG those fox bodies with mod motors do?

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My dad drives a 02 GT and we installed a vac gauge in his car. Averaging 80-85mph...i can easily suck 30mpg out of that car. Bone stock save a K&N filter

 

_jb_

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Apr 12, 2007

#17

• Apr 12, 2007

• #17

One word, N2O

 

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conv91lx

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Bloomington, IL. USA

Apr 12, 2007

#18

• Apr 12, 2007

• #18

Small turbo, big turbo, doesn't really matter. As long as you are out of boost the car will get just about the same gas mileage as before. You will get 350hp easy with good turbo kit, even with all the stock top end stuff. Will need a few other items in order to do it safely though.

 

stangjunkie

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Apr 13, 2007

#19

• Apr 13, 2007

• #19

Woodrow said:

Buy a corvette....

Click to expand...

yeah he beat me to it

 

5spd GT

"the 5.0 owns all"

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Apr 13, 2007

#20

• Apr 13, 2007

• #20

Corvette cost much more. Probably not an option....

The t56 has basically the same final overdrive gear ratio so that will not help and possibly hurt with more drivetrain loss....

You do not want to high of a gear that causes you to 'lug' around on the highway...or to low of a gear that causes unneccessary rpm (fuel/air).

I would personally contact Ed Curtis at www.flowtechinduction.com in which he sells custom cams....he can throw a heads/intake package in with it. You tell him what you want - 350bhp and 25mpg - and I bet he can get you close if you get it tuned...

Just my opinion