2:73 = Bad Gas Mileage???

[LiquidGT]

I was under the impression they were a little wider with the disc brakes, but that the mounting points for the control arms/shocks were the same? Any one here that's actually swapped in a turbo coupe rearend?

I looked into it, they are just as wide as a sn95 rear because of the abs exciter rings. Pretty much the same as a sn95 brake swap, need bigger MC, different e-brake cable, and ect... Get some North Racecars brackets and use fox length axles. The only thing thats different is the quad shock mouting holes, just drill them 2 in lower. Then when I do the 5 lug swap I'll be halfway there. And will give me time to save up for new 5 lug wheels and tires.

 

[HISSIN50]

To be clear, the 94-98 axle housings are the same width as 87-93's. They had longer axles (0.75" per side IIRC).
The NE stangs had wider axle housings and wider axles.

Just clarification to not lump comments about all SN95 rear ends together.

 

[85_SS_302_Coupe]

If i built a nasty turbo car that made huge power numbers i'd probably go as low as 3.08 gears, but i think the 2.73s are an automotive mistake. I remember we had a debate about top speed a while back and that with 5th gear in a T5 and the 2.73 gear the top speed was something well over 200mph...that's ridiculous. That was Ford's failed attempt at getting decent mpg out of the 5.0s.

 

[mavmavv]

When I had my AOD, 4th gear + 40mph = 1000 RPM. It was practically idling.

Yeah, I dont even use OD unless im on the freeway and the damned motor struggles like hell to get over 1200RPM. Its really bad. Next time I get to the pick N pull, im gonna check out some rear ends.

 

[mavmavv]

If i built a nasty turbo car that made huge power numbers i'd probably go as low as 3.08 gears, but i think the 2.73s are an automotive mistake. I remember we had a debate about top speed a while back and that with 5th gear in a T5 and the 2.73 gear the top speed was something well over 200mph...that's ridiculous. That was Ford's failed attempt at getting decent mpg out of the 5.0s.

GM's 700r4 has a really steep 1st gear, making very tall rear gears bearable and highway driving pretty fuel efficient. The Ford transmissions + tall gears just dont go well together at all.

 

[bloopbloob]

Yeah, I dont even use OD unless im on the freeway and the damned motor struggles like hell to get over 1200RPM. Its really bad. Next time I get to the pick N pull, im gonna check out some rear ends.

pick n pull???? i'd suggest the peelers. you'll likely have much better results. (but not always a guarantee!!! )

 

[mavmavv]

yeah, Ill call around. That might save me some time, all I know is that the rear I have now is seriously trashed, I think it will be cheaper to pick up a "new" one than rebuild the current one.

Bearings are shot to hell and clunking louder than ****.

 

[twistedwankel]

I have a 273 rear end and I did a 5 speed swap, I was wondering if my engine was being bogged down and giving me 16mpg mostly highway driving like a normal person. ...My dads 5.0 explorer gets better mileage with 373s and it spins at 2300'ish rpm at 65mph.

My 92 with 2.73 rearend and AOD that kicks in at 35mph gets avg of 26 at 73mph on cruise. High of 30mpg and low of 23 depending on hills. 1900rpm

My 84 with 3.27 rearend and AOD that kicks in at 45mph gets avg of 20mpg at 70mph on cruise. High of 23mpg. 2000rpm

My 96 5.0 explorer used to get 20mpg at 70mph in cruise. 2200rpm

I suppose it depends on the 5th gear ratio effect on final drive in your car. It might be lugging if too much a drop in rpm causing you to induce more throttle to compensate? This would happen in cruise too. Try replacing your TPS as that can really kill mileage and you are having one major symptom of that with your idle.

 

[RMODEL65]

when i did my 5spd swap, i had my 2.73s in my 91 gt vert i got a bump in mileage i went from 24mpg to 28mpg

 

[LiquidGT]

I'm starting to think that my problem is something electronic, before my old stock motor died it dwindled down to 16mpg. I thought it was because the motor was tired, now the new motor gets 16mpg and it has a lot of new sensors and stuff.

Anyway you look at it the 2.73's still suck.

 

[Neuwave]

I'm starting to think that my problem is something electronic, before my old stock motor died it dwindled down to 16mpg. I thought it was because the motor was tired, now the new motor gets 16mpg and it has a lot of new sensors and stuff.

Anyway you look at it the 2.73's still suck.

agreed, you have other issues going on there. My car has about 57k on the rebuild, had 2.73's in it till the middle of this summer and got an average of 25 traveling at 70/75mph in 5th at about 2k on the tach

 

[NEG1071]

My 2.73 AOD can only muster 10-12 mpg. Its just a daily driver that isn't driven hard w/only 110,000 miles. I thought I might improve the mpg with the items I changed chasing down a cranking problem. I have a set of 3.08's waiting and if that don't improve it some, hopefully a new set of O2 sensors will. So, no you're not alone!!!

 

[1.8kmint]

I've been wondering this also my mileage is way below what it should be and i drive it easy everywhere. Im thinking tryign driving it outside of overdrive and harder and seeing if it changes.

 

[90_Red_LX]

My cars never seen the fuel mileage with 2.73s that a lot of people see or with any combo I've had period. I'd get 17 or 18 mostly stock, best was 23mpg almost all highway. Now 13-17 depending on city or highway, best was 19.

 

[91green5.0]

I really feel bad for you guys. My old 89 had the 2.73 geers and it had headers punched out cats and flowmasters a k&n filter with a 110lph fuel pumpe and when i went to wyotech on the highway i was getting no lie 29mpg and im not sure what in city driving because i never checked it.

 

[LiquidGT]

Well I fixed the tailpipe rubbing on my tire, that helped a little. I still not seeing anywhere near this magical 28-29 mpg though.

I think the colder it gets outside the mileage goes down respectivly.

I can best 19 mpg now, usually 16mpg with both my old and new motor. I squeezed 24 out of my old motor once, but I was driving really really impractically slow.

I wonder if our cars computers are calibrated differently, I know theres auto/manual, high/low altitude, change by year ecu's; is my car in the wrong part of the contry or something?

 

[1.8kmint]

I'm thinking it could be the gas also... Just another variable to throw in there.

 

[Sicarius428]

Winter gas does suck for gas mileage. I get about 20mpg on everything in my sig mostly freeway. I have the 2.73 and my motor strains to get the torque to move the thing. Doesn't help that the tko600 1+2 gear ratio's aren't torquey like the t5.
Kevin

 

[865.0HO]

Winter time w/2.73's I average 20mpg mixed driving, 22-23 hwy. Summer time I've got as good as 25mpg mixed and 27 hwy. 200k+ stock longblock w/5-spd. 3.27's coming this spring.

 

[callys]

Hahahah the engine pulls the car most easily at its torque peak. If you gear the car to where the engine stays at its peak at cruise... it is going to get the best mileage.

Also, as someone mentioned... The lower the rear gear ratio (to a certain point), the better mileage the vehicle will get around town. All the gear ratio is is a different form of torque lever. The longer the lever, or the steeper the ratio, the easier it is for the motor to move the car. Of course this changes when you hit the highway.

I wouldn't ever cruise it below 2k rpm on the freeway. Use your 4th gear. I have found my stock car other than exhaust gets the best mileage at about 2200 rpm cruise.