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Topic: What kind of gas mileage you getting on your 5.0? (Read 5367 times) previous topic - next topic

What kind of gas mileage you getting on your 5.0?

Reply #15 –
My Thunderbird with the mods below, 3.73 gears, and a non-lockup torque converter gets 14 city and around 22-23 highways at a steady 70 mph cruise. Highway cruise speed is about 2800rpm at 70 mph. I could maybe get a mile or two more per gallon if I drove it like I do my DD Focus but I tend to, ahem, use the power. That results in poorer fuel economy. I didn't set up the car to get good gas mileage but instead be fun to drive.
88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, bunch of other stuff.

What kind of gas mileage you getting on your 5.0?

Reply #16 –
Quote from: thunderjet302;423263
I didn't set up the car to get good gas mileage but instead be fun to drive.

Yep, but most of it is in the gears. With the economy drop from 2.73's to 3.55's, and the fact that the tires would permanently break loose/drift sideways on the 1-2 shift at WOT in the middle of summer when using 3.55's, 3.08 seemed like a decent compromise, and got the highway back up over 30. I've missed the extra torque multiplication though - dry weather only breaks traction on the 1-2 for a second now. 3.55's were quite a bit more fun, but performance wise, the 3.08's provided more daily drive-ability in economy, safety, and more torque multiplication at "passing speeds". 3.55 has to shift right below the speeds where you normally find yourself stuck behind a slow driver, when using the 4R70W's ratios.

With the right combination, anything is feasible. It's easier to just throw on big parts and enjoy the incremental performance increases.

Stock, 18 city, 32 highway is probably the max one can expect, with an average of 20-22mpg. Expect 14-16mpg if you average 15mph in stop and go traffic - that's where the v8 really gets you.
1988 Thunderbird Sport

What kind of gas mileage you getting on your 5.0?

Reply #17 –
These gear ratios are so low (or high I should say) compared to what I'm used to hearing when I had my Rangers, we had 3.45 3.73 and the 4.10.

My last one was a '96 2.3 manual 2wd with 3.45, I got 25 mixed EASY, but it couldn't get out of it's own way. The one before that was a '03 3.0 Auto, also 2wd, with 3.73, that thing was slow as well, and drank as much gas as a CFI 5.0.
Current: 1986 Thunderbird, 105k 3.8/C5, 2 tone  Midnight Wine/Medium Taupe, wing windows, wire wheel covers.


Former: 1985 Cougar GS 115k Oxford White/Regatta Blue, 5.0, full console, 14" 8 hole aluminum T-Bird rims, Edelbrock valve covers.

What kind of gas mileage you getting on your 5.0?

Reply #18 –
im not buying it for a minute anyone here gets 30 to 35mpg in these cars be it a 4, 6 or 8 cylinder unless your going down hill both ways.

I get 22 in my appalachian mountain highway / byway roads
I get a hard steady 25 mpg in flat land states.

typically i get 19 city.

i even  have a 2.73 gear

What kind of gas mileage you getting on your 5.0?

Reply #19 –
how much do you use cruise control? that actually eats up quite a bit.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

What kind of gas mileage you getting on your 5.0?

Reply #20 –
I use it all the time when it works.. but its been broke twice and with thousands of miles with and without cruise.

im up to 260k now

seek,
i worded all that wrong above,, i should have said what i said differently and sorry for how i typed it out.
your a very tech savvy guy and what i should have said was "how in the hell are you doing that"?

maybe the quarter horse engine managment system you have?

What kind of gas mileage you getting on your 5.0?

Reply #21 –
do 55-60mph max on the freeway. ill bet you see 2-3 mpg right there.

until a few years ago, we had a state wide speed limit of 65. since they bumped it up to 75 and even 80mph in the middle of no where, I've lost quite a.bit when driving those speeds.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

What kind of gas mileage you getting on your 5.0?

Reply #22 –
Quote from: jcassity;423290
im not buying it for a minute anyone here gets 30 to 35mpg in these cars be it a 4, 6 or 8 cylinder unless your going down hill both ways.

I get 22 in my appalachian mountain highway / byway roads
I get a hard steady 25 mpg in flat land states.

typically i get 19 city.

i even  have a 2.73 gear

I got 30 mpg in my 87 LS with V6 all the time on trips between Maryland and Mississippi and Maryland to Florida.  I also got 29.5mpg all the time on those same trips in my 96 MarkVIII.  Speeds were not slow.  The sage green 85 wasn't anywhere close to that and it also had a V6.  My V8 Cougars aren't anywhere close to that either.  They are 24, 25 max with similar driving.
"lol.. because not too many people care for that style of car"
[size=-2]Click on paw print \/[/size]

What kind of gas mileage you getting on your 5.0?

Reply #23 –
Quote from: jcassity;423315
seek,
i worded all that wrong above,, i should have said what i said differently and sorry for how i typed it out.
your a very tech savvy guy and what i should have said was "how in the hell are you doing that"?

maybe the quarter horse engine managment system you have?

No worries.

I've had a lot of variables over the years. With the stock motor, I was using 35psi and I do not remember if it was using cheaper/harder tires at the time. All of my highway testing was done filling up right before getting on the highway, and engine already warm. Longest calculated highway trip I've made is 310 miles, which matched numbers I was seeing on the weekly 140 mile trips (each way). While I did add a quarterhorse somewhere along the line, it wouldn't affect closed loop, where I kept the vehicle. What I do recall:

Completely stock, I didn't know that much about cars, newer driver, etc -30-ish mpg at who knows what speeds.
SO with HO intake, 35psi tires, 2.73 - 32-33mpg at 65mph
SO with HO intake, 35psi tires, 2.73 - 30mpg at 75mph
SO with HO intake, electric fan, 35psi tires, 2.73 - 34-35mpg at 60 or 65mph (do not remember the exact speed on this morning - I was shooting for consistency between mechanical/electric fan tests rather than other comparisons)

The start of engine work, building for efficiency, and trying to get the most out of the vehicle (including more even tire tread wear) - tire PSI did not seem to change much in economy with softer unidirectional tires, but it was higher:
GT40 engine with HO cam, electric fan, 45psi tires, 2.73 - 34mpg at 65mph
GT40P engine with HO cam, electric fan, 45psi tires, 2.73 - 34mpg at 65mph
GT40P engine with HO cam, electric fan, 45psi tires, 3.55 - 26.5mpg at 65mph
GT40P engine with HO cam, electric fan, 45psi tires, 3.55 - 24mpg at 75mph
GT40P engine with HO cam, electric fan, 45psi tires, 3.08 - 31mpg at 65mph (consistently)
GT40P engine with HO cam, electric fan, 45psi tires, 3.08 - 34mpg at 70mph pulse, 55mpg decel fuel cutout glide on a different highway, commute to work
TF 170/ported GT40 intake engine with HO cam, electric fan, 45psi tires, 3.08 - no clue. Haven't driven it enough.

On that note, I'd like to try improving drag resistance as a learning experience. With what I have learned about my Insight, I could probably improve back up to/over 35mpg with enough under body modifications. I don't know if I want to try leaner fuel mixtures with the aluminum heads.

And for comparison:
2000 Honda Insight 5 speed - 75mpg at 75mpg (22:1 AFR 50% of the time)
2000 Honda Insight 5 speed - 86mpg at 65mpg (22:1 AFR)

With a V8, the big difference comes at idle or low speed - there are much higher losses in city driving with a v8, than with a v6 or i4. Highway speeds, rolling and wind resistance impact things more. This is only true to an extent though, as obviously going to higher numeric gearing/higher rpms obviously hurts economy greatly also.

These are all "maximum" numbers, with simply using cruise control and never dropping out of closed loop. The numbers also varied between winter and summer. The Tbird numbers are still nice considering we've had E10 fuel for some time. I'm not comfortable enough trying to tune the vehicle to run on E10 better, because of all the timing issues that could arise.
1988 Thunderbird Sport
 

What kind of gas mileage you getting on your 5.0?

Reply #24 –
My old 88 XR-7 used to get in the mid 30's on the highway.  Towards the end, it was the best part of her.