Best magnum MPG?

[Infecteddog]

I agree real world gains are small that's why it's not worth spending too much money on improving fuel mileage it's hard to recoup the cost. But weight does make a difference especially intown driving. The resson gains aren't huge cause for huge gains percentage wise is actually small in actually mpg numbers.

My 5.9 jeep gets 12.5 mpg average. I would imagine it would at least get 15 mpg in my cuda that's a 20% increase but actually equals to a 2.5 mpg increase and that's a 1500 pound difference.

All I was trying to say is it takes a certain amount of hp (fuel) to move a certain weight and aerodynamics that's why I said ultimately. Over 20 mpg in town would be hard and expensive.

My point is real world gains don't exist and it's foolish to account for that over gear ratios within the transmission, axles, chassis and aerodynamic characteristics, engine fuel demands, and available torque. I'm not discussing in-town. That's far more heavily dependent on driving style, idling time (i.e. traffic), and as such usually not very comparable in my mind.

The thing is if you compare a 4000lb car to a 2900lb car with the same everything those differences marked are rare. Same when comparing a 2900lb Jeep to a 4000lb Jeep- often the economy's just about the same. Same motor will typically do a bit worse in a Jeep, a bit worse than that in a full frame Jeep, and than even worse in a full frame truck. That doesn't mean it'll have to do horrible, but it will do less. By the time you're typically talking of the utilitarian barn-door aero designed full size truck it's typically far lower, even if that full size truck is 200+lbs lighter than the car.

Factory manufacturers have spent millions of dollars trying to get any advantage when it comes to mpg. They spend millions of $ and tons of time in wind tunnels making bodies more aerodynamic so you get better mpg. If vehicle weight made a huge difference, they would spend more time on a scale and less time in the tunnel....its all about aerodynamics, much more than weight. The weight factor comes in when you are talking about puny engine like aprius that simply cant push more than 2500#s. In a V8 with lots of torque, its the profile of the body lines that matter most.

That I completely agree with. And I'll add I'm impressed you've seen 20mpg out of Wranglers. I think that's also why they've all pretty much gone to these VVT style setups so it'll cut power at cruise but it'll have the power under load to perk the maxes up even though they may be totally unobservable.

 

[273]

Infecteddog

You've done a full circle and basically agreeing with my original post I stated in my first paragraph I stated weight aero and engine efficiency are a given basically saying there ain't much you can do about them.
And my second paragraph was about gear ratio one of the biggest help with mpg especially on the highway.

I'm glad we agree

 

[magnummopar]

My point is real world gains don't exist and it's foolish to account for that over gear ratios within the transmission, axles, chassis and aerodynamic characteristics, engine fuel demands, and available torque. I'm not discussing in-town. That's far more heavily dependent on driving style, idling time (i.e. traffic), and as such usually not very comparable in my mind.

The thing is if you compare a 4000lb car to a 2900lb car with the same everything those differences marked are rare. Same when comparing a 2900lb Jeep to a 4000lb Jeep- often the economy's just about the same. Same motor will typically do a bit worse in a Jeep, a bit worse than that in a full frame Jeep, and than even worse in a full frame truck. That doesn't mean it'll have to do horrible, but it will do less. By the time you're typically talking of the utilitarian barn-door aero designed full size truck it's typically far lower, even if that full size truck is 200+lbs lighter than the car.


That I completely agree with. And I'll add I'm impressed you've seen 20mpg out of Wranglers. I think that's also why they've all pretty much gone to these VVT style setups so it'll cut power at cruise but it'll have the power under load to perk the maxes up even though they may be totally unobservable.

Only on the ones we swapped in a 5.2 magnum and nv3500 5 speed. Typical mpg from same TJ with 2.5L was mid to low teens and doing nothing else but 5.2 swap has yielded 22 mpg in one I built and another got 21 consistently if kept under 70 on freeway. Our shop is 10 miles out of town on 199 Redwood Highway, 2-4 lane with 55-60 average speed and I would always get 18 "town" mpg which was about 1/2 199 hwy and 1/2 small town driving. We dont get traffic, just a lot of lights and stop signs. Customer lived it Sparks NV and got 20 driving to Reno for work, with real traffic.
My 2001 TJ with 325 hp 5.2 44RE 4.88 geared 8.8 Furd and 35x12.5 mud tires got 17 hwy/16 "town" and when towing my 2000# 18' North River Jet boat through mountains of Southern Oregon at 65 would get an easy 14 mpg(1100' ele to 6200' in 60 miles crossing 5K', 5.5K' and the big one 6200 by Crater Lake). Talk about a barn door, towing a barn....want to piss of a Chebby guy, blow past his Z71 PU on freeway in a TJ with 3 dirt bikes in a trailer going up hill, they get super pissed