You stumped me on that one. Define efficiency. How is producing 90HP with minor effect to fuel consumption considered "less efficient"? I'll take restrictions like that any day!
General definition of efficiency is the ratio of the amount of usable work to the amount of energy consumed to generate the power to do the work.
If you have two identical engines, and you put a turbocharger on one of them, it will have to work harder to push the exhaust out due to the turbocharger being in the exhaust system. That's energy that is unavailable to push the car. The bigger the turbocharger (higher boost capability), the harder the pistons will be working to push the exhaust out, that's why a mildly tuned turbocharger would waste less energy. On top of that, all of Ford's engines that used forced induction (TC, SC), as well as most others in the industry, had lower static compression ratio to avoid detonation under boost. This reduces the amount of useful work that can be extracted from combusting a given amount of fuel, which translates to lower efficiency.
Now, if you replace a larger normally aspirated engine with a smaller engine using TC or SC, you can gain efficiency as long as you don't engage the forced induction too much. Imagine a TC 2 liter vs a NA 4 liter engine in the same car. If you can run the 2 liter engine without making the TC generate boost, you're effectively running a 2 liter engine, and get better fuel mileage from the car. But if you push the engine hard and the TC generates say, 15 psig of boost, you've effectively turned it into a 4 liter engine, and you will have the fuel mileage of a 4 liter engine, sort of. This is why the TC Talon starts to drink gas as soon as you push the engine.
General definition of efficiency is the ratio of the amount of usable work to the amount of energy consumed to generate the power to do the work.
Your definition only confirmed my comment. A turbo as on my TurboCoupe nearly doubles the horsepower of the NA 2.3 and it doesn't take twice as much gas to do it. It's not free horsepower but it's not less efficient either.
96 4wdr - So you're saying up to 28 mpg is possible with a 3.0 with a 3:27 rear and aired up tires? How do you know this? Have you actually done it? Not doubting you, just wondering if you or someone you know has actually achieved these numbers. If so, then I'm sold on keeping the 3.0. I looked under the hood of a newer 2.3 Ranger today and it does look pretty intimidating. I know I can do the swap, but it does look a bit "pandorish" under there .
Here's what I'm thinking might be reasonable based on what you guys have told me:
1. Stick with the 3.0
2. Perform mods as follows:
Install a 5 speed manual shift.
Replace clutch fan with electric cooling fans.
Install roller rockers.
Install a torquier cam that emphasizes more low end torque (to help with the 3:27 gears) and slightly curtailing max rpm and upper end hp (perhaps detuning the 3.0 down to ~130 hp)
Install hotter spark ignition system.
Ensure engine is tuned perfectly and perfectly maintained with all sensors and computer working exactly as intended. Ensure injectors are clean and spraying properly.
Install free-flowing exhaust and cat.
Install low drag tires and keep inflated.
Run synthetic oils all the way around (engine, trans, diff).
Strip out interior of unused stuff to lighten up. This actually is a win-win for me because it will primarily be used as a cargo/camper van.
Install high ratio differential (i.e. 3:27 etc).
Ensure all wheels freely rotate when brakes are released. Ensure brakes are properly adjusted and not dragging at all. Ensure wheel bearings are properly set up, lubricated and adjusted.
Keep speeds under 70mph on highway.
Anyway, that's all I can think of for now. What do you guys think? What would you guess mileage would be if these mods were implemented? Think the resulting van would be undriveable? Does this seem practical?
In addition to keeping the top speed below 70, you can also slow down the acceleration, but still try to get to the highest gear as soon as possible. Hard acceleration is wasteful of gas as well. Here you will have to make the trade off between accelerating hard enough to quickly get into the highest gear that won't lug the engine.
Those of you over 40 may remember the Shell commercial where the guy put an egg between his right foot and the accelerator pedal, and tried not to break the egg while pushing on the pedal. I forgot what the claimed mileage would be, but it was some incredibly huge number, even by today's standards.
Of course as noted a smaller engine can use a lot less gas because the swept volume is less. But there are many other things in play. Generally small engines achieve their power ratings at higher RPM. VERY basically 100 HP at 6000 RPMs with 2L swept volume could be comparable to 100 HP at 3000 rpm with 4L swept volume. Gas mileage would likely be very similar with these engines however the 2L would require a different driving style would wear out quicker & would also be much lighter. Thats how the JAPS achieve there overall economy figures everything is built to do the job not over engineered. Their vehicles are generally more efficient because of this. To get considerably better gas with technology available today ....look at the hybrid set-up. Electrical stored energy discharged through an electric motor is hard to beat & it's better at reducing pollution!
Aeroman.
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Green-96, XLT 2wd, 3L Vulcan, from Ontario, Canada
All original powertrain except alternator & starter motor. 302,500 kms & going strong !
If adding boost for increased fuel economy was incorrect, then why is Ford comming out with it's 3.5L Eco-Force (formerly called Twin Force) twin turbo v6 that will be added to the Lincoln line in 2009, and shortly afterwards added to the Mercs and Fords as an optional engine that gets 30+ mpg (plus over 400hp/tq.)
__________________ '96 Ford Contour 2.0 I4 MTX 77k mi- Rear Ended 12/22/07 '97 Ford Aerostar AWD 4.0L v6 AT 81kmi '97 Chevy Lumina 3.1 v6 ATX 135k mi Parents old beater, temp vehicle
I accel at lights like a granny, and it does not help my 4.0 mpg..
city traffic in this vehicle kills gas mileage.
I did a long term before/after test of jeep cherokee,
swapped 2 diffs, transfer case, and trans to mobil 1.
result was app 3/4 better mpg.
That is a lot of 'stuff' that the aero does not have,
so the increase will be less when I do the van's diff...
( i do not think the auto trans in van would benefit from mobil1, jeep is manual)
Let's try to keep the distinction between boosting a smaller engine vs running a NA larger engine.
The strategy is to start with a small engine that should get better fuel economy than a larger engine, and add the turbocharger for getting the power of the larger engine, but only when it is needed. The idea is that most of the time, you will not be pushing the engine for all it's capable of putting out; you can't get fuel economy that way, even from a small turbocharged engine. Running a larger engine at lower power levels means throttling it more, which is less efficient than running a smaller engine at more throttle opening.
As an example, the Fox-3 Mustangs came with either 2.3 liter 4 cylinder or 5.0 liter v8. At a constant 60 mph, both engines will be generating about the same amount of power to push the car. But the 2.3 liter engine will not be spinning twice as fast as the 5.0 liter engine, even though it's less than half the displacement. The controlling factor is the throttle; the 2.3 will have it opened more than the 5.0, which means the 5.0 will be throttling more than the 2.3, and experiencing more pumping losses.
If the 2.3 liter engine was turbocharged, it will not be as efficient as the non-turbo version going a steady 60 mph, because of the exhaust back pressure from the turbocharger, and the necessary lower compression ratio. But it will still be more efficient than the 5.0 on account of less pumping losses, and the approximately half the number of moving parts.
It's interesting to me how underpowered VW diesel vans (most with less than 100 hp) only get about 28 mpg. That's 'only' 4 mpg better than my 3.0 Aero with near 150 bhp.
It also sort of shows me the mileage potential / power trade off for that sized vehicle.
I think the newest Toyota vans only get about 2 mpg better than my old Aero.
I guess there's not much potential for adding better fuel mileage to a 'sharpened brick' the size of an Aerostar.
It's simple physics; it takes a certain amount of energy to get a 4000 pound van up to speed, regardless of how big or small your engine is. This energy is scrubbed off and turn into heat when you apply the brakes to slow it down or stop it. Then you repeat the process until you get to your destination. It's going to be twice as much energy as for a car half the weight. Then there is the big frontal area that would be an effort to push through the air at speed.
If you have a smaller engine, it tends to be operated closer to its more efficient modes more often than a larger engine, so you can see a small improvement in mileage than a larger engine. Plus with a larger engine, it's easier to accelerate more than necessary than you would with a smaller engine, which tends to waste gas.
I'am new to the forum, I have a 93 4-ltr Aerostar, I changed the air filter to a K&N, my mileage is better on the highway 28-30 mpg depending on my foot and keeping to 100km. No difference at all on city economy just bad. I would love to try 273 gears or close to them as I had luck years ago gearing a Scout. I have noticed winter economy is really bad, none of the newer fuel injection engines draw heat off of the intake, I would like to know if anyone has re-plumbed there intake for the cold weather, early bronco 2 engines had this type of air intake.
I'am new to the forum, I have a 93 4-ltr Aerostar, I changed the air filter to a K&N, my mileage is better on the highway 28-30 mpg depending on my foot and keeping to 100km. No difference at all on city economy just bad. I would love to try 273 gears or close to them as I had luck years ago gearing a Scout. I have noticed winter economy is really bad, none of the newer fuel injection engines draw heat off of the intake, I would like to know if anyone has re-plumbed there intake for the cold weather, early bronco 2 engines had this type of air intake.
Snag
Welcome Snag!
I hate to be a downer, but Fords and K&N's don't work well together. What usually happens is the Filter oil coats the MAF sensor, causing it to burn out and become non-functional. You are better off replacing with a good paper filter (Motorcraft/Wix.)
__________________ '96 Ford Contour 2.0 I4 MTX 77k mi- Rear Ended 12/22/07 '97 Ford Aerostar AWD 4.0L v6 AT 81kmi '97 Chevy Lumina 3.1 v6 ATX 135k mi Parents old beater, temp vehicle
I hate to be a downer, but Fords and K&N's don't work well together. What usually happens is the Filter oil coats the MAF sensor, causing it to burn out and become non-functional. You are better off replacing with a good paper filter (Motorcraft/Wix.)
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