Increasing efficiency, within reason? (long post)

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Increasing efficiency, within reason? (long post)

September 18, 2005, 06:42:50 PM

Been toying with the notion of making this thread for awhile now.. but this little semi-emergency road trip I just got back from a little while ago (and more specifically, all the time we spent monitoring the IN MPG reading on the Mark's trip computer) has me finally posting it. This isn't limited to a discussion about my (or any) Mark.. it's about all these bigger Foxes. I'm actually getting the EPA rated 24 highway for that thing, at 75 mph.. but improvement wouldn't be a bad thing with gas prices the way they are.

From time to time I hear people claim part X or modification Y *MIGHT* actually improve mileage. Things like superchargers improving mileage when you don't have your foot in it, the logic being that it still helps pull air through the filter/intake system. (I'm not saying it's true or false.. just recounting things I've read)

There's also the comparison of the V6 vs. V8 T-birds/Cougars.. how they get roughly the same mileage with different horsepower ratings and different engines.

Sometimes I wonder if putting in something with a bit more torque (like my 351W, but converted to EFI and maybe using 5.0 HO brains and fuel delivery and all that, for example) would be a bit more efficient at getting two tons of LSC and myself moving from a dead stop. This isn't really a specific question, (although it's open to discussion) it's meant more to add some direction to this post.

One thing I'd like to say before I continue is that this discussion pre-supposes that tune-ups are done as required. We already know that keeping the tires inflated, the filters clean, the plugs fresh, the idle down, your foot out of the engine compartment, and all that other stuff helps.

Another thing this pre-supposes is that any car modified in an attempt to make it more fuel efficient will be kept (barring accident, theft, catastrophic breakdown, etc.) for a long enough time to make the expense of the modifications pay off in savings. We'll say at least 5-10 years. With only 92k on the clock for my LSC, I could see keeping it quite some time.

So, any ideas on improvement? Is there a discussion to be made out of this? Please try to avoid instant negative responses like "it can't be done, don't bother even thinking about it" and think about possible ways to imrpove things before dismissing it. Sorry for the long post.

Re: Increasing efficiency, within reason? (long post)

Reply #1 – September 18, 2005, 06:52:58 PM

as far as making more power with better milage I cant think of a whole lot. You could maybe try getting a customer chip burned to give you a higher ration of 14.7 : 1. That is the only thing that I can really think of.

Re: Increasing efficiency, within reason? (long post)

Reply #2 – September 18, 2005, 07:17:25 PM

More power isn't necessarily the goal here. I'm thinking equivalent power, or mild increases, but mainly I'm concerned with efficiency.

Re: Increasing efficiency, within reason? (long post)

Reply #3 – September 18, 2005, 07:33:10 PM

So pretty much you would like to keep the economy and hp about even

Re: Increasing efficiency, within reason? (long post)

Reply #4 – September 18, 2005, 07:43:54 PM

Don't mind horsepower staying in the low-200s.. (HO is stock in the LSC, remember) Just looking for a bit more efficiency (beyond what a tune-up can provide) without getting outrageous. I actually got like 23.9 MPG highway today at 75 MPH with the A/C on full blast on a 92-93 degree day.. so I'm getting what I should be getting, at least on highway mileage. Wouldn't mind a little help in the city mileage department. But I'm not entirely talking about myself.. I had this in mind for anyone who might be facing a decision about continuing to drive their Bird/Cat/Mark or finding something more fuel efficient. I might be starting work here this week, and my fiance starts training for a job tomorrow morning.. so I'll definitely be putting in more time behind the wheel of the Mark.

Re: Increasing efficiency, within reason? (long post)

Reply #5 – September 18, 2005, 11:17:50 PM

There are some things that you can do that will increase mileage while negatively impacting other areas:

You can install skinnier tires - instead of, say, a 225/60R15 you could put on 205/70R15. Wider tires increase rolling resistance. You can also install harder tires with stiffer sidewalls, and if you want to go extreme, a set of drag-style skinnies up front would help. Anything to decrease rolling resistance will help mileage. Of course, your handling would suffer.

You can also install a steeper rear gear, such as a 2.73 (I think Marks came with a 3.27) - this may net you a MPG or two but of course acceleration will suffer.

Using all synthetic fluids (rear, tranny, engine) will decrease frictional losses but will likely cost more than the fuel you're saving, given the limited life span of fluids

Swapping a t-5 into the car will free up some MPG's by decreasing parasitic drivetrain loss. This will make the car more fun to drive, but of course could result in a decrease in mileage if you drive it harder than you normally would

Swapping the BMW 2.4-liter turbodiesel inline six that was offered in 84-86 Marks would greatly increase mileage (plus allow you to use biodiesel), but finding one could be difficult. And your car would become a dog.

Lower the weight of the car. Remove the spare (and bring along a can of fix-a-flat or a plug kit), and lose some of the insulation. The car will be noisier without it, but the quietness you're used to costs money. If you carry a heavy tool box wherever you go, lose it.

Keep the A/C. It may burn some fuel, but most fuel economy experts will tell you that it takes less energy than it does to drive at 65+ MPH with the windows open. Aerodynamic drag is a big fuel burner. Around town, turn off the A/C and open the windows (likely not much of an option down there in Florida).

Install underdrive pulleys. Less drag on the engine will equal less fuel burned. This may create overheating or charging issues, though...

And of course, the simplest way to increase mileage: Slow down. At 75 MPH you're probably burning 10% more fuel than you would at 65 MPH. Might not be much fun, but the laws of physics are indisputable, and it takes a certain amount of energy to move two tons through the air at a given speed. Decrease the speed and it takes less energy. Use the cruise control to optimize efficiency - it can maintain a steady speed better than your right foot, and varying speeds burns more fuel.

Re: Increasing efficiency, within reason? (long post)

Reply #6 – September 18, 2005, 11:36:47 PM

To address a few parts of that:

- Yes, this has a 3.27 open rear, according to the codes.. if they're the same as Bird/cat codes.

- I've thought about going to a 4R70W and going with a numerically lower rear gear. Right now a stick is out of the question.. my fiance drives this from time to time, and I haven't taught her how to drive a stick yet. (mainly 'cause I don't have one) Current concern is getting work for both of us, which should be taken care of this week.. lessons like that can come later.

- Only I6 I'll be using in anything is a Ford one. :p (I could always track down one of the diesel Marks.. but there's no real point)

- After this weekend, I am NOT losing the spare. Mind you, when I bought this car, it had four new tires on it. (but unlike with the battery, came with no receipt) Within a week, one of them got a nail in the sidewall. Had that replaced at Sam's for about $100 total. Well, when I was about 130 miles away from home this weekend, I got a flat in that exact tire. Drove it long enough flat (trying to figure out what the hell that noise was) that the sidewall took some damage, and a chunk also got taken out of it aside from the initial puncture. (we didn't know about the chunk until the next day, today) The spare got us the 7 miles back to my uncle's house, where he proceeded to rawhide-patch the hole. Put the damaged tire back on and went off to their Sam's, to replace the tire. Ended up paying 78 cents (plus tax and a new road hazard policy, $12.50 for everything) for a brand new tire, no grief given or questions asked. Maybe a can of Fix-A-Flat would've worked, maybe not.. but I know the spare did its job and bailed me out on a very bad weekend, so it keeps its job.

- I am wondering about something: I am going to replace the funky oversized Mark VII 100A/external reg. alternator with a 3G at some point.. but should I see about buying a 200A alt and underdriving it, or get a 130A and leave it as is?

- As for slowing down: I don't think 65 vs. 75 makes a difference, to be honest. We spent a lot of time watching (my fiance more than me, for obvious reasons.. I had to drive) the trip computer.. and we were getting the same mileage at 75 as just about any speed. 75 in OD is only about 2200 RPM. Car had no problems with that. Calculated it out to about 23.9 MPG.. and the EPA rating on an '89 Mark is 24 highway. Honestly, I think most of the gas gets wasted getting it to a certain speed quickly.. once you get that car going, it stays going, and doesn't give you trouble about it.

At any rate, going any slower than 75 mph here is almost foolish. Speed limit in Florida on rural Interstates is 70, and flow of traffic is often 80+ on I-75. I spent far more time today worrying about the crazies coming up on my rear bumper than I did worrying about the crazies off my front bumper.

This thread is more of a general improvement thread. Focusing on the highway (which I rarely do, although with things being as screwed up as they are right now might become more common) detracts from trying to pick up something here and there for city driving. Even when I baby it, I don't do much better than 10-11 MPG city. I know there are some things to take care of to improve that, but I'd like to see just how far I can push that improvement. Like I said, I think sometimes about adapting the 351W to take the place of the 5.0 HO, in the hopes that a little more torque would equate to a little less pedal travel to get the same acceleration.

Re: Increasing efficiency, within reason? (long post)

Reply #7 – September 19, 2005, 12:04:32 AM

Assuming that you're car is completely box stock, I would recommend a K&N air filter, off-road h-pipe(with turbo style lers if you don't want it too loud) and set the base timing(with SPOUT connector removed) to 12-14 degrees. That should help with fuel economy and throttle response as well.

Re: Increasing efficiency, within reason? (long post)

Reply #8 – September 19, 2005, 01:51:12 AM

Bumping the timing would also require higher octane fuel... thus sort of negating the efficiency goal.

Re: Increasing efficiency, within reason? (long post)

Reply #9 – September 19, 2005, 02:30:31 AM

if it;s totally tock the hpipe would hurt him. the offroad anyway. motor has no work to breathe 2.5 inch pipe from the headers back. you could find beter ways to get gas mileage. how about an explorer cam you may loose some rpm's but you would get tourqe which pushes the car. or the whole elplorer /gt40/cobra pacage or cam n intake. but could get expensive

Re: Increasing efficiency, within reason? (long post)

Reply #10 – September 19, 2005, 10:33:09 AM

or he could go back to e6 head and the stock s.o. cam shaft and smaller fuel injectors.

Re: Increasing efficiency, within reason? (long post)

Reply #11 – September 19, 2005, 10:44:55 AM

Do this?

I believe I said I wanted to try to maintain performance.. not eliminate it. :p

Re: Increasing efficiency, within reason? (long post)

Reply #12 – September 19, 2005, 11:14:18 AM

Quote from: CougarCoupe88

if it;s totally tock the hpipe would hurt him. the offroad anyway. motor has no work to breathe 2.5 inch pipe from the headers back. you could find beter ways to get gas mileage.

The Marks came with 2.5in exhaust from the factory. Remember it has the HO 5.0 no the SO.

You could look into getting a set of equal length shortie headers for the car.

Converting to mass air is also an option.

Re: Increasing efficiency, within reason? (long post)

Reply #13 – September 19, 2005, 11:30:16 AM

The shorty-header thing is doable. Mass air, (I almost typed out "Ass air") I could do that too.. maybe when I attempt that DIY CAI from the article over at LoL:

http://www.lincolnsonline.com/article137.html

OK, so maybe I SHOULD ask about the 351 thing. Do you think that converting one to EFI but leaving it otherwise stock would get the Mark moving from a dead stop a little more efficiently vs. the 5.0 HO in it now? (my 351 is 210 horses as-is, carbed)

I've also considered things like switching to a 4R70W for the wider gear ratios, and then using a numerically-lower rear gear. (not that you can go much lower than 3.27s) Unfortunately, I haven't even run the numbers on that one yet.. and even if I did, it would probably be pretty expensive for a marginal gain on the highway. (and most of my driving right now is city-type driving anyway)

EDIT: Remember, when I contemplate any of these changes, I do so with the intent of trying to hang onto the car for at least 10 years.. so spread the costs vs. benefits out over that time.

Re: Increasing efficiency, within reason? (long post)

Reply #14 – September 19, 2005, 03:25:56 PM

As far as the exhaust goes it depends on where you do most of your driving. A set of Free flowing headers and H-pipe will help you on the highway. Probably won't do much of anything around town.....