RE: gas mileage

[FiveORookie]

OK ladies and gents. What mods can I get away with on an 87 5.0 LX M5 and not hurt my gas mileage.. I know a set of MSD wires and coil wouldn't hurt. Niether would underdrive pulley. But what else. Exhaust??? Electric fans???? What headers would be ideal for a mostly stock engine 1 1/2 1 5/8 ???? What mods have you guys done that have hurt your mileage????



FiveORookie

[mustanggt_50]

i'd go with 1 5/8 with a full 2 1/2 exhaust, cold air intake (though from what i have seen it doesnt do a whole lot, not sure myself though) maybe ram air, rear gears also, it might sound off but with my 87 AOD, when i put the 3.73s in, i got better mileage in town, and almost the same highway as long as i wasnt speeding. that just comes down to how you drive the car. thats my thoughts at least

[NotchJohnson]

There are many many things you can do to boost power without losing a considerable about of gas mileage. Ive got all the mods in my sig and havent noticed a difference. Gears dont even kill your gas mileage as much as some might think. I cant wait to get mine. - John

[84LX89GT]

My mustang right now gets 19mpg mixed city/freeway driving, mostly city. This is with 1.7 roller rockers, 73mm Mass air meter, cold air induction, stock heads with ported exhaust, 1 5/8" headers, 2 1/2" off road h-pipe and cat-back exhaust, MSD 6A ignition system, super conductor wires, 3.55 gears, T5 5 speed, 70MM throttle body/spacer and Trick Flow Street intake manifold.

Gas mileage after all these modifications was the same as before the mods.

[FiveORookie]

Thanks guys for the replys. My engine has a lot of miles on it 160,000. But it runs fine. No smoking no nothing. it runs almost like new. I want to freshen it up a bit but didn't want to do anything that would kill my mileage I drive way too much. When I do get a chance to rebuild it I was thinking of this combo.
Explorer intake
gt-40p heads
B cam
mass air conversion
and 1.7

I think it should make for a nice torque street engine that's still good on mileage.. Any comments

[bigred90gt]

I realize that stangs get pretty good mileage, all things considered. But, I've been told, and I definately agree, If you are concerned with gas mileage, you are driving the wrong car as a daily driver. My car actually gets better mileage that my f-150 with a straight 6. Just something to think about.

Caymon

[lx5091]

Certain mods actually increase gas mileage like a good ingition system burning more of the gas utilizing the energy otherwise lost by an insufficient ignition.

[crazypete]

Weight reduction!!! Big difference. Pull off the steel bumpers, the axle damper thing, at 160k I'm sure your a/c doesnt work anymore, so rip that out and get an elimanator kit. Use synthetic oil and get a set of march pulleys (get the most aggressive ones, the 1000 kit, I run a massive stereo and with everything going, the charge and coolant are fine). Pull out some soundproofing.

Maybe I'm crazy, but my car gets better milage with 3.73's as mentioned above. I should have gone 4.11 or 4.30. Use redline in the tranny and the rear axle. Dont listen to people who tell you that redline makes no difference in the tranny, mine could barely shift (synchros all shot)...after a few days of running on redline, It shifts almost perfect with an occasional grind.

Exhaust, as the good people have said. The mac's 1 5/8 works great on stock motors and sounds killer. I run the msd but I doubt it makes any real difference on a relatively mild motor.

Move the battery to the trunk (big difference) and get some good tires.

[FiveORookie]

i never thought about taking off the steel bumpers. I'm not sure if that's too bright down here in florida though where 4 out of 10 drivers don't have insurance. Believe or not my A/c was converted to 134a and works great. I have the spare and the other crap taken out. I'm dying to take off my smog crap will that affect any mileage???? How about having your timing bumped up. I had my timing set at 14 btdc and I kinda noticed that I was wasting more gas.. Might have been because I was accelerating a lot more but I'm not sure so I set it back to 11 degree. I was thinking also changing over to MAF just to pull a little more out of the mileage. Besides the mod factor later. My car is also running a little cool it never really gets past the second mark. between a and m in NORMAL thanks guys

[Hozer 88GTConv]

I understand what you are after but I had to experience this to really grasp it.
If you increase airflow and maintain the optimum constant air/fuel mixture you are going to burn more fuel.
Once you make the leap to heads, you will probably see a noticeable reduction in mileage, depending on how you drive of course. The more time you spend at WOT, the greater the affect on mpg.
I know this is basic, just don't kid yourself. I get on it every time I drive it, and spend my highway time around 90 mph. I also let my car warm up more often than not for around 5 minutes or so in the morning.
I'm lucky if I get 16 mpg...but damn it's fun

[mpj76]

I did it after the bearings went out. It's a 10 minute job to remove the pump and the tubing. I used a bypass cap to cap off the AIR tube coming from the back of the heads. I understand you can take the AIR tube off also and then put bolts into the heads. I don't know what size. I was too lazy to do it. Gas mileage or performance were not affected. Does anyone know a good way to block off the H-pipe end of the tubing? I was thinking about the rubber hose with bolt and clamp method but it gets pretty hot down there.

[Hozer 88GTConv]

That's exactly what I did.
High temp hose, about 6", with a bolt and a clamp.
No probs at all...
good luck...

[crazypete]

I put two large bolts in the back of the heads and shlacked them with rtv silicone gasket maker and it keeps them nice and tight so they dont shoot out. I didnt even know those holes were threaded.

For the air tube, there are plumber's pipe caps that you can get from home depot. There should be a bolt driven clamp on the air tube right now. Cap it and tighten the living hell out of the clamp. You'll like it cause that budda budda sound coming from the airpump will be gone.

[NotchJohnson]

I flattened about 4 inches of the tube that comes out of the h-pipe, bent it over, and put a small weld on the end. I bet it prob would have worked without the weld.

[FiveORookie]

is it really worth the trouble of removing the smog stuff??? What can I hope to gain by except maybe some minor weight reduction and a small parasitic loss of the smog pump?? I bought this car because I wanted a mustang and boy I'm a happy with it, but I'm concerned about mileage because I drive it everyday. For an engine with 160K miles on it, it chirps second rather well with a f**ked up T5 =>... I guess i'm just looking to make this thing as efficient as possible. Question: has anyone every tried the Explorer high torque cam???

[88workcar]

The only thing I disagree with on this entire post is the headers. Go with long tube 1 1/2" headers. More torque, better mileage. I have 4.30s, on a long trip I get right at 20mpg. It is more in how you drive. But doggen the crap out of it I still get 16mpg. Weight makes a big differance also.

[88workcar]

The only thing I disagree with on this entire post is the headers. Go with long tube 1 1/2" headers. More torque, better mileage. I have 4.30s, on a long trip I get right at 20mpg. It is more in how you drive. But doggen the crap out of it I still get 16mpg. Weight makes a big differance also.

[crazypete]

All the other stuff you can disconnect and throw away without noticing any change (except your cats will clog up mighty fast). The pcv and egr dont actually draw any power but the airpump will draw 1/2 a hp at operating speed. The egr, now, and bear with me since I'm one of those carb guys, but when I removed it, I had pure air/fuel billowing into the engine without dilution. I had to jet it up many sizes over the recommended holley specs to get it to run stoiciometric. That means I must be getting more power since I'm burning more fuel. Plus, it's a cinch to start, I ripped off the choke and I can start it right up. No heat problems.

Now with FI, the engine expects sensor inputs and gets all upset if the egr system is missing. Plus, the maps are calibrated expecting egr input, so I dont quite know what will happen.

One thing for sure. Next time your're up front and working near the airpump, unbolt it and lift it. Dude, that thing weighs like 20-25 lbs! March sells a nice alternator bracket with an idler. That bracket weighs a ******* ton too.

[FiveORookie]

Thanks for the advice 88workcar. I know you are on the speed density gurus. Only problem those damn longtubes are expensive.. What about shortie 1 1/2??? X pipes are much cheaper than the longtube x pipes..

[saltzstang]

I highly recomend NOT pulling the bumpers out unless the car will see track duty only.......think about it....if your still not convinced go to your local Highway patrol office and ask to see some pictures of wrecks at 10,20,30,40 mph...that will be probably enough to convince you. If gas miledge is an issue get a custom burned chip or one from Rff Performance.