Mods for better MPG's?

[TenGHz]

Like the title says, what are some good mods for increasing MPG's? I recently picked up an Intense FWI, which I read is supposed to add an MPG or 2. I haven't installed it yet, but will shortly!

Does getting a ported intake manifold, or ported exhaust manifolds help? Would changing anything in my exhaust help my SE for MPG's - high flow cat maybe? Dual exhaust? How about an Intense PCM? Anything else?

I'm not too worried about adding HP (which is why I put this in General Chat - if this should be in P&B, sorry mods!), but, if I could increase MPG's and HP I won't complain.

I'm not complaining about the MPG's I'm getting now, but if there are some relatively cheap/easy mods I could do to make it go up, I'm all about it!

[clm2112]

Well, a few random thoughts:

Power output and fuel consumption are directly proportional. Most power adding modifications increase fuel consumption. However, there's a catch: You don't always have to use that extra power. The modifications that increase the vehicles VE can also increase the efficiency provided they work at lower rpm's where the engine cruises.

The exhaust and intake modifications can help since they increase VE across the board. You do have to re-calibrate the motor back down to a leaner cruise mixture to make use of it. For power purposes, we tend to only look at the calibration's WOT power enrichment, for economy you have to look at the light throttle values.

Another gross change that increase mpg is to lower the final drive ratio in the transmission. If you have the torque available, you can run a numerically lower final gear..so the engine is turning slower in top gear while cruising. Knock off a hundred rpm from the cruise, you might pick up an extra mpg in fuel consumption.

[superchargedSSEi]

Cheap(ish) easy mods would be a ported LIM, PEMs, a pcm, maybe a high flow cat. They'll all work for the reasons Curt mentioned above. If you know someone with a tuner, you can use it to really take advantage of any breathing mods since you can recalibrate the VE and maf tables for the new setup, as well as tweak the timing, PE vs. tps, etc. to better suit your driving style.

The question you have to ask is...Is the increase in gas mileage worth the cost of the mods?

[bonnevillain]

CAI or FWI also

[TenGHz]

CAI or FWI also

Read my first post.

What is VE? Excuse my ignorance.

I'd say that 85% of the time, maybe more, I drive my car as intended - a family sedan. Maybe that helps?

[bonnevillain]

-_- sorry
Volumetric Efficiency

[gonzo4191]

he has granny gears

[TenGHz]

he has granny gears

Yep, sure do, and that helps. I'm just looking for some stuff to look into to do to squeeze out a few more MPG's.

Sorry villain, had to!

[superchargedSSEi]

VE = Volumetric efficiency...basically how efficient the engine is.

Now that you've mentioned your driving habits:
Cleaning up the LIM on the L36 will do you good no matter how you drive your car. There's probably still some gains in getting a front PEM/Plog, if nothing else at least both cylinder banks will have similar exhaust flow. IMO a pcm is optional...it'll improve the overall quality of the engine from the mid-range up but if you're feathering the throttle there's no real difference over the stock computer. Keep the OEM cat.

[clm2112]

What is VE? Excuse my ignorance.

I'd say that 85% of the time, maybe more, I drive my car as intended - a family sedan. Maybe that helps?

Volumetric Efficiency is the percentage of the displacement the motor can actually use. You have 3800cc of displacement, but you may at best be able to use 3500cc of it due to airflow restrictions. Normally, we focus on how to increase the top end VE...pack every cubic inch into the motor that is possible. Gas milage is just the reverse. You use the throttle to create the restriction and lower the VE of the motor.

Driving style is a big part of it. If it were a manual transmission, I'd skip gears as quickly as the motor will allow to keep the engine rpms down. 2nd gear starts, skipping 4th and 5th on light throttle. Not trying to accelerate hard, just keeping the motor in the bottom of the power band where fuel consumption is better. If you have enough torque at low rpm, you can shift to higher gears sooner.

[willwren]

Balance the cost of each mod over how long it'll take to 'earn' that money back with a 1mpg improvement over time.

The LIM is essentially FREE because if you have the OEM gaskets under it and the OEM UIM you need to change them anyway before your motor goes BOOM.

#1 on your list should be the LIM.

[rrounds]

I just bought new tires for my truck and to my surprise my gas mileage went up by 15%(20 vs 23 mpg).
I aways check my mpg at every fill up in my truck. The tires I have now have less rolling resistance than the Kumho tires(at the same psi) that came off the truck.

ROD

[00Beast]

I aways check my mpg at every fill up in my truck.
ROD

I try to do that as well, but if i'm really low, then on our truck, suburban, and on my tahoe, it stops on a credit card at $75.00, so that doesn't always work.

[Ol' Timer]

I aways check my mpg at every fill up in my truck. ROD

x3

Sort of like getting on the scale every morning to see if you gained or lost any weight.
WEIGHT! Now that's another free-bee. Lose some weight (get rid of your MIL...mother in-law). Nah! I mean the crap in the trunk and behind your driver's seat. Keep your car shiney clean. Now I'm Cheap (very) so I just replace the OE Air Filter every other year or so (when I replace the OE Plugs, Gas Filter, etc). And I found that a clean MAF sensor improves mileage as well.
IF you can change your driving habit(s).....like driving in the Granny Lane... you will see a big boost in Fuel Economy too. Try leaving 10 or 15 minutes earlier to any appointments that you have.

[b18jason]

i have noticed though, that driving too much like a grannie gave me worse MPG's and started loading the car up and it would start pinging until i stepped on it a few times. That was back when i was driving 100 miles a day and wanted to save every penny, but now i go through a tank in 2 and a half weeks so I'm not so worried how i drive

[SSEi95]

Implied, but not directly stated above, kep your car in good mechanical form. Keep up to date on all the maintence and check tire pressure, fluid levels, and all that as often as you can.

As for cruising speeds, you need to test out to find what works best for your car, and thr route you take. You may find that cruising at 55 nets less MPG than cruising at 60, or vise versa.

You also stated you drive it like a family sedan about 85% of the time. The other 15% (assuming you drive it like you stole it) will eat up most of the MPG gained from the 85% quickly. I have a 6.0L GMC. I've had better gas mileage towing a car for 2 hours (was eeasy on the pedal though), than what I get in daily driving, just because I tend to be pedal heavy.

[bonnevillain]

I aways check my mpg at every fill up in my truck.
ROD

I try to do that as well, but if i'm really low, then on our truck, suburban, and on my tahoe, it stops on a credit card at $75.00, so that doesn't always work.

you can just swipe it again, and get another separate receipt.. then add them together. i do it all the time.

[00Beast]

Yeah, but we don't need to fill it full unless we are going on a trip, then we just pay with check, unless there is no store attached.

[BonneMe]

Best mod is driving style by far. Getting off the gas before lights much sooner, coasting up to them longer, going quicker in corners, being in correct lanes so you're not stopping extra, etc.

[b18jason]

Another tip is to roll down your windows when driving in town versus using the ac, but when you go higher speeds, put your windows up and use the ac. I've noticed a big difference in mileage by doing this.