ok, first i want to start off saying i KNOW i will never see "good" gas mileage owning a modified v8. i may be optimistic but im not dumb lol

but long story short, i am currently seeing around 12 mpgs combined, with i'd say around a 60/40 mix of city/hwy driving. maybe 70/30 on some days.

granted, the car has full bolt ons minus a tb, and a cam, so i always chalked it up to the mods consuming more fuel than stock and left it at that.

however, the more i think about it im not 100% sure it should be THAT bad. the main reason is say this is two things.

first, on a cold start, i can smell gas in the car pretty bad, some days i even consider hesitating lighting a cigarette cus the fumes are so thick

second, most of my fuel consumption, judging from the gauge at least, seems to come from just STARTING my car. sometimes i seem to lose up to 1/16 of a tank from where it was when i parked it. just by turning it on. im no expert, but that just doesnt seem right in my mind.

couple things for mods that may be relevant, it DOES have cats, they're high-flow replacements, i havent looked inside them lately so cant confirm condition inside, maybe clogged. second it does have a cam, but i dont know the exact specs on it, it was in the car when i purchased it. i dont know if that could be impacting fuel consumption in any way other than the typical more power = more fuel needed. third, i need to get the shift points redone because what they were set at when i had it tuned are probably too high, it rarely shifts into fourth (recently this is where im thinking my mpgs went, but it was bad before this as well). i know cruising at 45-50 at 1800 rpms isnt exactly efficient, lol. other than that, there are no codes or anything, and the only known issue is an exhaust leak i THINK where the drivers side header and y-pipe meet.

any other questions feel free to ask, or give suggestions. any help is appreciated

thanks

 

I get about 12-15 on my H/C/I bolt-on car. Mostly stop and go with my lead foot.

 

yeah, im not 100% sure i'll see any gains, and i know it'll be nothing significant if i do.

like i said for the longest i just chalked it up to being a modified car and left it at that. but there are a few problems that COULD impact the mileage so i figure i'd ask.

which reminds me, i dont typically drive with a lead foot, i know that's one of the biggest contributing factors the mileage on these engines, but i tend to not step on it much. hell, a lot of the time i usually keep it below 2k, even accelerating from a stop to 45+ lol

also, stock heads on my car... for now. not sure if that'll make a difference or not but i'll mention it anyway

 

Ok, so you have full bolt-on car with a cam. (EDIT: Which cam?)

1. Did you get a tune?
2. Are your Oxygen sensors in good working condition (do they cycle properly) and when is the last time you changed them out?


I can tell you that #1 or 2 by themselves could easily cause your issue (much less together).

 

Im getting 16mpg city and about 22-24mpg hwy depending on how my foot feels.And even those numbers seem low to me with my mods.But i know i for sure have clogged cats and a slipping clutch not helping it,but i have 3.23 gear.

 

Yes, it is tuned, and the o2 sensors were replaced within the past year. The rears are tuned out, as I have long tubes.

Unfortunately I don't know the specs on the can, it was in the car when I bought it

 

I see 15-ish in enthusiastic mixed driving, close to
but never exceeding 20MPG on the highway. It was
a lot better before the cam, gears, etc. 13 or so
on a local-only tank.

 

Yeah that sounds fairly normal to me. With mods in my signature I seem to be getting around 12 mpg city and 18-20 mpg highway. Now things like heads, cam, compression, etc...really start to cause a drop

 

I get around 15 all around with a decent size cam, 3600 stall, and a Dana 60 with 3.54 gears. How long has it been since you changed the plugs?

 

Its fair.

 

I get around 17-18 city, rarely do any highway.

When was last time you changed your fuel filter? Spark plugs? Also make sure your air filter is clean.

 

jimmyblue mad props on the post that's crazy lol. dnt hate me but has anyone ever told you you look like Kenny powers in that pic you the man!! I love the all black "el negro" lmao

 

Kenny "******" powers baby lol....

Anyway 15 in the city here and a little over 20 on the highway...I'm sure the move to 3.42 gears will help my cause bc 3.73-4.11 aren't very gas friendly unless you have 6 speed with that stout overdrive

I would be getting that car retuned to at least make sure you aren't going pig rich (which by the smell makes me think you are)