Im want to know what milage you guys get both city and highway. I want to build up my motor to be into the 12's for a daily driver but want to know what type of milage i would be looking at. Right now i have had guesses that my car is somewhere in the mid 13's but i only get around 13mpg city if i keep my foot out of the throttle. I think there is something internally wrong with the engine but it runs and performs great. So what type of milage do you higher HP guys/gals get?

 

340 HP 305ci got like 19-20 highway with the 700r4. (75 mph at 3400rpm with 3.73's) With the 5 spd I have in it now with the same gear ratio, I havent tried to calculate yet. Bit better highway I imagine. Runs about 1000 rpm lower than the automatic did. If I get on it with my Holley and start opening up those secondaries a bunch, I can burn the whole tank in a little over half an hour. hehe

 

what kind of city milage do u get?

 

I don't do much freeway driving, but I get about 10-12 in the city. 350 TPI, probably needs a new ignition and a good tune up

 

This post AGAIN???



I get roughly 15/20



edit: I just read the "higher horsepower" part ....but I think, on average, most people get better than me, and people with the times you're talking about probably get close to what I get

 

I don;t know my city exactly. Not bad though unless i get on it.

 

A solid 13mpg city and an amazing 22 on the interstate at 2900-3000rpm. One day I gotta change these factory 14's.

 

i get about 6 period city and maybe 10 highway..........but you see i have this problem it's right footitus. cause i only take it out on the weekends and i drive it like i stole it

 

yeah i never would be able to calculate my gas mileage because for the most part i drive with a really heavy foot. Lets just say its a good thing i dont wear heavy boots otherwise id be getting 2 mpg

 

My Stock L98 with 146k miles gets ~13mpg city and 23mpg highway with 3:23 gears and a 700r-4

 

13 mpg driving around & 22/24 highways mpg. If you have a performance engine get used to the mileage and gas costs.

 

If you are going for performance, this is the mindset you need to have to not go crazy...

Joe Blow:How many MPG do you get with that??

You: I just fill it whenever it gets empty!!

 

Does anybody think it is possible to have an engine built that can do 12's all motor and still get atleast 13-15MPG city? Im thinking about having a performance shop build me a new eingine (350 or 355) with TPI but as much work done to it as needed. This probably wont be for at least another year or so though.

 

Off topic: I was just reading your banner. You could shorten it a bit by putting 285 FWHP instead of 285 hp (at the crank)

If you dont care neither do I, just an FYI you probably already know. I just want to feel helpfull!! lol

 

Thanks for lettin me know! lol

 

id say the majority of the fuel related issues would come from your cam selection? Or am i way off base. That being the case just be careful what you go with and dont use too much overlap or youll be spewing out tons o fuel

 

I would probably just use the same cam i have already. Its a 268* comp cam. It doesn't have a verry loopy idle at all, its pretty smooth but there is a slight detection.

 

The ZZ4 gets around 20 mpg with 2:73s and a 700R4. on the freeway.

 

My fathers carbed 355, 12.5:1, 264/272 dur @ .050 with .624/.667 lift got 21mpg with 2.73 gears and a 700R-4

Impressed me. Didnt think it could do it, hes since swaped to 4.56..

 

it is entirely possible to run 12s on motor and get the mileage you are looking for...take ls1s for example, my buddies 98ta runs 12.6@110 on motor and 11.7 on spray and get 26mpg...granted it has 2 overdrives but impressive nonetheless.

 

The only thing is, i have a new set of 3.73's in the back. so that isn't helping. Although i did have 2.77's before and with the switch i haven't noticed any difference in milage.

 

i love these posts.

heres the latest information on fuel economy. for you who doesnt know, my biggest concern with anything i drive is fuel economy. i spend days on tuning that alone. car is in sig.

24# injectors @ 43.5PSI, 52PSI fuel pressure = 26#/hr (52 = (26 / 24)2 * 43.5)

Duty cycle during cruise highway is 7.5%-8%. 26#/hr @ 8% = 2.08 Lb/Hr fuel per injector... *8 injectors = 16.64 Lb/Hr
fuel weighs approx 6.3 Lb/Gal... (16.64 / 6.3) = 2.6Gal/Hour..

This is at 70~ MPH... @ 2.6 Gal/Hour

Or 27 Miles per gallon

generally i get 220 Miles per 10 gallons of gas.. which puts my average @ 22 Mi/Gal... so my city is somwhere around 18 MPG...

I am improving it everyday however... Somthing stupid like a tire low on air lowers my fuel economy by almost 2MPG hwy. my suspension is shot, the car shakes like no ones buisiness on the highway. when i get the suspension straightened out, it should improve my fuel economy a lot. the A/C takes my fuel economy from 27 to about 22 on the highway... YEAH 5MPG!!!! its got a bad bearing though so i dont use it anymore.

my drivetrain is stock converter, stock 2.73s, and a lockup switch. since i use the commander i have to manually lock up it, but im programing a piggyback for the commander to lock it up.

Oh yeah, going from 43.5 PSI (stock) to 52 PSI helped my fuel economy a LOT. my theory is it lowered my BSFC because the fuel is better atomized.

 

If you want fuel economy, Buy a geo metro...

If you want some power and still fairly cheap, Buy a 3rd gen

If you wnant power and economy, Buy a 4th gen LS1 w/ 6 speed, or swap a 6 speed into your third gen...

what the last guy said was WAY to involved for me, I saw all the math stuff made me think back to Pre-Calc, not a happy memory...Im a simple guy

 

Don't know why but about 10 city and 16 hiway

 

90mpgs city. 11 on the highway.

Why the F doesn't anyone search anymore?

Did they ever search?

Do they know there's a search button?

Are all cars going to get the exact same milage?

Sorry for the mini-rant, but this Q pop's up at least once a week...you'd think after nearly 500 posts, the original poster would know how the hell to use the search function

 

Yes because I have one. Apperently the anceint fuel mixer still goes above and beyond most factory FI systems.

 

I get 19.5 mpg around town. My 300 hp engine is in my sig.

And it is just an ancient old QJet--pre-smog even

So let's see, fuel injection costs $1000s and doesn't get 19.5 mpg around town but ancient old QJet and Edelbrock Performer intake cost $250 Canadian and DOES get 19.5 mpg in town.

Which one should I use? Duh!

 

31 mpg highway and 17-20 mpg city

Thats with a 5-speed manual tranny and a 305 V8. I don't know any tranny info or gear ratios :S

 

i used to get 10 mpg in the city when i had 3.23 gears , i alsways kept the car in third, and now i have 4.10s and i get 8 or less on a 305tpi, i guess i floor it too much and i also maunally shift the car and keep it revving pretty high, but i dont have the car for gas mileage so who really cares. get another car if ya want mileage.

 

<b>Does anybody think it is possible to have an engine built that can do 12's all motor and still get atleast 13-15MPG city? Im thinking about having a performance shop build me a new eingine (350 or 355) with TPI but as much work done to it as needed. This probably wont be for at least another year or so though.</b>

just to add some insight, if you want to keep at least 20 MPG city and run 12's or better on motor your best bet is actually Somthing along the lines of a stealthram. since you have a cam thats perfect for fuel economy, and close enough to the 6,--- rpm cutoff point for power, you can spin it and make decent torque and rpm with that cam, produce most likelly about 330~RWHP, run your 12's... and have the fuel infection to keep the timing and A/F where you need it for great fuel economy.

My tpi with a HUGE cam (234/244 @ .050) was netting me about 15 MPG city, and not doing diddly in the way of power ( out of TPIS powerband...) but with a carbeurator on top of it.. the motor spit out about 380~RWHP... and after a week of tuning gave me a mid 12... but i was still only getting 10-12 MPG city... and only about 15 highway on a good day. the fuel injection goes a long way towards taking a wild motor and taming it for fuel economy. however with a mostly stock motor.. and proper gearing either carb or EFI is going to give you good fuel economy in my experience.

 

Stock 305tbi 19mpg driving like I want my rear tires to die.

 

If you want good freeway gas milage, a T-56 would be the eaisest way to go.

 

actually ive done a little research on the whole higher gearing = better fuel economy thing, and while it does make a little difference in duty cycle on the highway there are other factors that can negate your lower rpm fuel saving tactics.

for instance my car with 2.73's is out of its powerband below 65~MPH in overdrive. I HAVE to run it in 3rd gear or i actually use MORE fuel simply because the cam just sort of wastes it and the motor is under more load. I see less duty cylce NOT using overdrive, which is less fuel.

on the other hand when i switch the 3.73 i will be able to use overdrive... so it DOES HELP there is no doubt, but too much overdrive with too much cam is a bad thing. hell with 3.73s and a T-56 i would have to be doing over 90 MPH to use 6th... its a waste of a gear for my application.

 

Well I get 24highway and about 14 around town. I have 350 with TOI, XR276HR cam, 1.6 roller rockers, 10:1CR. I also have couple bad rings and really needs chip tuning. I never ran it in quarter mile but i ran 8.76 with tire spin in the eigth. I think with the proper chip burning I can get 30mpg. Oh i have a 700R4 and 3.42 gears. I don't remember where I think it was on here but I read a guy had a supercharged 427 vette and was pushing 700HP and was getting 27mpg. But did alot of chip tuning. So I think good mileage is all possible.

 

Holy mother of old posts, batman!

 

Well I get abuot 10 in the city and about 18 highway (2700 rpms at 70)