gas mileage expectations

[414banger]

The truck is a 65 c10 with a new 60 over 350 doublehump heads with 2.05 valves its got a 292 .488 lift cam has a weiand 844 intake with a holley 600 carb tranny is a turbo 400 with2700 to 3000 stall antd a 3:73 rearend i filled it up yesterday and put about 100 miles on it and ran out of gas does this sound about right to anyone else
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[Rich 5150 69]

Ya thats about right, loose converter, no bottom end cam, short gears...!

[61_FL_Apache]

That sounds like 6.25mpg.. My RV with a 454 gets that. Ouch!!

[414banger]

Ok i was expecting low numbers but darnit thats terrible looks like im putting a 32 gallon cell in the bed soon lol
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[jocko]

sounds about right to me. I had a T5 and a 283, and when I hit 100 miles, I was sucking up my seat cushion looking for a station...

[joedoh]

I had a mild 350 (cam, headwork) in an 82 blazer 2wd and it got 11 mpg half highway. I went to the shop who did the motor and he jokingly asked for my man card. I sold it two weeks later, I am not that much of a badass.

[414banger]

i didnt build it to be conservitive but i guess i was just expecting atleast 10 miles per gallon but ohwell it sure is a pretty bad ass ride also i plan to do fuel injection in the near future so i fiqure that will help alittle

[joedoh]

remember that power in = power out * efficiency loss

efficiency loss is not mpg, its how efficiently the system uses the power input, in this case gasoline. since gasoline engines are roughly 70% efficient, the loss would be .30 or 30%.

what I am saying is, if you have 500 hp, you have to put that equivalent hp + the expected loss INTO the system (as gasoline) so its never going to be a fuel sipper. If you add up what the fuel injection system might cost you may find it cheaper just to deal with poor mileage otherwise it may take a long time to break even for the small mpg increase savings. maybe not, but maybe.

this is the same reason I dont advocate diesel swaps, people spend 3-4k on a swap and higher fuel costs to go from 15 to 21 mpg. 4k in swap costs and figuring yearly miles driven works out to sometimes 3-4 years before break even

[LT1 Burb]

Holy crap, my 6 litre 3/4 ton gets 11 and it gets up and goes with a 410 rear, my suburban can get an honest 19 mpg if I stay out of it.

[pestwagon]

my 1964 C10 shortbed fleetside gets 9 mpg . TH350 Chevy 350 motor 3.73 posi rear.

[1963c-10]

Interested to see what my cam will do in the BB, comp extreme energy... its 268/280 with .515/.520 lift. Has more bottom end on the cam than the one here though.

[Crabshack]

I can squeeze 12-14mpg out of my 62 if I'm easy on her. EFI LT1/350 out of a 94 Impala SS, TH350, 3.90 rear end

[awbrown]

I cant tell what mine gets , the odometer doesnt work and I only drive it on weekends , but if it had more creature comforts it would see more use ....

['63GENIII]

Love the pic Joe! Puts it all in perspective.
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[fatgump]

I have a 350, 0.030 over with Dart heads 200 cc, 10:1, Cam 292 480 lift, Airgap intake, Edelbrock AVS 650cfm and 4:10s. I get about 6 MPG.

[Clyde65]

my old 350/400 got 8mpg, no matter where I drove it. With my 4.8/4l60e/3.73, I average 17 mixed, I have gotten 20.6 on the highway cruising at 65mph.

[414banger]

if i was to do a fast efi setup on this motor what do you think my gain would be as far as mpg not cost to gain comparison

[Rufton]

I installed a wideband air/fuel O2 gauge.
My analog AEM UEGO cost about $200 and allows me to monitor the carb tune all the time. This is important to control mpg and to verify sufficient fuel to prevent engine damage during those WOT splurges.

I swapped an aggressive cam (similar to comp extreme energy ) for a lower rpm torque monster cam (lower lift/dur) and the hwy mileage remained the same. Can't judge city mpg because function of foot weight

I would verify your intake is efficient at the rpms you cruise if $ a concern. A tall intake may be power efficient at 6500rpm but gas inefficient at hwy cruise rpm. A shorter intake can improve low rpm power and mpg at expense of high rpm power.

Rear gears can make significant mpg improvement if you keep rpms in the efficient range. Some have installed overdrive and lost mpg because engine not tuned for low rpm operation.

[joedoh]

Originally Posted by 414banger

if i was to do a fast efi setup on this motor what do you think my gain would be as far as mpg not cost to gain comparison

you might double it if you could keep your foot out of it, cant really compare it to a modern 4.8 but 12s shouldnt be unobtanium.

[pmkrew]

I would put a 750 cfm carb on it...

[MARTYZ]

If you enjoy it , it will cost you, So how much FUN do want to have, wifes mini van will get 25/30 mpg but not much fun to drive!

[Rufton]

Originally Posted by pmkrew

I would put a 750 cfm carb on it...

You could be right considering cam but probably won't easy gas pains, lol.

I think 414banger's advertised duration is 292; not sure of 0.05" duration. I don't know if 414banger's ride is set up for high rpm.

I tried 600 cfm w/ 0.05" duration of 224/234, 0.496"/0.52" lift in the interest of mpg. Idle sounded great. Not awesome below 2000 rpm or above 4500 rpm. Felt the kick from about 2500 to 4500 rpm. Kinda hard to judge high rpm power by seat of the pants. That cam shines w/ 750 cfm on tall intake up to about 6500 RPM.

[donthekawguy]

I have close to the same set up and get around 7 or 8 Im guessing. My rear end is around 4;72 I think. I'm taking it out next week I hope and will find out then.

[tincan1966]

Maybe I am missing something, but why 2700-3000 stall with only 3.73 gears? Depending on tire diameter, you could have a higher gear ratio. Seems like alot of stall to me, BUT I do not build much all out performance combos anymore, either. I'd think a 2200 stall would be plenty.

[414banger]

the stall matches my cam i had a 2400 in it before and it wasnt loose enough it wanted to push thru the brakes when i was stopped