who's runin A BB 6-71 and whats ur highway MPG

Do you drive it?
Whats Your Criusing MPG?
Whats your Combination?

This should be fun!!
I know a guy that gets 5 gallons to the mile?
He doesn't get out on the highway much-only good for short bursts!1

 

Get hold of Squirrel. He's been driving his BBC huffed for ages.

A blown motor doesn't have to get crappy mileage. It depends on a whole lot of variables, but set up right it sould get as good a mileage as any other engine. A well tuned engine is an efficient engine.

 

There is hope!

 

Depending on gears and how I drive, I get anywhere from 6 to 12. I have a relatively mild 454, th400, 9" rear. Engine has a hydraulic roller cam with about 235 degrees duration at .050, two 650 double pumpers, 7.5 compression. mostly stock iron rect port heads. Converter is switch pitch, so it will get either 1500 stall "off" or 3000 stall "on". I ran 3.25 gears the past few years, just changed back to 2.75. With the 3.25 gears I ran a low 11 at the strip in Phoenix, driving the car up there and back on drag radials. I run 87 octane almost all the time, I spend a few extra bucks and buy 91 when I go racing. The engine has about 90k miles on it total over 20+ years. I did take it apart and freshen it (rings, bearings, valve job) at 50k miles.

Mileage is not really the goal here...but it can get expensive to drive if you only get a few miles per gallon, especially if you have to run race gas.

 

Its not what you asked for, and it's mainly for just putt'n around.
2300 lbs, 327, th350, 6psi, 471, 1 700 holley, 16mpg freeway

 

Thanks guys,
you helped my quite a bit Sqiurrel with blower education in the past-Thank you.
I finally saved enough to purchase the unit
10% under
112 lobe sep on cam
248 dur @50 557 lift
single key crank?(i know) RP Crank end is stout-plus take it easy
3.23 gear
8-1 CR w iron heads
Dont have carbs yet -I will run what Squirel is running-Saved info from past

Thanks for helping!

 

ill chime in when i have more time, but a single key way crank on a bbc is more than enough for a 6-71 or 8-71 on the street. Your not turning that blower upwards of 30 or more pounds of boost.

 

i want to run 6psi to 8psi to get familiar with it...Tune ect... Dyno shop close to house to help eliminate a lean condition at initial start up
i should have gone Procharger but I LOVE THE OLD SCHOOL LOOK-NOTHING COOLER !!! Dont see a roots criusing around everyday either?
I have pulled my balls out of my wifes purse and i am getting ready to do the change over--exciting!!

 

How do you keep from having a lean condition if you run out of gas???/

 

Make sure you don't run out of gas....the fuel system needs to be up to the task. Although I've only run out of gas (like empty gas tank) when putting around town, good thing we have cell phones now.

 

if your running a BB and a 671 do you really care what the MPG is?

 

Depends on how much you drive. I've run about 8,000 gallons thru my blower motor over the years....the fuel bill adds up over time.

 

I like to get in my car and drive out in the country. not really an around town kind of guy so yes it does make a difference. Want to get as much MPG as i can. anything less than 4 will be a problem
If you run out of gas or your fuel pump quites won,t this ceate a lean condition and ruin your rings or pistons?

 

6-71 on a 392 Hemi
8-1 cr
225 duration @ .050
114 lobe separation
2 holley 600 vac referenced blower carbs
3.89 rear gears
33 1/2 height rear tires
700 r4 trans
91 octane
If I stay at 65 mph at 1900 rpm I get 10-11 mpg, around town driving the speed limit, normal acceleration 9-10 mpg, if I play all mpg stats are gone.

 

Who would even bother to try to calculate such a thing ??
Tom S.

 

If you're making a lot of power (like a full throttle run) and you have a fuel starvation issue to where it's running lean for a while, it might burn a piston. But in normal driving, running out of gas is not a problem as far as the engine is concerned

 

I have never ran out of gas, imo an occasional and I mean like once a year, would do no harm. If I ever was to run out, first sign of any sputtering, coughing, misfires I would shut down immediately no matter where I was at and check problems.

In my first post I failed to mention that I am 20% underdriven and running just under 5lbs of boost

 

I'm with the "if you can afford this kind of an engine, why would you give two hoots about mileage" posts. I have cars I can't keep my foot out of...I know the mileage sucks...I don't care....I'm a car person...not a friggin' accountant/bean counter.

dj

 

I know but i am going to the Mopar Nats and look forward to driving the 320 miles each way!! If i get much less than 6 Mpg criusing i will have to trailer it .
If its riding on a tailer and i am not going to the drags its NO FUN for me.

(im excited-sounds like at the performance level I will be running the blower at, motor melt down wont be as big an issue! COOL I have been lookin at it and setting it on my hood but now i am getting the confidence to start wrenching!!!

After i get it started i will take it to the dyno place and have them help me adjust my carbs so I am not running lean) i am going to be alright with this

 

I am cruising at 3100RPM now and 6mpg. Going to drop my gear to 2.94 for the trip (easy on a mopar)which should drop RPM to 2500. Plus running lower CR heads and I will try gas with less octane than 94. Should be OK?

 

There are lots of variables as far as boost, compression, fuel, chamber configuration, timing, etc.

 

Jumpin in!!!

 

I don't worry about the cost more as effects of running out because not enough fuel capacity to get me from one gas station to the other ( some stretches in Nevada,Mojave etc). So I did the calcs for that purpose

 

Must be geat to drive it out west?? Can you really open it up in certain area's?
I am a top end Ben!

 

Legally no. I live out in the country and know what country roads to use and it takes awhile to find a good one, the quality of our county roads are getting worse everyday. I run a built 700 r4 gives me that overdrive for the highway, but at the same time I can flip a switch at 65 mph and lock out the overdrive, chirp the tires and rpm goes to 2600, instant speed rush, flip the switch and bring it back down. Might want to look into an overdrive either manual or auto your choice

 

Thats Cool and oh yes i have been eyeing overdrive units!! $3000 seems to be the magic number fo everything these days?

 

this is in my 57 wagon...468 BBC 6-71 on 9 lbs boost and pump gas .850 solid roller and twin 1050 dominators makes over 750 h.p. @ 6300 rpm 4.11 gear 31" tall slick & 4 speed. I drive it around town/expressway dont know the exact mpg but the H.P./grins ratio makes it well worth it!!!!!!!
guessing if i had to make a 55-60 minute trip which is approx 55 mile round trip it would drink about 8 gallons but thats also mostly all expressway and a little side road drivin and floggin on it frequently and really runnin through the gears when ever I can! I've seen a lot of stock BB's in tow rigs and trucks that dont get that type of mileage! this combo has been dyno'd and tuned my A/F's are spot on through out the entire power band for 93 pump gas!

I am wanting my next hot rod to be blown as well!

 

Beins you bumped this old thread, I'll toss in my 2 cents...

On the highway, the 389 Pontiac in my 3200# Model A (10#s of boost, 2 750s) gets 15 mpg or so on long trips with 2.89 gears in the quickchange. In town with 3.89s she gets about 8. On the flip side, she does run 10s on street tires..

I spent 600 a month on fuel in the last year. But, I drive her every single place I go. Back and forth to work every day, going to the grocery store, pick up the kid from school, yada yada...

-Your mileage may vary.

-Abone.

 

A 6-71 @ 6% underdrive on a .030 over 454 (461). 400 turbo, Crane solid roller, 8-1/4:1 2 holley 850's, 9" Ford w/3.89:1 gears, 31-1/2" tires and I get about 8 mph if I don't beat it up too much. Car weighs about 3200 lbs.

 

Old thread I know but anyone else want to talk about it?