Fuel Mileage on your Hemi swap?

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Furious65

Furious65

C-body Guy
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With the cost of gas nowadays, I was curious what kind of fuel mileage people are getting out of their hemi swapped A body cars? If you have any mpg data on your setup please share! (vehicle, 5.7, 6.1, 6.4, stock/modified, transmission, rear gear, etc)

See, I would like to have my Barracuda be my daily driver since I can literally drive year round here in AZ. I'm thinking a stock '09+ 5.7 with an OD trans should get me much better mileage than my current daily Dakota (16city/20hwy) and yet still be a blast to drive.
 
just googled 5.7 charger fuel mileage and weight 69 barracuda (you neglected to state the bear or body)

for every 1000 pound decrease you gain 0.5% mileage


16 x 0.005 = .008
25 x .005 = .125

so the manufacturers numbers would be 16.008mpg city / 25.125mpg highway

the manufacturers numbers are inflated because they are not real world numbers they are on a test track / machine with a trained driver / operator or even a computer there days

an example of dollars saved for a 2mpg increase
10000 miles / year @ 16 mpg @ $5.00 / gallon = $3125 per year
10000 miles / year @ 18 mpg @ $5.00 / gallon = $2778 per year
a savings of $347 per year

about 5000 to have someone do it for you
about 3000 to do it yourself (I'm assuming you will be buying a kit to run the electronics sub $1000 BUT it will not be tuned for max economy with 1000s of hours of testing by Dodge)

14 year payback if some one does it for you
8 year if you do it your self


still wnat to do it just for the price of gas


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V8 Hardtop (Fast back 2990)
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Never said anything about doing it strictly for the mpg. I just said I would think it would have to be at least as good mpg wise as my Dakota, and I like performance, and I prefer to drive an old classic body style over anything made after 1974. I was curious what people were getting. Thanks for... trying to talk me out of it, I guess? smh
 
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Im curious as well. I have a buddy who has 2 hemi engines. Hes a chevy guy. He said whenever i want i can have either engine for free. I want to swap it into my 71 duster. But im not sure how much work its going to be lol
 
Furious65 said:
With the cost of gas nowadays, I was curious what kind of fuel mileage people are getting out of their hemi swapped A body cars? If you have any mpg data on your setup please share! (vehicle, 5.7, 6.1, 6.4, stock/modified, transmission, rear gear, etc)

See, I would like to have my Barracuda be my daily driver since I can literally drive year round here in AZ. I'm thinking a stock '09+ 5.7 with an OD trans should get me much better mileage than my current daily Dakota (16city/20hwy) and yet still be a blast to drive.
Click to expand...
I can only speak of my ‘18-1500 Ram’s mileage which will get 20 @ 70 mph Hwy. Not to darn shabby for a heavy aero brick. However, if I travel at a much slower speed and consistently, I have gotten 28 mpg. 55 mph is a bit slow from what I’m used to & not really OK on the interstate. While it maybe legal, I think it dangerous. No one is excepting to come up on you doing 55.
 
One swap I did was an 6.4 cammed/5.7 Eagle in a 74 Challenger. Aluminum case O.D. 833 with 3.23 gears. Owner reported back with aprox. 22 mpg. That one ran really well, but, could benefit from a tune for the cam. Another swap I did for a guy was an Eagle 5.7 with 545RFE in a 62 D-100 shorty. That one also has the 6.4 cam with the 6.4 truck intake/injectors, 3.55 gear, and headers. this one was fully tuned by a pro. Owner has reported aprox. 25 mpg.
 
I have a stock 2005 5.7 in my Duster. 833od, 2.76 gears. I consistently get 22-23 mpg in town and 27-28 on the highway. That’s with mashing the accelerator occasionally.
 
I have stock 2004 5.7 w/545rfe trans. 373 gears and get 18 in town and 24 highway(average speed 75mph). When I had 2.76 I also got 27 on the highway.
 
I have a 2014 5.7 for my 68 cuda.
Staying with VVT, using TTI headers and Tremec TKX. I have 3.23, 3.55 and 3.91 center sections for the 8-3/4.

Before I really get serious, I've been wondering what a 6.4 cam swap would do to mileage. Hate to leave 40HP or so on the table but 400 true HP is probably enough for me.

Any actual results from someone with real experience?

I drive my cars out of state and can coax every last MPG out of them. Last year I co-drove my buddy's Nissan Rogue to his daughter's house in NC. He drove the first tankful and I drove the second. He couldn't believe I got 37 MPG indicated which was 5 better than him.

I'm thinking I can coax 30 mpg in my cuda but a cam swap throws a curve ball.
 
KosmicKuda said:
I have a 2014 5.7 for my 68 cuda.
Staying with VVT, using TTI headers and Tremec TKX. I have 3.23, 3.55 and 3.91 center sections for the 8-3/4.

Before I really get serious, I've been wondering what a 6.4 cam swap would do to mileage. Hate to leave 40HP or so on the table but 400 true HP is probably enough for me.

Any actual results from someone with real experience?

I drive my cars out of state and can coax every last MPG out of them. Last year I co-drove my buddy's Nissan Rogue to his daughter's house in NC. He drove the first tankful and I drove the second. He couldn't believe I got 37 MPG indicated which was 5 better than him.

I'm thinking I can coax 30 mpg in my cuda but a cam swap throws a curve ball.
Click to expand...
See post seven.
 
408 swinger said:
See post seven.
Click to expand...

Yeah I saw that previously.

What I'd like to see is someone with a running driving 5.7 then later going to a 6.4 cam. A direct comparison between a stockish 5.7 then the same car with a 6.4 cam.

Your builds had a 6.4 cam from the get go, so no A to B..
 
I am running a 6.1 in my Demon and with the Tremec T60 if I am cruising on highway I am just north of 25mpg, blasting around town driving stupid I can still get 22! Basically stock engine with headers, CAI and Holley for fuel mgmt. making well over 400hp at tire, I would have to look at my dyno sheets but I think I was at 450 at tire?
 
I don't know in a A-body, but my son's Scat Pak 6.4/ZF 8 speed got 30 mpg on the road, averaged 27.5 mpg in the local area. I imagine if that drive train was in a A-body it would do even better.
 
KosmicKuda said:
Yeah I saw that previously.

What I'd like to see is someone with a running driving 5.7 then later going to a 6.4 cam. A direct comparison between a stockish 5.7 then the same car with a 6.4 cam.

Your builds had a 6.4 cam from the get go, so no A to B..
Click to expand...
Ahh, gotcha. :thumbsup:
 
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