Building a highly efficient engine (mpg)

[69 GTX]

So I'm thinking about my next build. I'm thinking either a early Ford Ranchero or a Dodge Rampage. It'll be a small block v8 auto/OD. So the goal would be 25-30 mpg. I chose these two bodies for being smaller and lighter. I can make either one work. So the meat of the question is how to build a highly efficient engine. So I'm wondering if anyone has any ideas or experience on this type of a build. I was thinking higher compression would be a benifit. Roller cam to reduce friction. I would like the peak efficiency to be in the 1750-2250 rpm range. I'd likely be using a newer OD trans with a lockup convertor. Now for the kickers, I'd like to keep it carbureted and keep it as simple (as few electronics as possible). Let the discussion begin.

 

[wyrmrider]

let's see going from 4 cyl FWD to V8 rwd
measure twice- cut once
I'd think about the 3.5 V6 either FWD or RWD
the v8 weight will kill you- were you thinking late Hemi?

 

[69 GTX]

Probably whatever is lightest or more efficient. I would think the late small Hemi would be a good canidate. I have good fab skills so the chassis isn't a problem. Just trying to come up with the best combo to start with.

 

[DeltaV]

Mount a Porsche Boxster flat 6 engine and transaxle behind the cab of the Rampage or Ranchero. Porsche Boxsters are plentiful.

 

[69 GTX]

Sorry it will be all ford, or mopar. I hate multi brand vehicles.

 

[1967coronet440]

Late model hemi seems to be the easy choice for your goal of 25/30 mpg

 

[67belvedere/225]

1750-2250 rpm
you need to take in account the stall speed of the torque your using, your cruising speed rpm need to be higher than the stallspeed

 

[69 GTX]

Lockup convertor

 

[not so famous bob]

Lockup convertor

If , I were doing something like this, I`d take a good hard look at a new mopar V 6, 300 h.p. and darn small, and lite.

 

[Mike67]

I would find a 4-6 cly diesel, no electronics needed....

 

[burntorng70]

I would think a 289 in the Ranchero would almost be there already. A mildly built engine with overdrive and good gears would definitely get you to 25 highway mpg or better. Our old 318 in a 1973 satellite sebring plus got 20 highway with no overdrive and 323 gears.

 

[69 GTX]

I agree, my dad had a 70 satellite 4 dr with 318 and I thought I remembered him getting 20 mpg on the hwy. The Ranchero would be easier with a 289/302, but I think the Rampage 318/5.2 would be cooler and have better aero. Maybe lighter too.

 

[1967coronet440]

I know you mentioned up want to keep a carb, but I would consider looking into a TBI system like fitech of Holley sniper.

 

[Don Frelier]

My 84 gran fury 318 la motor could do 25 mpg with a carb and lock up converter. I think a 5.2 magnum fuel injected could do better for sure.

 

[YY1]

If ford, I'd do a 2.3 turbo and a 5 speed.
Those 2300's have fairly long legs as built.
Off the shelf parts.

Making the rampage RWD will be a cost add that will eat up any efficiency gains.

For a RWD small Mopar, I'd use an early A body wagon, and use a roller LA 318 and an A500 (or 833OD). I'd build a tighter quench setup if possible on the already 9:1 LA roller with those 302 heads and maybe use a roller cam equivalent of a comp 256 cam with a 500 AFB or a Holley economizer on a high velocity dual plane.

 

[YY1]

...or maybe a 2.2 turbo in the early A (like a 65 Val), with a Dakota bell housing and NP435.

 

[Cranky]

I've pulled down 25 mpg with my Cummins powered (6BT) 2500 extended cab long box and that pig weighs right at 6000 lbs. Cummins also made a 4BT which are used in all kinds of stuff from boats to floor sweepers to bread trucks. Main problem is they are the same size as the 6BT height wise. It's more or less the same engine with 2 less cylinders and have the same bell housing bolt pattern. I've heard of people getting an easy 35 mpg when 'tuned up' and in light vehicles.

 

[YY1]

...of course a 2.2 turbo rampage would be a no-brainer, and meet all the goals almost out of the box.

...or a turbo pinto wagon...

 

[Cranky]

...of course a 2.2 turbo rampage would be a no-brainer, and meet all the goals almost out of the box.

...or a turbo pinto wagon...

Yup that would meet the goals but FWD just ain't much fun in my book. Stab and steer one handed with RWD is much easier than trying to do the same with FWD

 

[Derwud]

Rampage with Late model Dakota/Durango running gear, sounds like fun!