Building a highly efficient engine (mpg)

[YY1]

Yep, those non-equal half shaft FWD cars can sure be a hand full, which does NOT qualify as "fun" in my book.

My CS Daytona would literally change lanes on you while holding the wheel dead straight, if you got into the turbo and happened to hit a puddle on one side, or a moist spot.

Just yesterday I invoked the traction control in my FWD '15 Renegade turbo 6 speed merging from a 45 MPH 2 lane on to a 60 MPH 4 lane in a light mist.

It actually worked, and let me stay in the throttle without spinning (except one very small slip) and didn't effect acceleration that much.

 

[Cranky]

I used to have a 95 Intrepid ES with the traction control and yeah, it works. A car dealer buddy of mine used to bring over all the newest stuff and one time he brought over a GLHS cracker box. I had heard of them but never drove one until that day....and man, both hands had better be on the wheel! I power shifted 2nd and that was almost a mistake lol. Dry road and luckily the Camaro I had just ran against from a light didn't have enough to stay up with that little cracker box because it did change lanes!

 

[69 GTX]

Maybe a v8 D50 pickup would be easier. I did backhalf one for a friend in the late 80s as a drag pickup. It's still going strong.

 

[Cranky]

Maybe a v8 D50 pickup would be easier. I did backhalf one for a friend in the late 80s as a drag pickup. It's still going strong.

You know a 1st gen Dakota (up to 96) is fairly light. IIRC, my 92 5.2 SWB reg cab was right around 3300+ and with some work, you can get them on down. Mine had a 3.90 gear and other than that, it was bone stock and ran a traction limited 15.30 which was respectable back then and was right with the Mustang GT.

 

[451Mopar]

Maybe a v8 D50 pickup would be easier. I did backhalf one for a friend in the late 80s as a drag pickup. It's still going strong.

Getting hard to find D50s that are not all rusted. I sort of miss my '84 Ram 50 4x4, but sold it when the floor started getting rust through.
For power and mileage, a Gen III hemi would be cool. The 4-cylinder turbo diesel would be interesting and should get great MPG?

 

[PurpleBeeper]

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.

Well, one way to skin that cat.....using old-school technology.....would be a 318 (or 273) & use an overdrive manual trans from a "Dart Light" or "Feather Duster" with 2.76 (or similar) gear ratio.

I'm not knowledgeable about the magnum motor heads.... there's "something" about what intake fits / doesn't fit. I'd at least "consider" a 340 six pack intake (maybe epoxy the ports smaller to match the 273/318 head intake ports) just for the "cool factor"... but I'm a big fan of multiple carburetors.

 

[Bb70charger500]

I know of a Dodge Rampage two streets over probably could be bought fairly cheap it's been sitting on Jack stands for years I think the motor is out of it and it's already setup as a stick! I bugged him years ago but he said he was going to fix it up it hasn't changed since then

 

[Hemirunner]

Maybe a v8 D50 pickup would be easier. I did backhalf one for a friend in the late 80s as a drag pickup. It's still going strong.

Cummins swap right into the D50 would probably meet your goals if diesel is a consideration. Otherwise a late model hemi with operational vvt makes sense.

 

[wyrmrider]

WOw- great posts
I vote for the late Penstar V6 with the 8 speed or jeep Four wheel drive
Good enough for Maserati and Mercedes good enough for me. find a complete wreck
They should be showing up

Second choice would be a Shelbized GLH- goes like hell would be an easier install and easier to find

The 3.5 was around for years and is light and easy to work on- RWD versions available 4.0 available
does the DOHC fit? Turbo version- which trans fit

http://www.wkjeeps.com/wk_transm.htm

 

[moper]

A bodies can pull down 20mpg with a mild V8. A Rampage could no sweat. Rebuild a 318 with high quality machining with an eye for performance. I wouldn't use the roller but that's me. Heavy roller lifters and crappy pushrod angles aren't my thing. They're also not needed. Get a good convertor, mild gearing the rear, make sure the vacuum advance is functioning, the alignment is on, and the tire pressures are within a couple of the tires' rated max.

 

[wyrmrider]

I did not mention that I own a 93 one owner Chrysler Concord 3.5 SOHC it's FWD but that motor also comes RWD

1. most differences in HP are in the exhaust
   
   4.0 puts out more hp and torque than the hard to find Special 300M 3.5
   

Dodge Nitro 2008 had 4.0 and 5 speed auto 2009 had six speed manual

Jeep Cherokee
get your tape measure and scale out - sounds like a fun build

 

[YY1]

The reason I wasn't interested in a Nitro/Liberty, is that they didn't get 20 MPG.
(My boss' daughter had a Liberty, and averaged about 16-18)

I just kept my 14 MPG 360 Dakota. My Mom's 3.9 Dakota QC gets 18.

IMO the Nitro/Liberty design was a fail. Too bad, as they look good.

IIRC the OP wants a carbureted RWD.

 

[69 GTX]

Yes that was the original goal. I'm thinking a 318/5.2 is the way to go. Light weight wheels & tires and a OD should get me in the ballpark on a 3000 lb vehicle.
The Rampage is 2400lbs
Ranchero 2600lbs

Think I'll go with the Rampage. It'll be more work but it's probably better aero wise and allows me 600 extra pounds for drivetrain/reinforcement.

 

[Ranger16]

So the goal would be 25-30 mpg. Now for the kickers, I'd like to keep it carbureted

I think you'll need to find one of those 50 MPG carburetors that where developed way back in the '60's that "the oil companies bought and buried".

 

[YY1]

Holley economizer is IIRC 390 CFM

 

[wyrmrider]

My 92 Dakota 5.2 with 518 and 3:54 235-70 16 tires gets at most 20 on a road trip
93 Concorde closer to 30
around town there is a big difference
If SBM I'd check Hemi real close
That new V6 would do it
I've never worked on the 4.7 V8
better mileage than the Magnum?
for mileage the Magnum would be better with taller gears even with the OD- and your tires will be shorter
what rear end- IMHO 3.31 even 2.74- 2.91 would work- but you do not need a rear end as heave as a 8 3/4 unless really sticky tires
Ever ridden in a Shelby GLH?
too any choices
go light

 

[69 GTX]

I was thinking 2.91 for rearend, I would use 8 3/4 or 9" ford. I think if the Dakota was 1000 lbs lighter it might get 25 mpg

 

[YY1]

Over the past 2 decades, my family has owned a LOT of Dakotas.
Here's how they've done for average MPG:

CC/QC 3.9 with whatever the factory rear is for those- 18
CC 5.2 with 3.5 rear- 16
CC 5.9 with 3.92 rear- 13.5

I'd bet a short cab would get 1 MPG more.

A 2.2 or 2.5 turbo and a 5 speed (bell housing is available) would be a fun, parts shelf build.

That same 2.2/2.5 turbo is a relatively easy parts shelf build for the Rampage as well.

IIRC, my 86 CS turbo Daytona got about 22 average if I was able to stay out of the boost. It was heavier than I thought it should have been, but don't remember how much.

Two of my friends have owned 5 GLH/GLHS cars between them including #3.
That weight should be comparable to a Rampage, and I'd bet you could get 25-28 MPG and still do a 13 second or better 1/4 mile.

Not sure I see the point in the work to convert a FWD car to RWD, only to put a gas mileage centered V8 in it.

 

[69 GTX]

I want rear wheel drive & something different/cool for a daily driver. My 98 Dakota 5.2 ext cab auto 4x4 would get 18-20 on the highway. remove 1000 lbs a front axle, 100 pounds of rotating mass and better aero I would think it would be capable of 25.

 

[wyrmrider]

just about what my 92 2wd auto (with tow converter) long bed does- I agree
but there are much more modern motors with aluminum parts
I wonder if VVT would work with a carb- don;t see why not- it's hydraulic
what's the projected rear end width
Falcon-Mustang 9" is narrower than A body 8 3/4
but you might not need either one- both are not lightweight
maybe the Penstar v6 with the direct injection, cylinder deactivation all the goodies and replace the throttle body with a gutted 4 bbl for looks