Dude...i thought this whole short stroke engine idea was goin into something small...and light! Not a HUGE van!!
I have a 72 econoline supervan, its massive...with a 302 ford. all stock, its a 10.5:1 motor from a stang/torino or something. so, its pretty much the same idea! Guess my mileage at 55...8 mpg...and thats driving CONSERVATIVLY!!
Now, my 78 trans am thats has a pretty good sized 400 poncho in it, with a BIG carb, intake, big cam, headers, 9.5:1 comp, stock sized rod, ported heads that runs in the 12's...gets 16-20 at 70mph, cruising at 2650 rpm.
The problem is that with a big, heavy vehicle, you have to rap the small motor out in EVERY gear, to not lug the ***** out of it! Like a v-6 pickup, it has too LITTLE of an engine to get good milage. The engine has to work harder, has more load on it, and sucks more fuel/air while its struggling to accelerate. The small car that has a big motor, you have to just rest your foot on the gas to get up to speed, pretty quickly too!
If you want to get some good milage from the van....
1. Used overdrive trans, I can get one from a salvage yard for $500.
2. Get those 5.?? gears OUT of that thing! Its not a roundy-round car! try some 3.73's or even 3.42's since it has all that GLORIOUS torque from the 454.
3. Sell the van, get an econo-box, build a MILD 283, and put in said econo-box...GREAT acceleration, and amazing milage (for a v-8) with an OD trans.
Side note! If an OD trans wasnt more efficient due to turning another gear...why does almost EVERY car mad past 1990 have one? hmmmm!!
But, if your dead set on this working...try it...then you will take it back out when your tired of not being able to run on the interstate, accelerate in an orderly fashion from a stop light and losing MORE mpg...
Oh ya...400 block with a 327 crank...its a race engine...dont thing about putting it in a car. NO bottom end torque to move you, yes it will scream, but also burn MASSIVE amounts of fuel!
some say cubic inches are king...torque is king...