[racprops]

I have two projects going currently one is a 03 Crown Vic P71 that is an Ex-Cop car.

It is a replacement for a 2000 Mercury Grand Marques that did 30MPG pure highway at 65MPG stock and I was able after trying a number of things got up to 35MPG at 65MPH by running lean at 16.4.

I plan on trying a few ideas on it and may even put a second overdrive behind the stock transmission.

The second is a major rebuilding of the complete drive line of a 1993 Custom Chevy Van. My target is 25MPG at 75MPH.

Here is my plan, part one the custom 383 I have begun building.

OK Here is what I am trying to build for my 93 G20 Van:

A Chevy 350, bored .030 My pistons are KB Piston Style with a D-shaped cup: Piston Material: Hypereutectic aluminum: Block had been prepped for them. Keith Black hypereutectic pistons are made from 390 aluminum alloy and heat-treated to T6 standards, which makes them 30 percent stronger than ordinary untreated hypereutectics. Their 100 percent CNC-machined crowns, high upper compression-ring location, gas-accumulator groove, drilled oil returns, and spiral-lock retainer grooves make these pistons outstanding for performance applications. They have a lightweight, rigid-rib skirt design that stabilizes the piston in the bore. All of this adds up to pistons that fit tighter than forged types, provide improved oil control, reduce blowby, increase ring life, eliminate cold start-up knocking, and won't cost you an arm and a leg!

I got an original 400 crank and connecting rods to make a 383 type of engine. And yes I know this can cause more side loads on the pistons etc.( by Hot Rodding standards) This engine should spend 85% of its life running below 2500 RPMs. Sadly this is a project started back in 2001 for a Chevy van that I ended up replacing. At the time I spent a lot of money building a 350 and to build a 383 was beyond my reach at that time. The 93 engine was still going strong up until last spring when an oil cooler line let go throwing all the oil out and before I could shut her down froze the motor.

I cannot used an aftermarket crank because the newer cranks have larger counter weights and will not clear a piston with the short 400 rods.

So now I can build the MPG Motor I have been planning on for the past 26 years.

My heads are cleaned up #14102193...Swirl port 64CC 87-up...305/350......1.94"/1.5" valves with fitted perfect circle oiling valve seals as up until the 93 ever blasted Chevy motor I have owned has had leaking valve seals that would fowl the plugs. I plan only doing some gasket matching and light cleanup of the exhaust ports as again I have read for what I am doing a stock intake port is the best for my plans. Any sharp points will be removed.

I plan on running an 86 up TPI with MAF. I am counting on the claimed improvements of 30% more Torque, HP, and MPG with this set up. I have three complete set ups with spare MAFs.

I plan on running the PCM from a 85/90 TPI Camaro or Corvette (I have copies of both) AND I will be running an aftermarket controller board to replaces the EPROM with a flushable chip(s), this board allow me to super tune ever thing including highway mold which is a super lean cruse setting/highway mode to best match to my set up.

Cam will be the stock #193, 350 roller cam I want the engine to peek torque at as close to 2000 RPMs as possible. I found this in a write up on the engine: Torque net: 295 ft-lb @ apox 1800/1900 holds until 2300..WOW that is great…

My plan is to gear the van for fewer than 2000 RPMs at cruse speed of 75MPH. I plan on doing that by adding a second Over Drive. Current transmission is a 4L60E and the stock 343 rear end. A second over drive will give me the equal to a final drive ratio of 2:35. Cursing at 75 MPH at about 1700 RPMs, and with my low RPM motor it will not be lugging. This will be a removed old Borg Warner .70 OD unit.

OR I will swap in a 6L90 transmission, and then find a special old rear end:
“The 8.75" rear is known for being considerably stronger than the 8.5" 10-bolt in your van. That's one of the reasons I suggested it. What's more, it came from the factory with some pretty high gear sets in it already--2.28, 2.41, and 2.56, depending on the application.


There's some one of these rear ends in late 70's/early 80's B-body wagons, these rear ends should be about the same width as the one in your van, with the equivalent axle shafts and bearings, and equivalent brakes. In theory, all you would need to do if you bought one is cut off the wagon brackets, weld on spring mounts, and bolt it in your van. As you can see, there are several available with 2.56 gears, and at least one with 2.41 gears. Some also state that they have a posi. Some others don't specify either way, and for them you would need to call the yard to confirm.”



The great thing is an 8.75 is said to be a stronger better rear end and often can be found with 2.41 gears and even possi, and as these are not wanted by hot rodders prices should be fair.


I am very well aware of the pinion and “U” angles so know how to remount a replacement rear end such as this.


So, you could run a B-body wagon rear end, but if you wanted to keep the same track width you'd need to use 1.5" spacers.

OR I will have a local rear end shop swap the axles and tubes from my Van’s original rear-end, and at the same time rebuild the 8.75 rear end.

This is all about running very tall rear end gears...like a 2.41s. I am replacing the complete drive line with a custom low RPM high torques 383 with an 85/90 TPI system, a custom PCM, a 6L80E transmission and a stronger rear end with a 2.41 tall gears.

The great thing is an 8.75 is said to be a stronger better rear end and often can be found with 2.41 gears and even possi, and as these are not wanted by hot rodders prices are fair.


I am aware of the things needed to do such a swap including the angle needed for the pinion and "U" Joint for correct operation and possible mods to the drive haft and "U" Joint mounting. Cutting off old speing perches and welding on new ones.

WHY do I think this will work??

Here is the thing, the 1985/ 1990 Camaros with their TPI injection system which is much like Ford Panthers (All Mercury, Crown Vics, and Towncars) run, from 1998 to 2011 and I had a 2000 Mercury that was getting 30MPG highway with its stock setup and 327 gears.

In the USA these Camaro’s got 20/25 MPG, BUT the same cars in Australia got 30 to 35 MPG highway.

The cars down under did it with a special factory setting called then a Lean Burn Cruse, now called highway mode.

The PCM would shift into that mode under light throttle and load and then lean out, and would just as smoothly switch back to normal 14.7 when more throttle or load happened.

My testing on my 2000 Mercury show an improvement of about 5/6 MPG more during highway driving by leaning her to 16.4. So I seem to need a low RPM motor running a TPI intake and run the engine under 2000 and have enough torque to run light throttle at a lean burn setting.

My goal is to get a Van that gets 14MPG improved to 20 plus MPG, and I am hoping it will do 25MPG.