Some deep thinking on getting Best MPG in a VAN

[Shawn D.]

Originally Posted by racprops

Two “out there” ideas were Rhoads Lifters, and Power Valves, a special pressure control add on to the intake valves that closes very early, building higher pressure for real low rpm power.

Rhoads Lifters are not "out there" at all. I've used them on two different cams in the 350 that's in my '57 Chevy and they work great. Right now, the cam is a Comp 268H with Rhoads and it made 400 ft-lb of torque at 2,500 RPM on an eddy-current dyno. The version I have is the "original" and will bleed down overnight and cause rough starts, but they now have anti-bleed-down versions. I've found the owner of Rhoads to be very responsive, so I'd contact him to see if the cam you're considering is already too small to use with the lifters (you don't want to create excessive dynamic compression).

The specs of the engine that made 400 ft-lb are:

-Built in late 1993
- 355 (350 w/ 0.030" overbore)
- Melling high-volume oil pump
- ARP rod bolts
- Keith Black hypereutectic 17cc dish pistons
- Childs & Albert "Zero Gap Second" rings
- Ed Hamburger roller timing chain with needle thrust bearing
- Comp Cams 268H cam (218° @ 0.050" lift, 0.454" lift at valve)
- Rhoads lifters
- "882" iron heads, 76cc, 1.94"/1.5" Manley Pro-Flow undercut valves, DIY porting
- Edelbrock Performer 2101 intake
- Edelbrock (Carter) 600 cfm 4-bbl
- Mallory Unilite distributor
- Edelbrock Victor aluminum water pump
- Doug Thorley tri-y headers
- 2.25" dual exhaust w/ h-pipe and Borla mufflers

If they had been available back then, I would have used iron Vortec heads, which are widely regarded to be the best (best ports, best chamber) OE iron heads ever made for the SBC. They make more power and torque than the vaunted "Double Hump" heads, even though they have smaller valves.

FWIW, I just got 17.8 MPG on a 400-mile trip in the '57, and I was not trying for max mileage. All windows were down and I was doing 60-75 MPH most of the time. This is with a close-ratio 5-speed with a 0.82 5th and a 3.55 diff ratio (so a 2.91 final ratio).

The Power Valves concept is iffy, at best. Implementing them will not be inexpensive, and I bet they will not be reliable. This falls into the "hairbrained idea" category, IMO.

I might have missed it if you mentioned them earlier, but if you don't already have headers, they are a must for this, IMO. NOT large-tube headers, but Tri-Y or small-diameter long-tube headers. I know there are 1-1/2" primary long-tube headers available for your application, which are a great match for the RPM range you are trying to optimize.

[Varn]

Hi MPG van.
We are on our second full sized ford van. A 2005 E150. It is powered by the 5.4 Sohc 2 valve motor and 4 speed automatic. It weighs about 5700 pounds with all the rear seats removed.

At one point we were driving it 300 miles a week and wanted better economy. The best that we could average was about 20 mpg. It required driving 62mph on 4 lane interstate type of roads. Lower speed and higher speed delivered less mpg. We have a ultragauge instantaneous mpg meter in it. Air conditioning is normally off. Our Gen3 E150 had the 5 liter motor and never got to 20mpg. In the early 80's a friend had a Ford cargo van with the 300 ci 6 cyl and 5 speed manual and on road trips that we were on It always got 22 mpg driving 75 mph.

I have not had a chance to test it but we are now running light truck tires instead of car tires. They can be run up to 90 psi I suspect that running 60+ PSI should help. We have 3 metal window screens stuffed between the grill and radiators. The idea was to reduce the airflow through the motor. At one point we installed a black sheet of coroplast covering the grill opening.

The problem that I see with getting really great mileage is the frontal area. Getting real good mileage no matter what the CD is going to have to deal with a lot of drag and weight.

[Galane]

Since you do mostly highway driving with the van, I'm thinking about that grille full of all kinds of air catching nooks and crannies. Makes me wonder how much of an effect putting the turn signals back in their original locations then applying flat pieces of lexan over them and the headlights would have.

I wonder how difficult it would be to fit the newer Express Van grille to the G20 van? On the outside there wasn't a lot of change from 1971 to 1994. 1995 got a longer nose, which is an odd thing because the new Express Van was introduced that year.

If the G20 front corners are removable, fiberglass versions could be made and modded to fit the Express grille, then make new molds to make new Express to G20 conversion parts.

[Frank Lee]

My deep thinking says forget V8s; they are simply thirstier. Yes a Vette can do well but that is because it is relatively light and aero.

Sixes and even fours are powerful enough for this job which I understand does not involve towing.

[Phileaux4]

I used Rhoads lifters in my stock '66 Merc Monterey w/410cid V8 4bbl. Mpg went from 19hwy to 27hwy. Vacuume from 16in to 22in. Very happy with results.
Have you considered decreasing rotational mass? Lighter pully system, rims, driveshaft, etc. also brake springs to keep pad pressure off disk.
Belly pan: Online pic of underside of car spray foamed then fiberglass covered. You would have to be REAL confident on rust proofing. Driver did say the lack of air turbulence and foam made for a remarkably quiet ride.

Last word of advice: These projects can cause a lot of opportunity to overthink. Their will always be a "maybe this is better".

[racprops]

Thanks, now I have two questions to ask Rhoads Lifters, A) about the cam and B) do they make roller lifters.

Now about those Brake Springs, pad drag could be a problem, tell me more about these brake springs please.

Also at this time my van is drum disk.

A belly pan is out of the question as is reworking my roof. And adding a big duck tail also.

And I am aware of your warning: "Last word of advice: These projects can cause a lot of opportunity to overthink. Their will always be a "maybe this is better".

[racprops]

Originally Posted by Frank Lee

My deep thinking says forget V8s; they are simply thirstier. Yes a Vette can do well but that is because it is relatively light and aero.

Sixes and even fours are powerful enough for this job which I understand does not involve towing.

Again a 300 CI straight six as they used to be torque monsters but I tried a OLDs 307 and LOST big time power and MPG. And I do not remember Chevy making a 6 that big only Ford.

That is why I am going for a 383, and if I had not already done all that work on my 350 I think at this point IF I was starting over I would do a pure 400.

Rich

[Galane]

Originally Posted by racprops

Now about those Brake Springs, pad drag could be a problem, tell me more about these brake springs please.

Also at this time my van is drum disk.

They are springs that keep the pads moved *just* away from the disc so they're not causing any drag, like how properly adjusted brake shoes sit inside their drums.

You don't want the pads too far away from the discs because that can increase stopping distance and make the brake pedal go down farther.

Such springs likely work better with dual piston calipers than they do with any sort of single piston sliding calipers.

On a heavy, high drag vehicle like your van I wouldn't bother. The effect of eliminating the small drag from brake pads would be minimal, if it would even be measurable. Fresh pads on new rotors, or rotors turned smooth, will have the least drag before doing a spring mod.

Make sure the rear brakes are correctly adjusted, and if you install new ones see if there's a shop in your area that can arc them. That's grinding down the curve of the lining to precisely fit the curve of the drum. You get the performance of fully broken in shoes right away and they should last longer. A video on DIY shoe arcing.

https://www.youtube.com/watch?v=0n02-GU_VYs

[racprops]

Thanks, I used to do brake jobs and both had arc them and know how to adjust drum brakes.

And was aware of pad drag and how they are suppose to retract a little so there's no drag, but I also know they don't always, I put a front disk brake system on my wife's 69 VW Bug back in the 80s in LA and we had one fail to retract and coming down into the valley one had a red hot disk....

I was not aware of any retracting springs..and I do know of the problems with our one piston system and always make sure the calibers rubbing points are clean and add a touch of wheel bearing grease to those points and make sure the guild pins are clean and smooth.

Rich

[freebeard]

A belly pan is out of the question as is reworking my roof. And adding a big duck tail also.

Because you want to make your expensive engine-work less effective?

Concentrate on the front wheelwells and Moon disks.