Max MPG recipe for an F150

[MechRick]

I've been brainstorming over the past few weeks about a potential project. Right now I don't have a vehicle that I'm comfortable towing larger loads with, say car on a dual axle trailer or a small travel trailer. The Bronco II I have would probably be ok with 5k behind it (5.0L/M5ODR2), but I have plans to rework the suspension on it and install 35" tires. Another goal I have is to build a vehicle for casual bracket racing and Power Tour type events. For that, I have a 351 Cleveland just waiting for a performance build. So here's my idea:

Build a lowered reg cab short bed 2wd bullnose truck with a bed cover and a 300 six built with towing and MPG in mind.

Set the truck up to be able to drop in the 351c quickly for the fun stuff.

For the transmission, I have a 4R70W that I can control with a Microsquirt and have two different tunes for street/performance. The 351c would be built with quick change mounts/harnesses etc. so dropping it in would only take about an hour. There are 10" and 11" converters available that could be slid in with the V8 install as well. I can run an open 9" in the rear and install a spool in a second center section with gears for drag use.

I know there are hurdles such as the water outlets on the radiator and exhaust, and I want A/C, which will take some thought. Right now I need the recipe for the base truck. So far, I'm thinking stock cam, ported head, stock valve sizes, stock compression, Offy C, EFI exhaust, and probably a Motorcraft 2bbl carb, at least to start. I'll lower the front suspension by raising the pivot points on the twin I beams, install air bags and flip the rear axle over the leaf springs. Probably run 17" wheels with a suitable 55 or 60 series tire.

Ideas?

 

[Bronctopia]

Towing AND mpg are usually inverse correlated.
But you probably already know that.
When trailering, especially long/heavy, I like to have ALL the wheelbase.
When downgrades, a turn, and standard highway manners conspire to cause you to brake in such a situation, a long wheelbase will have more moment of inertia and leverage to resist hitch shove.

 

[pmuller9]

What year 300 six do you have?

 

[aussie7mains]

Diesel for economy and towing, nissan TD42t are is very popular here in Australia. The Cummins b series is a good one, but big and heavy at 6 litres. No old cast iron six running on petrol is going to give economy, they are just to inefficient thermally. Go slower when towing. As to racing, a BBF is the answer, 8 odd litres will shift a truck along, 351 is too small for 2500kg.

 

[pmuller9]

Diesel for economy and towing, nissan TD42t are is very popular here in Australia. The Cummins b series is a good one, but big and heavy at 6 litres. No old cast iron six running on petrol is going to give economy, they are just to inefficient thermally. No slower when towing. As to racing, a BBF is the answer, 8 odd litres will shift a truck along, 351 is too small for 2500kg.

MechRick wants the two engines to have the same bell housing pattern.

 

[MechRick]

When trailering, especially long/heavy, I like to have ALL the wheelbase

Max 6000 pounds. Car on a trailer stuff is fine for the wheelbase with caution, the Lightning pickup guys have been doing it for years.

Diesel for economy and towing

I would love a small diesel, but the US has declared war on them for years. And, whatever engine I choose needs to bolt to a small block Ford pattern.

I'm betting a lowered truck with a bed cover and a six could get low 20's.

I'm betting a nicely-built Cleveland could get a 4000 lb pickup in the 12's.

 

[MechRick]

What year 300 six do you have?

Nothing yet, we are in the very early stages. Assume 82-86' F150 and a rebuild on it's existing six.

 

[pmuller9]

Maxx MPG recipe for an F150 towing application.

You need a little more than a stock cam for towing.
The power band between 2000 and 3000 rpm needs to be boosted.
The custom grind with an .050" duration of 204/204 .050" with 448" valve lift does just that.

https://fordsix.com/threads/engine-out-refresh.84993/post-687813

Disclaimer: Flat tappet cam cores have not been reliable.
You can also wait for the hydraulic roller cam and lifter package including high mileage distributor gear from Straub Technologies

The EFI head has given the best results for power and economy.
Porting around the valve guide bosses with stock valves would work well.

The static compression ratio needs to be around 8.6
You can use the Silvolite hypereutectic 3171 "D" dish metric pistons and leave them .030" in the bore or
use the Silvolite 3158H round dish at zero deck.

Pierce intake manifold with Holley 390 or Quick Fuel 450 vacuum secondary carburetor.

DS2 distributor with MSD 6A.
Have Bill Ambler recurve the distributor timing for the EFI head

 

[63 Sprint]

+1
I would like to add, Take advantage of heating the Pierce intake manifold. It comes with a plate that mounts on the bottom of the manifold so engine coolant flows along the bottom of the manifold. Today’s E10 fuels need more heat to vaporize properly. Increased economy will be seen.

I’ve noticed an increase in economy and drivability by just keeping the engine temperature near 200 degrees. “I’m using a Motorcraft 192 degree thermostat.” I found that when using a cooler thermostat, economy and drivability suffered.

Added:
I would also like to add, my engine suffers no detonation with a 192 degree thermostat. I’m using E10 87 octane fuel.

The information posted in post #8 and here has been proven to work.

 

[PSIG]

Since you are familiar with the MicroSquirt for the trans, why not take advantage of EFI for the dual-table fueling and ignition? As economy is high on your list, a carb can't switch from light to heavy loads (empty and towing) with economy and power transition, but EFI can. It makes a huge difference in drivability to be able to pinpoint exactly where you want to transition from lean cruise to rich power fueling, for both drivability and response. For me that would be dropping-in EFI intake with your EFI exhaust, aftermarket ECM, and some tweaking of the valve timing.

 

[pmuller9]

a carb can't switch from light to heavy loads (empty and towing) with economy and power transition, but EFI can.

We have no problem tuning a properly selected carburetor to run lean mixtures for light loads and fuel mileage and have it also supply a rich enough mixture for heavy loads.
It’s not as easy as changing values in a table but with some effort a carburetor will do the job.

Also consider that this project includes swapping between an inline six and a V8.

 

[PSIG]

We have no problem tuning a properly selected carburetor to run lean mixtures for light loads and fuel mileage and have it also supply a rich enough mixture for heavy loads.

Different point. I tuned carbs for decades, and understand what you're saying - the all-in-one tune. I'm saying I certainly agree for one mode/vehicle, and you can tune a carb to do one mode really well, but not two, when mixing modes and demands. Carbs become a compromise.

Hypothetical example based on real-world experience — light load might cruise at 8"Hg and use a 6.5 PV for smooth rich transition from economy to power for that next hill. Heavy load in towing might cruise at 5"Hg, needing a 3.5 (different appropriate point of rich power transition). With a 3.5 PV tuned for towing, you will see crappy light power response for hills (stays lean too long). With a cruiser 6.5 PV the economy will be horrible when towing (goes rich too early into the throttle at level cruise). To boot, each needs different ignition timing curves to match the fuel curves; a critical element to both power and economy.

This is what I mean by dual-table, which can be two different switchable tunes in ECMs capable of it. We can't switch carbs with a switch, but we can switch tunes with EFI. If you only wanted just power, or just economy, and had the power to get either - then no issue - and although some drivability would be compromised it would get the job done. But you would not tune an economical cruiser for towing, or a power tow vehicle for cruising. Carbs - pick one compromise. EFI - take your specific pick, with a switch or 30 second tune swap. I hope that makes more sense for my perspective.

 

[pmuller9]

I hope that makes more sense for my perspective.

I replied in hopes that you would clarify.

However, with the combination specified above, we are seeing light cruising and moderate grades at 5"Hg and above.
A 4.5 power valve allows a smooth transition from lean to rich with a very good power response.
This is with a truck that is loaded with power lawn care equipment.

The problem here is that we present a well tested combination and then a Hypothetical example gets posted which is not pertinent and misleading.

If need be, there are numerous two stage power valves that can be used if the case is as you described.
Combine that with Quick Fuel's power valve restrictors and a person should be able to get a carb dialed in for just about any situation.

 

[63 Sprint]

I think I’m able to give my 2 cents here.

Had a 1993 Ford F150 with the 4.9 EFI setup. It had exact same drivetrain.
That 93 could only get 15 MPG no matter how easy I drove it. The truck had less power and torque than the 1989 that I have now. The 1989 F150 is better in every way in drivability. With the exception of about 20 seconds of mild stumbling in extreme hot weather when the gas boils in the carb. And that is corrected with 2 or 3 blips with the throttle. The truck is much simpler to work on. And cheap to fix.

Remember the Sniper fiasco? Well I look at All aftermarket EFI’s as a cheap Band-Aid. And no one will be able to change my mind. Over two years of frustration, waisted time and money. Over two thousand dollars invested and I was Barely able to recoup 1/4 of what I invested. Guess some would think that’s a real good investment. The green deal.

Anyone that wants to do aftermarket EFI, you have my blessings. With a Holley 390 carb, most needed parts are at auto parts store or in the warehouse. And I can have it the same day. As far as I’m concerned, the early EFI’s from the late 80’s through mid 90’s, and all aftermarket EFI’s are no good. But, that is what I experienced.

 

[PSIG]

Had a 1993 Ford F150 with the 4.9 EFI setup. It had exact same drivetrain.
That 93 could only get 15 MPG no matter how easy I drove it. The truck had less power and torque than the 1989 that I have now.

We also owned a '93. This describes one of the most common reasons for upgrading to a tunable ECM. The Ford factory tune was specific to their needs, which included horrible era emissions, that had the effect of killing power and economy. I first ventured this path about 20 years ago, converting a stock GM TBI Suburban to aftermarket. The results were noticeable power increase, but the big win was 38% improvement in average economy, with no hardware changes - all in the tune. Yes, I could have used a carb and mech distributor, just not quite as well or as easy. Finally sold it almost 80,000 miles later, running like a top, saving $900/year in fuel at those old gas prices.

The Holly was not originally intended to be user-tunable as other systems are, and was (and still is) partially limited by its internal control. Note I already knew advanced tuning for economy and super-tuning for street and track, which transferred directly to tuning the new ECM. So, to be clear, it is not a drop-in affair. It may not be your thing, and that's fine. Different strokes; it's obviously not for everyone, or even most. But for those it is or could be …

 

[MechRick]

The main reason for starting with a carb setup on both engines is cost. I'll be using a Microsquirt to control the trans, I would need another for the engine. Ideally, four would be the answer, to eliminate reflashing both the engine and transmission controllers when swapping engines.
It's been my experience with all four of the 300 sixes I've owned that mpg is roughly equal between the injected ones and the carbed ones. That hasn't held true for other engines like the Lima four and 5.0 V8. On those, aftermarket injection improved MPG.

 

[Bronctopia]

It's been my experience with all four of the 300 sixes I've owned that mpg is roughly equal between the injected ones and the carbed ones.

Were any of the injected 300/4.9 aftermarket?
I think the stock EFI is incapable of lean cruise, where as you can easily tune a carb to.
With micro squirt in control of injection, you will be able to access lambda greater than 1.0

 

[MechRick]

I've run them both ways, the aftermarket setup used a wideband in full closed loop. MPG was the same between factory/Megasquirt.

Ford was one of the first manufacturers to use lean cruise, EEC-IV would ignore the O2 sensor during periods of steady state throttle when the engine was within certain parameters (warm day, low load, etc.). But I doubt that feature was used on the trucks. Lean cruise. and brick aerodynamics is a good recipe for burnt exhaust valves/pistons.

PSIG, can you run dual table with the transmission firmware on a Microsquirt? I've done it on Megasquirt for E85/gas.

 

[PSIG]

I'd been a long time since I used MS TC (not M-shift) on a 4L80E. I can't say if current trans code does or not, and for which version; though it was on the wish list for years and work done towards it. Last I heard someone was working on a flash-based on-board library to switch trans tunes. Worst-case, it takes a minute or two to switch the entire tune to whatever you need. Other ECMs under 30 seconds, and is what I use for things like dual fuel as too much changes in my tunes to only swap tables, so I switch the whole thing as-needed whenever I have half a minute.

One reason I left MS stuff (not entirely) was cost, as it is not open-source and is a profit-based corporation, using volunteers for their development work and costs. That's fine, and one American way, but not for me. I have done the $500 EFI conversion challenge multiple times, which makes it less expensive than most new carbs. If not swapping tunes on one ECM (free), then a 2nd ECM is $100 to under $500 and again cheaper than a new carb. Cost is no longer a factor for most uses when going EFI.

 

[PSIG]

I also need to address a common fallacy of lean-burn and heat. Lean does not burn valves. In-fact, lean burns cooler than stoich (Lambda 1.0 or 14.7:1 for gasoline). Lean is not hot, but burned valves are late. Late timing. The late timing allows very hot or still burning mixture when the exhaust valve opens. Bingo, burned valves, and secondary effects such as increased coolant temperatures. Ignition timing is not only critical to lean-burn efficiency, but all areas of fueling to achieve maximum conversion of fuel to energy. AERA has some interesting data around this, and FWIW, the second most common reason for burned valves and seats is consistent rich fueling.