How bad is your gas mileage?

[t walgamuth]

As for the original thread question....if you have to ask you can't afford it!

[lnfletcher]

New 427w just broke in and I'm getting 16 best and 11.4 the worst so far. 14.5 overall average after 118 gallons and 1715 miles on it. Somewhat easy for the first 1000, not so much for the last 700!

[cycleguy55]

I'm thinking of going EFI primarily to improve my range. I'd like to be able to enjoy some longer cruising outside of urban areas and improved fuel economy would give me the range to do that. IMO it's certainly a better alternative to filling the entire trunk with a ginormous fuel tank. LOL

Any before and after 'real world' experiences with carb to EFI (both throttle body and multi-port systems)?

[eschaider]

Use the multiport alternative, Brian.

Give a good look at the MS3Pro Plug and Play system that DIY autotune has for the 03/04 Mach 1's. It uses an OEM harness with OEM sensors and is programmable for any engine size you might want to use. Great engine protection, traction control, knock detection and prevention s/w that uses OEM Ford sensors. Get an engine harness out of a salvage yard and you are good to go. Here is a link => MS3Pro PnP and here is an install video, click here => Install Vid. they ship it with a tune ready to go. When you change engine displacement the ECU scales the tune for the change in displacement. DOHC or pushrods make no difference unless you go for a TiVCT deal like a Coyote an then you just disable the variable cam timing with a mouse click.

ECU comes with a tune ready to go, OEM Ford sensor expectations, tuning software and data logging software.


Ed

[eschaider]

Talk about brain fade! I forgot about an intake for your 460 project. Here is an EFI Weber look-alike intake with throttle bodies, fuel rails, throttle linkage etc, that comes in at $2266;

Here os a link to the Speedmaster webpage, click here =>
Polished 460 Weber Style EFI Intake-Manifold System Complete


Ed

[Tom Wells]

Brian,

I've used the Holley MPFI setup for more than 15 years - maybe close to 20? Yeah, I was what amounted to a Beta tester for the things.

They're pretty good now though it would be good to have someone knowledgeable apply the final tweaks.

I use 60lb injectors.

The first setup I put together there was no manifold with bungs, so we had to drill & weld them in. Pain. That was on the 521.

The 557 has the Edelbrock 50665 manifold and was easier, although the manifold I received from Edelbrock was defective - and they refused to repair or replace it... I ended up filling their casting mistake at the front of the block with another piece of aluminum and it has worked fine for about 15K miles so far.

If you go this route, be sure to check the china wall at the front of your block to make sure the manifold extends far enough forward to capture the silicon bead that forms the seal around the distributor area.

The self-tune at first is pretty good.

Advantage was that the car no longer had any problems with underhood heat after a run on the highway. When it had a carb, the fuel in the bowls would boil the alcohol and geyser the fluid out of the bowl vents into the engine, which would promptly flood and quit. I tried for a couple of years with insulators, heat shields float levels - you name it. Never solved it. The EFI solved that.

I did have to use an Aeromotive Stealth (or was it Phantom?) in-tank pump and sump combo on one car and that works fine. On the Cobra I used a sump built into the bottom of the tank for the inlet to the pump to stay submerged while cornering. Think 3 dimensional drag racing fuel pickup tank.

Gas mileage is good, car runs fine on the street and track - for over 35K miles - no complaints.

If you're less concerned about the attendant problems of vacuum storage, air filters, airflow and linkage synchronization etc etc you might consider the 8-stack - it sure is pretty!

Unless you know more than the average Joe, the Holley (or similar) 1000CFM throttle body looks kinda liks a carb. Most folks don't see the fuel rails until I point them out. This throttle body gives an extra ~3/4" (forgot exactly) of reduced height compared with a carb so a taller air filter can be used.

If you are comfortably under (I think) 600 flywheel HP then maybe a throttle body with 4 healthy injectors might be another, possibly simpler, route to consider. You could use your present intake.

Keep us posted as to what you decide,

Tom

EDIT: Whoops! Almost forgot. My mileage seems to correlate quite nicely with the position of my right foot ;-) I'd love to know enough to tune that aspect of the setup; maybe I'll have to take a class from Holley (they do teach them in Bowling Green). As it is, 10 is probably the most frequent number I see if I'm driving gently. As to what's possible, a friend (Herb Smith) once tuned the carb on the 557 to achieve 16MPG at a steady 60MPH!

Tom

[Moto One]

We have the 8 stack injection, on a 363 and average 17mpg. Going on two years, and I still don't feel that we have a good tune on it. Almost ready to go backwards and replace the injection with a carb.

Mark.

[Dwight]

Moto One

what ECU are you using?

[TLHanna]

I'm curious too as my FAST 2.0 EZ works great. I would never scrap all of that in favor of a four barrel.

[Ace23]

427w with a QF 750 carb and a mildy aggressive cam. I would say 8 mpg no matter how you drive it.

[RB60]

Still 10-12mpg. if I'm not into it too much. Same as last year. Same as the year before that...

[Lou1119]

Roush 427 based on a 351W. Between 7 and 8 miles without getting into it.🥺

[bwcobra15]

Craft Performance Engines 427w, AFR205 heads, QF 780 carb, TK0600 close ratio .82 OD = 10mpg. 11mpg if I dont mess around...

[ront49]

Holy crap, you guy's actually figure your gas mileage? Good for you cause I don't have the ba**s to check mine...i guess next fill up I'll check it just for the hell of it. I've got a windsor stroked to 418 dynoed at 525 hp. 3:73 rear. I'm not real sure I want to know ablut this miles per gallon....sometimes ignorance is bliss!

[Luce]

I have a 427W and Megasquirt 2 and get between 19 on the highway putting at 2500 RPM in 6th to 6 or so keeping the R's high and driving full open or hard brakes

I also have MS2 on a 383 in a 71 vette with a cheap chinese 8 stack, and it's surprisingly well mannered. I'm running it in a hybrid alpha N/speed density mode that works very well. Under light loads where there is a vacuum signal it's speed density but when you open it up, it goes to alpha N and pours the fuel.

[Dwight]

When you plan on driving 1100 miles then you need to know what mileage your getting so you can plan your gas stops.

[Moritz55]

My 427SR Roush (351W) with QF 770 Holley & 5sp TKO-600 ... has 22k+ miles on it.... still get ~11.5mpg City... 16mpg Hwy ... Just tuned it 2months ago .. I can get 250-260miles on a tank full if I drive mostly highway with a couple gallons to spare...

[Mr Barnwood]

I have a Unique 427SO, Holley carb, top loader 4 speed and 3.55 gears and have never gotten better then 8 to 10mpg in town and maybe 12 on the highway. I’m sure like the rest of us the mileage would improve if I drove it like a Prius and not a Cobra.

[RB60]

Had a little fun with a few friends ('20 Porsche GT4 and an '07 supercharged and tuned Mustang GT) on the interstate today. Averaged about 7 mpg for the day

[S1965C]

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