Great another rabbit hole... 2F and adding EFI... MPG increase (1 Viewer)

[cvan1971man]

What started as a H55F question led to a gearing question, then to an engine swap question and now to an EFI on a 2F question.

What benefits could I see by adding EFI to a 2F. Currently running holley 2bbl, 4 spd, 31" tires, stock gearing and electronic ignition.

What I am reading is the EFI will lead to better cold starts, better MPG (but how much), etc.

Are there any downsides besides the $1500 price tag. if anyone is running it, what company efi do you recommend.

 

[GA Architect]

FWIW: I never did any MPG testing with the original Aisan Carb before my Sniper EFI install, but here is some MPG data post install with the original H42.

5.18.20 - "200 miles (10% highway & 90% back-roads), Fuel consumption was 14.4 gallons, Mileage = 13.89 mpg"
7.10.24 - "I'm getting 12.64 MPG with 100% country driving."

5 years with the Sniper, and I'm very happy with the unit.

 

[Grayscale]

The Aisan carb starts fine in the cold. Every time. It has never stalled on its own. It might be lacking as far as cold-driving-torque, but that goes away as soon as the motor heats up.

About the same as far as summer fuel economy.

I'd like to see Holley make manifolds for F / 2F. The injector rail is where I'd look for a performance gain. There is no point making small fuel droplets if they collect there and have to be scavenged by engine vacuum off the inside of a intake pleneum surface. Throttle body injection was abandoned by the OEMS a long time ago for multiport injection. https://www.holley.com/blog/post/sniper_fabricated_intake_manifolds/ It isn't like the OEM

 

[Skreddy]

My 40 has a sniper on an F engine with 33’s and 4 speed. I see similar results to @GA Architect. I don’t think I really saw much difference in mpg from carb to efi.

 

[SteveH]

My mileage with EFI (AFI) dropped to 10 mpg (from 12-ish with a carb), but it runs well and has seemingly more power. YMMV - literally!

 

[rlong]

Also understand some live at 4-5,000 ft elevation and regularly wheel to 9-10,000+ ft. EFI is much better at that. I’m building with a V8 now, and will go tbi EFI. Looks like your in Texas tho, just good to know another reason why for some.

 

[Grayscale]

I wheel at 10,300-feet with a carburetor, and it is as good as when I wheel it at home 6,800-feet. The only difference is the throttle needs to be opened more at higher alt. That, and internal combustion engines make less power at altitude. I know the factory used a high-altitude carb, but, the standard jetting for a non-USA 2F Aisan seems to be efficient and balanced.

 

[Rochfort]

My 40 has a sniper on an F engine with 33’s and 4 speed. I see similar results to @GA Architect. I don’t think I really saw much difference in mpg from carb to efi.

..was it worth it?

 

[rlong]

I wheel at 10,300-feet with a carburetor, and it is as good as when I wheel it at home 6,800-feet. The only difference is the throttle needs to be opened more at higher alt. That, and internal combustion engines make less power at altitude. I know the factory used a high-altitude carb, but, the standard jetting for a non-USA 2F Aisan seems to be efficient and balanced.

It may work, did for me for years.. but it’s still running rich. Does not adjust for air density. I love carbs, and am good at them (first rebuild was a Qjet at 14 in 1975); buddy’s calling me the professor fixing / tuning their Holley’s (jeep guy) and Edelbrocks (V8 FJ40 we built in HS) at Moab.

Well tuned carbs can work good and well tuned efi can work better! (And upside down if that’s your thing!) I also maintained my big glass window OEM’s on my 62’ FJ40 and 63’ FJ45 pre internet, hoping I still have one in storage! I can sell it to fund EFI!

 

[Grayscale]

I'm pretty sure that Bernoulli's Principle is all about fluid speed, independent of the ambient density of the fluid (air)? It governs how a carburetor works. It isn't like the carb bowl is pressurized. Yes, the carb doesn't adjust for air density, you do with the throttle pedal. Increasing the altitude reduces the amount of vacuum the engine can generate, which affects air speed and carb richness, but, the same is true of engine loads, and the motor is more than capable of working within a range of vacuum signals.

If a carburetor can't work to keep an air/fuel balance for an FJ40 on an alpine trail, imagine when they were commonly used in aircraft... The problem was ice forming in the carb, not fouled spark plugs.

 

[orangeyz]

I'm pretty sure that Bernoulli's Principle is all about fluid speed, independent of the ambient density of the fluid (air)? It governs how a carburetor works. It isn't like the carb bowl is pressurized. Yes, the carb doesn't adjust for air density, you do with the throttle pedal. Increasing the altitude reduces the amount of vacuum the engine can generate, which affects air speed and carb richness, but, the same is true of engine loads, and the motor is more than capable of working within a range of vacuum signals.

If a carburetor can't work to keep an air/fuel balance for an FJ40 on an alpine trail, imagine when they were commonly used in aircraft... The problem was ice forming in the carb, not fouled spark plugs.

They have a knob in the cockpit to adjust the jetting, which is needed constantly.

 

[Rochfort]

It may work, did for me for years.. but it’s still running rich. Does not adjust for air density. I love carbs, and am good at them (first rebuild was a Qjet at 14 in 1975); buddy’s calling me the professor fixing / tuning their Holley’s (jeep guy) and Edelbrocks (V8 FJ40 we built in HS) at Moab.

Well tuned carbs can work good and well tuned efi can work better! (And upside down if that’s your thing!) I also maintained my big glass window OEM’s on my 62’ FJ40 and 63’ FJ45 pre internet, hoping I still have one in storage! I can sell it to fund EFI!

..is it air pressure or oxygen makes the diff. More O\2 at lower elevations.
.

 

[White Stripe]

To see significant mpg increases with efi you will need a kit that has electronic timing control. Then too you will need a professional tuner to tune it that recognizes your desire to get good gas mileage and is capable of tuning it accordingly. Most tuners just care about peak power dyno numbers from what I've experienced rather than overall drivability. You could get good mpg with a vacuum advance distributor I guess but it all has to be dialed in mechanically. If you just slap efi on and go, you will not get the potential out of it. With 31 inch tires and 3.70 gears and a 4 speed, I would say you should be able to get 15mpg or better highway. 17mpg is probably not unrealistic.

 

[Grayscale]

They have a knob in the cockpit to adjust the jetting, which is needed constantly.

The Aisan has a power valve in the bowl that enriches the air fuel ratio when manifold vacuum drops - better for negotiating traffic.

..is it air pressure or oxygen makes the diff. More O\2 at lower elevations.
.

Because our lungs work on surface-area contact with the atmosphere, air that is less dense, like at altitude, will oxygenate us less. At high-altitude, oxygen is still twenty-one percent of the total, with nitrogen making up 78-percent, and CO2 being a measly .04-percent. What does vary considerably is water-vapor, a lethal greenhouse gas, guilty of creating frozen weather, floods and hailstones, it also kills a handful of people out of a million every year due to the heat-index, often when the air conditioning fails during power disruptions. Pardon my ramble, please.

 

[77mustard40]

I'm getting old... and learning to embrace it. My tired old 2F is carbureted and as others have said starts every time and runs fine when its hot as F#$K and cold as well. I'll worry about EFI when (or if) I consider and engine swap.

 

[Its me shaneus]

Installed a fitech 2bbl setup two years ago. Not sure I would do again. Lot to learn to make it compete with the holley 2300 I knew every bit of. No idea on mpg, odometer broken. Cold starts? Not good, needs more tuning, header don’t help.

Also have H55, its a big step up from 3spd. Would do again.

 

[cbmontgo]

Save the money and tune the carb. I get 15.2 MPG with the stock carb setup and am running 33s with a lift.

An Asian is a fantastic carburetor.

Oh, and I live at 9,100 feet elevation. You can still live well up here without EFI.

My two cents.