Testimonial: 12.5 mpg

[brider]

Second time I've checked it, but I'm getting 12.5 mpg 60/40 street/highway (hilly) driving in my '71 Pig. Most of the highway miles I'm using the Fairey OD, but the vacuum gauge using the Fairey is mostly down in the red (bad mileage) area because I have to keep my foot in it on these hills. So yes, the Fairey really just serves to keep the noise down.

But with a heavy Warn 5687 winch and big brush guard, box of heavy tools, and usually other junk in the back, I don't think that's bad for a stock F and 33's.

3 or 4 years ago, before it went down for ANOTHER tranny swap, I recall getting 16 or 17 on the highway with the same drivetrain. I don't think it was my imagination, but I haven't had a chance to check it again on a long road trip this last year. I will report when that happens.

 

[inkpot]

Howdy! You may get better mileage if you get out of OD on the uphills. Running at really low vacuum means low efficiency. I have a Range underdrive, and I use it like an overdrive. Whenever my vacuum is much less than 10, I pop it up a gear. The good news is that the Ranger is fully syncrod, so I shift up and down all the time. Doe s the Fairey have synchros? John

 

[cruiser_guy]

I really can't comment other than to say my turbo-diesel FJ55 is double the mileage of yours!!

 

[Lucy_FJ55]

I really can't comment other than to say my turbo-diesel FJ55 is double the mileage of yours!!

Hah! Diesel snob...

 

[weeboo]

One of these days, when I take a trip of decent length, I'll check my mileage, I have always been curious...

When people talk to me about my FJ55, the second thing they ask is always "What's the gas mileage?" I tell them: "Eleven. It's not about gas mileage."

 

[SuperT]

I'm getting 14mpg highway after I rebuilt and tuned my Holley carb, put in new plugs and wires, adjusted the timing, put in a new exhaust-headers back. That's with 33's and 4.10 gears plus the winch. Before, I was getting 9mpg.
I did the calculations assuming the 55 came stock with 28" tires. If that's wrong, I'm wrong.

 

[brider]

The Fairey is synchro'd, although for some reason, it doesn't like to shift OUT while in 4th gear without grinding. If I slow to 3rd, then I can shift out without grinding. Annoys me, but I live with it.

I know low vac isn't good, but I also know from watching my vac guage without the Fairey that on big hills, my foot was still in the carb, pulling low vac.

But yes, your point is taken, and on long hills I shift out of OD.

I have no idea what the stock tire size was, so I calibrated my odometer by marking it along highway mile markers for 5 or 10 miles, then checking that against what the odometer says. Mine has an 8% error, so my indicated mileage driven is 8% too low.

True, it's not about the mileage, but I feel better getting 12.5 and 16+ than 10.

No more tech here, just wanted to post my findings.

 

[wdFJ40]

What kind of diesel do you have cruiser_guy?

 

[cruiser_guy]

What kind of diesel do you have cruiser_guy?

Every one of my trucks has a 3B with a turbo. The BJ60 has the AXT kit, the FJ55 has a freshly rebuilt 3B with an AXT manifold and Volvo turbo and the FJ45LV has a 3B from a Dyna truck, a 13BT manifold and a Supra turbo.

 

[weeboo]

I did not check my odometer against the mile markers, but I calculated my mileage to be 13mpg over about 60 miles highway.

 

[Deathoncall63]

My MPG

Glad to hear the MPG is in the teens for most of you. Me with my 454 under the hood is getting around...well it's low. Again..It's not about the MPG. I have a honda civic for that.

 

[weeboo]

Glad to hear the MPG is in the teens for most of you. Me with my 454 under the hood is getting around...well it's low. Again..It's not about the MPG. I have a honda civic for that.

Yeah- that's my thought. I don't drive it for mpg, It's a tractor

 

[lc69hunter]

I got 14.5 mpg with my 40, pulling a trailer, on my last hunting trip. It has a 2F and 33's. I haven't had a chance to check the mileage on the new pig as of yet, but being heavier, and with an F vs 2F, it is probably less.

 

[cruiser_guy]

Any idea on speedo correction? My speedo is 16% under what I'm actually doing based on mile markers on the Interstate over 100 miles (speedo showed that I covered nearly 84 miles after driving 100 miles). That's due to 3.7 gearing and 33" tires. I know I can correct for the 3.7 gearing in the transfer case but what about the 33" tires?

 

[FineWynsFJ40]

For every inch larger tire diameter you add on, it is about 3.5% error. If I recall, stock Land Cruiser tires are 29" tall. Therefore, you have approx 4 x 3.5% = approx. 14% error. However, tire inflation, speedo cable and actual speedometer mechanism wear, among other factors, come into play. Plus your gearing. That's what I've found.

 

[PabloCruise]

Any idea on speedo correction? My speedo is 16% under what I'm actually doing based on mile markers on the Interstate over 100 miles (speedo showed that I covered nearly 84 miles after driving 100 miles). That's due to 3.7 gearing and 33" tires. I know I can correct for the 3.7 gearing in the transfer case but what about the 33" tires?

Your best bet is to check speedo vs. GPS.

My 40 on 33x12.5's is ~17% off, so when I want my miles traveld for mileage, oil change, etc, I multiply by 1.17 (117%)