Fuel mileage mods.
#21
02-10-2017 | 06:33 PM
Camel Trophy
Joined: Aug 2014
Posts: 4,734
Likes: 971
From: Southwestern Virginia
I've been chasing that MPG dragon forever. Here's what I've found.
Headers followed by a 2.5" dual exhaust or 2.5" into single 3" will gain you about 1 mpg. Better flowing muffler required and to be used in conjunction with CAI (check out my signature).
Switching to an electric radiator fan gains you 1mpg. again, check the signature for the link to the mods.
That's it. Nobody in the US tunes the Rover V8, rare earth magnets on the fuel lines don't do anything at all, these engines don't handle boost, a manual swap is a pain in the rear. Free-er flowing exhaust with factory diameter and factory manifolds doesn't do jack for MPG. If coupled with the CAI you'll get a slight seat of the pants improvement, but no change to MPG. At the end of the day, keep it maintained and run 92/93 octane in it. Traditional mods don't seem to do anything in my not-so-limited experience with the D2.
Headers followed by a 2.5" dual exhaust or 2.5" into single 3" will gain you about 1 mpg. Better flowing muffler required and to be used in conjunction with CAI (check out my signature).
Switching to an electric radiator fan gains you 1mpg. again, check the signature for the link to the mods.
That's it. Nobody in the US tunes the Rover V8, rare earth magnets on the fuel lines don't do anything at all, these engines don't handle boost, a manual swap is a pain in the rear. Free-er flowing exhaust with factory diameter and factory manifolds doesn't do jack for MPG. If coupled with the CAI you'll get a slight seat of the pants improvement, but no change to MPG. At the end of the day, keep it maintained and run 92/93 octane in it. Traditional mods don't seem to do anything in my not-so-limited experience with the D2.
#22
02-10-2017 | 06:50 PM
Pro Wrench
Joined: Dec 2016
Posts: 1,603
Likes: 229
From: Fall City, WA
From my experience on an NA engine, there are (4) factors to see an actual impact to MPG and I will list them in order of significance. Keep in mind I am speaking to a 100% Stock vehicle.
1. Tire Inflation
2. Intake (i.e. filter, MAF)
3. Exhaust (i.e. cats, O2s)
4. Oil
Tire inflation is free and has the largest impact on your MPG.
Intake, high flow filter and clean MAF. Both of these are cheap, however, you can spend $$ on intake manifolds but, the return on savings doesn't justify it.
Exhaust, old cats and old O2's cause breathing problems, the better your truck and breath the better MPG. Again, these are cheap, however, you can spend $$ on exhaust manifolds and/or removal of cats but, the return on savings doesn't justify it.
Oil, clean synthetic oil that is the right weight helps.
Obviously, adding any type of weight or things that will restrict airflow around the truck will reduce MPG.
Larger tires, I shouldn't have to say this but, obviously decrease in MPG.
How you drive. Using the sports mode saves gas over non sports mode if you don't drive like an asshat
Using ECO on your heater saves gas
Using non ethanol gas save gas
Of course all of this is my opinion so don't get butt hurt
1. Tire Inflation
2. Intake (i.e. filter, MAF)
3. Exhaust (i.e. cats, O2s)
4. Oil
Tire inflation is free and has the largest impact on your MPG.
Intake, high flow filter and clean MAF. Both of these are cheap, however, you can spend $$ on intake manifolds but, the return on savings doesn't justify it.
Exhaust, old cats and old O2's cause breathing problems, the better your truck and breath the better MPG. Again, these are cheap, however, you can spend $$ on exhaust manifolds and/or removal of cats but, the return on savings doesn't justify it.
Oil, clean synthetic oil that is the right weight helps.
Obviously, adding any type of weight or things that will restrict airflow around the truck will reduce MPG.
Larger tires, I shouldn't have to say this but, obviously decrease in MPG.
How you drive. Using the sports mode saves gas over non sports mode if you don't drive like an asshat
Using ECO on your heater saves gas
Using non ethanol gas save gas
Of course all of this is my opinion so don't get butt hurt
#23
02-10-2017 | 08:58 PM
Three Wheeling
Joined: Jan 2017
Posts: 73
Likes: 3
From: Chino and Lake Arrowhead CA
RE: Mileage, a few things to keep in mind...
I don't know about your disco but my speedometer was off with stock size tires (255/65R16.) When my speedo said 70 I was actually doing 63.
New bigger tires and i went the other way... when the speedo said 70 I was actually going 73!!!
Consider for a moment that if the speedometer is off, so is the Odometer. Every time you calculate your MPG you are using an incorrect reading of the actual miles driven.
False Data!
This can mean the difference between believing you are getting 14.5 and 16.5 mpg.
The same applies to how many miles you can go on one tank of gas. Of course the miles are the same but your odometer will tell you two different things. Neither one of them may be real.
When doing any mod it is best to get a known baseline of your actual MPG by driving over a known distance using a known amount of fuel.
These days google maps is a more accurate measure of how many miles between two points than the odometer on your vehicle.
Fill up the tank, go for a long drive, google that drive or use a GPS and get a read of exactly how many miles you went. compare it to your odometer. fill up the tank again and divide by actual miles, not the odometer.
You will likely be pleasantly surprised.
I don't know about your disco but my speedometer was off with stock size tires (255/65R16.) When my speedo said 70 I was actually doing 63.
New bigger tires and i went the other way... when the speedo said 70 I was actually going 73!!!
Consider for a moment that if the speedometer is off, so is the Odometer. Every time you calculate your MPG you are using an incorrect reading of the actual miles driven.
False Data!
This can mean the difference between believing you are getting 14.5 and 16.5 mpg.
The same applies to how many miles you can go on one tank of gas. Of course the miles are the same but your odometer will tell you two different things. Neither one of them may be real.
When doing any mod it is best to get a known baseline of your actual MPG by driving over a known distance using a known amount of fuel.
These days google maps is a more accurate measure of how many miles between two points than the odometer on your vehicle.
Fill up the tank, go for a long drive, google that drive or use a GPS and get a read of exactly how many miles you went. compare it to your odometer. fill up the tank again and divide by actual miles, not the odometer.
You will likely be pleasantly surprised.
You are so right with the stock speedo. When I had the factory 255/55/18 tires the speedo read too fast.
Now I have 265/60/18 tires and it reads just right.
Funny thing is my ultra guage reads 4-5 mph slower than my speedo. Guess I need to do the calibration some day.
#24
02-11-2017 | 12:50 AM
TReK
Joined: Nov 2011
Posts: 2,748
Likes: 505
From: Seattle, Wa
"Larger tires, I shouldn't have to say this but, obviously decrease in MPG."
Not necessarily. What larger tires do is change your odometer accuracy. So when you calculate your mileage it appears lower because you are dividing by an inaccurate number of miles, lower in the case of larger tires, which makes your MPG appear lower.
With new larger tires I ran 135 miles, confirmed by google maps and highway mile markers... filled up and found that my MPG did not change with larger tires.
Of course the odometer said i drove like 120 miles and if I had divided by that number my mpg would look worse.
This is the point of my above post... don't trust your odometer when calculating mpg.
As for the math, that trip took 8.2 gallons. at the actual 135 miles that equals 16.5, if i use the Odometer 120 miles= 14.6!
Not necessarily. What larger tires do is change your odometer accuracy. So when you calculate your mileage it appears lower because you are dividing by an inaccurate number of miles, lower in the case of larger tires, which makes your MPG appear lower.
With new larger tires I ran 135 miles, confirmed by google maps and highway mile markers... filled up and found that my MPG did not change with larger tires.
Of course the odometer said i drove like 120 miles and if I had divided by that number my mpg would look worse.
This is the point of my above post... don't trust your odometer when calculating mpg.
As for the math, that trip took 8.2 gallons. at the actual 135 miles that equals 16.5, if i use the Odometer 120 miles= 14.6!
Last edited by Dave03S; 02-11-2017 at 12:54 AM.
#25
02-11-2017 | 09:23 AM
Recovery Vehicle
Joined: Jul 2012
Posts: 796
Likes: 110
From: Mideast US
Changing tires size would have to be re-programmed in the computer for correct readings.
#26
02-11-2017 | 09:48 AM
Mudding
Joined: Nov 2014
Posts: 230
Likes: 53
The best mpg is when you don't use it but if you insist on V8's unfortunately the eco whizz kids have got there first with their dammed emissions junk.
My best recommendation is to fit a TD5 engine, okay, so it won't fly around everywhere but it's far cheaper to run on fuel and insurance.
Believe me, I owned a 4.0 litre D2 V8, never again, it cost a packet in fuel etc.
My best recommendation is to fit a TD5 engine, okay, so it won't fly around everywhere but it's far cheaper to run on fuel and insurance.
Believe me, I owned a 4.0 litre D2 V8, never again, it cost a packet in fuel etc.
Sorry to hijack this thread, but would you be willing to answer some questions I have about Bordeaux? My wife and I are visiting later this year. I tried to PM you, but your profile has that function turned off.
#27
02-11-2017 | 12:18 PM
Camel Trophy
Joined: Aug 2014
Posts: 4,734
Likes: 971
From: Southwestern Virginia
235/85 is a taller tire. Just a hair under 32"
Larger tires decreasing gas mileage is not a myth. Yes, they do change accuracy, but most of the time they also change MPG. Going larger will always give you a higher final gear ratio meaning you lose MPG when accelerating or going up hill. That, combined with the fact that 9 times out of 10 a larger tire is heavier can also decrease your highway mileage. Now, that does depend on the specific tire, but that is typically the case. This may be countered by the fact that he is going with a much skinnier tire which could save him some weight and will definitely save some rolling resistance, but I'm betting that he will still lose about 1mpg.
Keep in mind that using 235-85R16´s will give you more miles per gallon readings. Because those smaller-circumference tires will turn more times in a mile and the computing result is wrong, as traveling 12 actual miles instead of the reported 14 for the gallon consumed.
Changing tires size would have to be re-programmed in the computer for correct readings.
Changing tires size would have to be re-programmed in the computer for correct readings.
"Larger tires, I shouldn't have to say this but, obviously decrease in MPG."
Not necessarily. What larger tires do is change your odometer accuracy. So when you calculate your mileage it appears lower because you are dividing by an inaccurate number of miles, lower in the case of larger tires, which makes your MPG appear lower.
With new larger tires I ran 135 miles, confirmed by google maps and highway mile markers... filled up and found that my MPG did not change with larger tires.
Of course the odometer said i drove like 120 miles and if I had divided by that number my mpg would look worse.
This is the point of my above post... don't trust your odometer when calculating mpg.
As for the math, that trip took 8.2 gallons. at the actual 135 miles that equals 16.5, if i use the Odometer 120 miles= 14.6!
Not necessarily. What larger tires do is change your odometer accuracy. So when you calculate your mileage it appears lower because you are dividing by an inaccurate number of miles, lower in the case of larger tires, which makes your MPG appear lower.
With new larger tires I ran 135 miles, confirmed by google maps and highway mile markers... filled up and found that my MPG did not change with larger tires.
Of course the odometer said i drove like 120 miles and if I had divided by that number my mpg would look worse.
This is the point of my above post... don't trust your odometer when calculating mpg.
As for the math, that trip took 8.2 gallons. at the actual 135 miles that equals 16.5, if i use the Odometer 120 miles= 14.6!
#28
02-11-2017 | 02:04 PM
Baja
Joined: Aug 2013
Posts: 5,845
Likes: 368
From: Near Bordeaux, France
I don't live in Bordeaux but about 45 drive north of Bordeaux but we visit the city from time to time. So fire away with any questions.
#29
02-12-2017 | 05:24 PM
Mudding
Joined: Nov 2014
Posts: 230
Likes: 53
Hi, yep I certainly would help with your questions, sorry the PM function was disabled it was either accidental by me or a system glitch.
I don't live in Bordeaux but about 45 drive north of Bordeaux but we visit the city from time to time. So fire away with any questions.
I don't live in Bordeaux but about 45 drive north of Bordeaux but we visit the city from time to time. So fire away with any questions.
Great thanks!
I'll PM you. We are staying in Mirambeau, and one night in Bordeaux City.
#30
02-13-2017 | 02:01 AM
Rock Crawling
Joined: Dec 2009
Posts: 445
Likes: 31
From: Long Beach, CA
My trick for better mileage was going from a lifted FZJ80 on 33's to a stock D2. But really with my last Disco I did get a little more mileage by sticking with Chevron premium fuel, syn oil in the engine, diffs and t-case, keeping my tire pressure on the higher side around 38, and doing plugs every 20k miles.