look at the nuts on CleanMPG, An authoritative source on fuel economy and hypermiling it's a method called hypermiling. Not all of it I deem safe. Other than slowing down and enjoying the drive.
Squeezing more k's from every litre...
- Thread starter gbcruiser
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Hypermiling works best on petrol vehicles. Their throttle results in large pumping losses at low load cruising. So accelerating for short times at high throttle openings, then coasting between can reduce the average pumping losses and raise the efficiency quite a lot. But it's a frustrating and intensive way to drive.
On a diesel it still works if you can clutch in or pull the vehicle into neutral (illegal in some states apparently), but the gains aren't anywhere near as dramatic as your only saving is reducing engine rpm when in neutral, the pumping losses from the throttle body aren't significant and in most diesels don't exist.
235/85R16's should be just under 32".
Tire size calculator
Apart from testing our vehicles in a wind tunnel, are there any generic ways to reduce drag at the underside?
I recently read that truckers are now installing air dams at the bottom of their bumpers! What is the physical principle behind it? It seems so unintuitive to bolt on what essentially is a wall in front of the truck! Doesn't that create succion at the underbelly, which should create drag? I just don't get it...
Airdams make less air go through the lumpy underbelly and more over the (hopefully) smoother sides and top. Smoothing the underside will probably get you a better result but aerodynamics has still got a lot of "black art" in it.
If you've got a pyro and boost gauge, you can get a good feel for what makes your vehicle work harder and what makes it easier. It's not linear, but anything you do to reduce EGT and boost readings while in the same gear will reduce fuel.
I love how tire companies BS us. If we were take these numbers properly then those tires would/should be over 34.5 inches.
How do you figure that?
235x0.85 = 199.75mm.
199.75x2 = 399.5 = 15.7 inches of tyre.
15.7 inches of tyre plus 16 inches of rim = 31.7 inches.
yup thats correct for a metric tire calculation.
the manufacutre says 32 on their specs. They always round up. Some tires are bigger even thou they say the same spec as above. I have seen them listed as 32.7 in the charts from the manufacture. But I did not measure.
Here is Toyo's chart for interest. http://www.toyocanada.com/products/sizesLT.asp?Sizes=M55&Data+Request=Get+Data
Several important factors...
...
1) Stop and go driving turns fuel into heat on the brakes. Try to coast as much as possible. Try to accelerate gently and never hit the brakes as traffic ebbs and flows.
2) Alignment, alignment, alignment. Just a mild problem can rob 2 MPG
3) poor tire pressure.
4) Water injection or methanol injection can cool head temps and increase MPG
6) Don't bother with aerodynamics. FJ/BJ's have the aerodynamics of a brick.
7) Use cruise control. If you don't have it, install it.
8) make sure all brakes are fully unsprung and not hanging up.
9) synthetic oils and stuff can help, but maybe 1 mile per 10-20 gallons.
10) Clean injectors.
11) Tires with less aggressive tread. Crawling tires are meant for....crawling.
12) Stay in 2wd as much as possible.
13) Always be early for work. Air is cooler, traffic is lighter, and you are less stressed and aggressive. You use much less fuel.
14) Always relax on the way home. Traffic does not matter as there is no appointment and no client waiting. You will get home for dinner whenever. Just go with the flow.
You are still getting almost twice the mileage of a similar weight vehicle using petrol. That means Diesel fuel would need to be twice the price of gasoline before you would pay what most drivers pay, adjusting for mileage.
Best,
T
...
1) Stop and go driving turns fuel into heat on the brakes. Try to coast as much as possible. Try to accelerate gently and never hit the brakes as traffic ebbs and flows.
2) Alignment, alignment, alignment. Just a mild problem can rob 2 MPG
3) poor tire pressure.
4) Water injection or methanol injection can cool head temps and increase MPG
6) Don't bother with aerodynamics. FJ/BJ's have the aerodynamics of a brick.
7) Use cruise control. If you don't have it, install it.
8) make sure all brakes are fully unsprung and not hanging up.
9) synthetic oils and stuff can help, but maybe 1 mile per 10-20 gallons.
10) Clean injectors.
11) Tires with less aggressive tread. Crawling tires are meant for....crawling.
12) Stay in 2wd as much as possible.
13) Always be early for work. Air is cooler, traffic is lighter, and you are less stressed and aggressive. You use much less fuel.
14) Always relax on the way home. Traffic does not matter as there is no appointment and no client waiting. You will get home for dinner whenever. Just go with the flow.
You are still getting almost twice the mileage of a similar weight vehicle using petrol. That means Diesel fuel would need to be twice the price of gasoline before you would pay what most drivers pay, adjusting for mileage.
Best,
T
Just returned from a 833km road trip (just outside 100 Mile and back). Tootled up there with a highest average speed of 95kmph (2100-2200 rpm or so as it's got the Marks under/unders) and used 87 liters. I figure for a BJ74 that tips the scale over 5000lbs, 35" SSR's on steelies at 40psi, and bars on the outside that is pretty darn good. All GPS corrected.
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Sounds great to me. Lets see a pic of this truck. Not sure I have seen it yet on here.
I see a lot of good ideas but no real modifications. After talking to Mike McT from Coastal Cruisers he came across something that's been used for a while in certain applications and he is doing a home brew of it to test it out. I can't remember the name of the device but it basically makes hydrogen gas and you insert it into the intake. Take a small container, insert stainless steel plates into it (kind of like a battery design) apply voltage, anywhere from 5 - 10amps 12VDC, fill with distilled water and use a (this part I don't recall too much) number of different things, like Baking soda, or I think Lime, or some other stuff. The end result is that you have this fine mist of mostly hydrogen which goes into your air intake (either pre or post turbo) and it improves several things, fuel economy and performance included. I don't know what the long term effects of it are, if there are any side effects, but apparently there are claims about a minimum of 10 - 20% increase of fuel economy and performance. I am not sure how I feel about a Hydrogen plant under my hood but I will do a bit more research on this.
Matt from what I hear of Mike's driving - "like a bat out of hell" I think was the phrase used - his simple solution would be less weight on the skinny pedal. 
I am skeptic about this hydrogen plant for one reason. It takes energy to make energy. If you are running your alternator to make hydrogen, you are causing more drag on the engine and therefore using up energy. I think you would have to make a lot of hydrogen and I think you would likely be better off with the hydrocarbon of propane injection. The Aussies in the Patrol forum seem to be getting keener on this not only for the power increase but because if you set it up right you get better economy (provided your easy on the throttle). I was also reading somewhere a while ago that propane injection was first used a long time ago on naturally aspirated diesels. There was virtually no noticeble power increase but the economy of the engine improved. I will have to look for that aticle again.
I am skeptic about this hydrogen plant for one reason. It takes energy to make energy. If you are running your alternator to make hydrogen, you are causing more drag on the engine and therefore using up energy. I think you would have to make a lot of hydrogen and I think you would likely be better off with the hydrocarbon of propane injection. The Aussies in the Patrol forum seem to be getting keener on this not only for the power increase but because if you set it up right you get better economy (provided your easy on the throttle). I was also reading somewhere a while ago that propane injection was first used a long time ago on naturally aspirated diesels. There was virtually no noticeble power increase but the economy of the engine improved. I will have to look for that aticle again.
Save your time and money. It's a scam.
From a net energy expense versus energy produced (for the hydrogen), it certainly is and I second that.
But what about the claims of improving the diesel combustion process? There hasn't been much science devoted to test this theory but it's intriguing and I would love to see some real test results.
People tend to forget that, with any miracle fuel improver (especially those which present theories as fact and shore them up with human testimony) there is a very strong psychological component: as we expect fuel comsumption to improve, we also become more careful drivers and it's well known that the most important factor in fuel economy is driver behaviour...
But what about the claims of improving the diesel combustion process? There hasn't been much science devoted to test this theory but it's intriguing and I would love to see some real test results.
People tend to forget that, with any miracle fuel improver (especially those which present theories as fact and shore them up with human testimony) there is a very strong psychological component: as we expect fuel comsumption to improve, we also become more careful drivers and it's well known that the most important factor in fuel economy is driver behaviour...
Hydrogen works in exactly the same way that propane works. It preignites and makes the diesel burn faster. Effectively advancing your timing which makes your engine slightly more efficient but massively increases the stress on everything.
You can get exactly the same results by simply advancing your injection timing.
However, hydrogen can't be produced fast enough to make any difference to a running engine, the "browns gas" generators produce mostly water vapour, the amount of electrolysis happening is tiny, especially when you crank up the amps to try and make it happen faster.
In short Brown who named the gas was a fraud, the guy currently pushing these devices is Dennis Lee, go a google search and make up your own mind.
He's big on "free energy devices".
crushers
post ho
what ever...
sometimes you come across like you actually know something ...
then you post s*** like this...
<shaking head in disbeleif>
sometimes you come across like you actually know something ...
then you post s*** like this...
<shaking head in disbeleif>
OK, then, Wayne: what is your take on propane injection?
What I understand from propane injection is that it increases the heat of combustion hence the efficiency of the combustion. Assuming I am correct, when internal heat is increased, it would also increase the speed of the flame front during diesel fuel combustion, which has the effect of making more power available when it can be used but has the corrolary effect of increasing loading on the conecting rod and its bearing druing that concentrated energy output phase. In that case, excess loading is a legitimate concern.
Advancing the timing also increases the speed of combustion (the famous "rattle" Tapage was talking about) by having more of the combustion occur at maximum compression, so it seems reasonable to interpret the result of increased punctual engine loading as being similar to that caused by propane injection. In other words, increased engine efficiency, but alos encreased internal stresses.
To what extent and with what end result, that's another story...
Now, granted, there is a lot of speculation here. We peonies have no means of actually measuring fuel input, loads generated, heat of combustion and engine output. Or do we
What I mean to say is, where's the test data to prove the value of propane and or hydrogen injection as a means to improve engine efficiency (I understand propane injection is a reasonably cheap way to increase engine output)?
What I understand from propane injection is that it increases the heat of combustion hence the efficiency of the combustion. Assuming I am correct, when internal heat is increased, it would also increase the speed of the flame front during diesel fuel combustion, which has the effect of making more power available when it can be used but has the corrolary effect of increasing loading on the conecting rod and its bearing druing that concentrated energy output phase. In that case, excess loading is a legitimate concern.
Advancing the timing also increases the speed of combustion (the famous "rattle" Tapage was talking about) by having more of the combustion occur at maximum compression, so it seems reasonable to interpret the result of increased punctual engine loading as being similar to that caused by propane injection. In other words, increased engine efficiency, but alos encreased internal stresses.
To what extent and with what end result, that's another story...
Now, granted, there is a lot of speculation here. We peonies have no means of actually measuring fuel input, loads generated, heat of combustion and engine output. Or do we
What I mean to say is, where's the test data to prove the value of propane and or hydrogen injection as a means to improve engine efficiency (I understand propane injection is a reasonably cheap way to increase engine output)?
