Where is my fuel mileage??? HELP!!!
01-23-2009, 01:41 PM
#46
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01-23-2009, 02:22 PM
#47
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I have had as high as a consistent 23mpg... hand calc.
Enafzige: twins will not help your mileage either. I have had 3 different twin sets now and none of them had any effect on fuel mileage one way or the other.
Enafzige: twins will not help your mileage either. I have had 3 different twin sets now and none of them had any effect on fuel mileage one way or the other.
Did you ever have a big single on before you went the twins route? Reason I ask, is someone on TDR did a pretty extensive comparison of turbos over thousands of miles. He found that on his truck, the laggy 66 single charger cost him 2 mpg versus the stocker. When he went to a small/med set of twins, his mileage came back up...
Geez, why all the hate and disbelief? I can get right around 24MPG in my 2004.5 almost every tankful. Yes, hand calculated.
It seems like we all go over this on a monthly basis. Lifted trucks push more air, especially with leveling kits. Big tires use more energy to turn at any given speed, and use far more energy to get to that speed.
Throw in some towing mirrors, mudflaps and a lead foot, and mileage is crappo.
It seems like we all go over this on a monthly basis. Lifted trucks push more air, especially with leveling kits. Big tires use more energy to turn at any given speed, and use far more energy to get to that speed.
Throw in some towing mirrors, mudflaps and a lead foot, and mileage is crappo.
One of the prime examples is Justin Allen's post. I fully believe his numbers, and yours as well. Sure, lifted trucks and big course-treaded tires have an effect on economy. Thus, people with 2wd trucks (and 4wds with stock tires) are reporting mileage as good as 21 - 24 mpg routinely. Therefore, it seems consistant when Justin reports mileage of 18 - 19 with a lift and big tires...a 3 - 5 mpg hit is probably reasonable for the way his truck is setup.
What does NOT seem reasonable to me, is how Justin's truck that is lifted 4.5" (versus my 3" leveling kit) gets 6 mpg better than mine...and that's when I'm babying mine on low power levels, shifting at 1800 rpm, etc. His fueling, turbo, lift, tires, etc is very comparable to mine.
Again, I'm not whining here, just looking for answers and willing to pursue something different to get to where some of you guys are at.
--Eric
01-23-2009, 02:44 PM
#48
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Terry,
Did you ever have a big single on before you went the twins route? Reason I ask, is someone on TDR did a pretty extensive comparison of turbos over thousands of miles. He found that on his truck, the laggy 66 single charger cost him 2 mpg versus the stocker. When he went to a small/med set of twins, his mileage came back up...
--Eric
Did you ever have a big single on before you went the twins route? Reason I ask, is someone on TDR did a pretty extensive comparison of turbos over thousands of miles. He found that on his truck, the laggy 66 single charger cost him 2 mpg versus the stocker. When he went to a small/med set of twins, his mileage came back up...
--Eric
But what you posted has a lot of merit. Consider that going from the tiny 9cm EH that captures most of the exhaust energy to convert to boost to a say 16cm EH that bypasses a lot of that energy and it would be easy to understand the difference, and yes, this is what makes twins more attractive. When I made that statement I was thinking of stock perameters. I suppose when I put on my Captain Insano twins, I'll be in the same boat as you.
01-23-2009, 03:13 PM
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I don't care who doesn't believe that an 04.5 and up can get 20 plus mpg. I have done it numerous times, and if somebody doesn't believe me feel free to come spend a day with me driving and I will prove it.
01-23-2009, 03:44 PM
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I don't care who doesn't believe that an 04.5 and up can get 20 plus mpg. I have done it numerous times, and if somebody doesn't believe me feel free to come spend a day with me driving and I will prove it.
--Eric
01-23-2009, 03:52 PM
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That is a good point, and to that extent, it is true. No, I have not run the big single. I went from the stock turbo to tow twins, to bigger twins to even bigger twins.
But what you posted has a lot of merit. Consider that going from the tiny 9cm EH that captures most of the exhaust energy to convert to boost to a say 16cm EH that bypasses a lot of that energy and it would be easy to understand the difference, and yes, this is what makes twins more attractive. When I made that statement I was thinking of stock perameters. I suppose when I put on my Captain Insano twins, I'll be in the same boat as you.
But what you posted has a lot of merit. Consider that going from the tiny 9cm EH that captures most of the exhaust energy to convert to boost to a say 16cm EH that bypasses a lot of that energy and it would be easy to understand the difference, and yes, this is what makes twins more attractive. When I made that statement I was thinking of stock perameters. I suppose when I put on my Captain Insano twins, I'll be in the same boat as you.
Maybe later this year I'll be in a position to try a good-spooling set of twins, and a manual front hub kit.
If I remember right, Pat made a run from Missouri up to TST's dyno in Columbus, IN. He put down like 760 h.p., and then drove back on cruise at 72 mph and got 24 mpg! I think he was running either 285s or 295s Toyo M/Ts at the time, but not sure. At any rate, I've definately got alot of room for improvement, and I'm not giving up just yet!
--Eric
01-23-2009, 05:10 PM
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enafzige, the Smarty with beta 4.4 really helped my mileage. The biggest three things for mileage that I have found are beta 4.4, air pressure set to almost max in the tires, and most important I have found is speed, which is easy for me since most of my driving is on highways at 55-60 mph. I rarely get to do trips on the interstate at 70+ mph, but when I do mileage definately suffers, but still around 18 at 75 mph.
01-23-2009, 05:57 PM
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That's a great question I don't have the perfect answer to. I usually chicken out at around 650-700 miles. I've seen my DTE reading at 10 before, then it started climbing until it got to about 20 or thereabouts. Strange how it calculates. I put in around 30 gallons in to fill it up.
Anyhow, thinking about little ways my mileage may add up, I had one secret. My little '89 GMC S-15. It does a lot of my around town trips and short Home Cheapo runs. I know my mileage went down a little when I had the truck out of service for new ball joints last month. It forced me to drive the Ram everywhere, and my mileage went down to 19-20 MPG for a tank or two.
I'm also very fortunate that overhead guesser is pretty close. My hand calcs are usually within +/- 1MPG of the guesser. It makes it easier for me to adjust driving habits when I have a little faith in the numbers I'm seeing.
My truck also had a re-flash just prior to me buying it. The flash was in response to the previous owner's poor mileage, white smoke and inaccurate overhead mileage readings. I'd say it worked for my truck just fine.
garrett
Anyhow, thinking about little ways my mileage may add up, I had one secret. My little '89 GMC S-15. It does a lot of my around town trips and short Home Cheapo runs. I know my mileage went down a little when I had the truck out of service for new ball joints last month. It forced me to drive the Ram everywhere, and my mileage went down to 19-20 MPG for a tank or two.
I'm also very fortunate that overhead guesser is pretty close. My hand calcs are usually within +/- 1MPG of the guesser. It makes it easier for me to adjust driving habits when I have a little faith in the numbers I'm seeing.
My truck also had a re-flash just prior to me buying it. The flash was in response to the previous owner's poor mileage, white smoke and inaccurate overhead mileage readings. I'd say it worked for my truck just fine.
garrett
01-23-2009, 07:44 PM
#55
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The problem is not the RPM the engine turns, it is the amount of energy required to keep it at that RPM.
A really good way to gage the amount of energy used is to hook up a laptop with the software to read the throttle position sensor. We use Alex Pepers OBD-2 software. Ours reads in a percentage or voltage. Watching that reading will tell you how hard the engine is working to hold the engine RPM to maintain the speed you want.
Just like riding a bike, you will need to push on the pedals harder if you have a hill to climb or a piece of plywood mounted to the front of the bike. The piece of plywood represents the tall ride height of the truck. Big tires have huge friction coefficients that make the engine work even harder to maintain the speed. All this requires throttle input that is easily read and compared to either more trucks or the same truck with smaller tires or lower ride height.
TPS today is yesterdays vacuum gage
A really good way to gage the amount of energy used is to hook up a laptop with the software to read the throttle position sensor. We use Alex Pepers OBD-2 software. Ours reads in a percentage or voltage. Watching that reading will tell you how hard the engine is working to hold the engine RPM to maintain the speed you want.
Just like riding a bike, you will need to push on the pedals harder if you have a hill to climb or a piece of plywood mounted to the front of the bike. The piece of plywood represents the tall ride height of the truck. Big tires have huge friction coefficients that make the engine work even harder to maintain the speed. All this requires throttle input that is easily read and compared to either more trucks or the same truck with smaller tires or lower ride height.
TPS today is yesterdays vacuum gage
Exactly. HPCR motor are not as effected by rpms as older trucks are.. Its all about LOD and TPS (TPS data, at least on my 05, is not available in cruise so I look at LOD).
01-25-2009, 09:33 PM
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01-25-2009, 09:35 PM
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If Im getting double digits Im happy! LOL
With my 37's a good day is 12.5 But usually it sticks around 10.5, cause its a city driven mall crawler
The best highway I can get is 14.6mpg. I dont know what it got before all the mods...only had it a few weeks then did the work.
With my 37's a good day is 12.5 But usually it sticks around 10.5, cause its a city driven mall crawler
The best highway I can get is 14.6mpg. I dont know what it got before all the mods...only had it a few weeks then did the work.
01-26-2009, 08:02 AM
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I knocked down 15.4mpg this last tank just by putting the smarty back to level 2 instead of 3, and just keeping it under 75mph on the highway. Im thinking if I keep it under 65 I might be able to squeeze out a little more, its just hard around here because if you arent at least going 75mph you're going to get ran over!