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Originally Posted by redpoint5
The lift is hurting your FE more than anything else. It seems funny to talk about an underbelly when the truck is standing so tall and has such large tires.
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I understand that the lift hurts FE, thus the reason for the other post. Since my truck sees off road enough to bump up the ride height to begin with, it needs to stay. The other post I did was intended to get some feedback on the ideas I had about helping out under there as much as possible.
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Sure we can argue with the data. We have no idea how you controlled other variables or how you measured anything. In one sentence you say warm fuel will improve FE, the next sentence you say cold fuel improves FE. Which is it?
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Well the data was pretty simple since I did the mod in the middle of the trip... 800 mi going up mpg = x, 800 mi going back, mpg = 8 + 6.5%. It was the posts I read here that are claiming the FE goes up with warmer fuel, all of this relating to gas engines only. I do know that testing I did do on a dyno with a fuel cooler setup on a stock engine yielded a max gain of approx 13% in both hp & tq. Every gas motor I did this mod to had a nice butt dyno felt bump in the low-mid range rpms, only 1 motor did I dyno it before & after on the same dyno on the same day w/o pulling the car off the rollers. I believe there should be an ideal number to get the intake air temp & fuel temp to get the most out of it (diesel). Since when the ambient temps are in the 85~95ish range smoke output drops and motor feels stronger it leads me to believe that at those temps it is getting the best burn in the cylinder.
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On what principle of physics does heating or cooling the fuel improve the thermodynamic properties of combustion?
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Cant answer that, can only point to the before & after data I collected. I can say though that the "after" data had ambient air temps close to the 90's (gas engine) so if anything the gains might have been higher.
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I think you should chart your current MPG so that you have a baseline to compare with. Even better yet, do ABA testing with any mod that might affect aero or rolling resistance. Without this, there will be no evidence that any work you do has any benefit.
20mpg at 65mph should be achievable from a stock truck. Stop modifying the truck in ways that hurt FE, and improve the efficiency of the driver; this will help the most.
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Heading up to Washington Thursday morning with a light load so I will be seeing where it sits then. I have seen 20 mpg 2x in this truck, 1st it had 2.5" of lift with a wider well worn set of tires that were heavier than what I have on there now. the other time was with a tire 1" taller than the 34" tire that I have on there now, that had the same 3" lift thats on there now. At 65 mph the motor is spinning right around 1700 rpms which is around where the peak torque is. Another thing I can do is run a loop I"ve run in the past which was something like 100~120 mi and do before & after runs on the mods. Since I'm not working, regular runs like that are out of the question for now.
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Warming or cooling fuel just isn't something worth bothering with. It's not going to make a noticeable difference, and the truck is already designed to operate within a range of temperatures.
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I disagree on this one... it's an area of opportunity IMO. Someone also suggested straight piping the exhaust, also a bad idea (already did it years back & lost mpg) Free flowing exhaust like that will help develop the most power under WOT conditions.