Barrman
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300 mile trip in the M1009 last week and 21.2 mpg. 62-63 mph on the open road and speed limit everywhere else.
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Okay, I am about a week away from getting my 1009 on the road, assuming all goses well. Here what I got, I installed a 700r4 with a B&m lockup mech. thingy,a turbo and alot of other crap. I was wondering what others with similar cofiguration have gotten concerning fuel milage?
639miles/45.8Gallons = 13.951965066MPG...so what's the average class?
You can export as a CSV and paste the text.Here's my M1028 records -...
...Won't paste well into the forums as it came out of a spreadsheet.
Original 400 3-speed or a 700 4-speed?I'm getting from 17-18 mixed driving with my M1008, but I have 3.73 gearing and 33 inch tires.
I'll be honest, I don't see the MPG changing more than 1MPG on long-term average with only an exhaust mod. If your 86 really has 4.56 finals then your engine would have to be spinning 3190 RPM at 65MPH. The max efficiency zone for the 6.2L is 1600-1800 RPM, above 2000RPM the efficiency drops rapidly. At sustained 3000+ I wouldn't expect the engine to last very long......the 86 1009 with 4.56 gears 33" tires 16.8 mpg...
...the 86 rarely sees 65 mph. The 86 recently got flowmaster super 44 2 1/2" mufflers and 2 1/2" tails so I expect mpg to go up a bit...
Don't need to take a course at MIT to read lecture notes most of the time: http://ocw.mit.edu/courses/mechanic...on-fall-2006/lecture-notes/16diesel_contd.pdf...The max efficiency zone for the 6.2L is 1600-1800 RPM, above 2000RPM the efficiency drops rapidly...
With the calculator assuming no-lockup, that works out to about 2000RPM at 65MPH with 33" tires. Pretty good. If you can get the lockup back that should drop about 100RPM to about 1900.I have a k20 6.2 with 4.10 and a 700r4 and its perfect all around for cruising and towing...
They may have just cut the wire or unplugged the wire to the transmission. IIRC, the lockup solenoid has a pressure switch to detect 4th gear. You are also supposed to have the dual circuit brake light switch so that the lockup releases when you push the brakes. The circuit is supposed to go (from 12+ to ground): Battery+ --> fuse --> brake light switch --> 4th-gear pressure switch --> solenoid --> ground.I wish I still had lockup for cruising with a disable switch for something...
You were totally correct on your mpg prediction.Filled up today 340 miles 19 gals. fuel,but Im a bit heavy on the throttle because it sounds so good.I think I could get 19 mpg if I tried.My next low $ step is a 14x6 aircleaner and fresh air intake.Then regear to 3.73s or 3.90s.And then finally a 700r4 trans.conversion.After that turbo set up or maybe a set of Stans headers,just because I cant really find any reviews on them,seems like everyone wants to try them but nobody does.And yes you are correct at 65mph Im running nearly 3200 rpm,which I hate, and generally try to stay at 60 mph or less.I really don't like running a 6.2 above 2500 rpm.But at 2500 with this one Im only running about 54 mph.Thanks for your advice,and isn't it totally amazing these outdated trucks are capable of 22mpg and are so easy to work on after some learning.I think I have my soon retiring Dad talked into a cucv.I'll be honest, I don't see the MPG changing more than 1MPG on long-term average with only an exhaust mod. If your 86 really has 4.56 finals then your engine would have to be spinning 3190 RPM at 65MPH. The max efficiency zone for the 6.2L is 1600-1800 RPM, above 2000RPM the efficiency drops rapidly. At sustained 3000+ I wouldn't expect the engine to last very long...
With 33" tires, changing the finals to 3.73 will drop the 65 speed down to 2600RPM roughly - swapping the transmission to a 700R4 (which has overdrive) and leaving the 4.56 would get your 65 speed down to 2110RPM. Doing both would get your 65 speed all the way down to 1730RPM, and IMHO is the real sweet spot for this engine. If you can couple that with a lock-up converter that kicks in in fourth under lighter throttle, your fuel efficiency could potentially see the mid to high 20's in MPG. Not bad for a truck with the aerodynamics of a brick.
I used the popular "GrimmJeeper's" gear ratio calculator for the numbers in this post.
340/19 = 17.89, yup that's about 1.1MPG better than the previously reported 16.8MPG - engineering math is engineering math.You were totally correct on your mpg prediction.Filled up today 340 miles 19 gals...
Air cleaner with the wide open exhaust isn't going to do much (maybe another 0.5MPG or less) until you put in a turbo - then you want the restriction to be as close to atmosphere (nothing) as possible. Turbo especially if you see any altitude over 2000' above sea level - like making voyages south east into West Virginia... Note that if you do the turbo, you will not be doing headers - the turbo manifold pulls both sides into one turbo collector, and then out one pipe. Again, low restriction after the turbo will be your friend....My next low $ step is a 14x6 aircleaner and fresh air intake. Then regear to 3.73s or 3.90s. And then finally a 700r4 trans conversion. After that turbo setup or maybe a set of Stans headers...
I think these trucks prefer "finer vintage" rather than being labeled "outdated". Most like elder more experienced women. If you can manage to control yourself a bit with the right foot (no jack-rabbit starts, and keep it below 60MPH always - I know it's hard with those truckers out in Ohio), you could probably squeeze out 18-19MPG now....and isn't it totally amazing these outdated trucks are capable of 22mpg and are so easy to work on after some learning...
The previous owner had the lockup solenoid removed from inside the tranny.They may have just cut the wire or unplugged the wire to the transmission. IIRC, the lockup solenoid has a pressure switch to detect 4th gear. You are also supposed to have the dual circuit brake light switch so that the lockup releases when you push the brakes. The circuit is supposed to go (from 12+ to ground): Battery+ --> fuse --> brake light switch --> 4th-gear pressure switch --> solenoid --> ground.
Adding a toggle switch labeled "lock-up inhibit" with "inhibit active=open (off)", "lockup available=closed (on)" between the fuse and the brake light switch would do just what you want.