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+--- Thread: Fuel mileage (/showthread.php?tid=5135)
RE: Fuel mileage - DDlighttruck - 10-02-2019
(10-02-2019 )Rawze Wrote: pressureize the whole engine to 30 psi. Check for leaks.You read my mind. I started collecting pieces to be able to do this last week
Do you usually pressurize on the exhaust side of the turbo? Block off at the CAC air pipe where it goes into the intake? Or actually try to pressurize the whole motor?
RE: Fuel mileage - DDlighttruck - 10-02-2019
(10-02-2019 )Chamberpains Wrote: Being a big square Hood and an old cm870 you should be able to squeak out mid 6's into the 7's on fuel mileage. What tires are you running? there's also a lot of fuel mileage in having good driving habits also. Look into hypermiling on here
Steers are Michelin 11R24.5", the xline energy series. Drives were 11R24.5" kumhos or michelin XDS2, depending on the season. Now they are BF Goodrich DR444 275/80/24.5". According to the chart Rawze posted elsewhere the drives all seem to have a rolling resistance of 144. I never did look up the rolling resistance on the steers
RE: Fuel mileage - SIDE_SHOW - 10-02-2019
(10-02-2019 )DDlighttruck Wrote:(10-02-2019 )Chamberpains Wrote: Being a big square Hood and an old cm870 you should be able to squeak out mid 6's into the 7's on fuel mileage. What tires are you running? there's also a lot of fuel mileage in having good driving habits also. Look into hypermiling on here
Steers are Michelin 11R24.5", the xline energy series. Drives were 11R24.5" kumhos or michelin XDS2, depending on the season. Now they are BF Goodrich DR444 275/80/24.5". According to the chart Rawze posted elsewhere the drives all seem to have a rolling resistance of 144. I never did look up the rolling resistance on the steers
this one also had 1124,5s i forgot to mention that i swapped them for a set of gy lp 22.5s i had and saw about a .5 to mile increase before i went rawzes as well as better power it seemed like but that was prolly in my head lol
RE: Fuel mileage - Lonestar10 - 10-02-2019
It's more work but we found my head bad by removing rockers and letting all valves close then pressurized intake we found intake valves leaking by at 10psi. Valve seat pressure should be whatever the valve springs are rated
RE: Fuel mileage - DDlighttruck - 10-05-2019
[attachment=5523]
I had these made up this week, and had my exhaust guy make up an extra turbo flange.
I just didn’t have time to play with them today.
RE: Fuel mileage - tree98 - 10-05-2019
(10-02-2019 )Lonestar10 Wrote: It's more work but we found my head bad by removing rockers and letting all valves close then pressurized intake we found intake valves leaking by at 10psi. Valve seat pressure should be whatever the valve springs are rated
How do we know what the valve springs are rated for?
RE: Fuel mileage - Lonestar10 - 10-05-2019
im going to guess seat pressure has to be around 100PSI with around 300PSI on spring at full valve lift.... beleive that would be similar to 4 wheeler engines ive built. seat pressure has to atleast be more than the turbo could ever dream of pushing to keep it from pushing air in on an exhaust stroke as turbo your intake and exhaust are pretty much never open at the same time as they are in non turbo applications.
RE: Fuel mileage - DDlighttruck - 10-07-2019
Ok, how the heck do you drive down the road at under 10 pounds boost? I was on US-2 today across the UP, which is fairly flat going. The best I could consistently hit was in the 11-13 pounds boost range. Unless it was downhill. I was 15-1600 rpm, 60-62 mph, light load on a stepdeck. Barely stepping on the fun pedal with one toe.
RE: Fuel mileage - the missing link - 10-07-2019
Running from Seattle to prince goerge the long way ( dejong) with a low profile step . I am running light but have a 15` wide and 16 ' tall box on the back .I am getting 5.5 loaded and 8 the way back .this is with a 4900 star with a 2250.
My 08 9900 was around 5.5 us pulling super B's .I had better days and way worst days .
The tune is not the end of the world , your right foot is everything .it takes a long time to get used to every trick in the book and to be able to back out .
I am having a very hard time getting this star to hit what my 9900 did .
I still have a few more things to check . Running big heavy loads (9 axel) this truck is running roughly .5 lower loaded and 1 empty less then the 08 9900 driving the same .
Maybe this helps.