(10-07-2019 )DDlighttruck Wrote:  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.

(10-07-2019 )the missing link Wrote:  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.

(10-07-2019 )Rawze Wrote:  

(10-07-2019 )DDlighttruck Wrote:  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.

sounds to me like you might be also fighting some excessive drag somewhere. Maybe wind, maybe aero drag on the trailer or load, rolling resistance,.. who knows.

(10-08-2019 )Chamberpains Wrote:  11-13 ain't bad. You don't get great right away. Im a year and a half at this and still working at it.

A little help from neutral on the down hills and over those slight up hills (like overpasses) helps a lot out on the flat parts of the country. Use that throttle as little as possible. Lose a mph or 3 on the up hill side and nice and gently with the throttle, get it back on the down hill side.

(10-08-2019 )the missing link Wrote:  Still have it .
Good a really good deal on the star and a heavier truck for what I do is not a bad idea .
I put the star to work 2 months ago

(10-08-2019 )Chamberpains Wrote:  When pulling hills, its more important to keep your RPMs up. So keeping boost down at 10 isn't gonna happen.

When you down shift, you should see a spike in boost to somewhere a little over 20 psi. Then it's up to you to do the dance of pulling the hill and yet trying to keep boost as low as possible. I can keep mine under 15 pretty quick after the initial downshift spike. But it takes some serious discipline. And I downshift a lot till i find the gear that keeps my RPMs above 1500 and gets my boost at around 15 psi. I also monitor my tps reading and I can now say I can pull every mountain in the states by using no more than 60 tps or 3/5ths of the pedal and never pushing it any further. This is done with full 80000# gross using a Cummins cm870 450hp Uni-tune, 10 speed, 3.55 rears. I actually have very little need to use more throttle pedal. Except on the occasional short on ramp in heavy traffic. My fuel mileage is in the mid 7's and im just now starting to see 8's after I replaced my transmission and exploded pilot bearing.