Dave
07-09-2002, 22:40
Memorial Day week I took a trip from Ten Mile, TN to Charleston, SC and back. My truck was 100% stock, and my combination weight was 20,235. I followed I-40 east from Kinston TN to the junction with I-26 east in Asheville, NC. I then followed I-26 east to Charleston, SC. Much of this 1000-mile round trip was in the foothills of the Smoky Mountains and across them.
Through I-40 the truck would frequently down shift to 4th, especially in the Smoky Mountains. Nowhere on I-40 could I use cruise. Two hills dropped the truck to 3rd. On I-26 it was the same until I got east of Columbia, I could then use cruise and stay in 5th. The trip back was the same. Heading west up Saluida on I-26, 7% grade for about 3 miles, the truck and trailer was at 55~56mph in 3rd gear at 3100RPM. The clutch fan was engaged the whole trip up the grade and out side temp was 86 degrees.
The week of the 4th of July I took the same trip. This time I had the Power Edge Juice box and was at a combination weight of 20,450. The box was set to level 2 in the tow mode. I could use cruise on I-40 east until 30 miles or so east of Knoxville. The truck stayed in 5th. I did not use cruise though the Smoky Mountains, but the truck again stayed in 5th except when the Allison down shifted to slow me on the downhill. In fact the whole trip east on I-40 and I-26 the truck never downshifted from 5th to climb a hill. I was able to pull every hill at or above the posted speed limit in 5th. It did require a little care with the go pedal in a couple places to keep EGT below 1250.
The trip back west was much the same. Headed west I climbed Saluida in 4th gear at 59~60 mph and 2300 rpm. The temperature out side was 94 and the clutch fan run off and on. I did have to watch EGT on the climb. I never let it get above 1250, and boost was at 23 to 25 psi. I do believe if I pushed the truck as hard as I did with out the box I could have climbed it much faster.
Things I learned from these two trips. Weights were close, as were temps. However with the box the load was just over 200 pounds heavier and it was 8 degrees hotter. The Juice box is a big improvement. With the box the truck will upshift to 5th at 58~60mph in the tow mode where as stock it was 65~67 mph. Basically what required a down shift to 4th now is pulled in 5th and what use to require 3rd can now be pulled in 4th. Cruise can now be used where it could not be used. Fuel mileage is about the same or .5 mpg better with the box. I averaged 11mpg with out it in May and in July I averaged 11.5 mpg. The truck did not feel like it was working as hard and accelerated better with a load. The clutch fan was engaged less. Engine and transmission temperatures are the same with or with out the box.
I also learned I would not tow heavy with out an EGT gage with or with out the box! I say this because from the amount of time the clutch fan runs with out the box the truck must go over 1250 EGT stock. I never exceeded 1250 EGT with the box and the clutch fan ran less and the out side temp was hotter.
With the box you can exceed 1250 EGT. With very slight pedal modulation you can keep it at or below 1250 EGT. I do not believe it is safe to run above that temp for long. GM may feel different, I was tempted to climb Saluida again with out the box to measure the EGT which I am fairly confident would have been over 1300 or more.
The Juice box, Amsoil air filter and ISSPRO EV series gages are the only performance modifications to my truck. Would a better air intake and bigger exhaust help with EGT
Through I-40 the truck would frequently down shift to 4th, especially in the Smoky Mountains. Nowhere on I-40 could I use cruise. Two hills dropped the truck to 3rd. On I-26 it was the same until I got east of Columbia, I could then use cruise and stay in 5th. The trip back was the same. Heading west up Saluida on I-26, 7% grade for about 3 miles, the truck and trailer was at 55~56mph in 3rd gear at 3100RPM. The clutch fan was engaged the whole trip up the grade and out side temp was 86 degrees.
The week of the 4th of July I took the same trip. This time I had the Power Edge Juice box and was at a combination weight of 20,450. The box was set to level 2 in the tow mode. I could use cruise on I-40 east until 30 miles or so east of Knoxville. The truck stayed in 5th. I did not use cruise though the Smoky Mountains, but the truck again stayed in 5th except when the Allison down shifted to slow me on the downhill. In fact the whole trip east on I-40 and I-26 the truck never downshifted from 5th to climb a hill. I was able to pull every hill at or above the posted speed limit in 5th. It did require a little care with the go pedal in a couple places to keep EGT below 1250.
The trip back west was much the same. Headed west I climbed Saluida in 4th gear at 59~60 mph and 2300 rpm. The temperature out side was 94 and the clutch fan run off and on. I did have to watch EGT on the climb. I never let it get above 1250, and boost was at 23 to 25 psi. I do believe if I pushed the truck as hard as I did with out the box I could have climbed it much faster.
Things I learned from these two trips. Weights were close, as were temps. However with the box the load was just over 200 pounds heavier and it was 8 degrees hotter. The Juice box is a big improvement. With the box the truck will upshift to 5th at 58~60mph in the tow mode where as stock it was 65~67 mph. Basically what required a down shift to 4th now is pulled in 5th and what use to require 3rd can now be pulled in 4th. Cruise can now be used where it could not be used. Fuel mileage is about the same or .5 mpg better with the box. I averaged 11mpg with out it in May and in July I averaged 11.5 mpg. The truck did not feel like it was working as hard and accelerated better with a load. The clutch fan was engaged less. Engine and transmission temperatures are the same with or with out the box.
I also learned I would not tow heavy with out an EGT gage with or with out the box! I say this because from the amount of time the clutch fan runs with out the box the truck must go over 1250 EGT stock. I never exceeded 1250 EGT with the box and the clutch fan ran less and the out side temp was hotter.
With the box you can exceed 1250 EGT. With very slight pedal modulation you can keep it at or below 1250 EGT. I do not believe it is safe to run above that temp for long. GM may feel different, I was tempted to climb Saluida again with out the box to measure the EGT which I am fairly confident would have been over 1300 or more.
The Juice box, Amsoil air filter and ISSPRO EV series gages are the only performance modifications to my truck. Would a better air intake and bigger exhaust help with EGT