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View Full Version : My experience with the Forum and 03 Duramax (LONG)



jesshd
07-21-2003, 07:02
Been semi lurker.

Got my 03 Duramax in May. CC/LB 3500 LT with all of the toys. It has about 2900 miles on it now. I tow a 28ft. 10K 5th wheel. Previous truck was a 98 Dodge V-10. There is no comparison. Here in Colorado on I-70, you have to pull a 6-7% grade to the Eisenhower Tunnel at 10,000 feet to get over to the Western Slope. Dodge would pull it at 30 mph in first gear for the last mile. I pulled the same grade this summer on Memorial weekend with 500 miles on the truck. It would pull the same stretch in 3rd/4th at 60 mph almost to the wood. It was stock. Since then I have added the Predator first, then Dynomax 4 inch exhaust and boost and pyro gauges on the pillar. Also installed a K&N FIPK kit. Installed the pryo gauge in the right exhaust manifold. Then got a Juice from Kennedy exhaust to "try". I got the CA programming to start with on John's recommendation for smoking at the higher altitude. That is where the truck is at now. I also added the Line-X bed liner and a new Reese 16K 5th hitch. I have a 55 gal in box fuel tank that I moved over from the Dodge.

Fuel mileage vs the Dodge - The Dodge would get 10mpg on a good day dry. Pulling the 5ver, it would get about 3-6 mpg. Rotten. With the 35 gal. tank, I would worry about where the next station was. That is why I got the in-box tank. The 3500 gets about 10-12 mpg now towing. 15-18 mpg around town and highway.

Power - The Dmax is all over the Dodge. Read the above. The Dodge was a slug.

Stability - The Dog was a 3/4 with all of the towing options. The 1 ton makes a world of difference in stability with the 5th wheel.

Predator impressions - Love the diagnostic and calibration capability. I ran it on all of the tunes. I started with the 40 hp tune and then went right to the 100 hp tune. Lots of smoke at the higher levels. No gauges at first. Did a short tow to a RV dealer to get the trailer detailed at the beginning of the season. I could tell the difference, it was not like night and day. At first the shifting was erratic, then as time went on, it got better. Would still "slip" or defuel under full throttle and get worse as the power went up. I ran it on the 40 hp tune most of the time. Would not sping the tires with no power brake even on the 100 hp tune.

Towing with the Predator on 40 hp tune it would get warm with the gauges installed. I pulled some good passes and the tunnel with the Predator on 40 hp. Under full throttle with no load on 100 hp, it would hit 1400+ EGT before 70 mph. On the 40 hp tune, it would top out at about 1200-1300. Towing, it was not that hard to get it to 1300-1400 on a long pull in 4th or 5th. I would back out or force a down shift and it would drop to 1100-1200. Could tell there was more power there, but was a bit hesitant to wood the throttle to keep EGT down. Would also make about 3-4 psi more boost with the 40 hp tune. I set the power back to stock for the trip home. On some of the same hills and passes, it would not get over 1200 pulling to the wood. Most of the time was 1000-1100. Like the extra power of the Predator, but was a bit concerned about the EGT with the truck being so new. James' support has been absolutely excellent.

Juice impressions - I ordered the Juice when I got back from the first trip. The CA tune on 90 hp was not nearly as strong as the 100 hp tune on the predator. EGT was never over 1200 with the Juice to top end full wood. Also would not jump to 1400 quickly like the Predator would. Just did not get the snap or power feeling like the Predator had. Virtually no smoke on acceleration. Even the # 2 setting in tow mode felt weaker than the 40 hp tune on the Predator. Sent the Juice back to get the Fed tune. Installed it and set it to the 90 hp tune. It has the power. Felt much stronger than the CA tune. It also has more squirt and snap than the 100 hp tune on the Predator. Not a ton, but you can tell the difference. The EGT will hit 1200-1300, but it does not rocket to 1400 like the Predator does. I have not towed with the Juice on level 2 yet. I will be making a trip to the mountains in August for a week and will be able to give some feedback on EGT and power and such when I get back.

I also paln on adding the Dynomax downpipe to the system as well. This is a downpipe back system. I ordered the system and then found out that they don't make a LB version for the 03. The difference in about 3 feet shorter right after the flange on the downpipe. Very easy to correct. I just got 2 4 inch stainless bnad clamps and added a 3 foot section of 4 inch exhaust pipe between the flange and the downpipe. The muffler internals on the Dynoax system is HUGE. It is basically about a 1 foot can with two baffle sections in the fornt and back with nothing in the middle. I have used the Ultraflow mufflers on my other turbo cars and have had great success with the custom systems I made for them. The Dynomax has a bit of resonance at 2200 RPM and bellows a bit at that RPM. Under light to medium throttle, it is fairly quiet. Under full throttle, it sings a song. A bit throatier than I would like, but it works well. I gained about 1-2 psi of boost by adding it.

Tire spinning. My truck will not break the tires by just wooding it. When I got the Juice, I had to try it. I power braked to about 1500 RPM, the back tires starting breaking loose. Then let the brake go and floored it. They BOILED!!. Then kept spinning and smoking into 3rd gear when I backed out. There were balls of melted rubber all over the inside of the wheel wells and on the side of the truck. The black marks must have been 50-75 yards long.

First oil change today with Shell Rotella Synthetic. Will also change the fuel filter and tranny filter. Not sure on the rear end. I have not changed it yet and only want to use synthetic, but don't want to add something after market that will create warranty hassles.

That's it for now.

Jess

sdaver
07-21-2003, 08:59
WELCOME SOUNDS LIKE YOU GOT MOST OF IT FIGURED OUT :D I run the preditor on zero tune and the juice on hot.........this lets me dump the limiter(at least to 125)and adjust for tire size :D dave

DMAX Daddy
07-21-2003, 12:16
From my understanding CA juice has the same numbers, it just takes a little longer to get there. I hope anyway, just ordered a CA Super Juice smile.gif

Kennedy
07-21-2003, 16:22
CA programming just waits for a bit of boost to build before fueling. Worked well for me when out west.

I'd consider swapping the FIPK back to a stock box with stock or foam filter and see what changes it makes. You may be surprised. Most FIPK users get SES lights and semi limp mode...

jesshd
07-21-2003, 17:11
Full wood, the Ca tune just did not have the beans that the fed did. I have not thrown any codes at all with any of the combinations that I have installed right now. Running the Juice on level 4 and levle 2 tow mode.

Jess

KevinK
07-21-2003, 17:15
Hey Jess,

Where abouts do you live? I've been driving past a 50-75 yard dually burnout for the past couple of weeks on my way home from work and I keep looking for the truck that did it.

Kevin

[ 07-21-2003, 05:21 PM: Message edited by: KevinK ]

jesshd
07-21-2003, 18:56
Lafayette. Run was on Isabelle between 287 and 95th.

Jess

KevinK
07-22-2003, 08:09
It's a small world. I drive down Isabelle every night. Nice burnout. My test for performance mods is to turn south on 287 (from Isabelle) and see how fast I can get the truck going by the end of the merge lane. Stock I was at about 64mph. With the current mods, I'm at 82-83mph. I would love to take a ride in your Juiced 3500 some time.

Kevin

jesshd
07-22-2003, 08:45
Anytime. You can email me at jessmx5@earthlink.net

Jess

a64pilot
07-23-2003, 07:05
Jess,
The Dynomax your talking about, does it go all the way to the turbo?

jesshd
07-23-2003, 08:16
No. You have to purcahse the downpipe extra. $130.00. If doing it over, I would probably opt for the Kennedy exhaust.

Jess

Spartus
07-24-2003, 00:47
Jess, both Summit and Jegs have a 4" exhaust setup for the Dmax that includes downpipe for $300.

-Tom

jesshd
07-24-2003, 10:41
Too late. The Dynomax is on the truck and I have a ton of experience with turbo cars (gas) and using the Ultraflow welded mufflers when designing custom exhausts. That is one of the main reasons that I chose the Dynomax. Welded Ultraflow muffler (rated at 1080 CFM) and bang for the buck.

Jess