I need some help from the experts here please.

I have a 2005 3500 lwb cc D/A with a predator set at 40 hp, and tow a 16,000 lb. fifth wheel trailer. The truck came with 3.73 rear ends, and 215/85/16 tires. The stock tires made the truck look like an elephant on tricycle wheels. I replaced them with 235/85/16 and greatly helped the looks of the truck. My problem is now the hills are killing my speed and fuel economy. Tows fine of level ground. I need some help making a decision as to where my money would be best spent.

<>I can change rear ends to 4.10 ….. After market for around 2200 .. GM factory for 3000. Get a new 4”exhaust, manifold back eliminating the cat, and Juice w/ attitude for 1500 installed. I’ve already got the finger stick and the EGR blocker plate is on the way. No matter what I think I probably need the exhaust. Should I do some transmission work too? I know the cheapest thing would be to replace the tires with stock size, but REALLY don’t want to do that. Feels like I’m buying the truck all over again.

What should I do first? I can’t afford to do all at one time

<>Thanks, <>HenryL

Henry
Your tire size went fron a 30.39" tire to a 31.73" tire, not a big difference. I do not think that is hurting you much at all. Towing up hills with a load is hard for all 3 diesel makers. If you can hold 45 mph towing that kind of weigt uphill you are doing fine. I am also running the 40 hp pred and I am seeing pretty high EGTs going up hill so "BE CAREFULL".

Your tire size went fron a 30.39" tire to a 31.73" tire, not a big difference. I do not think that is hurting you much at all.Agree 100%. A set of properly heat treated aftermarket gears are just as good as factory so if you go that route save yourself the couple hundred $$$s. With that said 4.10s may help you while towing a grade but if your concerned about mileage 4.10s will hurt, just think of all those times you aren't towing. Additional HP from a Juice Attitude combo will help but you couldn't use the higher levels of power due to extreme EGTs. I'd say your best bet would be a 4" exhaust. Other than that just remember 16,000 lbs is alot of weight....how fast do you really need to pull up a hill?

I'm towing a heavy 5ver much like yours. When towing heavy like this tire sizes play a bigger role than normal commuting. I agree with McRat, the difference isn't that significant. If you are using the DIC for mileage it is likely inaccurate due to the tire size change. :rolleyes:

Have you done any other mods besides the tires we should know about? Intake, grille insert, tool box, etc. Also has the weather been colder? :confused:

You may need a little extra hp/tq that a programmer provides to offset the tire size change. Also check out water injection systems for lower EGT's and hp/tq bump. JJ :)

Welcome to the site. Just remember you also have a 7000+lb truck attached to that trailer so your total weight is 23000lbs. That's a lot of weight. I'd replace the exhaust with a 4inch system just for lowering your EGT's. Since you are running the predator maybe an EGT guage would be a good thing. Good luck!

FWIW, I am pulling ~20,000. I run the Predator on 85 all the time. 5" Summit exhaust, SC3, TTS converter, Finger Stick and blocker plate. I am running 365/65-16's which is 35" tall and about 14" wide. I have the tire size corrected with the Predator.

I have no idea what I am getting MPG wise with the trailer. I never seem to pull a whole tank. Probably < 10 MPG. Unlaiden, I get about 16-17 MPG mixed, which I consider good. DIC is a little optomistic at 17.5. EGT can climb into the low 1400 on a hard long pull. Boost tops out around 22 PSI.

My best bang for the buck came with the Predator and the tire correction settings. Everything else was to make the setup last longer.

IMO, bigger exhaust and make sure you correct for the tire size difference are the best things to do. I don't think the gear change is going to do you much good. Finally, make sure your tires are inflated to the max rating when towing! If they are low, it is like dragging an anchor behind the truck.

I have the same setup on my 2004.5 running the juice w/A running on level 2 which I think is 60hp. Runs up the hills with ~20,000# no problem. EGT's almost never an issue unless bucking a headwind or steep hills longer than 5 miles. Your tire change has reduced what the speedometer will show by about 5%. On my truck, made it so I was displaying 2% below actual speed, using road side markers and calc's.

My fifth wheel has ended up heavier than anticipated, approaching 17K pounds... so far I've traveled just a few thousand miles, where the trailer is parked for the season. My 2004.5 Chevy 3500 is still pretty much factory. I would like to proceed with some performance upgrades for the truck, such as Banks Big Hoss Bundle (tuner, loader, intercooler, exhaust+muffler & gauges, etc.) but I've owned exhaust brakes (Jake for Cu*mins and Banks' for Duramax LB7, etc.) and I question wisdom of investing in the "go" of this truck when exhaust brake for LLY is in limbo.

I am considering selling & moving on to MDT like Freightliner SportChassis. The reason I'm here with a 2004.5 3500 was the fact that GM 4500 and 5500 platforms are approved for my trailer weight with same Duramax engine and Allison transmission and my entire load is under all axle weight ratings....

Views on comfort level, dependability, etc. of using modified 3500 to pull 17K trailer-- I will be pulling in the mountains. Or move on to next truck? --wheeler

PS: JJDumax I tried to PM you with a question but your profile won't allow it? Can you PM me please? Thanx.

Thanks for all the good advice guys. I think I'll try the exhaust and Edge w/ attitude, the attitude as much for the gauges as anything. It seems the Edge is the programmer of choice for the LB7, so I feel like they'll eventually get the LLY figured out, and I'll be set. Probably save for some transmission work next.

Thanks again

Wheeler, not sure what is up since I am receiving PM's from others. I'll check anyway. Better yet I'll PM you and see wazzup! :)

HenryL, while you are at it check out water injection. Lowers egts, increases hp/tq, lubricates the engine better, etc. I'm going to install SD's WI system with E/J w/attitude and see the results. If EGT's are still an issue then exhaust is next. JJ :)

Planning on buying a 3500 to pull my 14,500 pounds fifht wheel, don't know if i should go 2 or 4 wheel drive. Need help

If you are not going to drive on dirt, not going to drive where it snows, then 2WD will give you the best mileage and best payload. But it sure is handy if you need it. Getting stuck can be a serious PITA if you are towing.

I'm on 37" BFG's towing a 10,000lbs trailer. I have the hypertech on level 2, pulling the steep grades at 55 to 65 MPH and my EGT's hit about 1000F to 1200F. no gear changes here, stock 3.73's.
I pass Ford's and Dodge's like nobody's business.

Andre', if you are going to put $40k in a truck, don't let an extra $3k keep you from using it to its full potential. Get the 4x4 and take the worry out of climbing loose gravel driveways at RV parks, pulling grades in inclement weather, etc. Resale value is better as well.

At the weight you are pulling you might also consider a dually. I never intended to buy one, but I absolutely love it. The RV websites can give you plenty of reasons to have a dually. FWIW. JJ :)

I must be missing something here, HenryL already has a Predator and running it on the 40hp tune; why does he need to purchase the Edge Juice?? Should he get some gauges to run with the Predator, yes. He can probably get the pillar mount and gauges for $200-$300 from DPP or Kennedy and keep an eye on what is going on inside. Should look into a 4" exhaust like MBRP maybe from Mark Craig. Probably under $500 for the exhaust and it's an hour to install it. $1500 to install the Edge Juice and Exhaust seem like robbery especially since he has the Predator.:confused:

Sprintmod1, good point! HenryL, did you correct for tire size with the Predator like Fingers? Didn't someone mention tire inflation, all around? :rolleyes:

I agree with SM1 that your money is likely better spent on either exhaust, or water injection as suggested previously. Exhaust will help with EGT's, while WI will not only lower EGT's but increase hp/tq and lubricate the engine better! Looks like you have some reading to do. ;)

Andre, 4x4 dude! JJ :)

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I pass Ford's and Dodge's like nobody's business.I'd like to see you try and pass me.:D

I'd like to see you try and pass me.:DYIKES

And the TWINS... thats hard to beat :bow:

Hey 1FSTDSL,

I see you had to add a couple of modifications to keep up with the big boys.
Silly Dodge, Tricks are for kids!
Sincerely
One Proud Chevy Owner!

You have a Dodge But you must be interested in Dmax or you woulldn't be here!

:grd:

You have a Dodge But you must be interested in Dmax or you woulldn't be here!

:grd:I have a contruction company and own all three ( mostly DT466's). I like all diesels and yes the Dmax can kick some A$$. I just happen to think the Cummins can kick just a little more. :ro)


Edit: I like them all except for the "sick.O" :D

Here we go! ):h Can't we all just get along and avoid kidnapping this post? ;) There isn't a Ford, Dodge, Chevy/GM truck out there that won't meet it's match on any given day. They're all capable of mo' power with all the mods coming out all the time! :D

Ya'll be quiet now, we don't want to wake Hoot and have him read this thread! ):h JJ :)

Can't we all just get along ...
Who's not getting along? :confused:

Who's not getting along? :confused:

I winked, didn't you see my wink? ):h Just didn't want to read another "Dodge vs Chevy vs Ford" dissertation again! :o: JJ :)

I hear ya. :D

Could you turn off your engine, I didn't hear what you said ...:muahaha: