Engine/Transmission (1998.5 - 2002) options for towing

[Jed]

Given my current set up what can I do to improve towing performance? I am new to towing but I just completed a 3,000 mile trip with a 5,000 lb travel trailer. So cal to texas.



Smarty set at 3, rpm 2100 or so with transmission in 4th and gear vendors in high for about 72mph. Boost 10 to 20lb, heat (pre turbo) 750 to 1100. Mileage 9 to 12 mpg

.

Truck ran good however transfer tubes started to leak and had to be tightened for some reason.



Goals are better mileage and better heat control.



Specific questions are can my turbo be modified for better towing performance?

Are my injectors too big?



As always any help is appreciated.

Jed

 

[DCreed]

need to know rear gears, turbo size(57/12,62/14/ect), and rpms @ cruize. its a fairly lite trailer ,I'm getting 14mpg towing a 8k goose.

 

[Trailduster79]

Yeah, that doesn't sound right.



I got 13. 5 towing my camper, about 5500. And I am bone stock

 

[JRBurton]

That doesn't sound right, I pull a TT 9K at 70 mph and get at least 13 mpg. Oh yea my truck is practically stock.

 

[Jed]

DCreed

rear gears are 354 or 352 or so I do not remember offhand

I do not know the turbo size I am trying to find out by the part number

2100 rpm 72mph at cruise 8lbs to 10 lbs boost, flat country no wind



It is my guess that my turbo is not sized for a towing application

 

[DCreed]

DCreed
rear gears are 354 or 352 or so I do not remember offhand
I do not know the turbo size I am trying to find out by the part number
2100 rpm 72mph at cruise 8lbs to 10 lbs boost, flat country no wind

It is my guess that my turbo is not sized for a towing application

Okay ,we're getting somewhere. first off, the best way to save fuel= SLOW DOWN!:-laf the motors "sweet spot" for milage seems to be around 1900rpms . your rears are 3:54 ,not the best for towing. but you tow lightly as I do so no biggie there. you're EGTs really aren't that high, what I'm guessing is the turbo is a 14cm or larger ex. housing and a 65mm wheel on maybe a 62 compressor so @ 2100 the turbo is lit but the mileage is hurting from the extra fuel going out the tailpipe keeping that charger lit. how old/dirty is the BHAF? let us know .

 

[Mundgyver]

Do you have an after market turbo or is it the original. If it is the original, I woud suspect that it is an HY-35. I notice that you also have a non-factory cam.



Have you had the truck dynoed to find out where your peak torque is at RPM wise. If you know where this peak torque is, and drive at that rpm, my bet is you will see your mileage go up.



A stock truck is designed to run at 65 mph. My sig shows my mods. At 65 mph I am turning 1800 rpms and get between 21 and 23 mpg unloaded. Loaded up with a goose neck and at CGVW of 23,000 I get 15. 5 mpg at 65 mph.



Anything over 65 mph for me is wasting fuel.



Food for thought. Find out what rpm you peak torque is and try driving that rpm when you tow. That should help you out allot.



Almost forgot, my gearing is 3. 54 in the pumpkins

 

[WrenchRat]

Agreed, that mileage doesn't sound quite right. The worst I've ever gotten towing was 11+mpg (stock) and that was aggressive mountain driving with an 8K trailer. Typical is 12-16 with my 6K, 27ft high profile TT. All depends on terrain, traffic and driving style. 75MPH = morrrre fuel. :-laf If I slow down to around 65+, mileage goes to 16 on flats.



I run my Smarty on SW#5 and standard boost of 20+psi max (for now) on the HX35. The MBRP 4inch exhaust was a major help in dropping EGT's down. I have been happy with the MBRP as it is a little noisier than stock, but not by much. No droning. Don't remember the exact improvement in EGT numbers. My airbox is std with a Fleetguard airfilter. (for now).



My gear ratio is 3. 54 and in combination with the taller 33inch tires, causes me to drop out of OD sixth on steeper grades that have any length to them. If I had 3. 73's or 4. 10's, I might actually get better mileage as it would match the sweet spot of the B a little closer and I could leave it in 6th without driving EGT's up too high. But, I don't want to give up my empty MPG and don't mind shifting.



I'll leave the specific turbo and injector question to those more in the know.



FWIW, the Bosch 275RV injectors helped usable power quite a bit when the truck was otherwise bone stock. I made the same mountain pass runs on AZ87 and I-70 through Denver with the same 8K load bone stock and with just the 275 injectors added and was VERY glad I made the mod. I did it again after adding the 4inch exhaust and WOW. I was able to use 4th and 5th and name my speed going up 5% and 6% grades with no EGT worries. (summertime too) I was passing a lot of other RV's and even some cars! All BEFORE the Smarty. What a feeling! Yessss!



Now the only reason I slow down with a trailer load is if traffic gets thick and/or conditions are less than optimal. Discretion is the better part of valor there.