project 30 mpg

revolutiondsl

revolutiondsl

Cat buys my Cummins parts
Joined
Jun 3, 2007
Messages
1,391
Ok so Im picking up a 98 QC SB 2wd 24 valve Auto 3.55s. I drive about 40 miles to work its a very straight flat drive with maybe 4 stop lights and 2 turns the whole trip and the speed limit is 60 mph.

So I was thinking of getting a cheap car to drive but I hate driving little cars and my company has about 50 Dodge diesels and offered me this one for 1800 bucks and its got tranny issues so im just going to build a good one for it and be done.

My question is with proper mods will this truck get 30mpg Im going to put a fass system on it, an edge box, 5 inch exhaust, and maybe a set of good clean injectors and a 62/71 S300 that I have. I know little things like an air dam help but Id like to get at least 28 but 30 just seems like it could happen but not on a daily occurance. What kind of mileage has anyone else got and what else can I do to help. Im not wanting to spend a ton of money. This truck is just a project and mainly to see if its achievable.

Sorry for the long post
 
best ive gotten out of my reg cab short bed 2wd that was lightened about as much as i could was 23mpg

but i also beat the hell out of it
 
My brother had a 98 12v qcsb 5 spd 2wd with 3.54's and he got 23 doin 75 like it was nothin so a suppose 28-30 is possible with a light foot good tune possibly some fuzzy math but its all good.
 
The best i've achieved with my 24 valve 4x4 5 speed is 24.6 mpg. I did a non-stop highway run from Utah to Washington State with the cruise set for 62-64 mph, and drove 760 something miles. I had half worn out michelin 265/75/16 highway/all-terrain tires. Edge Comp set on level 2, and 4" MBRP exhaust system.

When I added my 2" leveling kit, I lost an honest 2 mpg. Then I added some 315/75/16 mud tires and all I could muster was about 20 mpg corrected up for the 11% slow turning odometer.

I have since added Jammer 5's, Intake, HE351 turbo, and smaller 285/75/16 tires and my truck averages a lousy 16 mpg around town and 18.5 on the highway with cruise set for 72-74 mph. I'm confident my current setup could still get 20mpg if I slowed down to 62-64 mph range but the days of 24+ are long gone!

With the low front of the 2wd, I see no problem with an ordinary truck getting 26-28 mpg. Add in a few special parts like air dam and free flowing exhaust and you probably will get 30 mpg.
 
correct me if Im wrong but I think an auto has a better O/D doesnt it but I think it takes more power to turn it. I think a gear vendor might drop it down to low going around 60. I knew 30 was high but id like to see what it will do.
 
My brotherinlaw's 96 we short bedded and lowered a little will average around 22 on the highway. During the bad weather we had he never got over 60 going back and forth to work with only two stop signs to stop at and got a hair over 26 out of that tank.

It has some extra fuel but is mostly stock.
 
Do some small tires (especially in the front)*, keep the speed down. Topper wouldn't hurt. Edge Mileage max, RV275's, Synthetic oil in everything. TCC lock up switch. Coast to stops. Ditch the fan. Redo the entire front end and align. You'll get 30MPG. Been there done that. I'll post more little nuggets if I think of them. I had 5 inch exhaust and BHAF and AC completely removed.

*My tires were 245/75r16? in front and 265/75r16 in the rear. I got the front tires brand new for 10 bucks cash after install, so they might have been smaller. but I'm guessing they 245/75r16.
 
couldnt in the early 1st gens with the 3 sp auto you could get a 3.08. I would think they are available. Whats the difference between an Edge mileage max, an EZ and a Comp on 1 ( which is timing only). I was planning on going with 245/75/16 street tires on the factory 01-02 aluminum wheels, a tonnau cover, Amsoil everything, a lock up switch, I think with that set up Ill be high 20s.
 
Red Stroke said:
Yeah am am trying for the same goal with the same thread title, but I am using a 4x4, so far it has not been easy.

Project MPG: goal 30 MPG - Competition Diesel.Com - Bringing The BEST Together
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ya I read your thread I started this one since Im using a 2WD 24v Dodge but good reading. The 2 wheeler might get some 235/85/16s on it. Id really like to do a gear vendor I think it would be very possible then. I just want to be able to say I can get 30mpg. My CR only gets 18 with 4.10s, 285 tires and a snowplow so the if the 2wd even gets 25 id be happy
 
revolutiondsl said:
correct me if Im wrong but I think an auto has a better O/D doesnt it but I think it takes more power to turn it. I think a gear vendor might drop it down to low going around 60. I knew 30 was high but id like to see what it will do.
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0.04 or 0.06 for the difference in ratios compared to a 6 or 5 spd, respectively. It probably will not make a big difference in mileage, but picking where to shift definitely helps. I did a hand-calculated 24 mpg with my 02 (4x4, 6spd, ~7500 lbs) with an exhaust and intake. Cruise was on 72 mph and was strictly highway.
 
revolutiondsl said:
couldnt in the early 1st gens with the 3 sp auto you could get a 3.08. I would think they are available. Whats the difference between an Edge mileage max, an EZ and a Comp on 1 ( which is timing only). I was planning on going with 245/75/16 street tires on the factory 01-02 aluminum wheels, a tonnau cover, Amsoil everything, a lock up switch, I think with that set up Ill be high 20s.
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I don't know the difference between the two. However I have owned both, and am sold on the Edge Mileage Max for a MPG upper. The Dana 71 on the 1st gens are kind of rare and more narrow. AL rims should help too.
 
I also can't stress enough how key alignment is. If you are doing the alignment yourself, make sure Toe is on the lighter side.
 
If you gear it to high you'll be lugging it and mileage will go down. A hy or he341 turbo to build boost quicker on bottom end would probably help. a he351ve would be the ticket for the most boost at the lowest rpm's.
 
I think you need a different charger. Your gonna be low RPM and I don't think the charger you have. Possibly a 65 mm turbine with a 12 or 14.
 
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