I love diesle,love the sound of the turbo spooling up and the monster torque, i come from a otr back round and have seen some fine trucks out there doing incredible things with big loads in houston,so i was wondering, if and where there is a break in power v. milage. i figure with up to double the torque from the factory,there ought to be some really high numbers,coz so much power available at cruise speeds,if all things were equalized. know what ime getting at?say a stock tired 04 ram @265/70/17 factory tires running at stock hight.v. a truck with a heavily modified engine running over 750 to 1000 lbs of torque, i think the monster motor would get huge numbers at cruise vs the stocker,any one got any numbers?
wouldnt it be cool to find the right combo to get high milaage?? or just a pipe dream, ps.i could get my 15 litre cummins into the high 11's  mpg with 80k + on the road.most average 6 mpg  

It's all in how you drive them. I'll be putting up the results from the 2008 Diesel Power Challenge soon, and some of those trucks, even the ones that had crazy power and posted super-fast quarter-mile times, got 20 mpg or better on the open road.

15-liter? I'm assuming you're talking about a big rig. 11 mpg for one of those bruisers is pretty impressive.

Sometimes I have to wonder if the yahoos complaining about crappy mileage are always driving them foot-to-the-floor. Well, duh!  

im running 450 dyno proven hp and 1170 ft lbs, its not insane power but its not to shabby either, but my fuel mileage flirts with 23 highway, its the city that kills me, maybe 15 city but it aint bad,especially with 150 hp injectors. i average 18-19 mpg on a tank with 50 percent city and 50 percent highway.  

to give you an idea, my stock 98 24 valve gets 17 highway and 15 city.  

thanks for the come back! i figured that with like what duke boy was saying that torque figure IS impresive! but i know with this there has to be more fuel used as well, well these trucks are heavy weights! as for the 15 liter engine,it was in a class 8 international..my absolut best was 13.2 mpg,strait and flat and little wind and 80k!
My ideology totaly revolves around driving style.the same truck under a no brain idiot averaged 4-3.5 mpg,dumbbutt thought he only way to drive is foot to the floor all the time. btw,i blew the intercooler elbow off a cat in the 90's some thing in the computer wen nuts and got some crazy boost numbers for a few minutes,houston freightliner did a great job though and fixed it pronto,but it sure did make some funny noises and lost 90% of its power,wonder if its like this when ya do it to a 3/4 or 1 ton? thanks  

I'm pushing 500hp and 850 ft/lbs of torque in my DMax and can still get 18 city and 24 highway.  It's all about how you drive it.  That's why I like my adjust on the fly programmer, that let's me adjust output for different driving conditions.  

yes its the same in the 3/4 ton and 1 ton trucks, if an intercooler boot bows off, youll loose 90-100 percent of your power and smoke like a ***  

I drove my 2007 Dodge Cummins 5.9 about 275 miles or so this weekend I got in the high 25mpg's  But thats with the air intake CFM manifold, turbo, water meth injection, five inch exhaust and the torque converter.  Granted I have more done, but those are major peformance boosters I have, and the valve body of course.  

if you put to big of a turbo on them and its got a lot slower spool speed then it will drop your city driven mileage and some towing mileage to i know it did my buddys he lost about 1 mile to the gallon still gets 17.5 in a 1 ton but they said he would out grow a smaller one to soon if he did to many more mods i think a 62 instead of the 64 would be fine for most mods like programmers and maybe 50 hp injectors thats my goal anyway more power and still really steet able.  the larger turbos that spool slower would be better at higher rpms but city driving and towing i wouldnt want to have my foot into it  pulling a trailer all the time you might.