355 to 308 ratio?

[JimT]

(04-16-2022 )earnies2 Wrote:  I just can't seem to discipline myself to run 55 when I'm getting passed by prime and swift in Oklahoma where the speed limit is 75...

What do those other trucks have to do with your truck? your delivery schedule? your fuel costs? ... nothing! Who cares if they pass you? It's not a race against other trucks. Run your business based on your needs, not based on the actions of others. If you need to go faster to keep a certain schedule and your rates reflect the higher costs you will incur in fuel and maintenance then do what you need to do. But any time you can slow down and still get the job done then that means more profit for you in the end.

As for your original statement, you didn't specify what RPM, gear choice and boost levels go along with both fuel mileage scenarios. That is, when running 55 getting better fuel mileage what gear are you in, what's your RPMs, how much boost are you using? Same for the higher speed/lower fuel mileage. I suspect those details will reveal why the difference in fuel mileage and will help to find a solution.

[Rawze]

(04-16-2022 )earnies2 Wrote:  ...
Are the liners and engine differant on a 2018 versus my 2009? I'm basing my facts on all the newer trucks all have tall gears and get way better fuel millage than my 2009.
Please explain.

no, they are not.. that complete bullsH$it that you have been fed about taller rears and better fuel mileage comes from the idiots who do not know how to properly drive a truck. Here is an explanation of this...

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These newer trucks that are geared way too tall,.. they get better fuel mileage, directly at the expense of engine life. Not because the gearing is any better,.. it is much WORSE... but because when an engine is running in low rpm ranges (because it is geared too tall),.. it is COMPLETELY UNABLE TO MAKE FULL POWER OUTPUT! - and therefore is exactly the equivalent as someone who is geared lower, but stays off the pedal, and only allow their engine to only make that limited power as well. -- it is the mega-fleets latest bean-counter way of making the engine limit its power output production, while the idiot driver holds the pedal all they way to the floor all day long.


I.E.> gear it too tall, so that full engine power cannot be produce,. saving fuel at the direct expense of engine life -- OR,.. Gear it right (BASED ON PROPER LOAD APPLICATION) and learn to control/limit your engine's power just like the "geared too tall trucks" and get the same, or better fuel saving by learning to use your right foot better, and driving by your boost and pyro gauges.

-- Take even a 600HP, 2050 torque engine for example. If someone gears it tall, like 3.27's or some other ridiculously tall garbage then limits its rpm range to 1500 and below with gear-down protection + it can only go about 68 mph on a governor... then its average HP output for the engine is only 440HP to the tires when loaded heavy ... EVEN WITH a full 2050 torque. - As soon as you put a load on it and then try to go up a hill.. it falls on its face and that high torque beats the liners out of the engine 2x faster than normal.. cutting the engine life in half. - BECAUSE YOU HAVE ARTIFICIALLY LOWERED THE AVERAGE HORSEPOWER TO ABOUT 435 OR SO WHEN PULLING HILLS AND THIS IN TURN SAVES FUEL NO MATER HOW HARD THE TRUCK DRIVER SMASHES THE PEDAL DOWN >>>> BECAUSE THE ENGINE IS UNABLE TO MAKE A SUSTAINED FULL POWER!. -> ALL AT THE DIRECT EXPENSE OF THE ENGINE LIFE DUE TO LUGGING IT BELOW 1500!.

ANY VEHICLE THAT YOU GEAR HORRIBLY .. THAT CAN NO LONGER PRODUCE PROPER HORSEPOWER.. WILL HAVE BETTER FUEL ECONOMY BECAUSE IT WILL NOT BE ABLE TO MAKE ITS FULL POWER IN A SUSTAINED FASHION!... AND THE TRUCK OWNER COMPLAINING ALL THE TIME THAT IT FEELS WEAK!. -- AND IT IS ALWAYS AT THE COST OF ENGINE LIFESPAN WHEN YOU DO THIS!. THAT IS WHY THESE FLEET TRUCKS GEARED TOO TALL ALWAYS NEED AN IN-FRAME IN HALF THE EXPECTED TIME THEY SHOULD LAST!.

GEAR IT CORRECTLY.. SO THAT IT DOES NOT EAT THE ENGINE UP.. AND IT MATCHES THE LOADS AND APPLICATION.. AND THEN KEEP YOUR GODDAMN RIGHT FOOT OUT OF IT AND IT IS ACTUALLY FAR MORE EFFICIENT THAN THIS HORRIBLE LUGGING IDEAS... AND YOU DON'T EAT THE ENGINES GUTS OUT 2X FASTER ANY MORE!.. ITS CALLED DRIVING IT RIGHT VS SOME COMPLETE DUMBARSSE THAT HAS VERY POOR CONTROL ON HOW TO DRIVE A HEAVY TRUCK PROPERLY and holds the pedal all they way to the floor all day long.

THESE MEGA-FLEETS FIGURED OUT HOW TO LIMIT THEIR DRIVERS RIGHT FOOT BY GEARING IT WAY TOO TALL.. AND THAT SAVES THEM FUEL AT THE DIRECT EXPENSE OF ENGINE LIFE... AND THEY COULD GIVE A DAMN ABOUT LONGEVITY BECAUSE THEY GET RID OF THE TRUCK BEFORE IT BLOWS IT =S GUTS OUT.. LEAVING THAT PROBLEM TO THE NEXT POOR BAS#TARD THAT BUYS IT USED!.

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ref: http://rawze.com/forums/showthread.php?t...7#pid48627


SO YEAH.. SOMEONE HAS BEEN DRINKING THE COOL=-AIDE ON THAT ONE, JUST LIKE THE IDIOTS OVER ON SOCIAL MEDAI AND THE OTHER WEBSITES .. AND LIKE AN IDIOT, BELIEVES THE GARBAGE OUT THERE ABOUT TALLER REARS BEING ACTUALLY MORE FUEL EFFICIENT WHEN COMPARED TO SOMEONE WHO ACTUALLY KNOWS HOW TO DRIVE A TRUCK PROPERLY, IN THE CORRECT RPM AND GEARING RANGES, ETC... AND JUST LEAVES THEIR FOOT IN THE DAMN FLOOR ALL DAY LONG .. PLAIN AND SIMPLE!.


SO FOR EVERY SINGLE PERSON WHO CLAIM THEY GOT BETTER FUEL MILEAGE OUT OF A TALLER-GEARED TRUCK.. IS THE SAME PEOPLE WHO DON;T KNOW HOW TO CONTROL THEIR RIGHT FOOT,.. AND THEY ARE SIMPLY LETTING THAT LIMITED HP AND TERRIBLE GEAR RANGE MAKE UP FOR THIS FACT THAT THEY DON'T KNOW HOW TO DRIVE IT RIGHT.. OR ARE TOO GODDAMN LAZY TO PROPERLY SHIFT WHEN NEEDED!.

[Rawze]

This is also the same reasons that there is a gaggle of truck owners that have 600+ HP and big torque.. and always complain they "need a better tune" because their truck feels weak.. I HATE TO INFORM THEM BUT IT IS NOT THE ENGINES FAULT.. IT IS THE HORRIBLE REAR END RATIOS THEY USE AND ENGINE/DRIVE LINE CANNOT GET THE POWER TO THE WHEELS!.

[Kw9006nz]

My original ratio was 3:55 I got lopro 24.5 and a 13a trans with a 550 cat with 1.54 million.....currently in the process of selling because of parts and people paying an insane amount for them ha my gain.

[Waterloo]

I'm running the 3:42 with the 600hp 18 Spd, and can tell you your mileage will not differ by much at all, if any. I get my best mileage running in high 7 at right around 60 +/- 2 mph. The rpm is right around 1500 - 1600. I'm pulling a van, mid roof, so my fuel mileage is usually around 6.5 mpg, my truck is a bit of a pig, a heavy pig. I would stick with what you have and keep that money in your pocket. Like Rawze and others have said, you will just beat the motor to death... And having been through two in frames in my ProStar, you don't want to go there.

[Precisionw900]

(04-18-2022 )Waterloo Wrote:  I'm running the 3:42 with the 600hp 18 Spd, and can tell you your mileage will not differ by much at all, if any. I get my best mileage running in high 7 at right around 60 +/- 2 mph. The rpm is right around 1500 - 1600. I'm pulling a van, mid roof, so my fuel mileage is usually around 6.5 mpg, my truck is a bit of a pig, a heavy pig. I would stick with what you have and keep that money in your pocket. Like Rawze and others have said, you will just beat the motor to death... And having been through two in frames in my ProStar, you don't want to go there.

I’m running same set up except set at 550 and you are right. The high side of 7th or low side of 8th is the sweet spot, can run 60-65mph and keep below 20 psi of boost. I only use the high side of eighth unloaded on the big highway. I would never step over a 3.70 with a 10 speed.

[JMBT]

I have 3:70’s with a 10spd, and for my application it sucks! I need 3:90’s to run with my 10 SPD in my application. I run 22.5LP tires. When the motor was new and not too worn out I did ok, but now With the worn out motor, I have to hit hills at 65mph to keep the rpm range above 1500. My climbing speed with proper rpm range is 52 in 9th or 65 in 10th, anything less puts me below 1500. So 3:90’s would have been a better choice for me. I could then run 55-60 get the good fuel economy. And still be in the non-danger zone for rpms.