Engine fuel economy

BOBC. I "got around" the computer & my mpg went right back up to where it was initially.

please tell me how you "got around' the computer. I've spent big $$$$$ on this '99 Mack, 460, trying to get the mileage up, and so far nothing has worked. I can't hardly get 6mpg lightly loaded and when grossed near 80k, I have to really baby it to get 5 mpg. I 've even thought about slipping a S60 dd under the hood of this dog. Whats your secret. I know its got to be that computer holding me back mileage wise, Fine truck otherwise.

 

A 13 will cost you nothing and most have a 27% overdrive compared a 15% in most 10s

 

My Buddies cat 3406E # 475 in a pete 379 3:55 , 10 overgears gets about 6.2 running with my Detriot I get 6.4 with a 12.7 # 430 in an FLD condo 3:90 and 13 double over same exact run following each other I do tend to not baby it quite so much both loaded

We are both starting to more trucks this week a W-9 areo sleeper with a 470 Detriot 10spd 3:90s
And A frightliner Classic condo with a 500 detriot 13sp and 3:55s and will let you know how they compare

now my W-9 daycabs with cat Acerts@475 and 10spd 4;10s on the same trip get about 5.5

 

I am going to have to disagree with you here.

Whether it is a 9od,10od, 13 DBl od or an 18 dbl od they have the same final drive or almost.... All 97-08 Eatons are either .73 or .74
Meritors are a little different they have 4 numbers .72, .74, .80 and .87

The difference with both the 13 and 18 Eaton is the ability to run between the gears offered in the 9 or 10 od.

Overall given the same driver, truck, terrain, engine and rear-end gears I would have to say that more gears may tend to give better milage by being able to best match rpms to terrain and load.

In the case of Meritor the 10od should do better with milage since their 13spd has that outta nowhere .87??WTF?? and their 16spd??WTF?? has a .83 final VS .73 in the 10od.

If anyone is interested in the exact ratio for each gear for tranny's PM me and I'll give you the site. Got in trouble offering this help before so I am not posting the name again.

EDIT Per Brickmans request tranny info is located here vibratesoftware under the 1997-2008 help file

 

I can't tell you anything about the 460.
I don't have any "magic" to give you.
All I did was swamp out the signal from the speedo sensor while making the ecm think the speedo sensor was still there.
This put me closer to the factory settings despite the screwy programming the garage did.
I had my best performance with the factory settings.
Empty, I'd see upwards of 8-10mpg.
Loaded I'd get close to 7mpg average.
That's with climbing hills like Tahachapi etc.
Winter was a little different due to fuel mixtures.
Not much I could do about that.

I know the difference in performance between factory & company settings.
I would drive the trucks during breakin under factory settings.
Then, the company would trick us all into going to a Mack shop for some kind of trumped up service call.
They'd cut the trucks back there.
I'd run it for awhile with their crappy settings until I just couldn't stand it anymore.

I never understood why the company opted for the poorer mpg even after I showed them it could be considerably better.
Their settings were absolutely counter-productive to the "favors" they "asked" me to perform.
--------------------------
Edit: All my trucks needed a 13.
The S10 is a good tranny for me but a 13 would have been the icing on the cake.

 

I've been swapping back and forth between an 05 and an 03 mack this last week.

the 05 has 400hp 3.86 gears 8 speed. I get really good mileage thought the thing is doggy and you have to plan your move...

6.9 mpg loaded and easy... 7.5mpg running it hard empty.

the 03 has 350hp same everything else... and I had a hard time making 6mpg. tried all different rpms shifting cruising...ect... it is a stinking p.o.s.

managed 6.2 today for a round. can't get empty mpg to match my loaded with the 05... must be company tinkering??? I dunno???

you let the clutch out and stomp the accelerator and NOTHING happens, then about three second later it gingerly but ever so slowly picks up rpms... like it has to "think" about it first...

getting my regular truck back tomorrow, Thank GoD!!!!

am looking to buy now... and it won't be a mack... ever !!!! lol


and I'm very interested in the site with the tranny info... I want a 13 just didn't want to cut my own throat to have one... mpg wise.

still want to run the gear ratio / tranny ratio numbers to see what speeds at what rpms would be going on...

can't see buying and then finding out I'm not liking the cruising... or there is a mysterious dead spot at my favorit mph...

 

I'm looking real close at buying an 05 W900 with 475/10OD/3:36's, the ECM says 6.1 overall MPG for 386,000 miles, not great but not terrible and I can live with it. I doubt it would get much better with a 13 or 18 in it. BUT - doing the mods to the Kitty Cat that 550 described - extrude honing the injectors, muffler swap out and wires for a total investment of maybe 2K to get another 4 or 5 tenths and a buncha power are really exciting!

 

i would love to have the site as that is not what I have found I looked up the ratios for my 13 but was taking my buddies word on his but I do know they are not the same final drive as his 3:55 in high are turning a little more rpm then my 3:90s with his 10 both are eatons he is running 24 low/pro and I am running 22 talls

i will get his tranny number later and look it up