'86 Prevost, 8V92T mechanical, OE manual tranny, minimal conversion as yet.
Anyone got experience on this or a SWAG? 7?
TIA
Ted.
I calculated mine when I drove the bus home and I figured a little over 5mpg. My coach does not have an odometer anymore, so I had to use google maps for the distance. Also a note that I was pushing it pretty good, which will have a big effect on mpg.
Jeff LoGiudice
1986 TMC 102A3
Silver 6V92TA
Allison 740
Quote from: TedCalvert on March 05, 2016, 04:53:50 AM
'86 Prevost, 8V92T mechanical, OE manual tranny, minimal conversion as yet.
Anyone got experience on this or a SWAG? 7?
1981, 96" coach with 8V92T & a 10 speed Roadranger - so pretty similar. 42 - 44,000# Gross including the towed.
We got between 6 & 6.5 MPG but that's an Imperial gallon, not that wimpy @$# thing you guys call a gallon so probably barely 5 miles per wimpy @$# gallon. That's over a lot of miles - 100,000++. It went up a bit under ideal conditions (if I kept my foot out of it on the interstates) and down a lot under crap conditions (high furnace use).
6v71 may be slow but 8.4 mpg is worth it
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8.5 miles per real gallon. 7 per wimpy a** gallon. But you know, it doesn't really matter: all you can do is fill it up when it is empty,and keep driving. Enjoy now while the price is low. It has started going back up.
JC
My 8v92 TA with 5 speed gets a shade under 6 mpg. This fluctuates up or down a half gallon based on headwind, heavy foot, hills, etc. I am only 34,500# but always tow a Honda CRV.
YMMV - ha ha!
Mike in GA
87 8V92T, 36,000 lbs Allison 4spd, no toad.
Not too many trips yet, but so far, the results -
Pushing hard (75 to 80 mph) with gen set = almost 6mpg :'(
Taking it as easy as practical (55 to 65 mph) without genset = 6mpg :o ???
The conclusion I have come to is that it really doesn't matter. The benefits of "Taking the good life with me" out weighs the cost. That & the 300 gallon capacity allows time to get over the cost from the last time I filled it up. ;D
When fuel mileage becomes the governing issue concerning using our coach, it will be time to sell it & get used to staying home.
What Kyle said. If you really want to cry about mileage try owning a boat - our last fill barely broke 1.5 (nautical) miles per gallon. I'm ecstatic if I hit 2 MPG.
I haven't actually kept track of mpg, but I think that the EPA rates the MC5a at 18 city and 22 hwy. I am probably getting a bit less though.
Crown Supercoach ex schoolie. 1974, 40x8x10.5 ten wheeler. About 24,500# stripped. Small Cam Cummings 855 250hp with no turbo. RTO910 Fuller 10 speed Roadranger with 3.90 gears and 12.5x22.5 tires. About 1500 rpm at 60 mph. Got right at 10.3 US mpg from Palmdale CA to Cave Junction OR. Slight prevailing headwinds. Long ago.
The last 3 fillups in my 5A with the new rebuilt engine and a 4 speed Allison were 7.88, 7.86, and 8 on the nose. ;D
Fuel mileage is all about weight and the right foot
Interesting information and opinions. Thank you all.
In my limited experience, I would have hoped for around 7, but I guess I was being overly optimistic. I drove E-models in charter service when they first came out, they were equipped with a display. IIRC the company wanted us to aim for 7, 6 1/2 was more common.
The cost is what it is; nice to know for planning.
Lin, you are kidding, right? Did the EPA even exist when the 5 was built?
Ted.
About 7-ish-ish at a steady 60 MPH (or 95 KMH, sounds faster that way), weighing about 27K now but it's not fully converted yet. I've wondered about swapping to a 3.7 rear end, but because my bus has the aerodynamics of a brick karzi (it's not one of the Twinkie-shaped Crowns that can get up to 12 MPG) it may not mean any reduced fuel consumption if the engine's working just as hard but at 200 RPM less. It certainly wouldn't be cost-effective, not unless I had to change the diff anyway and I got a bonzer deal on a 3.7.
John
My 8v92TA with 3:36 rear gear,740 Allison @ 39,000 was a constant 7 to 7.5 mpg set at 450hp @ 68 mph, when I would up the HP up to around 500 hp then it 5 to 5.5 mpg
I expect my mileage to be poor. Better when I drive with my wallet between my foot and the throttle pedal.
Out on the interstate, running Toronto to Arcadia, did it both ways:
at 70 mph, 6 mpg US
at 60 mph, 7 mpg US.
Anything involving city, down it goes from there.
happy coaching!
buswarrior
I think Uncle Ned said he gets 12! (I might have the wrong guy)
6 MPG coming to a rally and 6 MPG leaving a rally for a total of 12 MPG :D ;D ;D
Steve It is all in the numbers. figures lie and lairs figure.
uncle ned
Just got back from Daytona last night pulling a 20 foot enclosed with 3 bikes inside at 68 MPH.
9.25 on the way down and 9 on the way back.
Wow, Ken, that's great!
Probably that gearbox keeping the engine in the sweet spot has a LOT to do with your mpg?
I've lusted after self-shifting gearboxes since I first heard of them. Took a short drive in a vanHool with ZF box and didn't realize it wasn't a slip-box until the owner told me. Just felt like someone competent was shifting with clutch. I guess that someone was 'Auto', lol
Congratulations on a great improvement.
Can one retrofit an Auto-shift to a mechanical 92 series? It has air throttle, so if the tranny computer has something like a 0-10 volt output to run the throttle, that could be used to vary air pressure; or is it way more complicated? Just thinking, may be too early for that!
3:30 something rear gives me about 1380 RPM at 68 MPH. I'm about 90% satisfied with the Ultrashift, red light to red light or stuck in a traffic jam it's a bit aggregating because it shifts so much.
Ken
so if I am hearing right you are complaining about to many gears ! ....if I could only be so lucky
dave
It really doesn't need all those gears because I'm only pulling about 40,000 lbs instead of the 80,000 it was designed to pull around. But yes, I'll take that over not enough gears.
Ken
The Allison TC -10 is making it's mark in the 10 speed world the drivers I speak with love that transmission. A food supplier here has 5 Internationals with the ISX 15 Cummins engines and 10 speed Allison the owner is claiming 1+ MPG better over the same truck and engine equipped with the Eaton.There you go Ken that will put you over 10mpg if it's true. It really is a nice transmission I wish I would have kept mine just to try it but the B500 does a good job for me behind the 60 series it's 7.3 mpg not bad for a 45 ft bus
I don't think the TC 10 will fit, too long, diameter too large or something. I'd love have it in place of my Ultrashift but I would need to change diff ratios to keep my RPMS's where they are now because top gear in the Allison is a little lower than the Eaton top gear. My goal is to always average 10 MPG or over and I still have 4 things left to try. Ceramic exhaust manifold and a conventional 14 liter turbo, larger injectors from the 630 HP 14 liter generator engine and a free flow exhaust system. I think it's possible, I'll just have to throw more money and time at it. Of course like most folks both of those are limited.
Ken
Kent (RIP) did a good job installing the M11 and B500 or it maybe a 10 speed I never looked in the 81 Prevost Kenny owns now I think he is over 10 mpg if Kenny would keep it under 75 mph but he likes to roll and roll it will
Yeah, an ISM common rail with a TC10 and the right diff ratio would be a sweet set up.
Ken
We run 3 MCI's with Eaton 10 speed auto shifts in our fleet, I like them if I am driving them myself, but can be difficult with different drivers. I personally really love them in the mountains, always have the best gear. When doing "regular" charter work with a good mix of city driving, we don't see a huge fuel mileage change over the B500's. On a highly interstate long distance trip we see .75 to 1 mpg difference. The big problem now is getting parts for the old auto shifts.