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Author Topic: I have finally figured out what's behind my repower obsession  (Read 3991 times)
RickB
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« on: October 17, 2010, 05:42:02 PM »

Hey all,

Went camping with the family at the interstate park in taylors falls MN this weekend and after all this flip flopping about whether or not I need a repower I finally figured why this had been such a issue for me. Since the accident and even for a few times before that I had went on a number of relatively short trips and had found myself agreeing with my friends who tell me i'm nuts for wanting to get rid of my very healthy 8V71 (I can hear you laughing Gumpy) and then this weekend's trip of about 40 miles each way was just plain miserable I had a reasonable headwind but I'm telling you it wasn't just slow up these hills it felt like it was too close to asking for a major engine malfunction due to the lack of power up relatively short and not all that steep hills. So what had changed between the week before and this weekend?
The tow vehicle.
That's it in a nutshell...If I want to feel relatively happy with the performance and reliability of my bus I am not going to be able to stay with my motor without mods (turbo, bigger injectors) or a completely different motor OR I'm not going to be able to tow my car anymore. It is just too close to feeling like I'm pushing a horse that is incapable of doing what I ask of it without major risk to it's well being.
With that in mind, all you 8V71 repower freaks out there, have you made the same connection.

I bought an awesome bus and then I added a tow hitch to it and that's when I became unhappy with it's performance.

That's it in a nutshell I guess. BTW the park and the time with my family was just too good for words.

I really am a happy camper.

Thanks

RB
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robertglines1
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« Reply #1 on: October 17, 2010, 06:10:46 PM »

I know the feeling..advice go big 4 stroke and go for better fuel mileage at same time. PS I pulled 8000lb with my 8V92 once and couldn't tell the differance from pulling the HHR..In the 89 prevost.
« Last Edit: October 17, 2010, 07:12:26 PM by robertglines1 » Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
Lin
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« Reply #2 on: October 17, 2010, 06:13:25 PM »

I agree.  Hooking up the toad changes everything.  You've got a big loss of power and maneuverability, adds greatly to your length, and not being able to back up means you are partially crippled.  If I could avoid it, I would.  If you ever find an inflatable car that could roll up and fit in a bay, let me know.
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longjohn
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« Reply #3 on: October 17, 2010, 06:47:56 PM »

"That's it in a nutshell I guess. BTW the park and the time with my family was just too good for words.

I really am a happy camper."

 Rick,
Isn't  that what it's all about. get your self one (or two or three)of those little scooters that you see running around everywhere. Smiley
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John O
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busnut104
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« Reply #4 on: October 17, 2010, 06:59:02 PM »

Pulled out the 8v-71 and installed a 8v-92 445 hp. just love it. Set the cruse and let her go.
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Ericbsc
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« Reply #5 on: October 17, 2010, 07:38:29 PM »

I know the feeling!! Two wks ago to Gatlinburg, I40. Can't get speed down hill for traffic, then 35-40 uphill with horns and fingers galore!! Yep, the 8-71 sound sweet runs great. It has no a** at all with a 16' trailer with bikes etc. Goin series 60 with world!! Got brakes, cruise, and better mileage!!
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Greg Smith
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« Reply #6 on: October 17, 2010, 07:39:25 PM »

Sorry, not wanting to hi-jack.

busnut104, did you notice any difference in fuel economy???

Greg
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luvrbus
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« Reply #7 on: October 17, 2010, 08:04:27 PM »

You guys are only kidding yourself if you think a 12.1 8v92 won't hang with a 12.7 series 60 and get just as good of fuel mileage and torque,stick with your 8v92 idea Rick no re gearing and all the electronic BS to worry with
Pull into a DD dealer and it will cost you 1000 bucks for a bad 50 dollar sensor I know this for a fact I am looking a bill from Stewart and Stevenson that I just wrote a check for to mail Monday  



good luck
« Last Edit: October 17, 2010, 08:06:48 PM by luvrbus » Logged

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Melbo
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« Reply #8 on: October 17, 2010, 08:47:54 PM »

A good running 71 might be alright but I had overheating issues and was told that it was time for a rebuild.

I had an L10 put in -- I have had to make a couple of changes since the repower --- It is fun to drive now -- I didn't add a lot of HP but I have no electronics to worry about and I have no heating issues

I notice the toad when I am going downhill in the mountains on the two lane roads -- the toad has brake assist and I have to use the brakes for it to kick in

If you have a healthy 71 and no heat issues you may be able to do something to keep you happy and not make major changes.

And yes the gearing can be an issue

Just my two cents

YMMV

Melbo
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robertglines1
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« Reply #9 on: October 17, 2010, 09:01:27 PM »

I have a 8v92 now 5 mpg..if I can get same power from 60 series and get over 7 that's a lot of fuel..I hear claims that the 8V92 can be tuned to get mpg but its past me and I am of the impression that I will not have to do anything to the 60 to get it to preform..S o yes I'm sure the experts can do it but at what cost..Guess I'm just dumb so will take the easy way out with guidance from others..  I'm hoping for over seven so Rick it's your decision.I weight 36,100 lbs plus 3000 lb hhr 5 mpg at 70mph.  healthy discussion  those who say they can do it should tell the rest of us how.  bob
« Last Edit: October 17, 2010, 09:04:01 PM by robertglines1 » Logged

Bob@Judy  98 XLE prevost with 3 slides --Home done---last one! SW INdiana
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« Reply #10 on: October 18, 2010, 04:40:08 AM »

Bob, no one is calling you dumb your XLE came with 60 series why change we are talking about a repower here big bucks.
With your setup you may get 7 mpg that is about what Jim gets on his 40 ft Eagle with a 60 series.
I know Hemphill Bros. have the H-45 with series 60 egr engines 515 hp and he tells me 4.8 to 5.6 mph tops.
Now I will tell you what dumb is a friend let the same guy that installed Melbo's engine into pulling a good 8v92 12.1 L and installing a L10 in his Eagle went from 450 hp down to 300 hp sad part he paid 10 grand labor plus the engine and parts
L10's are a good engine but on power they are not any better than a 8v71 or a 6v92.
I could never get the 9.5 mpg like Don on his 8v92 because of gearing but 7 to 7.5 with generator time at 70mph was never a problem give a 8v92 the right air to fuel and it will carry the mail as cheap on fuel as any engine on the road in it class and with a MUI engine no need to carry a Pro-Link in your pocket


good luck
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cody
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« Reply #11 on: October 18, 2010, 05:17:04 AM »

I have a 6V92 in my iggle and it doesn't seem to know if I'm pulling my full sized dodge ram 1500 4x4 or not and that truck is heavy, I don't seem to notice any power loss with the truck behind and the fuel usage seems to be the same either way, what am I doing wrong.
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Eagle Andy
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« Reply #12 on: October 18, 2010, 05:31:29 AM »

Well we have a 8v92 and when I first bought the monster I was leaving phoenix and was pulling sunset point with car on a dolly. Now never having drivin a 92 before I thought to my self (boy did I make a mistake) what a gutless turd. Then four years later and a few changes , Like bigger air cleaner I mean twice as big as what was on there , I also installed an air throttle bingo life is good . Now I don;t get more than 6.5 mpg in this old girl and she weights 34,800 lbs and we pull a 5500 lb Tahoe. It is what it is fellas if you got the money  do what ya gotta do but I'll stick with this ole 92 for sure  Grin
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RickB
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« Reply #13 on: October 18, 2010, 05:41:46 AM »

Hey Clifford I think I finally tracked down a TV7101 but I need all the stuff to put it on. Intake manifold (and I'm pretty sure the 8v92 intake/turbo mount has a different bolt pattern) I need the y pipe and all the plumbing. Also where am I gonna get an oil supply for this thing? I guess I could y off at the rear mounted oil pressure gauge but that would mean I'm pushing oil from the bottom of the engine to the top any thoughts?

Also, will I lose my emergency shutdown flapper? That thing kind of reassures me but the 8v92's must have a shutdown system as well right. I'm thinking a fuel shutoff switch.

Here's my logic regarding the other posts. With a 9 unless you are a fabricating genius and have hundreds of hours to work on your bus the repower up to anything other than an 8v92 or a 6v92 from a 8V71 has far too many unforeseen consequences and they are all expensive. I will never drive my bus enough to make back the 15k it would cost me if I got a mpg or two better mileage ( I can't weld and Brian Diehl said from experience "take what you think it's gonna cost to do a 4 stroke repower in time and money and double it".) and I would have to do major mods to the length and height of my engine compartment to do it.

In reagrds to the earlier post about cooling, I have completely rebuilt my cooling system with the larger 8v92 radiaitors and feel I could add a turbo to my existing motor or an 8v92 without any cooling issues.

Robert as far as the mpg issue goes Lea and I have discussed this at length and we have come to the conclusion that this is our main family source of recreation and yes with fuel at 3 bucks a gallon it costs me 50 cents a mile but it still works out in my favor when I compare my brother in laws trips with his family to Disneyworld with airfare hotels food etc. I used to think that 7-9 mpg would radically change my world but when you're only putting on 5k a year it just doesn't make that big of a difference. Some of you folks that are fulltiming it would make a really big difference but that's just not our reality anymore. I had to quit thinking of my bus as a 401k like I would invest in it and it would make me money. No matter how we look at it, if we are not using our buses for commerce (and I know we are all good little boys and girls Grin Grin and wouldn't dream of making money in our buses), this is an outflow of money to more or less of a degree and not an inflow.

I am leaning towards Don's advice to put a lo boost turbo on, some bigger injectors sneak about 50-75 more hp out of my existing motor and if she blows up then I don't have to argue with the wife about a repower Grin. Pretty sneaky huh?

Moving forward one way or another.

I can't ake another hill wondering if my 8V71 is gonna put a rod through the crankcase in protest of what I keep asking it to do.

RB

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Ace
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« Reply #14 on: October 18, 2010, 05:47:50 AM »

I too thought about re-powering UP to a 60 series for better mpg but after figuring in the cost of the engine, the misc items needed for the swap, it was going to be up there pretty good, and to me, that would be a lot of fuel money that I probably would NEVER get back in my lifetime!
A friend of mine just re-powered his neo-plan with a 60 series to the tune upwards in the 30k range and that is figuring in his old motor and trans in a trade. It took about 3 1/2 months working on it EVERY day! Sure it runs good, looks good and the only thing he will probably get better is pulling hills from the extra torque over the 92 series. As for fuel mileage compared to the 92, probably going to be close to the same or worse since he went up in hp by only 50 and he COULD have re-programmed his old engine to get that!

Mine runs good, runs cool, pulls the hills, and will run 80 easy, even pulling my stacker trailer for now, and IF anything ever was to happen to it, I MIGHT consider it, but until then, that money I would spend on the re-power, in this economy is staying with ME!
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Ace Rossi
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Prevost H3-40
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