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Topic: 8.3 and 34' Performance (Read 1126 times) previous topic - next topic

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  • jor
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8.3 and 34' Performance
Just got back from a 3500 mile trip much of which was in hilly and mountainous terrain . The 8.3 did great. When we first got this rig I expected that the performance of the 8.3 would be a disappointment when compared to the two M11s we've had...

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Re: 8.3 and 34' Performance
Reply #1
At 34 feet long, look at the length of the wheelbase. If a Vanagon or Porsche 911 can be on rails with their ultra short wheelbase, a 34 foot RV sure will be. So much for the armchair QBs and the unstable short rear engine RV theories.

8.3 Cummins...

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Re: 8.3 and 34' Performance
Reply #2
A lot of owners have regeared the rear axle to the later higher  ratio. 

Were you in the Rockies much?

Changing the fan drive controller to the 199 degree unit will free up to 50hp

Re: 8.3 and 34' Performance
Reply #3
Following on John's 8.3 engine comments: we have never been disappointed on the steepest mountain, pulling our 5,600 lb Jeep Grand. For us, its 50mph in 5th gear, 40mph 4th, 30mph 3rd and if going slow on very steep like a winding climb out of a...

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Re: 8.3 and 34' Performance
Reply #4
Changing the fan drive controller to the 199 degree unit will free up to 50hp

I know those fans are power hogs but has this 50 hp claim been dyno proven by any chance?  That's a lot, especially...

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Re: 8.3 and 34' Performance
Reply #5
Chuck,

I want back and pulled the engineering data from when I worked with Caterpillar Corp on this: ***Understanding Coach /RV Performance***  Full document clickable at the bottom of that page.

Fan HP demand depends on both engine RPM and engine...

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Re: 8.3 and 34' Performance
Reply #6
Thanks Brett, that is very interesting.  Never been able to sense a point when the fan kicks to high, probably because even when climbing and towing (my guess is) engine is not near near max hp and temp generally peaks near 200 deg.  I use Barry...

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Re: 8.3 and 34' Performance
Reply #7
My 34' does not track as straight as I'd like. I think I have worn bushings in the rear axle.

The hydraulic cooling fans are controlled by the "mechanical" wax capsule. It doesn't turn the fans on/off, it varies them (as far as I can tell).

I...

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Re: 8.3 and 34' Performance
Reply #8
Krush,

How about driving in a parking lot until the wheel is centered and then doing the string alignment from the back tires to the front? A little toe in keeps the coach pretty straight. Uneven front tire pressure can make it move around as...

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Re: 8.3 and 34' Performance
Reply #9
BTW, we are never full WOT full throttle pedal to the floor, even when climbing. It takes some light feathering to not push more than we need to go faster. Watching tach & EGT pyrometer keep us from pushing down too much on the throttle.

On our...

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Re: 8.3 and 34' Performance
Reply #10
Man, since we're essentially pushing half a billboard down the road with a flat nose coach, makes me wonder what hanging an auxiliary radiator and wind scoop (roof perhaps) would do.  Seems unlikely, given the dirty aerodynamics, there would be...

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Re: 8.3 and 34' Performance
Reply #11
Man, since we're essentially pushing half a billboard down the road with a flat nose coach, makes me wonder what hanging an auxiliary radiator and wind scoop (roof perhaps) would do.  Seems...


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  • jcus
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Re: 8.3 and 34' Performance
Reply #12
DEUTZ - Air cooled diesel engines
These Deutz air cooled engines are used on some ships as emergency generators, because they can be placed in the upper floors of the deck house, and it is not necessary to have sea water cooled heat exchangers,...

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Re: 8.3 and 34' Performance
Reply #13
DEUTZ - Air cooled diesel engines
These Deutz air cooled engines are used on some ships as emergency generators, because they can be placed in the upper floors of the deck house, and it is not...


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Re: 8.3 and 34' Performance
Reply #14
DEUTZ - Air cooled diesel engines
These Deutz air cooled engines are used on some ships as emergency generators, because they can be placed in the upper floors of the deck house, and it is not...


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Re: 8.3 and 34' Performance
Reply #15
We have the slightly newer 8.3 in our 34' and also do not have any complaints when it comes to performance. We have put a little over 3400 miles on our coach since we bought it . Now I don't have any real comparison to the M 11 or other coaches...

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  • jcus
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Re: 8.3 and 34' Performance
Reply #16
We have the slightly newer 8.3 in our 34' and also do not have any complaints when it comes to performance. We have put a little over 3400 miles on our coach since we bought it . Now I...


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Re: 8.3 and 34' Performance
Reply #17
Krush,

How about driving in a parking lot until the wheel is centered and then doing the string alignment from the back tires to the front? A little toe in keeps the coach pretty...


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  • John44
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Re: 8.3 and 34' Performance
Reply #18
Front and back the coach has 10 arms and 40 bushing halves,your bushings are probably as hard as a rock.

Re: 8.3 and 34' Performance
Reply #19
Sounds about right on the toe in. Wonder if you could have a bad or weak rear shock on one side? If I can get my wife interested, I like to be under the front of a vehicle and have her rock the steering wheel back and forth.

Pierce

Re: 8.3 and 34' Performance
Reply #20
I know you're in recommended range for static toe in measurement. As long as  you have a super tight front suspension. Easy enough to add some and see if it helps.  I was never satisfied with recommended.

Rear axle, seems like hard acceleration...

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Re: 8.3 and 34' Performance
Reply #21
Sounds really minimal for static toe in measurement. Unless you have a super tight front suspension. Easy enough to add some and see if it helps. 
Think he did but got feathering on the...

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Re: 8.3 and 34' Performance
Reply #22
When my Michelins aged out I recently replaced with Toyo M177 as well.  I measured toe at that point, realized I'd been running 3/8" on the Michelins and reset it to 1/8, thinking that the strong directional ribs on the Toyos wouldn't need as...

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Re: 8.3 and 34' Performance
Reply #23
The scrubbing on the old tires could also have been some weird wear from before I owned the RV.  I'm just a little more careful with the toe-in now that I have brand new tires up front.  The wander is not really coming from the front.  I'm not...

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Re: 8.3 and 34' Performance
Reply #24
Brett all the 97's have the same cooling system and hydraulic controls as far as I know. 

Fan on low until 165.  Then ramps up to full speed at 180.  So warmed up it's full speed.

As the 8.3 revs higher my thought it uses more power than a lower...

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