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Author Topic: Difference between 4104 and 4106  (Read 3097 times)
harleyman_1000
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« on: February 13, 2013, 06:37:32 PM »

 I know the engines are 6 and 8 cyl, but is there really that big of a difference in speed and power between them?  What other differences are there?
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Scott 
St.Louis Missouri

1958 GM 4104 Extended 2 feet, with a 6v92 and 5 speed automatic

http://s783.photobucket.com/user/harleyman_1000/library/Gm4104%20bus?sort=3&page=1
bkelly1011
Brad Kelly
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« Reply #1 on: February 13, 2013, 07:23:50 PM »

Scott -

Actually a pretty big difference in performance; the two additional cylinders makes a big difference, to the point where the 4106 is sometimes called the Sports Car of Coaches.  One of the other significant differerences - the 4104 uses air beams in the suspension while the 4106 moved on to use (rolling lobe?) bellows.  I'm sure there are others, although some aftermarket removal and re-engineering of parts on individual coaches levels the playing field at times.

Good old thread here on the topic including some great inputs from RJ:
http://www.busnut.com/bbs/messages/233/9932.html

Take care,
Brad
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pvcces
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« Reply #2 on: February 13, 2013, 10:50:32 PM »

Hi, Scott.

One reason that the performance is so different is that the net horsepower of the extra two cylinders goes right to the bottom line. The first six cover almost all of the effort of pushing the bus.

For what it's worth.

Tom Caffrey
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Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska
harleyman_1000
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« Reply #3 on: February 14, 2013, 04:33:08 AM »

  Will I notice a big difference in the towing ability? What is the towing ability of the two?
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Scott 
St.Louis Missouri

1958 GM 4104 Extended 2 feet, with a 6v92 and 5 speed automatic

http://s783.photobucket.com/user/harleyman_1000/library/Gm4104%20bus?sort=3&page=1
WEC4104
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« Reply #4 on: February 14, 2013, 06:52:00 AM »

Towing will depend a lot on the weight of what you plan to tow, and the hills you will encounter.  Speaking from 4104 experience, I would not plan on towing anything heavy or up hills, unless you are a man of great patience.   The previous owner had a heavy grade hitch installed on my coach, which I have since removed.  He said he used it to tow a boat, but he stopped towing the boat because he couldn't launch the boat at ramps using the bus.

I would suspect the 4106 would have substantially better towing umph, but I'll let one of these owners jump in.
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OneLapper
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« Reply #5 on: February 14, 2013, 08:00:59 AM »

I would suspect the 4106 would have substantially better towing umph, but I'll let one of these owners jump in.

Jumping right in........

Ok.  Yes, the 4104 a nice driving bus if you're in no rush.  Fuel economy is great, but towing a toad will ruin the fun.

I tow a 8000 pound car trailer with my 4106 regularly.  You can search my posts to find several threads on how I built my trailer hitch into the suspension sub-frame, almost completely avoiding the engine cradle.

After you build the hitch correctly, and use weight distribution bars, the 4106 still has its challenges while towing.  This biggest issue is the lack of gear ratios!  Period. Since you only have two "highway speed appropriate" gears to pick from (3rd and 4th), you need to pick your battles and drive smart.

Performance in 3rd gear is of the utmost importantance while towing.  Cruising on flat ground in 4th is no problem, you just have to overcome wind resistance.  But when you get to a hill, you'll need to downshift to 3rd (or even second).  I decided 60mph in 3rd would be my ideal speed up the hills while towing.  I spent many hours and numerous beers thinking about this in a rather scientific manner.  I took a recently rebuilt 8V71, changed the cam timing to Advanced, installed N65 injectors and had a pro tune the engine for 2450 no load rpms.  At 2400 rpm I can rip up the hills at 63mph on the governor.  Without a turbo, the engine needs to be wound tight to make the HP needed to get up the hills.  If you plan ahead and start your downshift at 65, you can hit the hills and maintain a decent speed for quite some time.

Ok, jumping out for now........


Mark

Footnote:  I can get 7.8 mpg with this style of driving while towing an enclosed 8000 pound car trailer.
« Last Edit: February 15, 2013, 06:43:05 AM by OneLapper » Logged

OneLapper
1964 PD4106-2853
www.markdavia.com
harleyman_1000
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« Reply #6 on: February 14, 2013, 10:05:23 AM »

Mark do you have design plans for your tow set up?
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Scott 
St.Louis Missouri

1958 GM 4104 Extended 2 feet, with a 6v92 and 5 speed automatic

http://s783.photobucket.com/user/harleyman_1000/library/Gm4104%20bus?sort=3&page=1
gus
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« Reply #7 on: February 14, 2013, 03:47:59 PM »

The only advantage to the 4104 I can see is it gets better fuel mileage and contains minimal steel structure (less rust), it is practically all Al. Also, the 671 is more accessible than the 8V71. Most people can't tell them apart.

I towed a small car on a dolly 800 mi with my 4104 and didn't even know it was back there, hill or not.

On the other hand, if I get another bus (Not likely!) it will be a 4106 because of the performance and it is easier to install an AT in than the 4104. It also has a superior air bag system.

The 4106 should definitely give much better performance on hills and top speed, but, in my opinion, the whole purpose in busing is to take my time and enjoy the good ole USA.
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PD4107-152
PD4104-1274
Ash Flat, AR
harleyman_1000
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« Reply #8 on: February 14, 2013, 04:25:31 PM »

 You no longer have a bus Gus?
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Scott 
St.Louis Missouri

1958 GM 4104 Extended 2 feet, with a 6v92 and 5 speed automatic

http://s783.photobucket.com/user/harleyman_1000/library/Gm4104%20bus?sort=3&page=1
uncle ned
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« Reply #9 on: February 15, 2013, 07:36:34 AM »


harley-man

come to blytheville ak   we will let you drive a poor underpowered 4104.  lol lol

uncle ned
huggy bear
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4104's forever
6v92 v730
Huggy Bear
TomC
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« Reply #10 on: February 15, 2013, 07:51:29 AM »

The power differences are substantial. When you compare the installed power usually using N60 injectors-the 6-71 was rated at 210hp @ 550lb/ft torque. With the same injectors the 8V-71 is rated at 280hp and 740lb/ft torque. With the 4106 you can either turbocharge the 8V-71 up to 400hp and 1200lb/ft torque, or install a 6V-92TA at 350hp and 1050lb/ft torque. Either way you can double the power compared to the 6-71. Course, you can also turbocharge the 6-71 to 300hp and 900lb/ft torque, but then you'll be pushing the strength limit of the 4spd transmission on the 4104. Also, the 4106 is relatively easy to install a V730 Allison automatic. Once you do that, you'll truly have a hot rod.

Differences between the 4104 and 4106- 4106 has the fore mentioned bigger engine, rolling lobe air bags instead of double convoluting air bags with air beams, 4106 has bigger windows and more squared front and back. Just a natural progression of a better bus. Good Luck, TomC
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pd4501-771
Tom McNally
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PD4501-771 "All 43 seats.....still a bus !"


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« Reply #11 on: February 15, 2013, 08:56:56 AM »

I agree totally with Uncle Ned.....head to Blytheville (april 4-6) and check out both models upclose and in-person. Several of each have already registered. For my money, hands-down, just looking at original styling, the 04 is the hard to beat. (maybe next to a Scenic!) But then I might just be bias! Heck my problem is I love em all! I would love to own an 06 too.

Tom
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PD4501-771
PD4501-1001
PD4104-3462
PD3751-686

If you know of the whereabouts of a PD4501 Scenicruiser - I would like to add the serial number to my registry of surviving Scenics.  www.tomsgarageonline.com
harleyman_1000
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« Reply #12 on: February 15, 2013, 09:24:29 AM »

  Can you give me the information on Blytheville?
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Scott 
St.Louis Missouri

1958 GM 4104 Extended 2 feet, with a 6v92 and 5 speed automatic

http://s783.photobucket.com/user/harleyman_1000/library/Gm4104%20bus?sort=3&page=1
B_K
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« Reply #13 on: February 15, 2013, 09:52:50 AM »

harley-man

come to blytheville ak   we will let you drive a poor underpowered 4104.  lol lol

uncle ned
huggy bear


Yeah right like "huggy's" underpowered!
I hear Don still wants to shoehorn a 16V71 in there!
Grin  BK  Grin
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RJ
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« Reply #14 on: February 15, 2013, 10:18:35 AM »

  Can you give me the information on Blytheville?

Scott -

It's right here on this board:

http://www.busconversions.com/bbs/index.php?topic=24151.0

GO!  It's only a three hour drive from you!  You'll kick yourself later if you don't!

FWIW & HTH. . .

 Wink
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RJ Long
PD4106-2784 No More
Fresno CA
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