| [GMCnet] A whole new world [message #316919] |
Mon, 01 May 2017 17:02  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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Hi Johnny,
This one has a Detroit Diesel Series 60 DDEC III. 13 liters and dialed for 475 HP and 1600 pounds feet of torque. Chassis GVW is just under 50,000 pounds but the coach weight is way short of that, below 43,000 IIRC so it performs well. I could not keep up with the Prevost in the GMC when the bus was driven by a pro driver for the mountainous run from AZ where we purchased it and NV where we took possession. The 6 speed Allison bus transmission (different from the motorhome transmissions - more cooling capacity and larger bearings) is a big part of the performance. Sure wish we could get a 6 speed automatic in our GMCs! In the Prevost case gear 4 is 1:1 and 5 and 6 are both overdrive gears. Final drive gearing is such that even steep mountain passes can be crossed in gear 4 at around 55-60mph. It has a dual stage Jacobs brake which really hauls this thing down going down hills.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 13
Date: Mon, 01 May 2017 15:45:52 -0600
From: Johnny Bridges
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] A whole new world
Message-ID:
Content-Type: text/plain; charset="utf-8"
Jerry, what engine does the Prevost use?
--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] A whole new world [message #316936 is a reply to message #316919] |
Mon, 01 May 2017 19:41  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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glwgmc wrote on Mon, 01 May 2017 18:02Hi Johnny,
This one has a Detroit Diesel Series 60 DDEC III. 13 liters and dialed for 475 HP and 1600 pounds feet of torque. Chassis GVW is just under 50,000 pounds but the coach weight is way short of that, below 43,000 IIRC so it performs well. I could not keep up with the Prevost in the GMC when the bus was driven by a pro driver for the mountainous run from AZ where we purchased it and NV where we took possession. The 6 speed Allison bus transmission (different from the motorhome transmissions - more cooling capacity and larger bearings) is a big part of the performance. Sure wish we could get a 6 speed automatic in our GMCs! In the Prevost case gear 4 is 1:1 and 5 and 6 are both overdrive gears. Final drive gearing is such that even steep mountain passes can be crossed in gear 4 at around 55-60mph. It has a dual stage Jacobs brake which really hauls this thing down going down hills.
Jerry
Jerry,
Well, you aren't quite doing an apples and oranges comparison, but it is oranges and grapefruit at best.
Your DDED 3 is a turbocharged engine. That makes a huge difference at any altitude, but it starts at as little as 5KMSL.
The reason you have a transmission with a lot of gears is simply that is what is needed to make up for the very narrow power band that the engine can actually run. The low end is limited by the low speed defuel so that the bearings don't get hammered out and the upper end also defuels but that is because the piston weights are so high.
Now, If I could afford to put a blower on a 455, I could run you over from behind on any climb. (I have built engines that could do this.)
We have limited engine braking because our coaches have a passcar transmission. Those have a sprage clutch (think of a silent ratchet) for the top gear.
Do I wish I had a diesel coach? Yes, but BHO smashed that dream real flat with the abrogation of the bankruptcy laws. 20+ years of scrimping and saving - POOF.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] A whole new world [message #316938 is a reply to message #316919] |
Mon, 01 May 2017 20:08 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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Me thinks someone gave you a little miss information Jerry. Unless Prevost did something unique I think you have a 12.7 ltr and they were rated 430,470,or 500 in bus/rv applications. There were some early DDEC11 400,425 and 450 ratings in trucks also. OTR trucks had some unique ratings such as 'cruise power' settings of 430/470, 470/500 where they produced higher hp in cruise control. Torque ratings ran 1450, 1550 or 1650. The DD13 wasn't released until 2010, a spin off of the DD15 and is in fact a 12.8 ltr motor. Most likely you have a 470 hp 1550 motor. The B500 and MH4000HD's are the same trans, only difference is software settings.The B500 was used almost exclusively in transit applications because of the shifting characteristics and weren't rated as high because of the software.. The 4000 series could be rated up to 650 hp, 1950 tq in RV service. The MH4000HD could be supplied with a deep pan and oil level sensor to check fluid levels from the shift pad,a really nice feature. In truck use they also had a deep ratio box that were used in trash trucks, off road or where ever a lower ratio box was desirable. Either can be had with a retarder, (R after number, ie. B500R) and they did have increased cooling with that option.
I sent you the contact information to my guy in Eugene, did you recieve it? Let me know, Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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