Home » Public Forums » GMCnet » "Bench Racing" the GMC - Modern propulsion
| "Bench Racing" the GMC - Modern propulsion [message #223635] |
Thu, 26 September 2013 17:31  |
JimGunther
Messages: 228
Registered: March 2007
Location: West Haven, CT
Karma: 0
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Tell me why this couldn't work:
O.K. - I don't even own a GMC anymore but, I still find them fascinating (and the best darned MH concept ever conceived).
I often think of the old saw, "With the proper lever a person could lift the world". So with the GMC, I think with the proper (modern technology) Engine, Transmission, and Differential the GMC could be an economical, high-performance vehicle.
I recently rented a Chrysler 300-C for a quick 1,600 miles round trip to Michigan. The car had a seven (7) or eight ( speed transmission and a 300-plus horsepower V-6 motor. It cruised smoothly at better than 70 mph while turning 1400 or 1600 RPMs. Gas mileage was over 27 for the trip (speed was consistently 10% over the posted limit with Auto Pilot engaged).
Why couldn't a modern (GM, Ford, or Chrysler) FWD Motor, Transmission, and Differential be "grafted" into a GMC with the (trouble free?) 1-Ton front end?
Presumably, the CV joints (and the transmission itself?) might be the weak link but wouldn't a transmission with a greater selection of gears be able to transmit the torque in a smoother(and more trouble prone) manner.
I have NO IDEA of the strength of a modern transmission (could they handle more than twice the turning load they were designed for?) but, I know (from knowledge gained from racing) CVs and axles can be made practically bullet-proof.
As far as a small versus large displacement motor: Isn't Ford now running a 4 Cylinder motor in their pick-up trucks (and that 3.6 litre GM V-6 is a real honey).
Jim Gunther
www.LotusV6.com
now former owner - ;(
73 GMC-II 2600
by Explorer
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| Re: [GMCnet] "Bench Racing" the GMC - Modern propulsion [message #223648 is a reply to message #223635] |
Thu, 26 September 2013 18:35  |
Ronald Pottol
Messages: 505
Registered: September 2012
Location: Redwood City, California
Karma: -2
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Senior Member |
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I believe the transmission is going to be the killer, anything that can
handle pushing 12,000-20,000 pounds down the road for hours and over hills
etc will not fit, and anything that will fit cannot handle the sustained
load.
Note that when they went to the TH325, no one built a motorhome on that
(that I know of), all the TH425 based designs either went extinct, or
redesigned their MH. I suppose an Ultravan could have gotten away with
that, but they were long gone.
I don't know enough to know why, but I've heard it enough from enough
places about enough things that I believe it about transmissions.
Fit is a bear, being both short, and going not too far behind the front
axel. I would guess that any TH425 replacement is going to mean intruding
into the vehicle somewhat.
Ron
who likes to doodle on napkins and such
On Thu, Sep 26, 2013 at 3:31 PM, Jim Gunther <JgmcG@riskmanagementsearch.com
> wrote:
>
>
> Tell me why this couldn't work:
>
> O.K. - I don't even own a GMC anymore but, I still find them fascinating
> (and the best darned MH concept ever conceived).
>
> I often think of the old saw, "With the proper lever a person could lift
> the world". So with the GMC, I think with the proper (modern technology)
> Engine, Transmission, and Differential the GMC could be an economical,
> high-performance vehicle.
>
> I recently rented a Chrysler 300-C for a quick 1,600 miles round trip to
> Michigan. The car had a seven (7) or eight (8) speed transmission and a
> 300-plus horsepower V-6 motor. It cruised smoothly at better than 70 mph
> while turning 1400 or 1600 RPMs. Gas mileage was over 27 for the trip
> (speed was consistently 10% over the posted limit with Auto Pilot engaged).
>
> Why couldn't a modern (GM, Ford, or Chrysler) FWD Motor, Transmission, and
> Differential be "grafted" into a GMC with the (trouble free?) 1-Ton front
> end?
>
> Presumably, the CV joints (and the transmission itself?) might be the weak
> link but wouldn't a transmission with a greater selection of gears be able
> to transmit the torque in a smoother(and more trouble prone) manner.
>
> I have NO IDEA of the strength of a modern transmission (could they
> handle more than twice the turning load they were designed for?) but, I
> know (from knowledge gained from racing) CVs and axles can be made
> practically bullet-proof.
>
> As far as a small versus large displacement motor: Isn't Ford now running
> a 4 Cylinder motor in their pick-up trucks (and that 3.6 litre GM V-6 is a
> real honey).
>
> --
> Jim Gunther
> www.LotusV6.com
>
> now former owner - ;(
>
> 73 GMC-II 2600
> by Explorer
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Plato seems wrong to me today.
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1973 26' GM outfitted
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| Re: "Bench Racing" the GMC - Modern propulsion [message #223649 is a reply to message #223641] |
Thu, 26 September 2013 18:51 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Hi Harry: while there have been some success in putting Chevy engines in the GMCs using tranny adapters and making motor mounts and exhaust the 350 Jim B is using is an Olds engine. Basically a direct swap. Same engine as 403 sept for bore and stroke.
| Harry wrote on Thu, 26 September 2013 18:59 |
I'm all for new ideas, but the GMC weighs in at 12,000 lbs., compared to 3,500 for a car. The multi speed trans may help to get it rolling. JimB has a 350 Chev in a GMC, so anything is possible given enough time and money.
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C. Boyd
76 Crestmont
East Tennessee
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| Re: "Bench Racing" the GMC - Modern propulsion [message #223652 is a reply to message #223635] |
Thu, 26 September 2013 19:15 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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GM did a concept truck that was to replace the one ton dual wheel trucks. It was front wheel drive and a beefy four cylinder with six or seven speed manual trans. Never went anywhere but I thought it was cool. Rear axles were similar to the GMC motorhome. Was supposed to be the future of heavy trucks.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: [GMCnet] "Bench Racing" the GMC - Modern propulsion [message #223660 is a reply to message #223648] |
Thu, 26 September 2013 19:58 |
JimGunther
Messages: 228
Registered: March 2007
Location: West Haven, CT
Karma: 0
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Senior Member |
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'Course nobody said it couldn't be transverse mounted - In fact, such seems to make sense.
PS: Another crazy question: Does electric power steering require a straight shaft from the steering wheel to the rack? or is it remote? fly-by-wire kinda' deal?
| Ronald Pottol wrote on Thu, 26 September 2013 19:35 |
Fit is a bear, being both short, and going not too far behind the front
axel. I would guess that any TH425 replacement is going to mean intruding
into the vehicle somewhat.
|
Jim Gunther
www.LotusV6.com
now former owner - ;(
73 GMC-II 2600
by Explorer
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| Re: "Bench Racing" the GMC - Modern propulsion [message #223674 is a reply to message #223635] |
Thu, 26 September 2013 21:20 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Senior Member |
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I have a 2005, 2010 and a 2011 GM Pickups.. Ok the 2005 is a CheV.. all with the same size 305 (whatever in litres) engine.
The 2005 has a run of the mill transmission and the 2010 & 2011 have a 6 speed (or whatever) never stops shifting transmission.
The 2005 used to be my pickup and now its the shop truck, The 2010 is my Managers truck so I haven't driven it more than 200 of its 200,000 kms. The 2011 is my daily driver. the 2005 and the 2010 have cab high cappers and carry about 1000lbs of tools and equipment.
My 2011 has a frustrating tonnel cover and less than 100lbs in the back.
I'll tell you both my manager and I miss our 2005 pickups. Step on the gas and they go. The 2010 and 2011 with the fancy transmissions and reduction to 4 cylinder mode get the same average MPG as 2005s we had, but they suck. They drive like a mid 70's first generation pollution controlled 6 cylinder 250ci.
My 2011 with no capper or weight in it can't keep a constant cruise controlled speed on the flat land around here. It drops in and out of 4 cylinder mode and back to 8 and any little grade will cause it to drop speed and doesn't take much to make it drop a gear or 2. Passing takes the same care as driving an 18 wheeler.. lots of time required.
So it gets 13.5 l/100km and maybe down to 11 when its in 4 cylinder mode instantaneous. We have a 3000lb gvw flatbed utility trailer. Hook that on the back empty and you know it. Suddenly its down to 20+ L/100kms and the coach has more getup and go. Thats about the same MPG as the coach. Stick my Kubota tractor on the trailer and I bet my coach gets better mileage.
My 2005 with its run of the mill transmission gets about 16 l/100km towing the same trailer.
Hook a trailer behind that car, and I think you would have a hard time getting up to the speed limit and mpg would approach zero.. and soon thereafter you'd be leaving a trail of drive trail of parts on the road.
just say, my experience is give today's drivetrains any kind of work to do and their mpg and power goes to pot.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
[Updated on: Thu, 26 September 2013 21:24] Report message to a moderator |
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| Re: [GMCnet] "Bench Racing" the GMC - Modern propulsion [message #223693 is a reply to message #223685] |
Fri, 27 September 2013 05:40 |
JimGunther
Messages: 228
Registered: March 2007
Location: West Haven, CT
Karma: 0
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Senior Member |
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Thanks Bruce,
One of the things I noticed in the 300-C was the tendency to shift into a lower gear (esp between 62 and 70 mph) but the shifts were "seamless" with the revs only bouncing from 1500 to around 2000. I was also impressed how "locked on" the selected speed the Auto-Pilot (on the Chrysler) was. Seemed like it was tied to a very smart computer.
Now, the 8 cylinder to 4 cylinder deal -I understand - CAN be a problem (I have no experience or knowledge here) though, it seems you'd want that feature available when you're driving the GMC at 70 mph down a flat highway.
>>>>>Hook a trailer behind that car, and I think you would have a hard time getting up to the speed limit and mpg would approach zero.. and soon thereafter you'd be leaving a trail of drive trail of parts on the road.
just say, my experience is give today's drivetrains any kind of work to do and their mpg and power goes to pot.<<<
That occurred to me as soon as I asked the question. That said, I'd GUESS, if it's really a drive-by-wire deal with the shaft as a back-up, you could get away with a more flexible in-direct shaft alignment, no?
| Steve Jess wrote on Thu, 26 September 2013 23:27 |
I saw a "Jay Leno's Garage" where they drove a Ford Focus with electric steering and talked about this question. There is still a shaft from the steering wheel to the rack. The electric motor is a power assist. I think it has to be that way, for safety reasons.
Steve Jess - Aguanga, CA
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Jim Gunther
www.LotusV6.com
now former owner - ;(
73 GMC-II 2600
by Explorer
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| Re: [GMCnet] "Bench Racing" the GMC - Modern propulsion [message #223695 is a reply to message #223693] |
Fri, 27 September 2013 06:47 |
mschultz
Messages: 113
Registered: September 2010
Location: Maple City, MI
Karma: 0
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Senior Member |
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Not to knock ideas, I have them all the time. Money and time always the constraint. Again I will state that the GMC is still at 10 mpg the best economy of any vehicle I own, including motorcycles when you add in the weight factor. 12000 lbs. for 10 miles and one gallon. For 1 mile that is 12000 lbs. for 1/10 gallon or .0000083 gallons per pound per mile. The R850 R BMW is 650 lbs with rider at 50 mpg. One mile is 1/50 gallon. It uses .0000266 gallons per pound per mile. What I call GPM. The soon to be Toad Volvo is 2500 lbs. with one driver at 30 mpg. It's GPM is .0000133. The GMC takes 1/3 the amount of gas per lbs. per mile then the BMW and not quite half as much as the Volvo gas per lbs. per mile. Maybe we are just looking at it wrong. Maybe bigger is better.
M Schultz
77 403 Palm Beach 'The Pickle'
Michigan
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