Home » Public Forums » GMCnet » GMCs, Mountains, Fuel Injection, Electric Blowers, Gears (Any valid tests vs theories and guesses)
| GMCs, Mountains, Fuel Injection, Electric Blowers, Gears [message #179865] |
Sat, 11 August 2012 14:30  |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma:
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Senior Member |
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I've been reading the net too much recently. Many different but related topics.
"PS - The lack of performance out of this engine at altitude has made me decide that the Paterson engine I have in Houston will be
fitted with EFI" Rob Mueller
"Anyone out there who has any input on how a GMC runs at 12,000+ feet? " Mark Hickey
"Your last post on EFI reminded my of my conversation with James. He said it made the most incredible difference traveling over Eagle Mountain or Mount Eagle. He fooled with his carburetor and finally threw in the towel.
I suspect the carb in his coach was never exactly right, but others have said that the EFI really makes a difference in higher altitudes." Stick Miller
" 13% grades both up and down, lots of 6 to 11% stuff, some 20 to 40 km long. The coaches are holding up well for the most part. It is a real testament to Manny trans, Manny one ton from ends, alum radiators and the large cooling lines from trans to radiator. Lots of smelly brakes from the coaches without the larger one ton from rotors and calipers. A few with over heating issues on stock radiators, but for the most part every one is making it." Jerry Work
The quotes above all relate to Gmc's performance in the mountains.
I live in the mountains @ 4500' and have to climb to 6000' before getting down to 300' on the Sacramento River at Red Bluff.
Seventy miles of up and down grades with many slow (15 to 25 mph) curves.
About once a month I go to So Cal over the Grapevine @4144'. every 2 to 3 months I go north to Oregon over the Siskiyou Summit @4310'.
I have driven 5 different GMC's over various mountain passes including Deadman Pass 8047", Conway Summit 8143' Tioga Pass 9943' all in California and Monarch Summit in Colorado 11312'
Coaches were:
23' 455 3:07
26' 403 3:07
26' 455 3:07
26' 455 3;07
26' 455 3:07 and 3:70
All had carbs- none had Mark's electric blower. All made it up the grades; slowly and in 2nd gear.
I suspect that neither fuel injection nor electric blowers will make a "significant" difference in power/performance when coaxing a 12,000 pound brick up a 7 mile 6% grade.
Long steep grades and or slow switchback curves seem to have more effect on performance than thin air at higher elevations.
Last week I traveled to Florence, Oregon to see the newly completed shrine to Mr.ERF at Mickey D.'s He's honored as their most regular customer.
Coach, 1976 Palm Beach has 455 w/carb and 3:70. coach weighs~11,000 lbs.
Northbound on I-5 between the Oregon border and Canyonville (about 100 miles) you encounter Siskiyou Summit 4310' (highest point on I-5) 7 miles of 6% grade on both sides, Sexton Pass (named for GMCer Dennis Sexton?) 1960', Smith Hill Summit 1730', Stage Road Pass 1830', Canyon Creek Pass 2020'
All of these hills except Canyon Creek Pass required downshifting to second for part of the climb. Plenty of air volume available at these elevations.
When speed drops below 50 mph and rpm drops below 2500 and vacuum is 5" or less I manually shift to 2nd.
Any of you Great North West Netters travel this route? With FI or carb? What is your experience?
We are all hoping/trying to improve performance but it seems that many "upgrades" don't actually improve performance (headers come to mind) and some have unexpected issues.
The 76 Kingsley that I drove from Boston to San Francisco last Sept. had OEM exaust. It generated substantially less heat and noise in the cockpit than my daily driver 76 Palm Beach with headers.
Enough rambling.
Hope to hear more from the Cross Canada Ramblers on their experience in the mountains. Good opportunity to compare a variety of coaches over the same terrain at the same time.
Comments please.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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GMCs, Mountains, Fuel Injection, Electric Blowers, Gears
By: gbarrow2 on Sat, 11 August 2012 14:30 |
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Re: GMCs, Mountains, Fuel Injection, Electric Blowers, Gears
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Re: GMCs, Mountains, Fuel Injection, Electric Blowers, Gears
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Re: GMCs, Mountains, Fuel Injection, Electric Blowers, Gears
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Re: [GMCnet] GMCs, Mountains, Fuel Injection, Electric Blowers, Gears
By: USAussie on Sun, 12 August 2012 13:12 |
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