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Old 02-09-2005, 01:42 PM   #1
Join Date: Feb 2005
Location: Winnemucca, NV/Reno NV
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Year: 2003
Coachwork: 2003 Thomas E-350 shorty
Chassis: E350
Engine: 7.3 Powerstroke
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Acceptable RPM

I've got a '90 Chevy/Carpenter Skoolie with a Detroit 8.2 Turbo, Allison 4sp Auto (not sure which model) What is an acceptable RPM level with this engine for sustained highway cruising? The rig has 57,000 miles on it, and I'd like it to last , but also don't want to take forever getting there. It turns close to 3000 rpm @ 60mph at it's current home near 5,000 ft. elevation. (don't know if denser air near sea level will help). Is this reasonable, or should I back off a bit?? Thanks all, I'll put some links up when I get moving on the conversion. Right now it's a yellow shell with 3 captains chairs. And yes, I think the mileage is original- supposedly it was an "activity bus", not daily service. The undercarriage, etc. looks almost new!!
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Old 02-09-2005, 01:53 PM   #2
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I run my bus with my foot to the floor (it does have a governor), I imagine this is the way most buses are run all their life.
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Old 02-09-2005, 08:35 PM   #3
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Originally Posted by Steve
I run my bus with my foot to the floor (it does have a governor), I imagine this is the way most buses are run all their life.
I second that ! I have an alluminim stick i use to keep my pedal to the metal. I refer to it as my "cruise control"
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Old 02-09-2005, 09:32 PM   #4
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Location: New England
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Year: 1993
Coachwork: Ward Genesis
Chassis: International
Engine: DT466/MT643
Rated Cap: 77
3K sustained for any diesel is probably a bad plan. I'd try to keep it to ~2500. FWIW, the T444E/AT545 International 3800 shuttles at work spin ~22-2300 at 65, & are governed at 2900 (the Fortd version of the same engine will spin 3400). You probably also have the AT545.

My bus (Ford B-700, 460 gasser) doesn't even need half throttle unless pulling a STEEP hill.
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Old 04-09-2006, 04:45 PM   #5
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Location: Twin Falls, Idaho
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Diesel engine speeds

Most diesel engines have a engine speed limiter named a govenor. The engines are designed to operate at the govenor speed forever. The only reason to operate a diesel at less than govenor speed is to save some fuel. There are several general types of diesel engines and those are high speed or low speed design. The high HP/displacement engines are usually of the low speed design, at a governored speed of 2150-2350RPM. The high speed diesels like to rev up to as much as 3600RPM. My Cummins turn about 2250, but my powerstroke turns about 3450 RPM.
Recently, I begged a ride in a fairly new 550HP Cat over the road big rig. This engine has so much power, it is hard to understand. The excellant driver was loaded with 80K pounds of machinery and gave me a demonstration of raw hi torque power. After climbing a long shallow hill and getting on the "loud" pedal, te driver called my attention tothe speedometer. The speedometer indicated about 76MPH. The driver then said look at the tach. The digital tach was indicating about 1780RPM. I remarked, how can this be true. The driver's reply was, electronics , my boy, electronics. The engie knows best. The driver said his milage was now about 6.8---7.1 miles per gallon. The Peterbuilt truck was a 2002 with about 370Kmiles. The magic of electronics.. Frank
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Old 04-10-2006, 04:46 AM   #6
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Originally Posted by jimmyaustintx
I didn't ask about adjusting it maybe next time any help? and can't post pictures since I don't have a site yet
You don't have to have a site, you can post your pictures in the gallery for all to see!
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Old 04-10-2006, 10:00 PM   #7
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Location: Savage, MN
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Year: 1992
Coachwork: Bluebird
Chassis: International
Engine: 7.3 diesel
Rated Cap: 14
I have seen some buses with a horseshoe under the pedal that was either welded or bolted in place. I removed a few of them and it gave it a little more throttle to play with. I don't know if there are any bad things that came of the ones I removed them from.
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Old 04-11-2006, 07:27 AM   #8
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I run my DT360 between 2700 and 2900 rpm (60-65mph) for the most part but often run for a distance, down long hills mostly, at 3000 rpm (70 mph). The engine seems very smooth at these speeds but all of my experience prior to this bus has been with gassers so I'm not a good judge. I hope I'm not damaging anything.
1993 Amtran (Ward) 77 Passenger body on an International frame. DT360, Allison 545 AT. The avatar is my first skoolie, "The Rocket" may it Rust In Peace. Follow the links at the bottom to see the horrible details at
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