Rocky Mountain High....Temp

[Beatenbo]

I have really been proud of the fact my 6V92T runs 175 degrees on the flats. Mount Eagle, TN Black Mt, NC 90 outside 180 dgree 40 mph climb all I ever saw til today I-70- 60 miles from Denver towards Grand Junction are some places this baby saw 25mph 220 degrees at 11,000 ft alltitude. My first time across this far in the Rockies. Wouln't punish my coach often like this often. Only Rocky Mt high bis temp. Sure is beautiful though. Just dawned on me Got to come back across in a few days!!!

[Dallas]

Hey BB and everyone else... Ya gotta remember that as your altitude rises, the boiling temperate goes down.

I think it might be something like 6.5° per thousand feet. But don't quote me on that... my mom taught us boys to cook millenia ago so we wouldn't need a ?WOMAN?

Here's a calculator to play with:

http://www.ajdesigner.com/phpadiabatic/adiabatic_lapse_rate_altitude_change.php

[Burgermeister]

Dallas, 

We're not dealing with a standard lapse rate.  The temperature of boiling would be controlled by the pressure cap, as it raises the coolant temp by the rated value of the cap.

What's more prevalent is the lesser mass of air passing thru the radiator core, since it's the mass of the air that has the capacity to carry away heat.

The point about boiling temp was correct but probably a bit obtuse for most.    Let me put it in perspective.  The boiling point is important because it establishes a baseline for introduction of "aeration" into the coolant.   Thing is, engine can be below the "improved" boiling point (benefitted from the pressure cap) but still get aeration introduced into the coolant, lowering the overall capacity to take away heat.  The aeration can be affected by lots of different things and the aeration can result in "superheating" a cylinder head or cylinder wall, leading to a hasty failure.

If you really want to learn the "skinny" on cooling systems, make it to Arcadia

Bob Sheave, RJ Long and your's truly are trying to work out giving an improved version of the "All you NEVER wanted to know about cooling but were afraid to ask!" seminar given at Rickreal in July at Jack's over New Years. 

Guess I should start with seeking Jack's permission?  How'boutit, Jack?  Got room for us?

Onward and Upward

[Busted Knuckle]

Air/Fuel ratio needs also changes with altitude changes ! Which in turn has an effect on operating temps too!

[JackConrad]

Always room for a seminar from people like Bob Sheaves, RJ Long and Marc, as well as Jim Shepherd, Ewen Steele and others that are in a bus related field of endeavor.  Jack

[rv_safetyman]

Thanks Jack.  I posted a reply on seminars on a different thread.  Bottom line, we will be glad to do whatever seminars that make sense for your agenda.

[Buffalo SpaceShip]

Beatenbo,
Another thing to consider is the effect that an auto tanny has on creating heat whilst climbing. For the rest of this post, I'll assume that you have an auto. If it's a stick... nevermind.

Running an Allison un-locked (when the torque converter is spinning), it's making massive heat. Most tranny cooling systems transfer this heat into your engine cooling system, which is already strained by the high-altitudes and heavy loads (= heat) of climbing.

Some Allisons can be made to lock-up in first via throttle position (Tom C knows all about this). Some can also be modified with a lock-up button (I think it was Brian Diehl that did this project). If you don't come out West very often, it's probably best to just moderate your climb and temps: Gear down into first manually (if you don't already), and watch your throttle position. Do not put your foot all the way into it.

225 on a two-stroke is much too hot, if that's a valid reading, and runs the risk of doing major damage. I hate to say it, but the climb EB on Vail Pass and Ike Tunnel are even steeper than the WB grades. If it gets too hot during climbs, pull over and let things cool down. Better late than... dead DD. Also watch the downgrade into Denver. The signs will warn you and other truckers... "you're not down yet!". Heed them.

The fact that you have a turbo puts you light years ahead over my 8V71 when I make these climbs at altitude. But when I "hit the hills", I always shift my V730 manually, and keep the revs between 1700rpm and 1900rpm under partial throttle when climbing. These driving tidbits are one of the many things I've learned from Bus Trainer Extraordinaire Russ (RJ) Long.

HTH,
Brian

EDIT: Fixed spelling of Brian D's name.

[Brian Diehl]

Hi Brian,
Yes, I did do the manual torque converter lockup override on my HT754.  I REALLY am glad I did it as it made a world of difference climbing in 1st gear WB out of Denver this past June.  I had no problem staying below 195 for the entire climb as registered on the dash gauge.  FYI:  I Have  96A3 with a 6v92.  You can read more about my setup on my website (see my profile for the link).

-Brian Diehl

[gumpy]

Hi Brian,
climbing in 1st gear WB out of Denver this past June. 

Your bus was down to 1st gear on WB 70 out of Denver?  That surprises me. I think mine only dropped to 2nd on that climb. About 35 mph. I would have thought yours would do better than mine with less weight and seemingly more power.

There were a few hills between northern CO and Pueblo this summer where we were in 1st gear, but only 2 or 3, I think. I have never had problems with temperature on those hills at those low speeds. My temp problems seem to come up when crossing the plains in 95+ heat at 65 mph, usually with a crosswind.

[Brian Diehl]

Keep in mind I have the numerically lower differential gears known as the Californial fuel saver gears. I was climbing in 1st at about ~20mph at ~2000rpms.  I believe the ratio is 3:18 or 3:33s if I am remembering correctly.  Been a long time since I looked at the number...

I could have run 2nd gear without torque converter lockup, but I was afraid it would have caused overheating .  I shifted into 1st manually when I couldn't maintain 2nd gear in lockup, which happened around 25mph at ~1450rpms.

My bus currently weighs in at about 30,000lbs plus the 4500lb toad.

[Buffalo SpaceShip]

On the big I-70 pulls, mine bogs down to 1st gear  @ 1900rpm or so... unlocked, of course. My V730 is different than your t-drives for sure. Just over 25,000# and no toad. Ugh. Maybe 22mph @ 7% grades. Major black smoke, due to N65s and not advanced-timed on my 8v71. 195-200 deg. F. and I really have to baby it. The normally-aspirated mills just run out of steam above 10,000 feet, and the hot-rod injectors are of no help. Ironically, in July we pulled 10% grade up to Mt. Rushmore and it was faster/ easier because of the lower altitude.

Once I get some cash (by selling a house), I'm gonna try Brian D.'s lock-up project AND go with C60 injectors (and pay some 2-stroke pro to run the rack). Going over the Divide (which is just in my backyard) in the SpaceShip is too much of a pain without these tricks.

Brian B.

[robert]

Rocky mountain climber.

i can relate.  My wife does a show in Norwood CO and we climb that I-70 4 times a year. The one thing I have learned is I leave my rear door open from Denver to Grand Junction. My 6v92 does not have a tack but i have to keep my oil pressure above 40. I climb most hills in 2nd or 3 rd gear with my 5speed spicer. Good luck and have fun on Vail Pass.

[Beatenbo]

I failed to mention I have a 3:33 rear that dosen't like hills to begin with. I am leaving Grand Jct Fri night. I am going to see if night temp will help. I may even flip open engine doors, if that helps anythimg. I can sleep on Sat after I pass Denver. Smooth sailing eastbound to GA. Don't know if it was 225, usually would shut down. Use to 180-185 past that middle notch makes me nervous. I know  heat is DD two strokers worst enemy.

[Brian Diehl]

Beatenbo, I found opening the engine doors on my bus was worth ~ 5 degrees on the temperature guage during my past summer adventure out west.

[gumpy]

I've found that running the A/C fan motors is worth about 10* on the gauge. When I flip on the switch for the front driver's A/C, the gauge jumps up 10*. When I shut it off, it jumps down 10*. 

This is a pure electrical problem and I'm thinking I need to separate the grounds for the gauges and fan motors.