max sustainable rpms?

[LCconvert]

I recently returned from a trip which involved some serious highway mountain climbs. My 94' 80 really slowed to a shameful 35 mph but if I FLOORED it I could really gain some speed but my RPMs were around 4k to 4.5k. I wasn't sure if that was ok so I didn't do it very often.

How long could I safely run the engine at those RPMs up the mountain fully packed or should I ever? Should you ever fully put the petal to the metal?

thanks

 

[cary]

You should never floor the throttle on any car. Car manufactures allow the throttles to open all the way in an attempt to cause you to grenade the motor and then sell you a new engine.











Seriously, you aren't hurting anything as long as you have sufficient oil pressure and the engine isn't overheating. The engine can be safely run at 4000-4500rpm when climbing and many do that when in the mountains or towing.

 

[Brentbba]

Been there done that several time hauling our 3500 lb trailer up and down the grapevine in SoCal. Will be doing it again this weekend. Hard to believe you only got 35mph with only the cruiser loaded and not towing. I can maintain that and better with the trailer so long as I get a good running start and don't have to life off the throttle when some twit cuts me off or I get stuck behind a big rig.

Never a problem. Always have one eye on the temp guage, one eye on the oil pressure just in case and keep the third eye on the road. hehehe

 

[LCconvert]

Hard to believe you only got 35mph with only the cruiser loaded and not towing. I can maintain that and better with the trailer so long as I get a good running start and don't have to life off the throttle when some twit cuts me off or I get stuck behind a big rig.

35mph was when I would not let the RPMs go above 4000. If it wasn't 4000 it was 2600 or less... there wasn't much in between! I did get a good running start but this climb is steep and long!

When towing and going up hill do you run over 4000 rpms continously? What would be considered a normal speed for an 80 up a serious mountain grade, 35, 45, or 65?? I know "serious" is a relative term...

 

[Brentbba]

ECT is on and am constantly above 4000rpm for a good 15-20 minutes on the southbound I-5 up out of Grapevine. I can maintain a good 45-50. If I have to lift off for any reason, I plumet to about 35 mph. All of the above with my foot on the floor.

 

[LCconvert]

Brentba, thanks for your input!

So do others think that it is ok to run the engine at 4500 rpms for a "lengthy" period of time. I have never quite understood the redline concept. Does it mean you can run the engine all day long just under that point without risk of damage? Of course, assuming all things are working as designed.

 

[terry.mc]

From Denver to the top of the Eisenhower tunnel, I'm floored.
I'm floored going the other direction from Dillon to the top.

I regularly see the RPMS kiss 4800.

147K and counting.

 

[RavenTai]

take a look at your kickdown cable adjustment, you may need to adjust it some to get it to down shift earlier, soudns liek you are down shifting to late, or maybe to early I may be confused at the moment.

you would not want to drive arround all day every day at 4500 RPM, but to get up a pass you are fine, as said as logn as everything else is good

 

[semlin]

i am surprised you kicked down to over 4000 rpm from 35 mph. If I get down below 2200 rpm or so it will kickdown to the low 3000 rpms and my truck can hold 3200 rpm or so on a pretty steep hill.

i recently found with the addition of a temp gauge that the truck actually ran hotter on hills if you lugged it up in the 2200-2800 rpm range than if you kicked it down to the low 3000s.

 

[dfmorse]

LC;
Know what u mean. U must have been on RabbitEars pass. I can remember pulling that at 40mph in second gear, around 4000rpm.
At 11000 ft, the poor engine really runs out of steam.

Then I installed the Katzuma. Friggin hauls ass. Fun.

...

 

[devo]

I have to deal with the same thing climbing these hills of Colorado and don't worry too much about the engine at high revs.
But what about the tranny when it's in 2nd or 3rd gear for as long as it takes to climb up and over the top?

devo

 

[cary]

I have to deal with the same thing climbing these hills of Colorado and don't worry too much about the engine at high revs.
But what about the tranny when it's in 2nd or 3rd gear for as long as it takes to climb up and over the top?

devo

The only issue with the tranny is the possibility of overheating it. If you are in third, depending on the year of your truck, shutting off the overdrive will cause the torque converter to lockup above 40mph in third which will keep the tranny from heating up. Even in second there should be enough airflow through the cooler to keep the tranny from overheating. As a precaution, you can make sure you change the tranny fluid regularly (every 15-30k) and use Synthetic ATF which will be much less likely to burn and varnish if you do overheat the tranny.

 

[e9999]

eh, eh, with my nifty thermocouple system, I have the temp of both coolant and ATF visible and set up for automatic alarm....!
So I can keep the third eye on the lookout for redheads in classic convertibles...

(of course, I would never run my beautiful engine over 3000 rpms... watch out! granny at the wheel! )

 

[Romer]

I was towing a 2200lb trailer back from Moab and going up Eisenhower tunnel was only able to do about 30 as well. My issues was the RPMs were staying at about 3200 and it would not down shift. Got to the top and then thought I should have just downshifted myself, from D to 2 to L as required.

 

[Russ in California]

ECT is on and am constantly above 4000rpm for a good 15-20 minutes on the southbound I-5 up out of Grapevine. I can maintain a good 45-50. If I have to lift off for any reason, I plumet to about 35 mph. All of the above with my foot on the floor.

Do you drive with the ECT on or off under normal conditions?

 

[Brentbba]

Do you drive with the ECT on or off under normal conditions?

Off - I only use it in the hills and mountains.