RPM' s going uphill?

[HBRod]

Hello, I have a 2003 Yukon XL Denali and will be pulling my toyhauler this coming weekend for the first time. It has the 6.0L and my question is....what RPM's should I use going uphill grades?

[wingnut60]

Interesting question--does your tach have a redline on it? If not, the engine is probably computer-controlled to limit rpms to a safe range.
Joe

[JimM68]

No, a modern chevy / gmc doesn't have a redline marked on the tach.
My 04 silverado SS shifts at right around 6000 rpm, but will go to 6400 if I hold it in gear manually.

But torque is best at around 4000. And no way would I push her uphill pulling as load any harder than that.

[chaunclm]

Do you have a transmission temperature gauge?

The transmission will get pretty hot at 4000 rpm in a lower gear. Don't worry about holding highway speeds. Go slow, things will be easier on you and your truck.

Does your truck have a factory towing package? If not you should consider adding a transmission cooler to the truck.

Going down a hill is a whole lot more dangerous than going up. We tow with a Chevy 2500HD and DuraMax/Allison. Our rig grosses 20,500 pounds. Here is what we do when we see a steep downgrade (6% or Better). We slow to 52 MPH, manually downshift to 3rd gear, set the cruse control, and let the engine hold the rig. If we have to apply the brakes we apply light steady pressure. The key to getting down the grade is to get control before you start down.

[450Donn]

What is the motors Red line? That is probably where you will be if you want to maintain any sort of speed.

[bluepill]

I like to keep an engine at about 80% of redline rpm for maximum pulling. That usually puts me at about maximum horsepower, with lots of coolant circulation. Going much higher than that really gives no benefit, since horsepower is actually going down.
If you can find what rpm your engine is rated for maximum hoursepower, I'd shoot for that.

[HBRod]

Thanks for the tips! The Yukon XL Denali max horsepower is at 4000 RPM's . I figure if I hold it around 2500-3000 I will be ok while going uphill. There is no redline in it. Yes, there is a tow package with transmission cooler.

[HBRod]

My concern was keeping the transmission and engine at a safe temp. The XL Denali is rated to tow 8200# and I will be around 6500#