Last week I finished bypassing the transmission cooler in the radiator and installed a 4454 cooler up front. I had a chance yesterday to give the cooler and my Tundra brakes the ultimate test.

I took the 4runner for a drive up the Pikes Peak highway here in Colorado. Its 20 miles of a non-stop STEEP (15%) grade (low gear the whole way). It starts at 8,000 feet and ends at the top 14,100 feet.

I had 4 adults in the runner, 200 lbs of cargo in the back and 225lbs of bumper and winch on the front.

On the way up the transmission never got over 190 deg F and that's measured on the fluid discharge line of the transmission. With the air getting really thin near the top 3.4 was working hard and near the top it was on the floor just to maintain 15mph uphill.

On the way down the Tundra brakes worked great. Even in low gear the 3.4 was very little help in holding the runner back so I had to use the brakes ALLOT.

I checked with a IR thermometer and they got close 300 degrees but even with the high temps they never warped and I didn't have any brake fade.

I think the 4454 cooler and the Tundra brakes have proven themselves after this torture test.

 

You need to let Ari Vatenen drive next time, I don't think he was in low gear very much

http://www.youtube.com/watch?v=TJsHlugRls4

 

Low gear as in first or 4low?

I bet your engine was loving that trip, hahah. Good to hear nothing went wrong.

 

I tried 4-low for about a half a mile and had to go back to high because it was too slow (was backing up traffic).

Yea you could hear the engine really loading up but it never missed a beat and the temp gauge stayed just a touch below the middle of the gauge like it always does.

Yea they are having the Race to the clouds this weekend where they race to the top of pikes peak at speeds up to 100mph !!! I was white knuckled just driving 15-20mph .

One thing I noticed is the 3.4 does benefit from higher octane gas here at higher altitudes. When I got upto Colorado I noticed the 3.4 seemed sluggish so I plugged in the OBD-II scanner and drove around and noticed the ECM was retarding the ignition quite a bit more than normal (sea level). I ran it almost empty and filled up with a tank of supreme and could see a noticeable difference in power and on the ignition advance/retard readings on the scanner.