Older Rig Updates: Cooling and Power
I thought I would post my latest updates to our Suburban. Had some nice weather yesterday and got some work done.
In my last post, I had regeared from 3.73's to 4.56's. My truck and trailer specs are in that post.
3.73->4.56 Regear Results
I am still super pleased with the change, even in daily driving. Towing was vastly improved. Towing fuel mileage also improved.
However one thing we ran into on our test trip was cooling on big grades...we pulled a few hills (11% grade when I looked them up later) that still required 2nd gear, and the temperature would start creeping past 230, so I started looking for solutions.
Fan and Clutch
The later model trucks had a much improved 11 blade fan. I happen to get a super cheap parts truck that had this fan and a brand new severe duty clutch. So I swapped them out.
Here is my old "HD Cooling Package" 5 blade fan with hd clutch vs the new setup.
There is a huge difference in the air moved by the new setup. Should help the AC function at lower speeds as well.
Exhaust Mid-Pipes
The second change I wanted to make for a long time is the mid pipes. The Vortec 5.7 1500 trucks had tiny 1 7/8-2" pipes that were crush bent, so they were as small as 1 5/8 at the bends.
The 3500 trucks with the same 5.7 had huge 2 3/4 pipes even though they had the same power rating. Seems that this might help reduce heat under sustained high rpm high load pulls.
Jeg's sells a 2 1/4 mandrel bent set that bolts in. My cats are already deleted in the tune so no worries there.
I also took the opportunity to replace my 138K mile 23 year old o2 sensors.
I got stainless steel so hopefully they don't give me any rust issues.
Payload guys will be happy to hear this shaved at least 20lbs off the truck, so I can carry more snacks and beer. :D
I still have the factory muffler and tailpipe so the sound output is only slightly louder. I do have a cat back exhaust for it but I don't want to be fighting drone while pulling the trailer.
The pipes cost $160 on sale, normally $230. The fan and clutch would have run me about $100 if I didn't have the parts truck. Less then a single payment on a base model new truck so I'm not to disappointed with that.
We have a few long trips planned this summer, so I will be sure to update with the results. First short trip is in 2 weeks, but its all flat roads. If I still have cooling issues on challenging grades I will move up to a 2 core radiator.
Love this old truck!
In my last post, I had regeared from 3.73's to 4.56's. My truck and trailer specs are in that post.
3.73->4.56 Regear Results
I am still super pleased with the change, even in daily driving. Towing was vastly improved. Towing fuel mileage also improved.
However one thing we ran into on our test trip was cooling on big grades...we pulled a few hills (11% grade when I looked them up later) that still required 2nd gear, and the temperature would start creeping past 230, so I started looking for solutions.
Fan and Clutch
The later model trucks had a much improved 11 blade fan. I happen to get a super cheap parts truck that had this fan and a brand new severe duty clutch. So I swapped them out.
Here is my old "HD Cooling Package" 5 blade fan with hd clutch vs the new setup.
There is a huge difference in the air moved by the new setup. Should help the AC function at lower speeds as well.
Exhaust Mid-Pipes
The second change I wanted to make for a long time is the mid pipes. The Vortec 5.7 1500 trucks had tiny 1 7/8-2" pipes that were crush bent, so they were as small as 1 5/8 at the bends.
The 3500 trucks with the same 5.7 had huge 2 3/4 pipes even though they had the same power rating. Seems that this might help reduce heat under sustained high rpm high load pulls.
Jeg's sells a 2 1/4 mandrel bent set that bolts in. My cats are already deleted in the tune so no worries there.
I also took the opportunity to replace my 138K mile 23 year old o2 sensors.
I got stainless steel so hopefully they don't give me any rust issues.
Payload guys will be happy to hear this shaved at least 20lbs off the truck, so I can carry more snacks and beer. :D
I still have the factory muffler and tailpipe so the sound output is only slightly louder. I do have a cat back exhaust for it but I don't want to be fighting drone while pulling the trailer.
The pipes cost $160 on sale, normally $230. The fan and clutch would have run me about $100 if I didn't have the parts truck. Less then a single payment on a base model new truck so I'm not to disappointed with that.
We have a few long trips planned this summer, so I will be sure to update with the results. First short trip is in 2 weeks, but its all flat roads. If I still have cooling issues on challenging grades I will move up to a 2 core radiator.
Love this old truck!
