Posted by Caleb in Kansas [172.68.35.19] on Monday, August 29, 2016 at 20:11:36 :
Well, i have just reached the 700 mile mark on my conversion and have many of the bugs ironed out. For anyone who has missed any of my posts about it, here are the specs:
Grantee: 1995 Chevrolet Suburban 2500 4x4 originally a 7.4L, 4L80, NP241C, 190xxx miles.
Grantor: 2001 Ram 2500 4x4 5.9L 24v Cummins, 47RE, NP241DLD, 270xxx miles
I kept the entire wiring harness from the 2001, but really all i needed was to cut the whole bundle where it goes into the power distribution center. The majority of the wires that need to be kept together are all running between the PCM and the Cummins ECM. In hindsight, i should have left that harness all together and connected with the motor/trans while i did some of the clean up, but i pulled it all off while still in the 2001 chassis. It would have made cleaning more of a hassle, but saved a bunch of pulling and replacing the whole thing. I'll do a better job next time.
Getting the transmission to work right took some royal and error but in my case it was compounded by a serious lack of power stemming from a bad MAP sensor that made it seem like the torque converter was not locking up...wrong. Originally, the transmission was in limp mode and only starting out in 2nd or 3rd unless you manually downshifted but that problem completely vanished when i went back through the harness and re ran every ground I could find! Yet another reason to keep the harness connected unless you have a better memory than I do! I would likely have gone down a major rabbit hole had I not had a programmer that read boost of the ECM, the fact that it read zero under full throttle told me it was either a bad connection or a bad sensor. A quick check to make sure i had 5v at the sensor, then some compressed air and a multi meter told the rest of the story. In lieu of spending $110 on a genuine cummins/dodge sensor and waiting a week, I had a cheapo $16 Chinese sensor in 3 days from Amazon (I'm still going to buy the real one) and in 10 minutes I had boost again! After a test drive (cause i couldn't resist) I ran a test using compressed air again to see what the output voltage curve looked like against a chart i found online, and though it went minimum to max at the correct voltage, the adventure between was a rocky road...exactly what i expected from a dirt cheap sensor. Working some throttle body cleaner through it while moving the pressure up and down knocked some brass "dust" out of it and it smoothed out some but watching the boost go, it's still not quite smooth, still no complaining for a sensor that cost me $26 after adding expedited shipping.
I am running the 7.4 radiator in front of the beast and it cools just fine cruising, highest temp I've seen was right around 190 in stop and go through town. I still haven't towed with it yet, but after i get a brake controller installed, I'll be towing my buddies 48 REO 1 1/2 ton truck about 40 miles so that should be a good test of the cooling capacity, i am expecting it to get warm.
Since the Sub has a massive AC condensor, i didn't have room for the transmission cooler in front of the radiator and CAC. My solution was to mount it behind the front skid plate which was modified by cutting holes between the ribs. When i build a new bumper, I'll incorporate a new skid that offers better protection. I also need to find an aux cooling fan to put behind it when pulling under stop and go conditions. Despite the relative lack of air flow, the max I've seen has been 170ish in stop and go on a 97 degree day but i normally see 135-155 while cruising at 70. The towing test is yet to come. I am still running the factory "pre heater" canister on the side of the motor.
Fuel mileage has been pretty much what i expected, i got 13 on my first tank but that had about 200 miles with the bad MAP along with a fuel leak back by the tank. My fill up today yielded a hand calculated 15.6 mpg which is right at my average when the motor was in the 01. Would i liked to have seen better? Yes, but i can't complain at all since the absolute best i could eek out of the 454 was just below 10.
I still haven't hooked up the AC wiring, modified the cable to hook up the cruise module, and still don't have a tach but it's been really fun to drive so far. One of the more fun things is to see the look on people's faces when they figure out that it's not the right barrel of hammers noise to be coming from a Suburban!
All told, I have right around $1300 in the swap. Big ticket items have really just been the conversion brackets from Autoworld at about $500 and i had almost $300 in fluids alone. The rest was in plate steel, misc wiring needs, and all of the other little odds and ends that pop up along the way. If i hadn't had the entire donor truck or ability to do the fab work for mounts and CAC mods, then the number would have been much higher. From my research before the swap, most DIY guys were in the $3-4k area and i saw a couple that had near nothing cost wise.
I'll update again in a while and hopefully I'll have it up in Iowa next summer! Now on to the Carryall!
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