Express Van Upgrade Cooling System With a 2 Row Radiator

[booster]

Fluid flow speed is one of the parameters they use to design cooler systems that are liquids and too fast can be a thing that can happen, but too slow is also bad. The transmission flow is really quite low and I was surprised how low. I think it was rated at something like 1-2 gpm at low rpm. IMO the big advantage of parallel coolers is restriction reduction, but they also have to match very closely in the total restriction from the cooler, lines, fittings etc so they both share the flow equally.

The calculations of heat transfer for vehicles is probably pretty complicated with varying aiflow, varying fluid flow, varying ambient temps, and varying heat input and on a moderate 70* day you can see running temps from 130 to 230* depending on conditions. All of this is why I choose to add thermostats to our systems most of the time, to limit the range the oil has to deal with. I think a lot of the newer transmissions do this also as the 6L90e in the later vans all seem to run over 200* all the time per the inputs owners have given.

 

[youngnretired]

A final post on our route 66 trip from Chicago to Santa Monica and an equipment update. The trip took 63 days, 10,216 miles, 4 nights in motels (2 were historic and 2 because they were the same price as an RV park), 25 nights in RV parks or campgrounds, and 34 boondocking. Averaged 13.28MPG and only had a couple minor issues that needed to be taken care of while on the trip. We really enjoyed boondocking in the the areas that we found, and especially the western parts of the country.


The radiator and fan clutch performed as expected, however, the transmission ran a little warmer than I had hoped for. As others posted, that factory style external cooler doesn't seem to do much, and it may only knock the high spots off, but we've never owned a van, nor a vehicle as heavy as this before either. I only had a scangauge and ran the van around town for 1 day to gather data before I embarked on the cooler and radiator changes. So I had very little factory stock data before this trip. A lot of valuable information was learned on the trip though. In most situations, the transmission runs at 90-100 degrees above ambient temps, excluding climbing hills. As we got into colder temps closer to home, the transmission actually runs at 110+ degrees above ambient when the air temp was in the 30s and 40s. As booster has commented, the torque converter lockup is crucial to transmission temps. Climbing hills where I could keep the converter locked, no problem, but when we'd start climbing with an unlocked converter, the trans temps started climbing. This spring I'll work on changes to the external cooler setup and see how that goes hopefully before the next trip. We're looking at an east coast trip into Newfoundland and Labrador Canada areas next year, so the learning will continue on that trip but that area of the world is pretty flat compared to the western US.

Thanks all!

 

[Bangorbob]

Thanks for the update.

 

[booster]

A final post on our route 66 trip from Chicago to Santa Monica and an equipment update. The trip took 63 days, 10,216 miles, 4 nights in motels (2 were historic and 2 because they were the same price as an RV park), 25 nights in RV parks or campgrounds, and 34 boondocking. Averaged 13.28MPG and only had a couple minor issues that needed to be taken care of while on the trip. We really enjoyed boondocking in the the areas that we found, and especially the western parts of the country.


The radiator and fan clutch performed as expected, however, the transmission ran a little warmer than I had hoped for. As others posted, that factory style external cooler doesn't seem to do much, and it may only knock the high spots off, but we've never owned a van, nor a vehicle as heavy as this before either. I only had a scangauge and ran the van around town for 1 day to gather data before I embarked on the cooler and radiator changes. So I had very little factory stock data before this trip. A lot of valuable information was learned on the trip though. In most situations, the transmission runs at 90-100 degrees above ambient temps, excluding climbing hills. As we got into colder temps closer to home, the transmission actually runs at 110+ degrees above ambient when the air temp was in the 30s and 40s. As booster has commented, the torque converter lockup is crucial to transmission temps. Climbing hills where I could keep the converter locked, no problem, but when we'd start climbing with an unlocked converter, the trans temps started climbing. This spring I'll work on changes to the external cooler setup and see how that goes hopefully before the next trip. We're looking at an east coast trip into Newfoundland and Labrador Canada areas next year, so the learning will continue on that trip but that area of the world is pretty flat compared to the western US.

Thanks all!

Your are very closely tracking with what we found in our development process, which is not surprising at all to me. I also think you may be able to improve the situation with more trans cooling, if it is good enough depends on how extreme the climbs you do get to. If you are on climbs that have safe speeds high enough that you can use a low gear and lots of rpm you will be able to stay locked on the converter and run cool enough. If the speed limit is too low to use even second gear to get enough speed to lock the converter (it locks on speed not rpm) you will run hot and have nothing you can do about except stop and let it cool off. Big coolers and fans can delay that overheat, but not eliminate unless you have a huge cooler with it's own fan and even that may not do it.

I would point you back to this chart which is the from out stock 07 Chevy concerning TC lockup points

It shows that in second gear, when you get near full throttle like is needed to climb hills, the converter won't lock until 50 mph so if you are on a curvy 35mph max steep climb there is absolutely no way to get the converter to lock up. It is impossible AFAIK to get the converter to lock in first gear.

The other thing you will run into is on the super steep stuff that require low gear just to move. The program in my opinion is bad on this because in the 1 position it will still shift to 2nd gear at low throttle points. If you let off the gas in a sharp curve all of sudden you are in 2nd gear and not able to pull the hill and it won't go back to 1st until you stop. It is now possible to reprogram that part also, but it wasn't when I started all this stuff. Ours is reprogrammed now.

 

[youngnretired]

I'm admittedly reluctant to reprogram transmission shift points, and certainly don't have the tool to do it. There were times when all I wanted was it to unlock the converter in 4th, but it would drop to 3rd and unlock. A few times I was able to get creative and instead of slowly pushing the throttle, I'd blip it to hopefully get it to unlock and stay in 4th. But in general, for someone who pays attention to transmission gear, throttle position, vehicle load and generally what's going on etc, I think a lot of GM vehicles could shift a whole lot better than they do. I'm sure there's a million things going on behind the scenes that make it more difficult than what I think it is, but I'll leave that up to the original engineers.

 

[dicktill]

I'm admittedly reluctant to reprogram transmission shift points, and certainly don't have the tool to do it. There were times when all I wanted was it to unlock the converter in 4th, but it would drop to 3rd and unlock. A few times I was able to get creative and instead of slowly pushing the throttle, I'd blip it to hopefully get it to unlock and stay in 4th. But in general, for someone who pays attention to transmission gear, throttle position, vehicle load and generally what's going on etc, I think a lot of GM vehicles could shift a whole lot better than they do. I'm sure there's a million things going on behind the scenes that make it more difficult than what I think it is, but I'll leave that up to the original engineers.

Considering how much effort you put into your cooling system, reprogramming the shift points would be a piece of cake for you. Of course, when I did it, I had the pleasure/luxury of @booster slow walking me through it all! I have mine programmed a bit differently than his, both because his '07 and my '10 have different computers, but also because of differences in personal tastes. Anyway, the results were well worth the effort.

 

[booster]

I'm admittedly reluctant to reprogram transmission shift points, and certainly don't have the tool to do it. There were times when all I wanted was it to unlock the converter in 4th, but it would drop to 3rd and unlock. A few times I was able to get creative and instead of slowly pushing the throttle, I'd blip it to hopefully get it to unlock and stay in 4th. But in general, for someone who pays attention to transmission gear, throttle position, vehicle load and generally what's going on etc, I think a lot of GM vehicles could shift a whole lot better than they do. I'm sure there's a million things going on behind the scenes that make it more difficult than what I think it is, but I'll leave that up to the original engineers.

I am guessing, but looking at the program and in particular the tow/haul vs normal programming (the tow/haul) moves the shift points and lockup up to even higher speeds), I think the engineers/programmers were primarily worrying about pulling power, not transmission temperature. To me a touch extra acceleration is pretty useless if you are sitting by the side of the road oveheated.

Dicktill and a couple of others have also reprogrammed their vans and are satisified AFAIK, and I am pretty sure every one is different because of driving style and taste. Dick not only has a different year, but also a 4.8 rather than a 6.0 so that also makes a difference.

A speed shop or custom truck place can do the programming if you tell them how you want it get a copy of one the ones the rest of us have done. Not sure what it costs now, but back when I did ours it was hardly more the $100 if you had a program and just needed it put in or a simple thing like speedo calibration to match a gear change or tire size change. The changes can be done just in tow/haul so you still can keep you factory programing in place.

 

[Bangorbob]

Booster, I have this thread probably 5-6 times and I don't quite understand the programming. When you say Get a copy of the ones the rest of us use. How do I get it?

 

[booster]

Booster, I have this thread probably 5-6 times and I don't quite understand the programming. When you say Get a copy of the ones the rest of us use. How do I get it?

All of this is more in language of hotrodders than RV folks, so not surprising.

The vans like all vehicles now days has a power control computer that tells the engine and transmission what to do. All of them have a "program" or "tune" as it is commonly called that sets all the data points for fuel, spark, cooling, etc in the engine and thinks like shift points and converter lockup for the transmission.

The cool thing is that you can get a little interface unit and some software for a laptop that will talk to the vehicle computer so you can read out all the settable parameters for that vehicle and then load those parameters into the laptop software where you can see, and even better, change them to what you want. You then copy them back out of the laptop into the vehicle and whatever you changed will be changed in how the vehicle runs and drives.

In this case, I worked only on the transmission settings to modify when the torque converter was in lockup as when it is unlocked in generates a LOT of heat into the fluid. Since when you lock the converter it doesn't boost torque anymore, you also have to move the shiftpoints to allow for that by putting yourself in the right gear and rpm to be able to pull the load.

Yes, it does require knowledge of how it all works, how it programs, and what you need to be careful of to prevent damage.

The copy I refer to is that the programming for one engine can be put in a different engine of the same style, so a flash drive with my programming in it can be loaded into your software and then into your van for instance. A lot of it is the need to understand the compromises you might need to make to get the benefit you need, but the good it you can put the changes only in Tow/Haul mode so it won't effect daily driving when you don't get hot.

Not hard to do once you know how and most of the users here that have done the changes, usually a copy of mine but with their preferences also, are old school racers or hotrodders and some even already had the communicator and software and knew how to use it.

For the one time user going to a speed shop and hiring it done might be the best thing to do, as they would know how and have the equipment to it, and also would be able to read one our our programs to see how and why it was done. They work on speed and horsepower stuff and have never heard of reprogramming a transmission for heat reduction.