Electric Cooling Fan Conversion - 2000 Endeavor DP

[RamiDav]

Great job Ted.
Did you bring the old fan along just in case?
Are you heading somewhere warm so we can tell better?

Safe travels

Ray & Marilyn 03 Windsor

[Ted DuPuis]

Originally Posted by RamiDav

Great job Ted.
Did you bring the old fan along just in case?
Are you heading somewhere warm so we can tell better?

Safe travels

Ray & Marilyn 03 Windsor

Yes, I have the mechanical fan under the bus in a storage bay. While I thought this would work I wanted to be prepared.

We’re heading to White Sands and Roswell after Moab, so I’ll get some warmer weather runs there. The fact that it climbed Eisenhower without needing more than 65-70% duty cycle on the fans was encouraging for warmer weather. I’ll report more results.

[Ted DuPuis]

We got home on New Years Eve from our 2750 mile trip, a day earlier than intended but that let us beat the winter weather that showed up on New Years and we wanted to get everything put away before that hit. I haven't crawled under the RV, we just unpacked it and stuffed it back in the shop before the weather dropped to below freezing and ice. With that said, I made a lot of observations of the results of work over the miles driven, and am really pleased overall. I'd done a whole lot of work, basically did a 20 minute test drive, and hit the road. The cooling fans were the big ones but there were other issues and upgrades too.

The oil leak I was having from the oil filter housing is now fixed, as is the leak from the oil pan. No oil dripping there at all, at least not that I noticed from the side. And that's a good thing.

The remote oil cooler I added to the system definitely is helping. The hottest oil temp I saw on the trip was about 215. However, the single cooler is a bit more of a restriction than I'd like it to be, and I think that in the summer when temps are hotter it won't cool as well as I'd like. So I'm going to do like I did for the transmission and run a second cooler in parallel. That will reduce the restriction and increase summer cooling. The oil didn't "overcool", even with OATs in the range of 13F so the system seems to work well.

Before this trip I'd installed a new fan-forced heater in the bedroom with a solenoid to shut of coolant flow when it's not turned on. That solenoid helped to make sure that the system would not heat the bedroom in the summer (we'd already proven that portion) but the heater worked great. It was cold enough that we were running that heater for more than 50% of the trip, and also running the heater up front. I'd insulated the hoses going from the engine up front so as to help that coolant stay hotter. Even in at night in sub-freezing temperatures, we were plenty comfortable in the RV without running any extra heat - something that was just not the case before. We'd need to be running the generator and electric heaters. We removed the propane heater last winter so we could fit a larger residential fridge, and this trip has shown that we're just fine without it.

Now, the big one - the electric fan cooling. I definitely learned a lot about the bus's cooling system on this trip. The short version is that the electric fan cooling absolutely works, and I have little doubt that it will work in the summer. OATs ranged from 13F up to about 70F. On our first leg leaving Kansas, it was in the low 20s/high teens and the fans didn't run at all. Natural airflow kept the coolant temps at 195 or so (with the mechanical fan, it would've been <190, and the thermostats are 190). As an added benefit, this helped the engine heater work better since the coolant was a bit warmer.

However the next morning heading towards Denver, the fans were working, and I would notice some odd behavior. The fans would seem to be doing just fine engine temps under control, and then all of a sudden the engine temp would climb and I would have a hard time getting it to cool back off. Pull over, temps would go back down to 195F or so very quickly (normally at idle the fans don't run at all I've found). Repeat process. After the second or third time this happened, I managed to catch what was occurring after I pulled over. The fan controllers were overheating and then shutting the fans off. Then they would ramp them up and back down again until they'd cooled off enough to be able to run them at a higher duty cycle. When pulled over, it didn't take long for things to cool off and then it would go back to normal. I experimented a bit and found that if I limited the PWM to a max of 70% (so max 70% fan capacity, assuming the PWM translates to fan speed) this wouldn't happen. I managed to figure this out before heading west on I70 from Denver, and it worked for the rest of the trip.

When I climbed up from Denver to the Eisenhower Tunnel it was 60-65F or so in Denver, and about 45F at the tunnel (11,000 ft elevation). That's far from worst case, but it wasn't frigid winter temps (like we then had in Grand Junction the next morning when we woke up). The fans didn't have trouble keeping the engine cool. The same was the case for any of the other numerous climbs I did on this trip going through the four corners. This was a mountainous, high altitude trip. In normal cruise, the engine mostly ran at around 200-205F (which is where Cat says it's most efficient), and extended higher throttle runs would get it to 210F (which is where the thermostats are fully open) and it would come back down after that. Currently the fan controllers base fan speed strictly on temperature, rather than doing some kind of control loop to specifically aim to maintain a temperature. So this variation is expected (and also what we'd see with the mechanical fan). Since I did this all with 70% maximum fan PWM (which should theoretically be around 70% of max airflow), that gives me some extra margin for summer.

One thing I was concerned about was reduced engine braking efficiency since the fan is no longer there to absorb all that horsepower. And the engine braking is a bit worse. However, not as much worse as I had expected it to be. I'm still able to keep things plenty controlled on the steep downhill grades, I think 8% was the steepest I saw on this trip. The Teton Pass that we drove last summer is the only time I've felt that engine braking was marginal, and so I might be more worried there. But for everything else, it's fine.

Is it faster? Yes, absolutely. It's a 30,000 lbish bus with the Land Rover in tow, and the engine makes 330 HP rated. It will never be fast. But the engine is definitely more responsive, and there is a lot more reserve horsepower. Flooring it on the highway to pass actually results in a noticeable increase in acceleration. Acceleration off the line is better. The engine is smoother, especially during shifts. Before, above 2,000 RPM it felt like it would hit a wall and just make more noise without doing anything. 75 MPH cruise was very strained in most cases. Now on level ground without a headwind, 75 isn't a strain on the engine. Heading home I had the cruise set at 80 for a while, and the engine felt unstressed and EGTs were even below 1000F (which is quite low for cruise on this engine).

Mileage? Way better. With the cruise set at 70-80 on level ground I was seeing 9+ MPG, something I'd never seen before. The worst I saw on this trip was still 7 or better through the mountains with steep grades, which is a significant improvement.

The intercooler is one area where I may need to think about this some more. The engine basically doesn't need the fans at all at idle. Sit there and there's enough natural cooling in most cases that it seems that it will keep it at 195 or so on its own. Maybe it'll run at the lowest setting for 30 seconds and shut the fans back off. What that ends up meaning is that if you floor it getting on the highway, the intercooler has no cooling and the induction air post-turbo gets really hot. I found out that the highest the ECU can read is 230F. Previously, the highest I'd ever seen was 175F, and now normal with lower fan airflow seems to be in the range of 160-170F. The higher temps in normal cruise aren't an issue, but at full throttle if nothing else that means I'm giving up a good amount of horsepower (even though it's still faster). So, I have to decide what to do there. I'd be really curious to try water/methanol injection. I've never messed with it before and it seems well suited for the use case of cooling for shorter duration high boost runs. However probably the more logical option is to add a boost sensor to the control computer and set in a loop to put the fans to full when boost gets above a certain amount.

So, there are some tweaks I need to do. Addressing induction air temps (at least for full throttle highway acceleration) is one. Another is fixing the overheating fan controllers. I have a few tests I want to do before moving them and redoing wiring, but this overall isn't insurmountable. If the controllers themselves can't handle the current, I may need to try to make something work with different controllers. Now that I know how to make the general idea work, that wouldn't be too difficult.

When I add in the second oil cooler, I am also thinking about adding in a logic to ground (turn on) the oil cooler fans if the engine temp is above a certain value, since that will help cool the engine. However I think that the oil cooler fan likely naturally turns on anyway at that point.

I also want to seal up some of the air gaps around the radiator. There clearly is a level of natural airflow, and I think that will help force a bit more air through the radiator. I had figured I'd do that after I proved out the basic system, but wasn't worried about it for the initial run.

All in all, for engineering multiple new systems, getting all this back together, doing one 20 minute test drive, and then driving it 2,750 miles, I'd say it went pretty damn well.

When I'd started this project, I couldn't find a single person who'd even attempted it on an RV (even though Prevost and a number of modern transit busses use electric cooling). A lot of people just said it couldn't be done. It was a significant project, definitely the hardest electric fan conversion I've done, but also with the best results. Next summer will be the real test, but based on this trip's results, I'm confident with tweaks it will work just fine.

[moisheh]

Ted. Amazing job. I was one of the doubters but am eating my words. I don't think this setup is for everyone. You have an intricate knowledge of what is occurring and seem to have the answers to any problems. Keep up the engineering!

[Ted DuPuis]

Originally Posted by moisheh

Ted. Amazing job. I was one of the doubters but am eating my words. I don't think this setup is for everyone. You have an intricate knowledge of what is occurring and seem to have the answers to any problems. Keep up the engineering!

Thanks for the kind words.

I’ll be the first one to agree with you that this setup isn’t for everyone. If someone asked me to duplicate it for them, I think it would be impossible to do in a bolt on kit - I’d need to see the individual RV and design accordingly. But one of the great things about our coaches is that we can modify them to suit our wants, needs, and use cases. And in my case, I enjoy the pursuit of improvement and learning new things while making this better suited for our RVing.

[bpu699]

Very cool. I always wondered why someone also doesn’t consider replacing the huge $$$$ radiator with some stock smaller radiators in a frame with the same surface area. Would make servicing way easier, and I suspect would be a marketable upgrade.

[Ted DuPuis]

Originally Posted by bpu699

Very cool. I always wondered why someone also doesn’t consider replacing the huge $$$$ radiator with some stock smaller radiators in a frame with the same surface area. Would make servicing way easier, and I suspect would be a marketable upgrade.

Having gone through this, I think a better idea would be the intercooler. The stock radiator (when clean) seems very efficient although also very cumbersome. I’m much less impressed with the intercooler. If I hadn’t just bought this new one, I think I’d try to do something else and make it work. It was about $500 for a new radiator and $1100 for a new intercooler.

[CRV2]

Ted DuPuis, good information to read.

One thought I had is that if the PWMs are overheating now then that will only be worse in the heat of the summer. Is it possible to relocate them so that they are in the fresh air stream? If not, then I would consider purchasing PWMs that are higher rated for the current draw, and\or perhaps a thermostatic relay where you can keep the PWMs set at a lower than maximum level and if the temp exceeds the thermostatic relay set point then full voltage would be applied to the fans resulting in the full fan speed until the temp is reduced then the PWMs would take back over. Anyway, just thoughts to share. ~CA

[bpu699]

Originally Posted by Ted DuPuis

Having gone through this, I think a better idea would be the intercooler. The stock radiator (when clean) seems very efficient although also very cumbersome. I’m much less impressed with the intercooler. If I hadn’t just bought this new one, I think I’d try to do something else and make it work. It was about $500 for a new radiator and $1100 for a new intercooler.

Wow. Most diesel radiators seem to be $5000+…

[sjholt]

Get back to us when the outside temps run closer to 100 degrees..

[Ted DuPuis]

Originally Posted by craigav

Ted DuPuis, good information to read.

One thought I had is that if the PWMs are overheating now then that will only be worse in the heat of the summer. Is it possible to relocate them so that they are in the fresh air stream? If not, then I would consider purchasing PWMs that are higher rated for the current draw, and\or perhaps a thermostatic relay where you can keep the PWMs set at a lower than maximum level and if the temp exceeds the thermostatic relay set point then full voltage would be applied to the fans resulting in the full fan speed until the temp is reduced then the PWMs would take back over. Anyway, just thoughts to share. ~CA

You've pretty much hit on my exact plan. I have a few tests I want to do before I move anything, but the plan is to relocate the controllers. Right now they're located behind the fans, which is where OEMs usually put them but it also means that they're being "cooled" with air that's gone through the radiator and intercooler, which therefore is pretty hot. I have several options I can do to improve that situation. And another option like you said is just to have separate relays that will put the fans just on to full above a certain point.

Originally Posted by bpu699

Wow. Most diesel radiators seem to be $5000+…

Maybe I just found a good radiator shop, it's one that the local Cat dealers use.

Originally Posted by sjholt

Get back to us when the outside temps run closer to 100 degrees..

I plan on it. Testing ain't over yet.

[Xmcdog]

following with interest.
Love conversions.

[Ted DuPuis]

At this point I've gone through a full summer with the electric fan conversion and I have about 10,000 miles on it total. I have not at this point done a summer run out west through the Rockies. However, we did 3 trips over the summer (2 of them towing our Land Rover toad, one empty) with driving temps in the 90s. I'm happy to report that the system is, overall, continuing to work very well.

In initial trips I had made the observation that, since the fans don't tend to run after idling, hard acceleration onto the highway tended to have high intake air temps due to low airflow through the intercooler. I added two pusher fans to the intercooler with a manual switch up front to turn them on and off, with the option to automate their operation at some point in the future (they're activated by a pair of relays, so easy to modify that). What I've been doing with them is either activating them before getting onto the highway or else if I see a hill approaching or otherwise need a little extra boost of cooling. While not nearly as much flow as the 4 pullers I have behind the radiator, they give a little extra capacity.

One thing I observed early on was that if I was running the fans at too high of a PWM (>70% or so) that the fans would end up shutting off, or at least some number of them would. This is an interesting interaction. If I have the engine not running, the fans can run at 100% indefinitely, the controllers are fine. However when you add in the heat (and specifically hot air) that the fans and controllers receive when cooling the radiator and intercooler, that causes the fans/controllers to get hot, and something within that interaction increases the current draw or otherwise overtemps the controllers, and they stop running until things cool off. I have the fans limited to ~70% PWM and this isn't an issue. However it would obviously be better if I could do 100% PWM. I have heard that the Dorman fans (which is what I used) have this issue when replacing factory OEM fans, so this is probably more of a fan issue, but if I had used fan controllers with a higher maximum current capacity then that would also resolve this. I may switch at some point in the future to a controller that is used in Corvettes (I believe C6s) but for now, I'm going to continue to leave this as-is.

Knowing this interaction now, if I were to do this over, I might've decided to do something different than just replace the intercooler with a stock replacement, and divorce the cooling airflow for the intercooler from the cooling airflow for the radiator. From what I've observed, it seems as though the intercooler's airflow and temperature influence this overheating condition of the fans/controllers more than the radiator/coolant temperature. Really, though, the biggest thing I would've done differently would be the fan control modules I used to some higher capacity ones. There is an argument to be made that I should've put in 180 degree thermostats instead of the factory 190s, since they would be fully open at a lower temperature, but my temperatures are still fine in the summer and our heating in the winter, even on a night drive in the low teens, was very comfortable.

I'll say again that this conversion isn't for everyone. This involved a lot of work and some significant changes to how the bus overall is plumbed and wired. I've got a total of 10 cooling fans related to the engine - 2 pushers on the intercooler, 4 pullers on the radiator, 2 fans for transmission cooling and 2 fans for oil cooling. To support this I had to upgrade the alternator, chose to add a second alternator (this was for other reasons, though) and run new, bigger wires to the batteries to support the extra current. However, compared to when I first bought this bus, all of my temperatures are cooler. The engine runs smoother and quieter without the giant mechanical fan. Acceleration and fuel economy are drastically improved, and the changes I've made to the electrical system give me more redundancy and reliability overall. So, while I haven't yet climbed the Wolf Creek Pass with this conversion, I have no reason to believe that it would do worse than what it did when I did this climb with the mechanical setup.

There are some other tweaks and improvements I may do to the system at some point, but for now, I'm focusing my efforts elsewhere.

[Fffrank]

Really appreciate the update! Glad it's working well!!