Thinking about a Bus/RV

The other day while out running errands I picked up some 194NA bulbs and threw those in the side markers. Smoke lenses reinstalled, and that is "done." And today while in the shop, I addressed another item - the residential shower we installed had been creating some black/dark dust. We couldn't figure out where it was coming from, then it hit me - it was the aluminum rails sliding and fretting against each other. Sure enough, the screws that are supposed to hold them in place had fallen out. I got some better screws, and more of them, and put those in. We'll see how that works out.

I've also been trying to figure out how to best run the solar panel wires down to the controller, and after doing some looking today, I think I figured it out. There's a cavity of about 6" between the rear of the interior and the rear of the bus. I can drill a hole into that cavity from the roof, run the wires down and through it and then that more or less will feed down to where I need them for access to the bay where the controller is. Tomorrow's goal will be to run all of those and cut the holes for the cooling fans as well (and maybe the supply hole so the cooling fan has a source to get air from). I'm still missing some hardware so I won't get the controller mounted, but I should get most of the way there.

While up there, I pulled the cover off of one of the air conditioners and found that, sure enough, they're both original. They're also both working (for now) and I also confirmed that, as I thought, they're the 13,500 BTU variants which in the RV world, means they could be upgraded to 15,000 BTUs since those are the two sizes available. I've been considering this for some time, but I think I'll put it off for the moment, at least a bit longer. One of the things that's come to mind, though, is whether to go with heat pumps again, or whether to go strictly AC. The reason for doing the latter is that it's much cheaper, and since the heat pumps only work down to around freezing on RVs (don't know why - but they do) and that heat is all coming from the top, it does present the question of whether I'd be better off putting in some baseboard heaters instead. Recall that I deleted the propane heater, so therefore electric heat becomes a requirement at some point if we go places in the winter, which we do. I need to think on this a bit more, but I'm not going to think about it too much more right now.

Probably. :)
 
I've spent some more time thinking about the rooftop AC/heat pumps, and then also thinking about general winter heating in the RV with the propane heater removed. One idea that's come to mind is going old school, and adding a couple of water-filled radiators, and then circulating water from the water heater through them. This would allow for some heating that's low electrical consumption since it would just be a pump and the propane water heater running. I need to look around some more at options. The apartment I grew up in had old cast iron radiators (still does) and I like how they produce heat. That would allow for a form of heat that doesn't include having the generator on (or hook-ups).

Basically the system would involve a couple check valves and a pump that circulates water out of the water heater, through the radiators, and then back. Simple enough, and seems feasible and not too difficult to accomplish. Of course hiding the piping would be important, and space is always a premium. So I'll do some measuring, see what I can find, and go from there.
 
While novel, the physical space required for radiators would probably turn me off this idea. Space is already at a premium and you need additional space for the plumbing and radiators and then stand off space for them, too.
 
TCABM said:
While novel, the physical space required for radiators would probably turn me off this idea. Space is already at a premium and you need additional space for the plumbing and radiators and then stand off space for them, too.
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This has been my thought as well and might be what would kill the idea. One thing I wish I'd done when we redid the floors was add floor heating, although that would've been electric.
 
The amount of plumbing leaks you would have to track down might be not worth the install. Does the current furnace draw a lot of power?

***BTW, the in-laws just bought a 34' RV to replace a small RV they had for years. This has sparked a conversation in my household on maybe becoming RV's owners. Cant have the sister having something we dont, or something like that. All that to say, I have been learning a lot from your posts, so a heartfelt thank you. EOM****
 
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charheep said:
The amount of plumbing leaks you would have to track down might be not worth the install. Does the current furnace draw a lot of power?
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We deleted the propane powered furnace because it was loud, we didn't like using it, and cycled off and on quite a bit. So our heat sources are only electric, which therefore requires the generator or hook-ups.

***BTW, the in-laws just bought a 34' RV to replace a small RV they had for years. This has sparked a conversation in my household on maybe becoming RV's owners. Cant have the sister having something we dont, or something like that. All that to say, I have been learning a lot from your posts, so a heartfelt thank you. EOM****
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Glad you've been learning a lot from these posts. We've certainly been enjoying RV life, I can highly recommend it. It provides for some really cool and unique experiences.
 
Ted said:
This has been my thought as well and might be what would kill the idea. One thing I wish I'd done when we redid the floors was add floor heating, although that would've been electric.
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Radiant flooring would have been brilliant, especially if it could be run off a recirc hot water system.
 
TCABM said:
Radiant flooring would have been brilliant, especially if it could be run off a recirc hot water system.
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If we’d done it it would’ve been electric, but you’re right that doing it with hot water circulation would’ve been great. At the time I just didn’t have it in me to do that sort of extra effort.
 
Regarding radiators, this is the sort of thing that I was thinking about as size wise. Compact although the BTU rating isn't huge, as you'd expect:

https://www.plumbtile.com/plumbing-...Q4N7itss9wyusfD__WMG-LuXmdGZbu5gaAj5WEALw_wcB

Ratings seem to be fairly significantly variable, but these are low profile and could b. My gut tells me that it wouldn't be enough, but what it might allow for some level of heat without the generator during warmer temps, and during colder temps might augment some electric heat. I'm going to look at things a bit further and consider it before colder weather strikes. Last winter we had some cold days and overnights (mid to low teens) and the electric heaters did just fine with the engine off when the heat pumps couldn't work due to low temps.

I'll keep on thinking about it a bit more. It's not something I need to do before our next trip at all, but something to consider as winter comes up. Then again, if I was smart I would try to finish up the forward AC first since that might get it ready in time for next summer. :rofl:
 
@KzSheikh posted this video in chat:


And this was this week's Jay Leno's Garage video:


We're not in the market for anything, but it's always interesting to see what some of the higher end makers do, and get some ideas for things that could be fun to put on the list for updates or designs in the future - whether to this one or future RVs. I did like how they had done the generator isolation on the Newell coach, both for sound and vibration. Gives me some ideas for things that I could work with potentially.
 
That’s more or less the idea I’m going for. I was thinking not fan forced, but I suppose fan forced would transfer a lot more heat.
 
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Definitely agree in how much fans help to make radiators smaller. I'll do some more digging while I continue working on other projects with it.
 
Today I managed to get all the wiring for the panels finished up and run down the passage in back. Mounted the solar controller, the cooling fans, everything is hooked up and works. I have to finish some little wiring for the fan controller to keep the controller cool enough, and a couple other minor finishing details. Hopefully I can get those finished up in the next couple of days.
 
Got all of the little items buttoned up on the solar, and got the bus outside to check the performance. The load is low currently, and it's doing just fine:

upload_2022-7-27_10-25-25.png

I also found someone who was able to do a custom tune on the engine. My goal was getting some better fuel economy. On the initial test drive, I can tell that the EGTs are lower. Engine sounds strong and happy. Especially notice it seems happier at lower RPM. We'll see how it does on our next trip for fuel economy.
 
NealRomeoGolf said:
Well duh! ;)
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The guy who did the tune works on mostly semi truck engines so not as much in these little guys, but even he commented on how strong it sounded. Maybe he was just trying to make a customer happy (like “What a cute baby!”) but I do think it sounds strong and I’ve been told I know a few things about engines. ;)
 
MauleSkinner said:
What makes it “custom” tuned?
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It's mostly marketing. :)

Basically, guy went into the tune on the engine, made a few changes. It was mostly around advancing injection timing. The stock injection timing is retarded a good amount for various emissions purposes. The main thing that was changed was advancing it. Like with a gasoline engine, advancing the timing (to a point) increases efficiency and lowers EGTs. On the initial test drive, I definitely noticed lower EGTs.

A new (bigger) turbo may be in my future as well... but not today. I did order a new boost pressure sensor, though, as we found that it was acting up on the test drive. I'd been getting hiccups from time to time on hard acceleration at higher RPMs. My BlueFire setup is over bluetooth so there's a significant lag. His computer connected directly to the J1708 showed that when that happened, it showed a momentary spike from 32 psi to 45. That trips the overboost parameter, and cuts fuel. So, new sensor ordered.
 
Ted said:
It's mostly marketing. :)

Basically, guy went into the tune on the engine, made a few changes. It was mostly around advancing injection timing. The stock injection timing is retarded a good amount for various emissions purposes. The main thing that was changed was advancing it. Like with a gasoline engine, advancing the timing (to a point) increases efficiency and lowers EGTs. On the initial test drive, I definitely noticed lower EGTs.

A new (bigger) turbo may be in my future as well... but not today. I did order a new boost pressure sensor, though, as we found that it was acting up on the test drive. I'd been getting hiccups from time to time on hard acceleration at higher RPMs. My BlueFire setup is over bluetooth so there's a significant lag. His computer connected directly to the J1708 showed that when that happened, it showed a momentary spike from 32 psi to 45. That trips the overboost parameter, and cuts fuel. So, new sensor ordered.
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Same thing I had "tuned" on my FICM for the 6.0L. It doesn't increase boost pressure/cylinder pressure, it just adjusts injector timing and other tweaks to add roughly 40HP or so. The biggest difference I noticed on mine was the throttle response from a stop or other low-throttle situation. Drives much more like a gasser. Of course now after the new turbo I have another set of "custom" tunes that stack on top of the FICM tune, lol.
 
SoonerAviator said:
Same thing I had "tuned" on my FICM for the 6.0L. It doesn't increase boost pressure/cylinder pressure, it just adjusts injector timing and other tweaks to add roughly 40HP or so. The biggest difference I noticed on mine was the throttle response from a stop or other low-throttle situation. Drives much more like a gasser. Of course now after the new turbo I have another set of "custom" tunes that stack on top of the FICM tune, lol.
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A lot of tunes are just on injection timing with diesels. Like you said, it makes a noticeable improvement in throttle response and makes it drive more naturally aspirated - the turbo lag is less noticeable. I'll specify naturally aspirated because an old mechanical diesel, naturally aspirated or lower pressure turbo, was pretty responsive. My old 6.5 actually was pretty responsive. No power, but responsive with what it had.

I'll correct you on one thing, though. By advancing the injection timing, it is increasing cylinder pressure for the given fueling, that's how it makes more power. However you're still using the same horsepower going down the highway, and so you don't have a pressure increase under those conditions.

On the short test drive we did, the big thing I noticed was lower EGTs. I also noticed better torque/responsiveness at lower RPM, in that <1500 RPM range, with lower EGTs to boot. I'll be really curious to see what it does on the next trip.
 
Getting a new toy like a solar setup means that you constantly check it to see what it's doing and learn what it's thinking. MPPT charge controllers like what I use have a level of black magic that I'm trying to figure out still. One thing with the system is that it will only allow the panels to put out the amount of power that it wants to feed the batteries. So if the batteries are full (which they mostly were yesterday) the system won't put out much charge, just what it takes to maintain them. I tried loading up the system some, although the toaster might've been a bit much at 165A. Really, most of the higher power electric items are transient as far as the loads go.

Yesterday's stats were pretty decent. The system at some point put out 615W, 45A to the batteries. I'm guessing that was when I turned the toaster on before it then tripped the low battery warning from the high draw it had. I had it outside basically all day with the residential fridge and roof fans on. Not much draw, but fairly typical of what I'm looking at doing. Yesterday there were clouds a good chunk of the morning, today it's very cloudy, rain impending. So I'm curious to see how it does. It does seem like at the very least it does what it needs.
 
I'm interested in how well the cooling for the controller works and what you wound up doing there.
 
jsstevens said:
I'm interested in how well the cooling for the controller works and what you wound up doing there.
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Oh, thought I'd talked about that already. So, the controller requires per spec 6" above and below the unit for natural cooling. It has a max temp of 45C.

A friend sent me some used (but good) high flow server fans. They're fairly loud for what they are, but still quiet enough. I mounted those behind the controller, at the top, blowing outwards into a cavity behind the bus:

upload_2022-7-28_9-57-56.png

Because of where that's located, it shouldn't suck air in. This is what it looks like mounted:

upload_2022-7-28_9-58-20.png

I then needed to provide supply air so air could actually flow through this bay. I also wanted to try to make sure some of that air would go over/near the inverter so that it got some level of cooling flow potential. That inverter will sometimes overheat I've found. So, I took a few parts I had sitting around - a flanged adapter/mount and an air filter that came with the Cobra kit, drilled a hole, and put them in:

upload_2022-7-28_10-0-42.png

The fans are controlled by a cheap little programmable thermostatic switch. The sensor is on the case of the controller, I have it set to turn them on at 40C and off at 35C.

We'll see how it all works out. No water should be able to get in given how the holes are oriented.

I think the real question next will be figuring out the battery. I've been reading up on issues with directly charging lithium batteries off of an alternator. I've had no issues with that on the BMW so far, but that's a small battery. It seems the real issue is that because of how low of a resistance lithium batteries have, they'll basically run the alternator at max capacity until full. So that 270A (300A dyno output) that it can produce may be asked of it continuously, and will that overheat it. Others have used DC to DC converters or external regulators, which I'd rather avoid. I tend to think that this is probably ok on the whole, since the primary charging won't come from the engine and should be solar, plug-in, or generator.

That's going to be the next thing to think about... unless I decide to throw a bigger turbo on it. :D
 
I like it! Do remember to check the filter regularly-though desk dust should not be a problem in this application. :)
 
jsstevens said:
I like it! Do remember to check the filter regularly-though desk dust should not be a problem in this application. :)
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Yeah, I'm going to check the filter regularly. You'd be surprised how much dust gets in that area - remember it's behind the rear wheels, and we drive on gravel/dirt roads with this quite a bit.
 
I was able to observe the solar panels a bit more today walking outside now and then between work. After the clouds and rain of the morning first thing (not surprisingly, it didn't put out much power then), the sun started coming out late morning. I went out and checked the system at one point, and saw a couple things that surprised and initially concerned me. Max battery voltage was listed at 37V (12V battery system). This looks like it was a real voltage, and it seemed to have fried my $5 Amazon thermostatic switch for the cooling fans. It also showed 1400W of output for 1200W of panels.

After turning off power from the panels and batteries to the solar controller (which also turned off power to the fan controller, I was hoping this would reset it and it would work - it didn't) it lost my stats then, but then restarted new ones for the day. It recorded close to 1300W of max output at one point, I saw over 1000W at one random check, but normally around 600W.

I figured a few things. First off, the voltage spike was likely because the controller was still in "auto" mode for detecting battery voltage. It can do 12, 24, 36, and 48V. So I switched it to manual 12V. I also saw for some reason it had gone to sealed battery type from flooded and the capacity was wrong. I did a factory reset on it a couple days ago and must've just not adjusted those settings afterwards. So, made those changes.

The controller also seems to significantly cut down on current output when it gets warmer. Its rated max temp is 45C, and I noticed it listing its internal temp at 42C when I checked with decent regularity. So, I'm betting that was limiting what its output was to charging the batteries.

For the fan controller, I wired it right into the output from the solar controller to the batteries - which theoretically should be fine but will make it more prone to seeing the voltage spikes without it having the batteries as buffers. So I'll run those wires all the way to the batteries (which is not far, I was just being lazy) and that should take care of that issue... provided no more voltage spikes. And the observations continue.

I also got a new boost pressure sensor for the engine. This would be a 2 minute job, except Caterpillar updated the sensor to a new style. Now, this new style I'm sure is more reliable, better, etc. It also doesn't have a pigtail. The old sensor did have a pigtail. The wiring harness assumes that the sensor has a pigtail.

This is pretty much how how this went:

Caterpillar engineers: "This sensor design has issues and the pigtail is unnecessary. Maybe the pigtail is part of the issues. We'll update it to this new, better sensor style and lengthen the wiring harness to reach the sensor."

Me, 20 years later: "Wait what? Why doesn't this new sensor have a pigtail and why doesn't my harness reach it?"

Surprisingly, Cat doesn't sell an extension harness. Not a big deal. I just soldered in around 8" of wire to the harness for each of the 3 wires. I'll test drive it tomorrow and see if it is 1) working and 2) seems to have fixed the problem. But just running the engine it seemed that it was reading manifold pressure. It just doesn't make much boost motoring the engine.
 
Ted said:
Caterpillar engineers: "This sensor design has issues and the pigtail is unnecessary. Maybe the pigtail is part of the issues. We'll update it to this new, better sensor style and lengthen the wiring harness to reach the sensor."

Me, 20 years later: "Wait what? Why doesn't this new sensor have a pigtail and why doesn't my harness reach it?"
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Let me rewrite that for you in typical POA fashion:

Caterpillar bean counters: "We are evil, run the world, and do nothing except cut costs so that we can make sure our CEO is paid billions!! We are removing that pigtail and doubling the price because it's a feature. Screw the customer!!"

Me, 20 years later: "Neal, what the heck?"
 
NealRomeoGolf said:
Let me rewrite that for you in typical POA fashion:

Caterpillar bean counters: "We are evil, run the world, and do nothing except cut costs so that we can make sure our CEO is paid billions!! We are removing that pigtail and doubling the price because it's a feature. Screw the customer!!"

Me, 20 years later: "Neal, what the heck?"
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You forgot the part about Caterpillar conspiring against George Braly to prevent G100UL from being used in Cat engines. ;)

It does seem that when I replace parts I’m usually getting different parts (xxx-xxxx instead of xR-xxxx numbers). That’s fine by me - I’m getting the newer parts updated for the C7. It’s usually obvious what they changed and why it’s an improvement. But sometimes the other changes that went along with it are missed so it’s not a direct bolt in.
 
I went for a test drive a bit ago with the new boost sensor, and that didn't fix the hiccup behavior. However, I did spend some more time thinking about it, and I think I'm having a legitimate boost creep issue.

Initially, I noticed the engine hiccup last winter. This was after I'd put on the air inlet scoop (which did reduce EGTs significantly, my evidence it and the turbo were working), the high flow exhaust, and the new (non leaking) intercooler. I noticed it only seemed to happen at high throttle, higher RPM. It seemed to stop once I hit the mountains, and only happened in the lower elevations.

On subsequent trips this has continued to happen, but on the test drive the other day, we were able to confirm an error code that went with it for "boost pressure not responding", which was also tied to the ECU seeing a spike from ~32 to ~45 psi, looking like it was an instant jump on the computer. My BlueFire (bluetooth engine reader that goes through my iPad) never picked up this boost, but it has a lot of lag in its values being bluetooth.

I've noticed a few things. This only happens above 2000 or 2100 RPM (in the winter that was a bit lower). I already observed it only happened in the flatlands. Today what I also had noticed (noticed before, but was thinking about it as a fuel issue not an overboost issue) was that it only happens above around 60 MPH.

The turbocharger on this engine is undersized. It's very responsive and has almost no lag, but it seems by the intake air temperatures that it gets outside of its optimal compressor map range once you get much above around 1600 RPM. What I'm thinking is that, now that I've reduced the backpressure side of the turbo, given the turbo some ram air to reduce the restriction on the inlet side, and then also provided it with a leak-free system, that the wastegate isn't able to keep up and I'm getting boost creep. This would explain why weather conditions and altitude influence the behavior, but that it only seems to happen at higher RPM, full throttle, higher speed, load over a longer period of time. If you just floor it instantly, even at high RPM, it won't do it. It takes a bit before it starts hiccuping. And then after a hiccup, it takes a bit before it hiccups again. Cutting fuel will reduce boost very quickly, boost creep will take a few seconds to creep back up from an undersized wastegate.

This is a working theory here, but makes sense. I've redesigned the system quite a bit from how it was from the factory and so it makes sense that I may have gotten one of the components outside of its design point. Why the ECU is not showing that 32 or so psi gradually increasing to 44-45, just a jump, is another question. It's possible that this issue is still electrical related. But I'm also wondering if the Cat ECU doesn't peg the indication at 32 or so since that's what the max boost is supposed to be, and then doesn't show anything until it gets high enough to trigger the error. That doesn't sound entirely right to me, I'll admit, but I don't know how Cat ECUs are designed.

One thing I'm trying to figure out is whether I think that cooler intake air (that is, the intercooler flowing more air across it and thus lowering intake air temperatures). My thought is that would make this less likely to occur. Reason being, with cooler intake air you need a higher mass air flow to make the same boost. This was the other big thing I changed with the new intercooler, was I removed the big mechanical fan and replaced it with electrics. A downside I noticed since that was intake air temperatures went up in general. If the intake mass air flow goes up then that also means there's more exhaust mass air, but I think the equation should still work out such that the turbo will have to work harder if the intercooler is flowing more air.

This is a test I should be able to do while driving. However one thing I noticed on this test drive and the previous test drive was that my electric fans I added to the intercooler seemed to be doing nothing. Turns out they weren't turning on, and it looks like the issue was that I chose a bad ground location for the relays running them. That's been fixed, but I'm betting I didn't notice a difference because they weren't actually making a difference.

So more testing to do, more to think about, but I think it may be time for a turbo upgrade.
 
What about upgrading the wastegate? this would keep your no turbo lag smaller turbo.
 
charheep said:
What about upgrading the wastegate? this would keep your no turbo lag smaller turbo.
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The wastegate is internal, so I'm not sure what level of upgrade can be done to it. However yesterday after soaking it with some penetrating oil, I tried moving the wastegate actuator, and it seems pretty well seized. That would explain my issue for sure. I had thought I'd checked it and it was free. Maybe I did, maybe I'm remembering wrong, but it seems pretty well seized now.

The turbo I have seems to be a Borg Warner S300G. The S300 series is still in production, but it looks like it's been updated quite a bit since the late 90s when this one was designed. The good news with that is that I may be able to simply get this one rebuilt with some new style compressor and turbine wheels, and probably see a noticeable improvement in efficiency. So, I need to look into things more and see what makes the most sense. Obviously it would be ideal if I can keep my existing housings so everything bolts right up the way it was.

The exhaust housing is one thing that might be nice to change if it can be done. It's pretty small, and I suspect is a significant restriction, specifically on the outlet side. This turbo was used on engines rated from 250 to 330 HP. It expands quite a bit right after, so if I just have to make a new V-band ring/adapter to run from the turbo to the exhaust brake, that would be worthwhile if it improved exhaust flow.
 
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Ted said:
The wastegate is internal, so I'm not sure what level of upgrade can be done to it. However yesterday after soaking it with some penetrating oil, I tried moving the wastegate actuator, and it seems pretty well seized. That would explain my issue for sure. I had thought I'd checked it and it was free. Maybe I did, maybe I'm remembering wrong, but it seems pretty well seized now.

The turbo I have seems to be a Borg Warner S300G. The S300 series is still in production, but it looks like it's been updated quite a bit since the late 90s when this one was designed. The good news with that is that I may be able to simply get this one rebuilt with some new style compressor and turbine wheels, and probably see a noticeable improvement in efficiency. So, I need to look into things more and see what makes the most sense. Obviously it would be ideal if I can keep my existing housings so everything bolts right up the way it was.

The exhaust housing is one thing that might be nice to change if it can be done. It's pretty small, and I suspect is a significant restriction, specifically on the outlet side. This turbo was used on engines rated from 250 to 330 HP. It expands quite a bit right after, so if I just have to make a new V-band ring/adapter to run from the turbo to the exhaust brake, that would be worthwhile if it improved exhaust flow.
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You could also see if the dealer has a reman part available and just get a new one with core value.
 
NealRomeoGolf said:
You could also see if the dealer has a reman part available and just get a new one with core value.
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Normally I’d go this route, but when I looked it up, the dealer remans looked to be around $2k and would be a stock replacement (unlike most parts I get from the dealer which end up being upgrades/C7 parts). I want to look closer into upgrades, see what I can do that’s probably outside of what Cat does, and to be fair outside of what most Cat owners (other than C15 drivers) are interested in.
 
Ted said:
Normally I’d go this route, but when I looked it up, the dealer remans looked to be around $2k and would be a stock replacement (unlike most parts I get from the dealer which end up being upgrades/C7 parts). I want to look closer into upgrades, see what I can do that’s probably outside of what Cat does, and to be fair outside of what most Cat owners (other than C15 drivers) are interested in.
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I think PDI does some performance stuff for the Cat engines if you don't already deal with them. They have an upgraded turbo for about $2,400. I think Cat's higher-HP turbo was the 10R-3280 which is probably $1K for a reman.
 
SoonerAviator said:
I think PDI does some performance stuff for the Cat engines if you don't already deal with them. They have an upgraded turbo for about $2,400. I think Cat's higher-HP turbo was the 10R-3280 which is probably $1K for a reman.
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I’ve seen the PDI turbo. It’s a more comprehensive upgrade though and also requires an exhaust manifold upgrade. You’re in it for $4k by the time you do it all. While I love more efficient exhaust manifolds, I don’t think that’s worth it.

More research is required.
 
Oh, that C7 turbo - it is probably an upgrade and worth looking at some, but probably still not what I’m looking for. From what I’ve seen the older ones had the 7 blade cast compressor wheels. The 6 blade billet compressor wheels have better aero properties, with more efficiency. The turbine dude they’ve also made some significant design changes to.

The housings themselves don’t need to have changed, and of course you’ve got different inducer and exducer sizes, different A/Rs.
 
For those who like playing around with various computer simulations, the Borg Warner MatchBot is pretty fun:

https://www.borgwarner.com/matchbot/

It's a neat tool that gives you a lot of data, lets you play with different numbers to both pick out the compressor and turbine sections. It gives you steady state data and not transients. It assumes all turbos are wastegated, which remains my preference but it also seems a lot of turbos go with non-wastegated turbos for performance upgrades.

The Borg Warner S300SX-E is the upgraded and more better series of the S300G that my RV came with. Supposedly it's more efficient all around, better spool, more durable, etc. Durability really hasn't been an issue for me, but the efficiency is what I'm going for. Because of how this thing is used, I'm tending to think leaning towards the higher end of the curve on the turbine side is better. Give up a little lag but get some reduced backpressure and efficiency.

You can play with it some yourself to see. But it seems to me that the 83S74 S300SX-E is a good turbo option with a 74mm 1.05 a/r or 76mm 0.91 a/r turbine housing. Seems like that's a hair bigger and better than what I have now, should provide less backpressure. Need to play with it some more, though, and figure out what might make the most sense. I'm not planning on a complete new turbo, rather ideally new components as part of rebuilding this one. However that may or may not work out, especially if I want to upgrade the exhaust housing since it may be harder to find a wastegated one. And I'm pretty sure the exhaust housing is something I want to upgrade.
 
About 2 years ago (on page 7) I posted the pictures from taking delivery of the RV. For reference, the post was:

https://www.pilotsofamerica.com/community/threads/thinking-about-a-bus-rv.127160/page-7#post-2955009

2 years and not quite 30,000 miles later, it's really been a great adventure. I think I've touched virtually every system on this thing. It's been a lot of work, but I don't think that any other RV in our price range would've been less work.

Part of me still wonders about how things would've gone if we'd gotten that 45' one that we missed out on. On the whole, though, we're able to get into a lot of spots with this one that I don't think a 45' would've fit in. The turning radius on this is really good and that's one of our favorite features of it. The Freightliner chassis doesn't have a reputation for riding fantastic, and that's probably valid. But the Freightliner dealer is good, local, and I've had no problems getting parts for this thing.

The 3126 has been an overall good engine. I don't really want for more power, but I think a 7L class engine for something of this size really is too small. Something with a big more displacement and lower revving on the highway would be nice. But I've gotten it pretty good with the effort done to it, and it's been reliable.

Overall, the thing hasn't let us down. RVs are mostly built terribly, and within our price range we were going to be dealing with some level of that. We've overall put in more effort than I think we were expecting, and there are a lot of projects I probably wouldn't have done with something that was better out of the box. But it is what it is, it's personalized, and suits us well. We do keep on thinking about how an upgrade might be nice, but have a hard time figuring out what the real benefit would be for this phase other than bunks for the kids. That would be nice, but it's not proven a big problem.

Definitely no regrets.

But I still need to do something about this turbo.
 
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