Big Blue's Transformation

[Gary Lewis]

Ummm, gas law says if you halve the volume you have twice the pressure, so the inverse would have to be true..

"Air" is obviously a complex blend of gases and moisture (you can compress vapor -steam- but you can't compress water)

Been thinking about this and just looked at the California Air Tools 2010A specs, which are 3.10 CFM @ 40 PSI & 2.20 CFM @ 90 PSI. And I remember lots of other compressors I've looked at over time didn't have neatly proportional spec's, meaning that CFM x PSI didn't equal the same constant.

I've looked a bit on why this is but haven't found anything.

[ArdWrknTrk]

Ummm, gas law says if you halve the volume you have twice the pressure, so the inverse would have to be true..

"Air" is obviously a complex blend of gases and moisture (you can compress vapor -steam- but you can't compress water)

Been thinking about this and just looked at the California Air Tools 2010A specs, which are 3.10 CFM @ 40 PSI & 2.20 CFM @ 90 PSI. And I remember lots of other compressors I've looked at over time didn't have neatly proportional spec's, meaning that CFM x PSI didn't equal the same constant.

I've looked a bit on why this is but haven't found anything.

I think what you're finding is that the pump has different efficiency when pumping free air than it does against a head.

The air in the tank is going to behave as it would in absolute terms.

Look how an engine (which is just a self driven air pump) has an optimal rpm depending on valve timing, compression and a host of variables, like air density and back pressure.

 

[Gary Lewis]

I think what you're finding is that the pump has different efficiency when pumping free air than it does against a head.

The air in the tank is going to behave as it would in absolute terms.

Look how an engine (which is just a self driven air pump) has an optimal rpm depending on valve timing, compression and a host of variables, like air density and back pressure.

Yep, I agree. Saying it another way, the air in the tank behaves according the gas law, but the pump's efficiency is something that has to be measured rather than calculated for us mortal men.

[ArdWrknTrk]

Yep, I agree. Saying it another way, the air in the tank behaves according the gas law, but the pump's efficiency is something that has to be measured rather than calculated for us mortal men.

Given the tiny size of the port behind the inlet muffler, I'm going to suggest that's limiting volume at atmospheric pressure

[Gary Lewis]

Given the tiny size of the port behind the inlet muffler, I'm going to suggest that's limiting volume at atmospheric pressure

Probably true. And the tiny port is part of what keeps it so quiet - sound can't get out for the air coming in.

[Nothing Special]

Probably true. And the tiny port is part of what keeps it so quiet - sound can't get out for the air coming in.

Gary e-mailed me and asked me to weigh in again on the current plans for Big Blue's on-board air. As I understand, the current plans are for a Harbor Freight (Horrid Fate? Hardly Great?) 110V air compressor powered by a 3000W inverter.

Capability-wise it seems really good. Gary's estimate of 3 cfm at 40 psi is double the 1.45 cfm rating of my 12V compressor, and my compressor is only rated that at 0 psi. I can't put a number on how much faster this will be than what I have, but it will be well over twice as fast, probably over 4x. And since my setup is almost adequate (~15 minutes to air up 4 tires from 15 - 30 psi) 4x or more faster seems really good.

Also capability-wise, having 110V available will be nice. I have a tiny inverter that plugs into the 12V power port (aka cigarette lighter for us old folk) that I got to recharge a camcorder battery back before everything came with 12V charging cords. I've also used it to recharge my laptop battery when on a Scout trip. And I've heard of people really liking being able to use electric drills and angle grinders when they break a steering knuckle on the Rubicon (but the on-board welder they use to power those tools has another use in that situation as well).

That said, I don't think that I'd go this route. Not saying that you shouldn't, but I don't think I would. The killer issue for me would be fitting it all on a Bronco. That would be made worse by the fact that I'd still need a lower draw 12V system for flat towing, so I'd have to add the inverter and 110V compressor to my current setup. You've got a lot more room and don't flat tow Big Blue, so you have different constraints.

The other issue for me is simply that it's not a common approach. This isn't a very overwhelming reason, and if it's working well for Jim, that's certainly some track record. But without a lot of people using something that was really designed for the purpose.... Again, I'm not saying that it's a bad idea, or that you shouldn't do it. I'm probably just being overly conservative. And also again, fitting it in is the killer for me, so I don't really get to decide on this last issue. Who knows, maybe I'd come around too. But you asked what I thought.

And by the way Gary, although I haven't posted on this thread in a while, I do log in pretty much every day, and I always look in on your build threads. So feel free to call me out there too. My wife and I now have separate computers, but still share an e-mail account. We manage that by only having e-mail on her computer, so while you can still send me e-mail there, I won't necessarily get it any quicker than I'll see something on the board.

[ArdWrknTrk]

Gary e-mailed me and asked me to weigh in again on the current plans for Big Blue's on-board air. As I understand, the current plans are for a Harbor Freight (Horrid Fate? Hardly Great?) 110V air compressor powered by a 3000W inverter.

Capability-wise it seems really good. Gary's estimate of 3 cfm at 40 psi is double the 1.45 cfm rating of my 12V compressor, and my compressor is only rated that at 0 psi. I can't put a number on how much faster this will be than what I have, but it will be well over twice as fast, probably over 4x. And since my setup is almost adequate (~15 minutes to air up 4 tires from 15 - 30 psi) 4x or more faster seems really good.

Also capability-wise, having 110V available will be nice. I have a tiny inverter that plugs into the 12V power port (aka cigarette lighter for us old folk) that I got to recharge a camcorder battery back before everything came with 12V charging cords. I've also used it to recharge my laptop battery when on a Scout trip. And I've heard of people really liking being able to use electric drills and angle grinders when they break a steering knuckle on the Rubicon (but the on-board welder they use to power those tools has another use in that situation as well).

That said, I don't think that I'd go this route. Not saying that you shouldn't, but I don't think I would. The killer issue for me would be fitting it all on a Bronco. That would be made worse by the fact that I'd still need a lower draw 12V system for flat towing, so I'd have to add the inverter and 110V compressor to my current setup. You've got a lot more room and don't flat tow Big Blue, so you have different constraints.

The other issue for me is simply that it's not a common approach. This isn't a very overwhelming reason, and if it's working well for Jim, that's certainly some track record. But without a lot of people using something that was really designed for the purpose.... Again, I'm not saying that it's a bad idea, or that you shouldn't do it. I'm probably just being overly conservative. And also again, fitting it in is the killer for me, so I don't really get to decide on this last issue. Who knows, maybe I'd come around too. But you asked what I thought.

And by the way Gary, although I haven't posted on this thread in a while, I do log in pretty much every day, and I always look in on your build threads. So feel free to call me out there too. My wife and I now have separate computers, but still share an e-mail account. We manage that by only having e-mail on her computer, so while you can still send me e-mail there, I won't necessarily get it any quicker than I'll see something on the board.

Welcome my fellow 'no bullnose' compatriot!

I use my 2000W (4K peak) to occasionally run my California Air compressor but I use it most any day in winter to run a 1100W Samsung microwave.

The inverter is intended to provide 120V.

The compressor is intended to make pressure, with a much higher duty cycle than any 12V unit I've seen.

The 6x16" tank will easily fit in the space above the frame rail that Gary has, and the pump is about the same size, mounted on four rubber isolators.

I believe Gary's plan was to bolt it inside the tool box and run a braided stainless line to the tank/regulator/cutoff module.

I don't really have any question it will work as it always has for me.

Having regular outlets and a USB charger is icing on the cake.

[Gary Lewis]

Gary e-mailed me and asked me to weigh in again on the current plans for Big Blue's on-board air. As I understand, the current plans are for a Harbor Freight (Horrid Fate? Hardly Great?) 110V air compressor powered by a 3000W inverter.

Capability-wise it seems really good. Gary's estimate of 3 cfm at 40 psi is double the 1.45 cfm rating of my 12V compressor, and my compressor is only rated that at 0 psi. I can't put a number on how much faster this will be than what I have, but it will be well over twice as fast, probably over 4x. And since my setup is almost adequate (~15 minutes to air up 4 tires from 15 - 30 psi) 4x or more faster seems really good.

Also capability-wise, having 110V available will be nice. I have a tiny inverter that plugs into the 12V power port (aka cigarette lighter for us old folk) that I got to recharge a camcorder battery back before everything came with 12V charging cords. I've also used it to recharge my laptop battery when on a Scout trip. And I've heard of people really liking being able to use electric drills and angle grinders when they break a steering knuckle on the Rubicon (but the on-board welder they use to power those tools has another use in that situation as well).

That said, I don't think that I'd go this route. Not saying that you shouldn't, but I don't think I would. The killer issue for me would be fitting it all on a Bronco. That would be made worse by the fact that I'd still need a lower draw 12V system for flat towing, so I'd have to add the inverter and 110V compressor to my current setup. You've got a lot more room and don't flat tow Big Blue, so you have different constraints.

The other issue for me is simply that it's not a common approach. This isn't a very overwhelming reason, and if it's working well for Jim, that's certainly some track record. But without a lot of people using something that was really designed for the purpose.... Again, I'm not saying that it's a bad idea, or that you shouldn't do it. I'm probably just being overly conservative. And also again, fitting it in is the killer for me, so I don't really get to decide on this last issue. Who knows, maybe I'd come around too. But you asked what I thought.

And by the way Gary, although I haven't posted on this thread in a while, I do log in pretty much every day, and I always look in on your build threads. So feel free to call me out there too. My wife and I now have separate computers, but still share an e-mail account. We manage that by only having e-mail on her computer, so while you can still send me e-mail there, I won't necessarily get it any quicker than I'll see something on the board.

Bob - Thanks! I understand the constraints on where to put things in a Bronco, especially an early one. But as Jim said, I plan to put the compressor, and maybe the inverter, in the tool box where there is both room and protection from the elements. So I have the room.

As for why others aren't doing it, part of that may be the fairly recent advent of these smaller 120v compressors with decent spec's. When Jim first proposed this solution I did some checking on the older style compressors and the running and in-rush spec's were so high it would take a really big inverter to run them. But when he pointed me at the California Air unit he runs on his inverter it was a whole different world. The HF compressor pulls only 7 amps while running and 16 amps on in-rush which equates to 840 & 1920 watts, respectively. Easily doable on the 3000 watt inverter I'm going to use.

But my main reason for asking you to weigh in was in the airing-up issue as you are the one that does that on a frequent basis. Would this be enough air to make that exercise reasonably short in your estimation? And it appears that it will be. Great!

And I understand about the email and computer situation. Janey now has her own email address 'cause I get so much "Ford stuff". Anyway, I'm glad you are following along. You've helped so much many times and I value your input. So thanks!

[ArdWrknTrk]

Bob - Thanks! I understand the constraints on where to put things in a Bronco, especially an early one. But as Jim said, I plan to put the compressor, and maybe the inverter, in the tool box where there is both room and protection from the elements. So I have the room.

As for why others aren't doing it, part of that may be the fairly recent advent of these smaller 120v compressors with decent spec's. When Jim first proposed this solution I did some checking on the older style compressors and the running and in-rush spec's were so high it would take a really big inverter to run them. But when he pointed me at the California Air unit he runs on his inverter it was a whole different world. The HF compressor pulls only 7 amps while running and 16 amps on in-rush which equates to 840 & 1920 watts, respectively. Easily doable on the 3000 watt inverter I'm going to use.

But my main reason for asking you to weigh in was in the airing-up issue as you are the one that does that on a frequent basis. Would this be enough air to make that exercise reasonably short in your estimation? And it appears that it will be. Great!

And I understand about the email and computer situation. Janey now has her own email address 'cause I get so much "Ford stuff". Anyway, I'm glad you are following along. You've helped so much many times and I value your input. So thanks!

Gary, that inrush is below the constant wattage my cheap HF 2000W Jupiter delivers.

With a 3,000W inverter that has 6,000W surge I can't foresee ANY issues.

Of course, it will start squaking and shut down if the trucks battery runs low.

IGBT has changed welders and all types of transformers.

It's truly a new world out there.

And yes Bob, I thank you for sharing all your personal experience.

You've certainly opened my eyes to some things I hadn't even considered.

[Gary Lewis]

Welcome my fellow 'no bullnose' compatriot!

I use my 2000W (4K peak) to occasionally run my California Air compressor but I use it most any day in winter to run a 1100W Samsung microwave.

The inverter is intended to provide 120V.

The compressor is intended to make pressure, with a much higher duty cycle than any 12V unit I've seen.

The 6x16" tank will easily fit in the space above the frame rail that Gary has, and the pump is about the same size, mounted on four rubber isolators.

I believe Gary's plan was to bolt it inside the tool box and run a braided stainless line to the tank/regulator/cutoff module.

I don't really have any question it will work as it always has for me.

Having regular outlets and a USB charger is icing on the cake.

Jim - Having the regular 110v outlets and a USB charging port certainly will be icing on the cake. But that has me re-thinking where to mount the inverter. Perhaps behind the seat would be a good place. That way I could run the USB power to a port on the dash, maybe replacing the ash tray, and could lean the seat forward to access 110 volts.

That would minimize the big 12v cables to run it, although I may not run cables big enough to provide the full 3000 watts when I don't need that much power. But I'm on the fence on that.

And, as we've discussed, I may utilize the remote port by having a switch in the row of them above the radio to switch the inverter on and off. It only pulls 1.2 amps while idling, so that's not an issue, but it might be handy to bring the compressor on that way.