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Message |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 2:33 am: | |
I’m finally dumping my air-cooled gas Onan genny, with its plugs, points, choke, and mixture screws. Goodriddance! I bought a slightly-used 6500 kW liquid-cooled diesel genny. Yeah, baby! I pick it up tomorrow.
The only rub is that the beast won’t fit in my ‘06’s old condenser compartment where the Onan was, so it has to go in a baggage bay. Short of cutting in some “cheese-grater” expanded metal into the door of the bay, how can I get some cooling air to the radiator? Through the floor? How big of holes?
I'm also toying with the idea of remote-mounting the unit’s radiator in the condenser compartment (no shortage of air there) and running the hoses through the bulkhead. Hmm…
The other issues seem pretty straightforward: running a fuel line to my bus tank, piping the exhaust through the bay floor. Oh, and punting the old 50 gal. gas tank to get some bay space back. And then figuring out what to relocate to the condenser compartment. I'm thinking the LP tanks maybe.
Thanks in advance for any and all advice,
BB |
Jerry Liebler (Jerry_liebler)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 6:26 am: | |
Brian,
I wouldn't give up so easily on fitting it where the HVAC was. Do you still have the heater core,evaporator and blowers in the center of that bay? are you using them? I have an Onan 7.5kw diesel mounted, on a homemade slidout, with it's crankshaft parallel to the axles in the right front 1/4 of the old HVAC bay. To put my generator there I did have to relocate the main air tank. Also my generator's mufflers are near the top of the old HVAC bay and the exaust runs under the bay floor, tucked up in a channel, to where it exits out the left side,just in front of the left rear wheel. I also have my house battery bank, 4ea L16's, my inverter, SW2512 and my propane supply in the old HVAC bay. With room left over for some tools and misc.
Regards
Jerry 4107 1120 |
Jim Ashworth (Jimnh)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 7:30 am: | |
You will end up with a quieter installation if you remote mount the radiator. The genset compartment still needs an air supply for breathing and getting rid of the heat of the block and exhaust manifold. This is an easy way to get the genset into a smaller space,too. With the radiator removed will it fit into the condensor compartment? The separately mounted radiator can have the air come in and go out through the floor, just a small deflector to guide the exhausting air away from the intake is all that is needed.
Jim |
marc schlabach
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 8:35 am: | |
If you are traveling on dusty roads, bringing the fresh air in the bottom is not a real good option. I used my old condensor door screen to bring in the air from the side. It keeps you from getting dust and grime all over your genny. I draw the clean air over the inverter and battery bank before the genset. Works great for me and my mc9. Just my opinion. Marc |
Jim Bob
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 10:27 am: | |
Remote mounting the radiator allows you to really silence the diesel noise. You'll never get it quiet while the engine noise is coming out through the radiator. Many good installations use a 120V squirrel cage fan to cool the radiator.
Whatever compartment you install the genset in, you should arrange it so that the back of the generator part can draw clean air in from the side, not the road. Usually the back end has a grille. The entire size of this opening must be used. The generator windings need about 3 times as many CFM of air to cool as the engine needs to burn. The air must be allowed out through at least as big an area. Usually, the intake & exhaust air are ducted with at least one right angle in each duct. (Sound does not like to go around corners.) The ducts are lined with sound absorbing mat'l. If the air outlet opens into the gen compartment near the top it will do a better job of getting the hot air out.
If you build these right, you will not need an electric fan to remove heat. If you do not assure cooling air to the gen end, it's life will be shortened, like a power tool with dirt in the air grille. If you just put the gen in the compartment & do not fit an intake duct to the back of the gen portion, the air that goes through it just recirculates & gets hotter & hotter. I have seen installations get hot enough to melt components in the commection box & cause the regulators to fail. Also, the engine puts out less HP as the air & fuel get hotter.
Jim-Bob |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 16, 2005 - 10:28 am: | |
Jerry, all of the stock HVAC stuff is gone. On the '06, though, the condensor compartment backs up to the diesel tank. Forward of this are the doors for the old blowers, old heater cores, etc. Rearward of these are the much larger baggage bays. There's a funny angle to the condensor compartment that gets too narrow at the back foor the new genny.
For structural reasons, I didn't think I could cut too much material out of the bulkheads to enable me to have part of the genny sticking into one of these other compartments.
Jim, I'll see if once I remove the rad. if it can fit in the condensor compt. The floor in that bay was built up by the converter, I guess to get a muffler under the Onan, so I need to see if there's enough height also.
Thanks, Marc. Good point on the floor intake.
My unit has a quiet box on it and a five gallon fuel tank, so maybe after I start pulling that stuff off I'll be able to squeeeze it in a tighter space. Here's a link to my genny model. It's not a purpose-built RV genny, but fits my budget ($2500)and should be a lot better for my use than the Onan. Burns less fuel, uses same fuel as bus, quieter, less maintenence, etc.
Thanks,
bb |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 17, 2005 - 1:04 am: | |
BB, I started to give advice and tips on remote mounting the radiator, (I just did a 4106 last year), BUT after looking at the link and reading that it has a 68 db sound rating, I would bite the bullet and leave the noise reduction shroud system intact. If you open it up, your sound rating is going to go to something like 95 db. When you get it home, start it up with a temporary fuel tank, and then open the door on the unit and listen to the huge difference it makes with the cabinet open/off.
We butchered a Honda, and put it in Charles C's '06 and now he wishes he had left the sound proof cabinet alone.
Cheers...JJ |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 17, 2005 - 2:37 am: | |
JJ, I'll check it with my SPL meter with the doors up. I ran the unit when I agreed to buy it and it wasn't too bad. It even idles down when there's not a load on it. It was also able to hold voltage to within one volt when I loaded it on and off with two hairdryers. The Onan just steadily degrades voltage under increasing load.
Even though the sound pressure might seem high, the frequency of the noise is so much lower than the higher-pitched whine of the air-cooled Onan, at least to my ears.
Since we don't boondock (yet), we'll use it mostly just tooling down the road and the few times when we're between the P.P.s on an overnight stop. So when we're rolling, the road noise should mask most any noise it makes regardless.
I'll have to play with it, regarding remote-mounting anything. Getting it to cool itself in the bay is the main priority. I should be able to stick a different muffler on it coming under the bay, so that might help also in attenuation.
Since it's a 3000 rpm unit, it'll be much louder than a comparable 1800 unit no matter what I do. The price is about all I can afford at the moment, and I prefer, at least conceptually the idea of having a liquid-cooled diesel genny over an air-cooled gas unit.
I'll keep ya'll posted on my progress.
Thanks,
bb |
Jim Bob
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 17, 2005 - 8:48 am: | |
Brian, when I wrote my reply, you had not posted your link. My advice is intended for the more typical 1800RPM non housed genset. The priciples hold true for anything though. Having looked at what you are buying, I agree with JJ. I would leave the shield intact and fabricate a duct from the rad outlet of the shield out of the gen compartment, maybe through the floor. You will need an intake opening too. A good rule of thumb is that the inlet & outlets should each be a minimum of 1.25 x the rad opening. Don't just drill a bunch of 1" holes everywhere & hope it'll work. (It might when moving but not when sitting.) Try to arrange it so the air can't go out & back in the intake. Positive cool air flow is key & even more important with a "compartment in a compartment".
We boondock here in Florida (it's 88 here now at 8AM!) & run the gen continuously when it's hot. We also use the gen for AC when driving. (No bus air)
Jim-Bob |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 17, 2005 - 11:07 pm: | |
Brian, 3k RPM is not necessarily louder than 1.8k, since yours obviously is rather quiet at 68 db. Sound attenuation is important. My 4 cyl. homemade genset runs at 1340 RPM, but is quieter at near 1600. I think it is because of the exhaust pulses, and harmonic vibration. Many motors are like that. My car is quiter at 70 mph than 50, and my old Cherokee was quiter and smoother at 2750 RPM than 2600. Something to do with the prop/exhaust resonance. I can't get my genset below about 87db. so love what you have! ...JJ BTW, beg, borrow or steal a digital frequency meter, and set your rpm by it to achieve 60 cycles. The Voltage will follow automatically, your microwave and computer are more sensitive to frequency fluctuations than voltage problems. Most equipment can quite readily stand 15 volts under and up to 10 volts over with no problem. but more than 2.5 to 3 CPS off spec will cause you grief. |
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