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May 5, 2011 4:39 p.m. curtis73 Dork

So... in the engineering/designing stages of my 66 Bonneville project I came up with a possibly lame idea... or a brilliant one.

The car will have an air suspension and (since the engine will be a duramax) I have the option of a belt-driven pump. Having driven a few air-suspended cars I have always been disappointed in their performance. You let it sit for a week and then you have to wait for it to build air pressure. It kinda takes a daily driver and turns it into a bit of a burden to drive unless you go way overkill with huge tanks and lots of electrical draw for large pumps.

So, I have this CO2 tank sitting here. Its rated for 1800 psi and probably has a capacity of about 4 gallons. Theoretically if I charged it to 300 psi, it would have the same capacity as an 8 gallon tank at 150 psi. What if I were to charge it to something like 500 psi? Can I find a pump that will do it? Will such a pump break the serp belt or cause it to slip like crazy?

I'm just thinking of ways of making the system more compact/efficient. I feel like adequate air generation and component size is the big limiting factor in air suspension performance.
May 5, 2011 5:10 p.m. MrJoshua SuperDork

Land Rovers have electric air pumps. They are decently quick at picking up just the rear of a Disco with leaky air springs. You know there are plenty of dead Disco's around.
May 5, 2011 5:44 p.m. Junkyard_Dog Dork

+1 for cheap-as-free LR pumps, tanks, etc. being a great source of parts. I might even have what you need in a box on the "For Sale" shelf. I'll know later tonight after I reorganize the garage.

Again
May 5, 2011 8:55 p.m. xFactor New Reader

500 psi? I don't know anything, but I'm betting that you would need a two stage pump set-up.

I've done a few air ride cars, and the big dual electric pumps pull a measured 70 amps. I like the belt driven pump, and I've heard of people using a modded sanden a/c compressor. Built-in mag clutch goodness and gobs of pressure. 500psi, I don't know, prolly an Ooogle search away.

later, matt
May 5, 2011 9:11 p.m. oldtin Dork

Sanden 508 a/c compressor - a couple of mods make it a decent 300 psi/8 cfm compressor. Normally this compressor is lubed by a/c refrigerant. The mods use synthetic grease. Pressure switch to tank and pressure relief valve, compressor and hoses...under $100 (not counting tank). 508s are on a lot of mazdas and jeeps. 7 series sandens also work, but supposedly not as well as the 5 series. ymmv edit. there's other options of an oil supply tube - a little bulkier, and a bit more maintenance. Add a coalescing filter if you want to keep oil out of the tank.

endless air
May 6, 2011 5:24 a.m. curtis73 Dork

oldtin wrote:

endless air

This. Bingo. Thank you
May 6, 2011 6:48 a.m. DILYSI Dave SuperDork

Jeep guys use a york internally lubed compressor that has some impressive CFM. Dunno that it gets you the pressure you're talking, but I bet the CFM it pus out lets you not need the PSI.
May 6, 2011 8:01 a.m. njansenv HalfDork

So...what's stopping someone from using something like the SD508 to build an air compressor at home? 9cfm and 300psi? For real?
May 6, 2011 8:57 a.m. dculberson Reader

njansenv wrote:

So...what's stopping someone from using something like the SD508 to build an air compressor at home? 9cfm and 300psi? For real?

Probably just the power needed to turn it! I bet a 5hp 220v motor would have a lot of trouble turning that bad boy under full load. But the results would be spectacular once you got it set up right.
May 6, 2011 9:00 a.m. curtis73 Dork

I know new a/c compressors are a lot more efficient but I know that old compressors like my A4 on my 73 can draw as much as 15 HP to cool the car at peak loads.

... but my Bonneville will have a souped up Duramax in it making about 450 hp, so I think I can spare 10-25 hp
May 6, 2011 9:36 a.m. dculberson Reader

I love 66 Bonnevilles, and I absolutely adore the idea of a 450hp Duramax Bonneville. I can't wait to see the results!!
May 6, 2011 10:27 a.m. curtis73 Dork

Its been a long, slow process. I've been stalled for the last several years because I'm a terrible body guy. Its completely disassembled. I have almost all of the chassis/driveline figured out (with the exception of actually buying the duramax). It has spindles and brakes from an 8-lug 3/4 ton truck up front and a full-floater 10.5" rear.

I finally found a body guy who is going to work with me to do the body work. That will keep costs down and still hopefully have a killer straight body in the end.
May 6, 2011 10:49 a.m. oldtin Dork

DILYSI Dave wrote:

Jeep guys use a york internally lubed compressor that has some impressive CFM. Dunno that it gets you the pressure you're talking, but I bet the CFM it pus out lets you not need the PSI.

The yorks have their own oil resevoir and work well, but are starting to get less common and more expensive in junkyards. They're also huge in bulk and weight. Extreme Outback sells a modded sanden 5 series for around $400. I picked one off a jeep commanche for $20. The modifications consist of tapping an existing port and blocking it off to keep grease only on the backside of the pistons and installing a zerk to keep it lubed. I added a small tank with a manifold - so the car has full air power.
May 6, 2011 11:03 a.m. mad_machine SuperDork

if you are going diesel.. how about the airpumps the big trucks use for their airbrakes? I am not sure on the PSI, but they generally have to make a lot of CFMs on an almost minute to minute basis
May 6, 2011 2:15 p.m. curtis73 Dork

Max psi on the big rigs is 120-150. The pumps can do more, but once they get up into the 150 psi range their CFMs are super low.

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