FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
|
Members Helping Members help Buying a non Pontiac item, transportation help, Handy-man advice, directions, vacation ideas, places to dine, ebay and generally anything you think might help other members. |
Reply |
|
Thread Tools | Display Modes |
#21
|
||||
|
||||
The 3 HP 21 Gal model was listed at 14.3 Amp under load, requiring a dedicated 20 Amp circuit at startup. I don't have that info for the 4 HP 10 gal model.
My real question at this point is, is a little more cfm better (5.6 cfm @ 90 psi vs. 4.9 cfm @ 90 psi) OR is a lot more tank volume (21 Gal vs. 10 Gal) better? I'm choosing between a little extra cfm, or a tank that's twice the size.
__________________
Touch my car and I'll bite you! |
#22
|
||||
|
||||
CFM is the most important thing when buying a compressor. Tank size is usually matched to the cfm except with cheaper manufacturers who put a large tank on a small compressor to fool you into thinking its something its not. Figure out the most cfm you will ever use and go one size bigger.
__________________
Derek B. Current best: 11.97@110 1.65-60' !!! '74 ventura, (Fired july 14/06) '74 462 4-bolt (9.5-1), SCAT, Ross, T-II w/850DP (shaker455), TH350, Conti 10'' 3800, Supercomps, Magnaflow, 3'' Pypes, 3.73's, 28x13.5-15 ET streets. 1970 Beismeyer 17' flatbottom vdrive, 11.8:1 455P, ported heads, dual Qjet tunnel ram. |
#23
|
||||
|
||||
And, MichaelD -
You don't need a second 220 volt outlet. All you need is more air hose. As a matter of fact, that's kinda what the manufacturers recommend, as opposed to using an extension cord. Hope this makes sense to you. cm
__________________
If the rules don't say something is illegal, I have to assume it is legal -- Smokey Yunick |
#24
|
||||
|
||||
Don't go too crazy with the hose either though.You will see a pressure loss the longer your hose is.
__________________
71' GTO -original 400/4-speed/3.23 posi 13.95 @ 102.1 on street tires @ 4055lbs. ‘63 LeMans- ‘69 400 w/ original transaxle. 2.69 gears. |
#25
|
||||
|
||||
Well, shoot.
I've got two votes for the slightly higher cfm, and two votes for the larger volume tank (one on the thread, one from my brother, an engineer [though not an auto engineer who has restored cars for 20 years as a hobby]. I'll try to find "the compressor guru" at Harbor Freight and talk to him before I buy. There's one other thing: the 10 gal but higher cfm unit weighs like 75 lbs, and the 21 gal but slightly lower cfm unit weighs 150 lbs. All things being equal, the sheer size of the thing might make my decision for me. I'll post back as to which one I got, and what I've learned, for the sake of posterity (i.e. the next guy in my shoes) or further discussion.
__________________
Touch my car and I'll bite you! |
#26
|
||||
|
||||
Quote:
|
#27
|
||||
|
||||
Scotzz,
Good luck on your purchase. It sounds like you've got a plan. I got the 21 gal model. I talked with a few of the Harbor Freight guys (certainly they aren't all "experts" there, but one of the fellers I talked with has been with H.F. for quite a while and knows his way around tools pretty well. Anyway, the skinny that led me to get the 3 horse 21 gallon model can be summed up in a few points: 1) Durability. For one thing, the 21 gal model has been around for a while, and has been a good solid unit. With a larger tank, the unit has more volume, and the motor won't be continuously running, as it would be with the 10 gal model. That 10 gal model - according to my friend - isn't nearly as "tried and true." 2) Tradeoff in volume's favor. The 5.6 vs. 4.9 cfm @ 90 psi represents a 14% increase, whereas the 21 gal vs. 10 gal volume represents a 110% increase. While cfm rules, it can't totally dominate with disregard for every other feature. I was hoping that some of the wise compressor gurus might give me further insight into this aspect. Had the cfm been significantly higher, I would have gone with the smaller tank. Interestingly the motor looked identical in size and appearance on both units (and maybe it WAS identical; both are actually RATED at 3 HP, and both units are made by the same manufacturer). One of the Harbor Freight guys noticed that the copper air connections were smaller on the 10 gal model; is it possible that they obtain higher flow per minute by forcing the air through a smaller hose? If so, then that seems like a gimmik. Scotzz has a point about the small size of the 10 gal model; it almost seemed like a kid's toy next to the 21 gal model. But that 21 gal model weighs 150 lbs, and is NOT very portable. Having a small unit has its advantages. If you're looking for a big, powerful compressor, there's a lot of info available. But if you want a smaller unit, you're pretty much on your own, I found. I hope this thread is useful for the next guy who wants a smaller air compressor.
__________________
Touch my car and I'll bite you! |
#28
|
||||
|
||||
michaeld,
It doesn't sound like you read the thread from Hotrodders that I linked. I hope you are not disapointed. scotzz, If you try to use a blaster with either of those two compressors you will be disappointed. The compressor I replaced was much larger that those and I had a hard time blasting with it. Do some research on Hotrodders before you buy.
__________________
You lost me at LS. |
#29
|
|||
|
|||
I am on my third air compressor
First i bought a craftsman 110v 4HP 7cfm@90 that didnt keep up with much and ran alot then soon spit oil due to being run to death. Then i bought a 220v stand up tank oil less 5HP @ 11cfm@90 that was much better but was flying apart blowing rods as they have a limited life span. Then i was determined to buy only one more compressor in my life as it was getting old at this point, I bought a campbell hausfeld 7 peak HP 17cfm@90 60 gal upright tank cast iron 4 yes 4 cylinder pump they slowed the pump speed down to make it last longer as well or it would have more cfm. it was around 800.00 But anyways my advice would be buy bigger than you think you need so you dont end up spending twice as much in the long run by things falling apart from overuse do to being to small. The min i would advise anyone to buy would be a oil lubed upright tank with at least 10cfm@90psi it wouldnt keep up totally with a DA and you would have to give it breaks to build up pressure for sand blasting BUT at least you could do those tasks with it. |
#30
|
|||
|
|||
MichaelD
Glad to hear you found something in your price and usage range. Just curious, does the motor have a amps rating or wattage rating? Dan |
#31
|
||||
|
||||
michaeld................I'm not sure which one to go with.............for sure the 10 gal does not have an undersized pump but looking at the cfm of the 21 that may not be true........I am willing to bet that the motors/pump are the same and that is why the cfm is lower for the 21 gal.............I'll makemy final decision when I go check them out tomorrow...........
|
#32
|
||||
|
||||
Quote:
Last edited by scotzz; 02-08-2008 at 10:17 PM. |
#33
|
|||
|
|||
www.eatoncompressor.com even if you don't buy from him read what he as to say re comparing compressors. the man is sharp and builds on of the best compressors on the market.
mike
__________________
so many pontiacs, so little time.................. moderator is a glorified word for an unappreciated prick.................. "Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein "There is no such thing as a good tax." "We contend that for a nation to tax itself into prosperity is like a man standing in a bucket and trying to lift himself up by the handle." - Winston Churchill |
#34
|
||||
|
||||
Quote:
I actually haven't unpacked the crate yet, but according to the manual the motor is 120V 60Hz 14.3Amp (load). I learned something else when I was at Harbor Freight the other day that Scotzz might find interesting. I discovered that there are polishers and there are polishers. There are smaller polishers that my new compressor will be able to handle - 4.5 cfm @ 90 psi - and then there are big "manly" polishers that would be too much for my little guy to power. I bet that there are sand blasters that are the same way: there are probably small blasters that have a smaller, more limited radius, and then there are the big boys that can do a much larger area. If this is the case, then it is simply a matter of matching your tool to your compressor, rather than it being the case that you can't polish (or paint, or blast) with a 5 cfm compressor.
__________________
Touch my car and I'll bite you! |
#35
|
||||
|
||||
Quote:
|
#36
|
||||
|
||||
scotzz,
The thing about blasting and painting is not so much having a compressor that can keep up, but rather having dry air, as I mentioned in my first post in this thread (#7). A compressor that runs continuously or near continuously never gives the air time to cool off ,thus never allowing the moisture to condense so the moisture separator can do its job, this moist air can make freshly blasted metal rust before your eyes. I know because I have seen it happen and I was only blasting my air cleaner lid with a spot blaster. Now maybe if you live in a dry climate this is not a problem but where we live here in the Northeast with our humid summers it is a big problem. BTW I am just trying to give you the benefit of my experience, I don't believe I said it couldn't be done.
__________________
You lost me at LS. |
#37
|
||||
|
||||
Quote:
michaelb............I wound up buying the 10 gal unit.........it was $10 cheaper than they advertised so it came out to be $119...........and I bought a touch up gun that uses 3 cfm................let me know how you make out with the 21 gal unit |
#38
|
||||
|
||||
Scottzz,
I'll try to let you know. The 10 gal model had one obvious benefit compared to the 21 gal model: it was small. Space is a premium in my garage. I hoped that the 21 gal's extra size being vertical would alleviate that. But there is still the 150 lbs vs. 75 lbs of weight. In addition to the sale price, I had a 15% off coupon which brought the 21 gal model down to $126. There was more minutia to buy than I realized: I bought a 50' hose and an air regulator/oil lubricator unit for 18.99 each (on sale) along with the extra plumbing connections I'd need to install it. My plan is to use smaller tools, and to always remember that patience is a virtue. My fear at this point is NOT that the compressor won't be powerful enough for me; but rather that I simply won't use the darn thing. Basically, I figure I'm out a lot less to buy a 21 gal unit I won't use than I would have been to buy a 80 gal macho unit I won't use. From what I've read, if you have the capability to keep a compressor on "continuous run," you should do so if the motor kicks on more than 20 times per hour. In terms of 69lm's point, I live in about as dry a climate as one could come across. So hopefully I shouldn't have to deal with the same set of issues he's describing. Humidity DOES play a big part in a motor's performance: when I was in Panama when in the Army, we actually had to get out of the Blackhawk helicopters a couple times and help lift them to get them off the ground when the humidity got real bad. Never had to do anything like that in "drier" climates. If someone comes across this thread, and knows something about the "junior" compressors (such as the models scotzz and I have been discussing), drop a line and give us your expertise on analyzing which set of features would likely be best (i.e. 110% more tank volume, or 14% more cfm). I still don't feel like I've heard that discussion from any of the posters to the thread thus far, and am interested.
__________________
Touch my car and I'll bite you! |
#39
|
|||
|
|||
Be careful of the lubricator, your air line will get a coating of oil in it and spray oil when you want dry air. Like even filling a tire with air. I oil my tools manually.
Dan |
#40
|
||||
|
||||
Quote:
__________________
Greg Reid Palmetto, Georgia |
Reply |
|
|