Suction power in Car Vacs ?

[CheckeredFlag]

What do you look for, when you buy a Vac ?

I need to replace my old one, I don't need one mounted to the wall, it will just be for personal use. (I'm not in the detailing business)

I don't want a cordless one, they never seem to last as long as I would like anyway.

I would like one with lots of suction power, a blower option would be fine as well.

I've seen HP ratings (like 6.5, for example)

What do you have / recommend ?

[g26er]

I have a 5 gallon 5.5HP Shopvac from Lowes. Very portable and comes with attachments more oriented towards car cleaning (ex: crevice attachment). I've had it about 5 years I guess and it's still running strong.

EDIT: To add... you mentioned a blower option. If you're thinking to use it for drying your car I'd think twice. I'd get something dedicated to drying so you don't have any dirt particles in your air stream.

[daveinsweethome]

power flite 51 amazing and small and really sucks

[BobbyG]

What do you look for, when you buy a Vac ?

I need to replace my old one, I don't need one mounted to the wall, it will just be for personal use. (I'm not in the detailing business)

I don't want a cordless one, they never seem to last as long as I would like anyway.

I would like one with lots of suction power, a blower option would be fine as well.

I've seen HP ratings (like 6.5, for example)

What do you have / recommend ?

A note about shop vacuums and horsepower…

For years I’ve scratched my head how manufactures advertise these massive horsepower ratings so I’ve done some digging and here’s what I’ve come up with.

I'm not an electrician bit common sense tells me when Craftsman and several other vacuum manufactures boast about Peak Horsepower I get this feeling that I should immediately sit done to protect myself...

The numbers


1 horsepower = 745 watts
Watts \ Volts = Amp


Craftsman (6.5hp X 746) / 115 volts = 45.25 amps
RIGID (5hp X 746) / 115 volts = 32.5 amps
Shop-Vac (6.5hp X 746) / 115 volts = 45.25 amps

Regardless of manufacture, they all do it and in my opinion BS...

I guess I should be running my old Craftsman vacuum on a #6 wire and a 50amp circuit breaker but I never have. It's always run fine on a standard 15amp circuit breaker...:dunno:


So, is this horsepower thing just a gimmick? Mostly.

The underlying truth of what the manufacturer is probably not telling you (or the salesperson simply doesn't know), is that a so-called "five horsepower" device really means that, under very particular conditions, it is capable of developing 5 HP of peak power -- for a very brief interval of time. This is not continuous, full-load power. Note that they might use the term "develops" or "peak" immediately preceding the horsepower figure in the rating claim. Often stated as "develops 5 HP."

The peak power of a motor in this situation is calculated by measuring its electrical power consumption at its stall torque, as simulated in a laboratory. A mechanical load such as a braking mechanism is applied to the running motor, which causes the shaft to stop turning. At that precise moment in time, the motor will draw its peak electrical power (kids, don't try this at home). At that point, the motor is suddenly drawing an abnormally high amount of current -- a phenomenon called "locked rotor current," which is similar to inrush current. You may witness this phenomenon when your circular saw momentarily binds up while cutting wet wood (notice how the lights dim when this happens!).

The whole concept of peak power is silly, because the motor is not intended to be operated in this condition for more than a brief interval. It is not a practical measurement of the motor's true capabilities.

A motor in a device such as a saw is better defined by the power delivered while continuously doing its intended job - cutting wood! Stalling an electric motor for more than a few seconds will cause it to heat up and possibly burn out, though your circuit breaker will (hopefully) trip first. The motor is, for a very brief moment, drawing much more current than normal.

The manufacturers cleverly use this abnormally high electrical current transient to calculate its "peak" horsepower, using the same equation discussed above. This mathematical sleight-of-hand affords the manufacturer some distorted bragging rights as to power. Take a look at the amperage, the secret lies here...

In short, it's a way to deceive the customer into thinking horsepower is king..........It is but only on the racetrack...:props:

[Bill1234]

Shop vacs are one of tools that will only work if cared for. You MUST keep the filter clean in order for it to take in the air and whatever you are sucking up. I have a 5 hp rigid which is nice, but I reccomend the original shop vacs

[paskett]

Very well said BobbyG. Just when I buy a new vacuum for the home, you always want to look for the most amps. Most home vacs bost about their amps which are typically 10 and 12 amps, up to 14 and even higher on some high end $500 models, so check the amps, the higher the better!

[paskett]

Oh, and what Bill said. Also, keep in mind the longer your hose the more suction you'll lose!

[CaptJon]

I just use my rigid shop vac that has a detachable blower to vac and dry. Figure the dirt particles are hitting my truck harder and faster at highway speeds than what's coming out of a cheap shop vac anyway.

[g26er]

I just use my rigid shop vac that has a detachable blower to vac and dry. Figure the dirt particles are hitting my truck harder and faster at highway speeds than what's coming out of a cheap shop vac anyway.

Some people use a blower to get most of the water (especially cracks and crevices) then finish up with a towel. If you want to wipe your paint after you just blew dust all over it, that's your call. :props:

Better to be safe than sorry besides we aren't sure what he wants the blower feature for anyways.

[scrubs147]

I look for "water lift" (or sealed pressure) ratings. If it doesn't have at least 90 inches of sealed pressure, I won't buy it. Now that sucks!

[CaptJon]

Some people use a blower to get most of the water (especially cracks and crevices) then finish up with a towel. If you want to wipe your paint after you just blew dust all over it, that's your call. :props:

Better to be safe than sorry besides we aren't sure what he wants the blower feature for anyways.

Did I say i use a towel after I blow dry? You are correct about not knowing what he wants the blower for, I just assumed since he mentioned it on a car detail forum.

[CheckeredFlag]

Lots of good to know info

Thanks !

[sahrcar]

+1 for the Powr flite p51. I just ordered one for myself and have been using it for about 2 weeks now. It is so much better than my 15 gal Craftsman shop vac I have and better than any other vac Ive used. It has a whole lot more suction and instead of doing an entire suv in about 20 min I can do it now in about 10 or so. And I was also thrilled to discover that it also has the blower feature too.

I see many have commented about blowing the debris inside of the unit onto your vehicle. I wonder how many have actually used a shop vac with blower to dry a vehicle ? Yes the first initial blow may have debris from the hosing but after that first 1 or 2 seconds the pipes are cleared and then its just air from the motor on top being blown through. It is safe to use as a drying aid for vehicles.

[tuscarora dave]

A note about shop vacuums and horsepower…

For years I’ve scratched my head how manufactures advertise these massive horsepower ratings so I’ve done some digging and here’s what I’ve come up with.

I'm not an electrician bit common sense tells me when Craftsman and several other vacuum manufactures boast about Peak Horsepower I get this feeling that I should immediately sit done to protect myself...

The numbers


1 horsepower = 745 watts
Watts Volts = Amp


Craftsman (6.5hp X 746) / 115 volts = 45.25 amps
RIGID (5hp X 746) / 115 volts = 32.5 amps
Shop-Vac (6.5hp X 746) / 115 volts = 45.25 amps

Regardless of manufacture, they all do it and in my opinion BS...

I guess I should be running my old Craftsman vacuum on a #6 wire and a 50amp circuit breaker but I never have. It's always run fine on a standard 15amp circuit breaker...:dunno:


So, is this horsepower thing just a gimmick? Mostly.

The underlying truth of what the manufacturer is probably not telling you (or the salesperson simply doesn't know), is that a so-called "five horsepower" device really means that, under very particular conditions, it is capable of developing 5 HP of peak power -- for a very brief interval of time. This is not continuous, full-load power. Note that they might use the term "develops" or "peak" immediately preceding the horsepower figure in the rating claim. Often stated as "develops 5 HP."

The peak power of a motor in this situation is calculated by measuring its electrical power consumption at its stall torque, as simulated in a laboratory. A mechanical load such as a braking mechanism is applied to the running motor, which causes the shaft to stop turning. At that precise moment in time, the motor will draw its peak electrical power (kids, don't try this at home). At that point, the motor is suddenly drawing an abnormally high amount of current -- a phenomenon called "locked rotor current," which is similar to inrush current. You may witness this phenomenon when your circular saw momentarily binds up while cutting wet wood (notice how the lights dim when this happens!).

The whole concept of peak power is silly, because the motor is not intended to be operated in this condition for more than a brief interval. It is not a practical measurement of the motor's true capabilities.

A motor in a device such as a saw is better defined by the power delivered while continuously doing its intended job - cutting wood! Stalling an electric motor for more than a few seconds will cause it to heat up and possibly burn out, though your circuit breaker will (hopefully) trip first. The motor is, for a very brief moment, drawing much more current than normal.

The manufacturers cleverly use this abnormally high electrical current transient to calculate its "peak" horsepower, using the same equation discussed above. This mathematical sleight-of-hand affords the manufacturer some distorted bragging rights as to power. Take a look at the amperage, the secret lies here...

In short, it's a way to deceive the customer into thinking horsepower is king..........It is but only on the racetrack...:props:
My father pointed this little paragraph out to me the other week when I was talking about how much my vacuum sucks up dirt compared to a regular shop vac.

Copy & paste from Wikipedia

Suction is popularly thought of as an attractive effect, which is incorrect since vacuums do not innately attract matter. Dust being "sucked" into a vacuum cleaner (http://en.wikipedia.org/####/Vacuum_cleaner) is actually being pushed in by the higher pressure air on the outside of the cleaner. The higher pressure of the surrounding fluid can push matter into a vacuum but a vacuum cannot attract matter.


So your theory of looking into amperage instead of HP makes a lot of sense to me, as does someone's mention of maintaining a clean filter. The higher amp draw you have on a vacuum motor and the less obstructed the filter is, the more negative pressure it will likely be producing allowing the atmospheric pressure to push more dirt into the vacuum cleaner's hose.