[IK6SPEED]

Fairly straight forward question.

What is the general recommended PSI and GPM (for safely but effectively) using Foam Cannons and general Car/Wheel Washing?

I’ve seen numbers all over the place.

[Skyhigh]

There is no limitation/recommendation for foam cannons. You can adjust the spraying on the cannon itself. Any commercially available power washer would do.

Rims - use highest setting on power washer. No risk of damage (unless you go insanely close). I use full power on my Kärcher K7 (the most powerful commercially available model) and was as close as 10cm if neccessary to remove dirt from the rim. Otherwise maintain 20-30cm.

Car paint itself - I do suspect I dented my BMW door on 3 places with 90% power setting on the K7 and some 40cm. distance. Sounds unbelievable, but I have no other explanation. Never had any damage on my Audi.
So if you have anything comparable to a K7, I'd recommend 60-70% power and sufficient distance from the car. Of course always with quick movements and angle, do not spend too much time on the same spot, rather revisit.

[IK6SPEED]

Originally Posted by Skyhigh

There is no limitation/recommendation for foam cannons. You can adjust the spraying on the cannon itself. Any commercially available power washer would do.

Rims - use highest setting on power washer. No risk of damage (unless you go insanely close). I use full power on my Kärcher K7 (the most powerful commercially available model) and was as close as 10cm if neccessary to remove dirt from the rim. Otherwise maintain 20-30cm.

Car paint itself - I do suspect I dented my BMW door on 3 places with 90% power setting on the K7 and some 40cm. distance. Sounds unbelievable, but I have no other explanation. Never had any damage on my Audi.
So if you have anything comparable to a K7, I'd recommend 60-70% power and sufficient distance from the car. Of course always with quick movements and angle, do not spend too much time on the same spot, rather revisit.

What is full PSI power / GPM of Kärcher K7 to understand perspective?

[Skyhigh]

160 bar / 2320 psi

[IK6SPEED]

Originally Posted by Skyhigh

160 bar / 2320 psi

What kind of GPM/LPM?

[Skyhigh]

Features of the Kärcher K7 Premium
Flow rate (l/h) max. 600
Induction motor (refrigerated with water) ✓
Max. water inlet temperature max. 60ºC
Pressure (bar/MPa) 20- max. 160 // 2- max. 16
Clean tank solution ✓
A3/4" garden hose connector adaptor ✓
Connection load 3 kW

[hrdboiled]

The psi of pressure washer is going to affect the consistency of the foam. I have a gas powered 3100 psi pressure washer and the thickness of the foam is similar to whipped cream from a can. It's thick and clings to the car. you can't get that from an electric pressure washer. I had a 1600 psi electric and there is no comparison. the consistency of the 1600 was more runny like when you spit out your toothpaste after brushing your teeth.

[IK6SPEED]

Originally Posted by Skyhigh

Features of the Kärcher K7 Premium
Flow rate (l/h) max. 600
Induction motor (refrigerated with water) ✓
Max. water inlet temperature max. 60ºC
Pressure (bar/MPa) 20- max. 160 // 2- max. 16
Clean tank solution ✓
A3/4" garden hose connector adaptor ✓
Connection load 3 kW

So that's 2.65 GPM/2321 PSI

[Skyhigh]

Originally Posted by hrdboiled

The psi of pressure washer is going to affect the consistency of the foam. I have a gas powered 3100 psi pressure washer and the thickness of the foam is similar to whipped cream from a can. It's thick and clings to the car. you can't get that from an electric pressure washer. I had a 1600 psi electric and there is no comparison. the consistency of the 1600 was more runny like when you spit out your toothpaste after brushing your teeth.

I disagree. In my experience:
- The foam density is very dependent on the cannon/nozzle itself. I have 2 different which produce different "thickness" from the same foam products.
- Thick/dense foam does not mean better washing results! It is more a show-off effect than anything else. I achieve better cleaning results with a product that produces less thick foam and better "wow" effect for the neighbours with a foam product, that doesn't really help the washing much. Don't be mislead by that.

I am sure the pressure plays a role as well, but I do think there are more important factors and aspects.

[louielouie]

Originally Posted by Skyhigh

I disagree. In my experience:
- The foam density is very dependent on the cannon/nozzle itself. I have 2 different which produce different "thickness" from the same foam products.
- Thick/dense foam does not mean better washing results! It is more a show-off effect than anything else. I achieve better cleaning results with a product that produces less thick foam and better "wow" effect for the neighbours with a foam product, that doesn't really help the washing much. Don't be mislead by that.

I am sure the pressure plays a role as well, but I do think there are more important factors and aspects.

+1

There's a YT video from Obsessed Garage where he reviews a Sun Joe unit vs his Kranzle 1122TST ($150 vs $2,000) which he primarily uses. Foam density produced using the same foam cannon/product isn't 100% identical but very similar.

[Skyhigh]

I'll repeat but I feel it is important - the amount and density of foam is NOT indicative for the cleaning effect of the chemical! If you want to impress your neighbors - fair enough! But if you are after a clean car - do not judge based on that alone. Ignore how sexy the foam looks and look at the effect once you rinse.

[IK6SPEED]

Originally Posted by Skyhigh

I'll repeat but I feel it is important - the amount and density of foam is NOT indicative for the cleaning effect of the chemical! If you want to impress your neighbors - fair enough! But if you are after a clean car - do not judge based on that alone. Ignore how sexy the foam looks and look at the effect once you rinse.

So what soap formula(s) are the recommended best?

[Sea-Tac]

Originally Posted by Skyhigh

Features of the Kärcher K7 Premium
Flow rate (l/h) max. 600
Induction motor (refrigerated with water) ✓
Max. water inlet temperature max. 60ºC
Pressure (bar/MPa) 20- max. 160 // 2- max. 16
Clean tank solution ✓
A3/4" garden hose connector adaptor ✓
Connection load 3 kW

Thanks...good information...

[IK6SPEED]

Originally Posted by Skyhigh

Features of the Kärcher K7 Premium
Flow rate (l/h) max. 600
Induction motor (refrigerated with water) ✓
Max. water inlet temperature max. 60ºC
Pressure (bar/MPa) 20- max. 160 // 2- max. 16
Clean tank solution ✓
A3/4" garden hose connector adaptor ✓
Connection load 3 kW

Originally Posted by IK6SPEED

So that's 2.65 GPM/2321 PSI

So a power washer I am looking at is 2.4 GPM and 2700 PSI

Should I be worried at 2700 PSI as that is about 20% higher PSI than yours and certainly 2x the 1400 PSI someone else stated?

[Skyhigh]

Are you unable to limit output power?
If not - I would be extremely careful and always maintain extra distance!
As I said, I suspect the 3 vertical dents on my door came from 90% setting on my K7, normal distance. No one believes me though and I have always washed my Audi the same way without any trouble, but that is the only explanation I can find for 3 dents with no top-coat damage, discovered during a wash.