Choosing vacuum pump CFM

The easiest way is to use a salvage, or aftermarket new, OEM brake booster vacuum pump - no science needed there. Some also have pressure switches.

remy_martian said:

The easiest way is to use a salvage, or aftermarket new, OEM brake booster vacuum pump - no science needed there. Some also have pressure switches.

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First of all, thank you for replying. The vehicle already has a brake booster as well as a vacuum reservoir, so I just need to add a vacuum pump & pressue switch, right? no need to get another brake booster, the thing is how to know what size vacuum pump I need regarding how much vacuum does it pump, which is CFM as I understand. Thank you,

If you use an OEM brake vacuum pump, no math involved and you have an automotive qualified component. There are many to choose from. The GM ones are pretty inexpensive.

I have a pump with 12 liters per minute of vacuum capacity. I would go 20 LPM minimum, this pump is a little small and if I'm pressing the brakes a lot at low speeds I can lose some travel on the pedal. Not a big deal just takes a bit more leg strength.

Upon the realization that we forgot we need a vacuum for the cabin air valves in the climate control even though we are using a iBooster for our brakes, I am getting these to add to our project as well as try them on the next conversion with the standard brake system.

Power Brake Booster Electric Vacuum Pump Assembly 20804130 31317530 009428081 US | eBay
New Electric Brake Vacuum Pump Switch for Booster 28146 | eBay

But we also plan to set up our VCU for max regen so we should only be using the brakes in emergency situations (or misjudging the lift distance for 1PD)...

Don't forget the relay for that Chinesium vacuum switch.

@reiderM What pump are you using?

remy_martian said:

Don't forget the relay for that Chinesium vacuum switch.

@reiderM What pump are you using?

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Vacuum Pump 12V Mini Diaphragm Air Compressor with Silicone Tube https://a.co/d/7vghfOu

This one. Lol. No problems so far but it's loud as hell. For $25 new I have no complaints though.

Not exactly weatherproof, either 😬

I would not use that backwards aquarium pump for brakes in a car, but one actually made for life under the hood of a car. One from salvage shouldn't be that different in cost...

Like all things in life, the noise you get depends on how you're mounting it.

It's noisy even when not mounted... Just a noise unit 😅