water injection - pump position

**sambb** · 30-01-2016, 07:16 AM

I'm going ahead with my water injection install. I'm hoping to keep the control gear and pump located within the engine bay. I just have a question about tank position relative to the pump. I can either use the windscreen washer bottle (with distilled water and the appropriate filters) or have a boot mounted tank. I'd rather the windscreen bottle for stealth, boot use and ease of installation.
My only concern regarding using the windscreen washer bottle is that the only place I can see to mount the pump is possibly vertically in the void behind the drivers side headlight. If I do this the pump inlet will sit about 400mm higher than the tank outlet. Just wondering if anyone has done there's this way and whether or not they encountered any priming problems because of the pumps elevation? I've done a few little bench tests at that elevation which seemed ok but things usually go very differently when put into service.
If I must go with a boot mounted tank, what did you guys find was the easiest way to run the fluid line? I'll be using 8mm pneumatic hard line so was thinking that the underbody route between the cars undercarriage and the removable undertray would be the go?? I've never had that off before so any clues to whats lurking under there?

thoughts
sam

**h100vw** · 30-01-2016, 09:24 AM

Originally Posted by sambb

I'm going ahead with my water injection install. I'm hoping to keep the control gear and pump located within the engine bay. I just have a question about tank position relative to the pump. I can either use the windscreen washer bottle (with distilled water and the appropriate filters) or have a boot mounted tank. I'd rather the windscreen bottle for stealth, boot use and ease of installation.
My only concern regarding using the windscreen washer bottle is that the only place I can see to mount the pump is possibly vertically in the void behind the drivers side headlight. If I do this the pump inlet will sit about 400mm higher than the tank outlet. Just wondering if anyone has done there's this way and whether or not they encountered any priming problems because of the pumps elevation? I've done a few little bench tests at that elevation which seemed ok but things usually go very differently when put into service.
If I must go with a boot mounted tank, what did you guys find was the easiest way to run the fluid line? I'll be using 8mm pneumatic hard line so was thinking that the underbody route between the cars undercarriage and the removable undertray would be the go?? I've never had that off before so any clues to whats lurking under there?

thoughts
sam

Boot mount, pipe behind the plastic work. That comes off with a few 10mm plastic nuts. You want the pump to be gravity fed, not sucking the fluid up.

Mine is in the driverside rear quarter panel on the S3. Pump and reservoir.

Gavin