marco137

iTrader: (1)

Hello all,
I am currently in the planning stages of my water injection setup, and thought I would post up my plans and ideas to get advice and opinions from people far more knowledgeable than me. I have searched and couldn’t find anything directly related, but if you know different then fee free to call me names and post the relevant links!

The idea is to employ water injection on a set of BNRs whilst still running sequential and possibly another nozzle post intercooler (if required). I currently have an Aquamist HFS 5 kit, whist is going to be the basis of the kit, but obviously this is going to needed to be expanded as required.

The primary turbo and post intercooler can be run off IDC without a problem (although as I don’t have the rotary summer, I may have to be creative with the signal to the WI controller) however the problem is the secondary turbo. If the nozzle for the secondary is run with the other two, then it will spray water onto a non rotating turbo with nowhere for that water to go- as such it would end up pooling. Not good! The plan is to take a tap off for boost just downstream of the secondary compressor, which will be able to determine when the secondary turbo is rotating and hence provide the activation point for the nozzle for the secondary turbo.

the problem is that if the secondary turbo is run separately to the primary and post intercooler, then it will be dumping a lot more water into the engine once the secondary comes online- what is required is to reduce the primary and post intercooler to account for the secondary so to keep the total volume of water (compared to IDC) fixed. The only way I can see this being done is to have 2 high speed valves (I am assuming that the primary turbo and post intercooler can be run together) and control them independently - is there an injector driver on the market that can do this? I guess it pretty much has to run a map for each HSV.

Another option would be to use this boost tapping on the secondary turbo to control activation for all the nozzles- this would make the control of them simpler, but would mean the WI didn’t come online until further up the rev range. I was hoping to employ WI through out the rev range to see if it would help with emissions, but I guess this is more of a ‘nice to have’ rather than ‘need’.

Another quandary I am having is nozzle placement for the pre turbo nozzles- reading around I see that a number of people aim the nozzle onto the compressor nut, and I can see the reasoning behind that. however I am a little concerned that due to the small inlet size on the twins, the nozzle plus the required mountings would block to much of the inlet- as such I am debating placing them in the wall of the 90 degree bend prior to compressor mouth- this would make me at the mercy of the atomisation/ droplet size, but I am willing to take that risk.

Ok, so a long post with more questions than info, but as I say I would be very gratefully for your opinions and advice!

Marco

devilsown

I am personal not real big on pre compressor. My business partner is. Pointing it at the nut usually requires the use of a 90 deg fitting to index it into the intake. This can cause a reduction in air flow. So imo its just best to have it 90Deg to the intake air flow,.

marco137

iTrader: (1)

i think due to the small size of the turbos, size of the nozzle would block too much of the inlet, so have plumped for fitting the nozzles as normal. another plus is that it will save some fab work!.

I am still trying to determine the best course of action for contolling the set up however. It boils down to wanting to have a set ratio of water to fuel throghout the rev range, but to vary the loation of injection according to boost. from what i can gather, the programmalbe injector drivers control all the nozzles 'as one', i.e. it is not possible to have seperate maps for each nozzle. as such it would require seperate drivers for each nozzle- which would be prohibitively expensive.

as such i need to find a solution that whilst not quite as 'perfect' as the one above, would approximate close enough. the more i think about it the more i want to inject water off boost to help with emmissions, so that needs to be IDC controlled. the way i am currently looking at it isthat the pre turbo nozzles should be controlled as a function of air flow, whilst the post intercooler should be to top up the amount of water injected to achieve the correct fuel/water ratio.



oooh hang on, i think i have had a brain wave! what if i control the post intercooler and primary pre turbo on IDC of the primary injectors, and secondary turbo on the IDC of the secondary injectors? that would maintain the correct fuel/water ratio at all times, as well as allowing me to run water off boost. any comments about this?

marco