I read the nozzle sizing thread, but got completely lost, very quickly.

I'm installing an aquamist 1s system, it will be taking washer fluid from the stock tank. Or distilled water if I discover that it cools better. I will be installing the nozzle just before the throttle body.

The only performance mod on the car is a 3" downpipe, which, like the aquamist, is meant for improved reliability and engine life (less heat). It is possible that in the future, I may add a catback, and, but much less likely, an intake or an SMIC. Boost will stay stock 10psi, despite any possible modifications, as I will always adjust it down with either pills, or an EBC.

The only nozzle that I have is a 0.3mm 4mm hosetail jet. Is this the ticket, or should I use a different size?

 

I guess I will have a go with the .3mm and hope it goes ok

 

I'd also like to know what people recommend. I'm in a similar situation.

 

From what I've gathered, you'll want water delivery to be about 10-15% of fuel volume at maximum torque delivery. Since this is a simple on/off delivery system, a lot of experts recommend spraying just before peak torque.

So, for a stock car: 255fwhp x .64bsfc = 163.2 lbs/hr or 1713.6 cc/min fuel required.

10-15% of 1713.6 = 171-257cc/min.

Now that you know what you need, Aquamist has made it easy to choose what nozzle based on this graph:



If you are using a pressure switch (instead of an RPM or load sensing switch) around 8psi you'll be hitting a broad range of RPMs, peak torque is around 6500 iirc, so I think you should err a little conservatively and start with the 4mm tip, but a 5mm will probably serve you best.

 

how are you getting these numbers???

 

i come up w 2124 to make 255 fwhp.... which is close to the above number.

so let's take 2124 and 1713 and /2 = 1918. * .125 = 240 CC/min. i would start w 300 CC and go from there...

howard

 

Hmm... Call me curious, but how did you calculate your figure? I used a BFSC of .64 x 255fwhp x 10.5 to convert lb/hr to cc/min. I'm trying to calculate my own nozzle size now, and I trust you more than me on this

 

I come up with different numbers than both of you... I calculate water injection needs based on percentage of fuel MASS instead of volume and since density of gasoline and water are different the calculations are as well. So the question is, do we need a percentage of volume flow (cc/min) or mass flow (lb/hr)? The results are quite different for both.

255 fwhp with 0.64 BSFC = 163.2 lbs/hr gasoline

15% per mass would be 24.5 lbs/hr water or 186 cc/min

I use these values for the calcs:

gasoline = 6.073 lb/USgal
water = 8.32 lb/USgal
USgal = 3785 cc