WMI tuning and results.

Gday guys,

I have been playing with water and water meth injection on my car for a few years now. Thought I would share some info from my experience so far.



In 2011 I bought and installed a HFS3 system on my FJ20 turbo powered Datsun 1600. Using a single 1mm jet, fitted post intercooler and injecting 100% water, the car was retuned on a chassis dyno. Boost pressure was increased 5psi to 28psi which resulted in a power figure of 382hp, an increase of 32hp.

Last year I decided to get a little more serious with my water injection set up so I upgraded to a HFS4 v3 system. I was chasing around 400hp so I used the aquamist guide on 1-1.5c/1hp to calculate the required WMI flow of 600cc. For the jetting I used a bit of everything, 4x 110cc direct port, 1x50cc pre turbo and 1x110cc post intercooler. On the dyno, the car made 358hp @22psi without WMI, 390hp with water injection and 418hp@30psi with water meth injection.



http://www.aquamist.co.uk/forum2/vbu...ead.php?t=2787

I recently installed a new ECU and had to have to car retuned. While setting up and testing the testing the WMI system, I realised that two of the direct port nozzles had a non uniform spray pattern. The car hadn’t been used in over 12 months so I decided to pull the jets apart and give them a clean. This did not go as planned and I ended up causing further degradation to the spray pattern, making the jets unserviceable. As this was the morning of the dyno, had to come up with a new plan because I had lost two of the direct port jets. Going through my spare parts pox, I found the jets from my previous HFS3 kit. So I plumbed a 1mm and a 0.8mm jet post intercooler and a 0.4mm jet pre turbo and plugged the direct port holes. Total flow capacity at the 30 psi boost I intended on running was now 830cc. On the dyno, the car made 370hp @ 24psi without WMI and 455hp @ 31psi and 6 degrees extra timing with WMI. That is a peak difference of 85hp but in the at 5000rpm, the difference is 125hp. It should be noted that the latest dyno tuning was conducted on a hub dyno, while the ones previous were done on a chassis dyno.






Data log showing RPM, manifold pressure and flow sensor input.

So what does the future hold? Well my plan is to get some new, larger direct port and post intercooler jets to increase to the water meth to 50% of fuel. I am currently running 750cc injectors with a max duty cycle of 80%, 2400cc. So I’ll be looking at 1200cc of water meth. I also want to bring the WMI on a lot sooner. At the moment i have the THRES set fully ccw but WMI is still only beginning at around 36% injector duty cycle. I'm thinking of connecting the map sensor to HFS4 and adjusting the PI/R dial till the required activation point is reached. The other option is to set up a 3D table in the Link eco and use a ppm output to activate the HFS4. Thanks for reading my rant and please feel free to add any advice or criticism.

Kind regards, Orlando