J OOPS, I don't get here very often but here is my 2 cents worth. My last reactor was huge and I was never able to explore its upper limits because my power supply would not supply all the power it wanted. It is hard to explain but I will try. It was actually 2 seperate reactors hoohed together. Each half had 7 sections. Each section had 14 plates that only measured 2"X4". Each section had a total active area of 104 sq inches. Each half had 1456 sq inches reactive plate surface for a total of 2912 for the entire reactor. I ran out of power at 10 LPM and started blowing breakers in my house. I could unhook half of it and still get an easy 10 LPM from total of 1456 Sq Inches surface area with no heat build up. In fact I went far enough as to insulate the entire reactor trying to make it warm up some. I guess I am trying to answer your question as far as size. If I could make 10 LPM with 1456 sq inches reactive syrface area then you can get 6 LPM from around 1000 total sq inches with ease. You might want to upsize that some as I was only running at 13.1 to 13.3 volts. I was never able to approach 2 volts per section without blowing a breaker. An automotive system will make from 13.8 to 14 volts. My reactor would have run away with itself at high KOH concentrations at that voltage.
One thing you will need to pay extra close attention to will be plate prep. If you don't media blast your plates then my best guess would be to triple the size and expect lower effeciency. If you do media blast your plates then passivate them very well before you fire it up. You will need to get that Chromium Oxide layer built back up because you blasted it off. A very thin layer will automatically form due to exposure to the air but it needs to be thicker. I wish the thread was still up but it went down with Nicksrealm. There was alot of good ideas there from the many that contributed ideas to that build.
I will try and hang around here more as soon as time permits. Summer in Alaska is very busy for me. I will be doing the rebuild this winter.
Larry
2008 Nissan Frontier 4X4 Nismo. 12 MPG baseline with my normal commute and heavy stop and go daily driving. Generator installed and working on 3/29/2009
Up to 14.5 MPG with no enhancers. Still testing the effects of lots of HHO and no electronic enhancers.