Introduction
Well it had to happen someday and it did. The program director (wife) decided she did not want to drive a bi-fuel Cavalier anymore and wanted an SUV. After looking at some used SUV's we decided on a 2008 Chevy Trailblazer. It had low miles, large cargo bay and a full steel frame. Unfortunatly the Trailblazer would turn out to be a diffucult vehicle to convert to SVIS (Sequential Vapor Injection System). Below is my documented adventure from start to finish. It should help you get an idea what a CNG conversion is really like. Enjoy!
The Real Story
You already know most of the backround information from the main page and above introduction, so I will not bore you with more dribble. Over the years I have collected many CNG parts off Ebay to repair my Cavaliers. Tanks and cradles, nozzles, fittings etc. With such a surplus, I figured someday they could be used in some kind of future conversion. So alot of what you see here are used parts. With that, the first order of business was to select a conversion kit. I wanted a kit that was computer tuneable via a PC and USB cable. It had to be port injection with good support, so I choose technocarb. Here is the contents of the kitspread out on my assembly table. The next order of business was to design and fabricate the tank cradle and cradle mount. It just so happens that I had 2 CNG tanks, cradles and miscellious parts for a Cavalier, stowed away from an Ebay purchase 9 months ago. So now I need to cut the straps out of the two cradles in preperation for the mount design. Once the two strap assemblies were ready, it was time to do some preliminary fit up in the Trailblazer cargo bay. This will determine how much modification, if any, is needed. Once the fit up and design work is complete, it is off to fabricating the main tank support and attaching the tank straps. The design work was done with AutoCAD Mechanical Design software. It is truely sweet to be able to design to scale and transfer that design into a perfectly fitting assembly. Once the fabrication was complete, it was time to paint the main supportand add the rubber isolation strips. The main tank support was then installed in the Trailblazer cargo bay. Durring the main support install, I had to fabricate some underfloor support plates which are needed per NFPA 52. With the CNG tanks installed, I needed to replace the Chevy style HPL (High Pressure Lock-off) with a Ford style one. That is where I found the dreaded left handed thread. After I got the HPL issue out of the way, my attention turned to routeing the CNG tank supply pipe, electrical tank connection and installing the vent booting. Moving on, my next task wasinstalling the fill nozzle on the rear frame. At this point I decided to take a look under the hood and begin some planning of components there. I chose to install the injector nozzles first. This entails removing the intake manifold and what a job that was. With the intake manifold finished, I turned my attention to installing the CNG regulator. The regulator placement was important in that multiple connections needed to be made and working clearance was a high priority. It also needed a special bracket made to position it correctly.
