Project Red Devil Hybrid Vortec


Project wasn’t named Red Devil because of how mean or wicked but rather the headaches and frustration it caused in getting it to run correctly. Showing just how important it is to have some diagnostic tools and even then sometimes its just trial and error figuring out painful projects. We all would want our projects to go together and run perfectly from the starting point. That NEVER happens with any of my personal projects and many customers have as bad or worse issues than I do and so this project is to show you some of what can go wrong and how to diagnose it.

This is the first project with some dyno results for the Engine Quest CH350G hybrid vortec heads that the TBI intakes will bolt right on and while the dyno results weren’t quite up to par they aren’t bad and I think with a bit more work can be right up where they should be.

so whats the build.

350 with CH350G engine quest hybrid vortec heads
Comp cams CL12-256-4 camshaft 212/218 duration @ .050 which has become quite popular with TBI projects
Edelbrock 3704 intake bored to match a larger bore throttle body from
Patriot long tube headers. Look good but do have an issue with poorly placed o2 sensor bung in the number 5 cylinder exhaust tube.
dual exhaust with flowmasters.
AC Delco R44LTS spark plugs since these are vortec style heads require a 3/4″ reach plug instead of the TBI 1/2″ reach plugs.
Pertronix distributor and MSD 8226 Blaster coil.
K&N air filter lid setup

now to the issues. Brandon contacted me stating it was running poorly and so we tried a few things and he even got the datalogging cable from and used the TTS Datalogging software off the website but truck ran so poorly it wouldn’t go into closed loop and just at a loss trying to diagnose this thing from here so after months of trying to figure out what was wrong, Brandon loaded up the truck and towed it 6hrs to leave it with me. I typically dont take on other peoples projects like that as I really only turn wrenches on my own stuff and my available time is VERY limited but I knew he needed help desperately and I was interested in messing with one of these setups with those CH350G engine quest heads.

so I fired it up and sure enough it ran horrible. Undrivable bad. So I pulled the number 4 spark plug and it was WHITE. So I went and I increased the fuel 20% and it did run significantly better and so I went another 20% and it was drivable but duty cycle was way too high on those injectors at that point so I contacted SPR Performance and I borrowed some 350 injectors from him and waited for their arrival and so expecting the injectors to be the wrong size which happens more than you would think, I went back to the original programming and changed injectors and it ran awful again so I changed to the 40% increase programming and it ran good again. So I knew it wasn’t the injectors so I put the first set back in and hooked fuel pressure tester gauge Actron CP7817 to the fuel supply line. Fuel pressure was about 6 psi. I changed the spring in the throttle body which was the little stock spring to my 18 psi spring and that got me to 12psi and found that the regulator was adjustable changed at some point and so I screwed more tension on that spring a few times until I got the 18psi. I went back to the original programming and motor ran dramatically better but still had a part throttle and light throttle miss. Over 50% throttle it was fine but dip below that and it would miss again. Also the computer was still not going into closed loop on the datalog. O2 sensor was a single wire o2 in that number 5 runner tube so I welded a bung in the exhaust just behind the main driverside header collector and put my 3 wire heated o2 sensor kit in. Went for a drive and computer went right into closed loop but data didn’t look bad and still had the miss. So I went and pulled spark plugs and the coloring was off. Some looked perfect and others looked funky and then I found number 7 was BLACK which theoretically isn’t possible with TBI with 2 injectors and 8 cylinders so I changed the plug and it did run better but not right so I went and changed the spark plug gap from the .040″ that I typically set these to down to a tight .030″ and then it ran GOOD with no issues at all. So if you have a symptom like that try gapping the plugs tighter. This is just a bandaid though as that tight gap is really too tight except on supercharged or nitrous applications and can affect performance. Limited on time and not wanting to spend too much labor on the project that the customer could do now that the truck ran well. I went ahead and strapped it on the dyno.

the very first dyno pull was pretty close and only took about 6 pulls and adjustments to get it pulled in where the AFR was nice and flat and changes didn’t affect the power more than 1 or 2hp.
206hp and right around 300hp at the wheels. Now this dyno is more stingy with its numbers than the one used on like the plum crazy project which made a similar horsepower number but less torque. With 20% drivetrain loss puts the horsepower and torque right at 265hp and 375lb of torque at the flywheel which is a little low for that combination but I am sure the ignition system is guzzling up a good 20hp or more which can be either the ignition coil or spark plug wire choice or both. Personally, I would change both. Plug wires were just auto parts store replacements not performance wires. I really like the Accel 9000 series wires as they outer covering is pretty tough and they test considerably lower resistance than these wires tested. This truck also still ran mechanical fan and standard crank pulley which I would have changed.

Hope this project listing gives people some diagnostic aid for their TBI projects.