Here is Jons daily driver 1994 Suburban
Vortec heads have become the basics for many TBI project vehicles and for good reason. This suburban is even more budget than my budget vortec truck was. This suburban is running all stock, restrictive original TBI exhaust as well as the tiny little 42mm 450cfm throttle body. All that has been done is my custom chip kit to increase the fuel capacity to support the vortec heads. This motor isn’t a true vortec motor, its just the vortec heads on top of the original TBI block and still sporting a flat tappet cam but the cam was a sealed power CS274 194/203 duration @ .050″ flat tappet cam http://www.summitracing.com/parts/SLP-CS-274/ which is really close to the factory specs on the vortec roller cam that would have been in a true vortec cam. Jon wasn’t looking to make the most power from this engine as he drives modestly and new he would never drive it over 4000 rpms and all he does is cruise down the highway. This setup is running GM vortec intake along with EGR tube and function EGR and everything. Also Vortec heads requires my custom chip kit to upgrade the fuel system and programming to run this engine. This suburban is one of many 4×4 GM products that came with pathetic 3.42 gears and with the increase in tire size to a 265/75R16 31.6″ tire the stock motor only ran good down hill.
If you look at the dyno graphs you will see that power peaked at 4300 rpms and while it pulled 190hp at the rear wheels at that 4300 rpms it still pulled a good 148hp at 3200 rpms where the dyno settled out after the initial throttle hit. That 148hp is right where the stock plum crazy project started out with a hot chip in a stock motor at its max of 4500 rpms. A 4×4 is going to have a good 7-10% more parasitic drive train loss than the 2wd plum crazy project. So what this means for Jon is that his motor is making as much power at only 3200 rpms where it used to take 4500 rpms to get and when you have wimpy gearing that is important. The next thing is if you look at the torque numbers from those vortec heads that motor is making 25lbs of torque more than plum crazy did at its finished project level and while plum crazy did make a tad higher numbers at its finished level it took 700 more rpms to get that power and that isn’t factoring in that extra drive train loss.
For a good low end cheap torque motor check out this setup. With 27% drivetrain loss which we have been factoring in for automatic 4×4 trucks and less than everyone tells me I should be using for drivetrain loss that comes out to 263hp and 380lbs of torque which is a bit better than Gm pulled from a stock vortec 350. Jon does plan to upgrade the throttle body and exhaust on this truck as funding allows and I don’t see why that shouldnt yield him another 30hp from this combination.
Jon has reported back that his heavy suburban is getting right at 17.8mpg on the highway with a little mixed driving in there too which isn’t too bad for that heavy Chevy.