This should work, right?

[camnutz]

First off, thank you all for being here!!!

What I have: 88 K5 Blazer 350TBI, no engine mods, very tired.

Parts I have: 97 vortec w/less than 15K miles but cracked head. 69 camel hump heads from an old project w/less than 5K on them, screw in studs, 1.6 rollers, Manley race flo valves 2.02/1.60 unshrouded will have to CC them, guessing about 65. 85 TPI lower, 89 TPI upper, 7730 ECU, 22lb injectors, Edelbrock tubular exhaust, no AUJP yet, but since I plan on burning, do I need it?

What I'd like to do: Put it all together! The cams I'm looking at for this are rollers with 209/213 dur 444/477 lift on 112 or 206/210 dur 480/512 lift on 112. Thought about a bit larger, but TPI has its limits and from what I've read here MAP tuning gets uglier with duration. The heads will affect the low end, but will handle the lift. I'd like to get close to 400HP as possible, and keep some mileage.

I need your help in the tuning of this. I've built many engines, but this is my first computer controlled motor. Any advice is welcome and appreciated!!! Bottom line is, I love my old Blazer, but it needs some kick to keep up with the new stuff. I will be buying the needed programming equipment. I'm tech savvy, just not familiar with automotive systems. Thanks!

[Six_Shooter]

Those 22 lbs/hr injectors will not support 400 HP, they will be good for about 280 HP.

The choice to use the camel hump or vortec heads really needs to be done with a good physical comparison between the heads. At first I would say find another Vortec head, but if there has been extensive port work done to the other heads they may work well for you, and will bolt up easily to the TPI intake. To use the Vortec heads would require an aftermarket lower or modified OEM.

As far as the cams go, they seem a little mild to me, if I was doing I'd go more "wild" than that, but I have been able to get a couple combinations to work well that I was told by "experts" would NEVER work. You do have to realize though that going to wild, does mean that you have to make some concessions on how to tune it and how to make it all work. Just like with a carbed engine, some drive-ability and street manners will go away with a more wild combination than you would have wild a mild one.

That being said, you need to asses just how you're actually going to use the vehicle, since it's a truck, you really want more torque than power, and so a mild cam that promotes velocity at lower RPM will be a better choice than a large race cam. Getting the engine to breath better, both through the intake and exhaust will help as well.

Just a tip on the tuning equipment, if you're debating on whether you should spend the extra coin on an emulator to be able to tune in real time, just do it, it saves so much time being able to tune while the engine is running and see the results immediately.

[Fast355]

Those 22 lbs/hr injectors will not support 400 HP, they will be good for about 280 HP.

The choice to use the camel hump or vortec heads really needs to be done with a good physical comparison between the heads. At first I would say find another Vortec head, but if there has been extensive port work done to the other heads they may work well for you, and will bolt up easily to the TPI intake. To use the Vortec heads would require an aftermarket lower or modified OEM.

As far as the cams go, they seem a little mild to me, if I was doing I'd go more "wild" than that, but I have been able to get a couple combinations to work well that I was told by "experts" would NEVER work. You do have to realize though that going to wild, does mean that you have to make some concessions on how to tune it and how to make it all work. Just like with a carbed engine, some drive-ability and street manners will go away with a more wild combination than you would have wild a mild one.

That being said, you need to asses just how you're actually going to use the vehicle, since it's a truck, you really want more torque than power, and so a mild cam that promotes velocity at lower RPM will be a better choice than a large race cam. Getting the engine to breath better, both through the intake and exhaust will help as well.

Just a tip on the tuning equipment, if you're debating on whether you should spend the extra coin on an emulator to be able to tune in real time, just do it, it saves so much time being able to tune while the engine is running and see the results immediately.

22 lb/hr support more like 350 HP and a set of 24s about 380-400 HP. The flowrate for the factory injectors on my L31 was 23.2 lb/hr and I put down 310 RWHP running about 85% duty cycle.

I would not use the factory bosch TPI injectors. Look instead at modifying your TPI base slightly and using LT1 injectors. I simply filed down the stands that hold the TPI fuel rail slightly. With a large, coarse file it took me about 5 minutes a stand to get the stands short enough to fully seat the shorter LT1 injectors into the intake using the TPI injector clips.

[Six_Shooter]

I've been able to get more power from injectors than what they should but after going with properly or slightly oversized injectors, I will not try to push injectors again. The way the engines respond when using larger injectors makes the expense worth it.

I'm also spec'ing the injectors at 80% DC max, not higher with the above HP estimates, again due to what I have found when using too small of an injector compared to right size or slightly too large.

[mytmouz]

Have the older heads been upgraded to hardened valve seats? If not I would scrounge another vortec head. They are pretty cheap...

[camnutz]

Thanks for the replies! Yes the heads do have hardened seats. Six shooter; I'd really like to hear more about your builds, do you have some prior posts that detail drivability, mileage, horsepower, cam specs and fuel map issues? I have built carbed motors with flat tappet cams with 240+ dur @ .050 and close to .600 lift that are really fun to drive, but use an insane amount of fuel. I also have to have this emission tested. :( Perhaps a 210-212 duration cam would be a better choice. I agree I went to the mild side, the one cam's specs with 1.5 rockers is just slightly bigger than a 92 Z/28 TPI cam, that is what I used for a starting point. The one thing that I'm not clear on is the chip to run. Do I have to get a AUJP? Or can/do I burn maps to a different factory chip or a new one? As for ECM choice, the 7730 is better than the 7747 correct? The pinout part is easy, and I'm making a data cable to ‘plug n play'.