do i need a tune? if so which is the best place to go?

[Niterider73]

Hello there. I just acquired a 1993 k2500 with a 5.7 tbi. The intake manifold was busted so I have pulled the engine apart and going to a full rebuild along with a few performance upgrades. I am not sure if I will even need a chip for the upgrades, that's why I am asking for your honest help. Its a standard bore and stroke. I am installing vortec heads with maybe a gasket match port and polish along with maybe a 3 or 5 angle valve job. Also I will be installing a new distributor with a hotter coil. And a carb intake with a tbi adapter. Of course the tbi mods will be done to the throttle body. And also looking to install a melling mtc-1 camshaft. Later on down the road I'm going to install long tube headers, flowmastef y pipe and high flow cats. Maybe in the future as well have a functional ram air hood and roller rockers installed too. My question is, will I need a chip or a tuned ecu? If so which chip will I need? Thanks again for your help it is much appreciated.

[dave w]

The quick answer is, Yes. The modifications you are planning, especially the Vortec heads, will require a custom Tuned Chip.

Most members here, including myself, use TunerPro RT software to custom tune a TBI chip.

When I custom tune a TBI chip, I first modify the timing tables and fuel tables. The fuel and spark changes in the chip are based on my personal experience from engines with similar type modifications. The next step is to record data logs (sometimes several), and make the necessary changes to the chip for spark knock and rich / lean fuel conditions identified in the data log.

The "Ultimate" TBI modification is a custom tuned chip!:thumbsup:

dave w

[89S10_Project]

I am just learning the EFI tweaking part of things, and am surely no expert, but I can tell you for certain that with the changes you are making to the engine's ability to move air (engines are really just fancy air pumps, and you're making it breathe much better) you are DEFINITELY going to need changes to the tune ie changes to the program (what you're calling a chip).

Also, it's unlikely you will find a pre-burned, ready to plug in chip that you just have to buy and plug in. You're going to have to do your homework and be willing to experiment. This forum is full of folks that have bought chips from the supposed plug-and-play shops that didn't work out. It's also full of good places to start in terms of the definitions you will need, and advice on where to proceed from here.

I'm pretty much right there with you at present, and am working through the steep knowledge curve of GM EFI tuning.

[Niterider73]

Let me ask y'all this. Its going to need a custom tune. Which there is a tuning shop in my state with a good reputation. MY question is can I drive the truck there without damaging it? Or should I have it trailered?

[89S10_Project]

If you have an unknown state of tune and a long highway drive, you just answered your own question.

[Fast355]

Let me ask y'all this. Its going to need a custom tune. Which there is a tuning shop in my state with a good reputation. MY question is can I drive the truck there without damaging it? Or should I have it trailered?

From previous experience I can tell you trying to run with the factory injectors, stock fuel pressure and stock chip, it will not even be driveable!

[Niterider73]

I'm going to bump up the fuel pressure. Thinking about going with the 91 z28 fuel pump as well. Would 18 psi be a good place to start? Or is that too much?

[89S10_Project]

I'm going to bump up the fuel pressure. Thinking about going with the 91 z28 fuel pump as well. Would 18 psi be a good place to start? Or is that too much?

I believe that will be WAY too much unless you're planning on going to forced induction.

(EDIT: nevermind, listen to the folks that know more than I do- apparently I'm missing a lot! :) )

[Fast355]

I'm going to bump up the fuel pressure. Thinking about going with the 91 z28 fuel pump as well. Would 18 psi be a good place to start? Or is that too much?

You are going to need 20-26 psi depending on the cam and exhaust configuration.