5.7vortec to a 5.3 new generation ?

**wheezer** · 02-14-2010, 11:05 AM

I have a 1999 Tahoe 4x4 with a seized 5.7 vortec. It got ~12mpg and not a lot of power when it ran. I have been told that a newer generation 5.3l would give me better milage and more power. I am looking for any information on what would be a good swap/upgrade, without extream modification. I not looking to make it into a hotrod, just a dependabel vehicle with good power. Can anybody help me or point me in the right direction.

**Iaintscared1969** · 02-14-2010, 12:10 PM

You will need a harness and an ECU. Plus the goodies like the MAF, Etc. If you get a donor motor get everthing together. The rest should bolt up fine. Techrods makes a very good harness and are resonably priced. You do get better fuel economy/HP with the 5.3. I install these all the time in the Toyota Landcruisers and they are a great combo.

**wheezer** · 02-14-2010, 12:45 PM

What specific motor should I look for, and what years? Could you list all the goodies that I will need. This is my first time doing something like this and would appreceiate ALL the specific information I can get. Thanks.

**Iaintscared1969** · 02-14-2010, 04:28 PM

Depending oon the state requirments for your vehicle you have a host of options. But the easy thing to do would find a good late 05 and above. Due to larger injectors and flex fuel. Then get the motor,mounts,MAF,airbox,manifolds and flanges, and ecu. Then get the harness from Techrods since it is a lot easier than grafting in the donor harness unless you are a wiring junkie. Then install the motor and hook up the fuel and electrical. If you reuse your 99 fuel pump make sure you get the correct end on the harness for it. Also if you want some flash work done Exatorq in Garland is a really good company in Dallas I use and they have almost next day service. Since youll need the VATS deleted off the ECU.

**joejenkinsglass** · 02-14-2010, 04:33 PM

The 5.3 is a great motor, but your 5.7 has more bottom end power. If it were me I would rebuild the 5.7. As stated before get the whole package if you do the "swap".

**wheezer** · 02-15-2010, 10:17 AM

Thank you for the information.

I keep hearing conflicting opinions. some say the 5.3 is stronger with more torque than my 99 5.7l. Some say just the opposite. Living in Iowa I don't have to worrry about state requirements.

Also, would it be easier to get a gen III engine that is closer in age to my Tahoe. Would it make the swap easier?

joejenkinsglass where in Iowa are you? I'm just north of Davenport.

**bigrondownhiller** · 02-15-2010, 01:25 PM

With all the parts you would need look for a low mileage wrecked truck. Then you can get all the small parts that will add up fast. Ever thought of a diesel swap? I have a 95 tahoe with the old tbi engine and get 15+ mpg. Maybe you just need some maintenance on your truck.