I have just recently acquired a 1998 GMC 4x4 with the 6.5L diesel and auto. It is bone stock except for K&N Filter and the black box being relocated with a cooler. What should I do to gain some power and maybe increase fuel economy.

4" exhaust, Heath TurboMaster and ECM is my recommendation. Fill out your signature in the User CP in the tool bar so the more experienced guys can help you easier.

The very first thing you should do before you start giving a Diesel more power is guages. The 6.5TD is easier to burn up than most Diesel's because it is an IDI. Atleast put a Pyro guage on at a minimum, if your Pyro temps get to high you will no longer have a running truck. Do some searching and read the stickies. You will learn more about the 6.5TD in there than you ever will asking questions.

Take pride in what you drive and update your Signature line. It helps us to help you! Use the link in my Signature line if needed to make it easier for you!

Welcome to the Diesel Place!

That black box on a cooler, is it still located inside the engine compartment?

If so, you may want to put it outside before it gives up. It makes no sense to mod it and the truck is not reliable.

This is the order I used:


PMD Isolator
K&N Intake
4" Exhaust
Gauges
PCM
Turbo-Master
Fuel Injectors


I cannot stress the importance of gauges on these motors. Stock, they will burn the tops out of the pistons. Simple things like the air intake and exhaust to make the motor breath better make a difference. The PCM, Turbo-Master and Injectors completely transform the truck, but only if you have gauges to baseline with. Relocating the PMD out of the engine compartment is crucial for reliability.