I have a 2000 k3500 crew cab DRW with 6.5 turbo. I'm wanting to try to get some more power out of it. I pull a 35' three slide fifth wheel with it and just dosen't like it too much, but I love the truck other wise. Have been reedin some on the 18:1 pistons with an intercooler and turning up the turbo,but didn't know what all I need to do. Also read something about milling the old pistons down to size but didn't know how much or if will be able to take the heat. Thanks for the help!

 

Well that is pushing it a little to pull that big of a trailer.
Intercooler is a nono on the 6.5 they don't like it.
Turning up the turbo is good you will feel it but you need a turbomaster.
Get a Heath computer reflash, get injectors standard output, and an open exhaust with a crossover pipe and bigger down pipe

That's good for the small stuff and you will feel like you have a new truck.

Gauges are a must!!!

However, Here is a good explanation about 18:1 pistons.
To me, it sounds like a waste of money to what your going to get
The goal is to get as many little oxygen molecules into your cylinder as possible before the valve closes. Once the valve closes, you are stuck with that much oxygen, no matter what your compression ratio is.

Most engines are oxygen limited. Fuel will only burn properly in a strict ratio with oxygen. Too much fuel in the ratio, you will not have enough O2 to combust cleanly. As all piston engines (gas or diesel) are basically air pumps, they are air limited in how much power they make. In simple terms, getting air, and thus into (and out of ) the engine is the key to power. Turbos, tuned intake runners, port and polish, high lift cams, its all about getting as much O2 into the cyl as possible.

Lets look at a thoretical 1 cyl 1 liter normally aspirated diesel engine. This model assumes 100% efficiency at sea level.

When the piston completes its intake stroke, the cyl is filled with 1 liter of air at 14.7 psia. Oxygen content of air is ~20% so you have 200 cc of oxygen available for combustion. If the cyl compression ratio is 22:1 then that cylinders pressure would be 323 psi BEFORE factoring in pressure gains due to heating of the air. In the real world, the actual cyl pressure would be closer to 450psi. But for this instance, we will ignore heating pressure for the sake of simplicity.

So with only 200 cc of oxygen, we are limited to how much fuel we can inject, and thus, how much power we can make. We can inject WAY more fuel than this amount, but injecting too much will just produce smoke, and increase EGT's without making any additional power. There just isn't enough oxygen to combust this amount of fuel.

So, its obivous that we need more oxygen in the cylinder to allow more fuel to be burned. So we bolt on a turbocharger, and set it up to run at 14.7 psi of boost.

Now when the cylinder completes it intake stroke, It contians 1 liter of air at twice atomospheric pressure (29.4 psi) so you actually have DOUBLE the volume of air in the cylinder. So now we have 400 cc of oxygen available for combustion. we can inject TWICE as much fuel and make twice as much power. Life is good!

Except... Lets say our engine cannot take more than 550psi before bad things happen.

So with 14.7 lbs boost and a 22:1 com compression pressure at TDC is 646 PSI. and this would blow the head gaskets out of engine. So lets reduce the compression ratio to 18:1, this lowers the compression pressure to a more manageable 529 psi.

True, if you could build the engine to survive at 14.7 boost with 22:1 compression, it would out perform a comperable 18:1 engine, but a high boost 18:1 will make much more power than a low boost 22:1

So in summary, when we are limited to how much compression pressure the engine will tolerate, its better to pack extra air into the cylinder with higher boost, and compress it less, than to pack less air into the cylinder and compress it more.

That, in a nutshell is the benefits of an 18:1 compression engine. It allows more boost safely. The pistons in and of themselves will do nothing to enhance power. As a matter of fact, installing 18:1 pistons without increasing boost will reduce performance. They are the FOUNDATION to building power.

Hope this helps

 

Id be more concerned on turning up the boost to compensate for lower compression. the lower end wasnt designed for any over 10psi boost and would be risky with main webs already prone to crack the best solution would be to get a p400 revised new 6.5 diesel engine they make 250hp and 550 tq n arent prone yo cracking other than that id suggest a chip exhaust cold air intake #9 resistor.

 

Intercoolers are not bad for these engines-you just have to chooses an intercooler that does not restrict airflow.

Also,if you use water injection-do it after the intercooler.

An intercooler also allows higher boost levels(with an aftermarket tune) because the IAT's will be lower-air heats up when compressed so cooling it will make a denser charge and more boost is a benefit then.

An aftermarket turbo like a HX 40 or ATT will help also,the stock turbo lays down an dies above 2400 rpm,when towing you tend to need the power above that rpm often because of gear changes on hills ect.

 

Feed The Beast Mod Feed The Beast, Part I & Part II Improve fuel to IP is something you can do now to help sustain ability to pull and help also when coupled with aforementioned mods for performance. 18:1 not the best bang for buck mod I know of from feedback of those that do it, not really necessary. Adding an IC with GM turbo is only required because you are trying to push it where it really loses efficiency, now with additional mods that allow one to run efficiently at higher boost pressures then some sort of after-cooling can be beneficial be it WMI or IC