Hey Lonny,
Our engines are different enough that most books won't help you out.
Some good combinations. Feel free to correct me if I’m wrong on the hp numbers.
600 to 750 hp set up
62mm turbo matched up with a 71,72,74mm turbo
650 to 850 hp set up
64mm turbo matched up with a 74,76,80mm turbo
800 to 1,000 hp set up
66mm turbo matched up with an 80mm, + turbo.
For our trucks, you want to find a high pressure turbo (the little one) with a turbine A/R between .65 and .75 wastegated. Most in here agree that a .70 seems to be a great option and the 75 is a little large. I personally like an external wastegate for the tuning and the fact they are usually bigger.
Your low pressure turbo (the big one) turbine A/R will vary depending on exactly what hp turbo you use. It should be anywhere between a .95 to a 1.36. This is where the experience of the person you are buying it from comes into play. There are a few companies out there willing to work with you and change out components until the set up is right, while others just say what you bought is what you get. Make sure you do your homework when you buy a compound setup.
One way to know if you have the right set up is by checking back pressure. For a street driven vehicle you are looking for a backpressure range of 1.2 / 1.3 to 1. Meaning if you boost is 40 your back pressure should be between 48 and 52. For racing applications, the backpressure should be around a 1 to 1 ratio. Since it is for racing, the fact the set up is little laggy is a acceptable because the trade off is more horsepower from less backpressure.
Now you can have the best compound set up in the world but if you don’t have the fuel or supporting components, it won’t mean anything. So, when you start upgrading your truck, think about the end goal and work towards it wisely.
