Holset Turbo Size Question
 

I'm new to the world of forced induction, and I've taken on the project more to educate myself then for any performance gains. I have a 1999 F-150 with the 4.2 v6 engine, and I recently got a great deal on a Holset HX30W turbocharger. What I want to know is if this turbocharger is too small. I'm looking at running between 4-6 PSI of boost, most likely through an eBay intercooler. My goals right now are to bring the truck from it's stock 205 HP rating to the 260 HP of the 5.4 v8, but this goal really isn't important. What is important is the safety of the engine, and decreasing performance below stock numbers by using the wrong parts. Based on my calculations, I will need about 450 CFM at 6000 RMP (The redline of the truck); however, I never race this truck and I never come close to the redline, and I only need about 300 CFM at 4k RPM. As you can probably tell by this point I have no idea what I'm doing when it comes to these calculations, and figuring out what I need. I'm having a difficult time reading the few compressor maps I can find for this turbo. Using a java program that recommends a turbo based on displacement, redline RPM, and desired boost level, I am recommended a Garrett GT25. I see this turbo is roughly the same size as mine, with a turbine/compressor size of 54/53 mm, compaired to my 65/40, meaning I could use this turbo. Thank you for reading this far! Any thoughts you have are greatly appreciated!

the hx30 will be a good turbo for low end boost. it is small enough that it will spool up quickly with your 4.2l engine which is what you want on a truck engine. of course 93 octane fuel will need to be used from here on out. 4-6 psi doesnt require an intercooler but its always a good idea. i would at least boost it to 8-10 psi otherwise the time and money invested isnt really worth it. your next challenge will be tuning.

Glad to hear it won't be too small! I'm thinking about not running an intercooler and using the money elsewhere in the project. 93 octane is what I was planning on running, and VMP tuning claims they can help me get everything tuned right.