I'm about to do the home depot boost controller mod. I searched but still don't understand what the pre-spool controller does. does this valve control the transition b/t the primary and secondary turbo? rob says to start w/ it closed but how do you know where to set it to get "the spike characteristics your looking for"? any help would be great. thanks, nick

 

The pre-spool controller changes when the secondary comes online. If it is adjusted too far one way you get huge lag between the primary and secondary turbos. If it is too far the other direction you get a huge boost spike at transition. I did that mod and it helped quite alot to get my boost pattern fixed when I was living in Colorado. I get it from 10-4-8 to about 10-6-10. If you see something close to 10-8-10 already it probably isn't worth doing the pre-spool controller.

 

thanks tom. so your saying if i don't see a bad boost pattern then i should just leave it alone and install the valve for just the boost controller? i usually see 10-8-10 patterns, never anything lower than 8 when i'm on the gas. thanks, nick

 

If it ain't broke, don't fix it. It is really easy to install anyway if you need to do it later down the line, but for now I say stick with what works. I had a big dip at transition/spiking of the primary turbo and the valve solved my problem.

Matt

 

It is a pain in the butt to get adjusted properly. Like Matt said, "if it ain't broke, don't fix it".

 

I was getting a nice boost patten of 10-8-10 or 12-8-12 low v/s high boost settings, but wanted to try and shorten the time of the dip. I did a bunch of 3rd gear pulls and logged them all with the datalogit.

With a combination of adjusting the pre-control rod length (nearly the same effect as you would do with your valve), and adjusting the transition rpm's a bit in the datalogit, I was able able to reduce the time of the dip from about .8seconds to .4-5seconds. The lag during transition during the dip is noticably shorter now and is very evident when graphing boost vs rpm on an excel sheet from the datalogit log file.

K