Brian Goble's Non-Sequential Conversion, Part 3

Brian Goble's Non-Sequential Conversion, Part 3

(note: scroll down to skip to the pictures)

After a month of work, the conversion from stock sequential turbo operation to non-sequential operation was complete. At first, I was running without a boost controller, so I was limited to 7 psi by the spring in the wastegate actuator.

After a couple weeks of rest, Jim helped me install my Apex Super AVC-R boost controller. Now I run .80 bar on "low" (11.6 psi) and .85 bar on "high" (12.2 psi). I can also monitor by injector duty cycle with the Apex unit.

At first I was running with the midpipe, but I was unable to control boost--even with the ported wastegate...there was just too much flow. The car was also a little too loud (although this one fun at times). I put my hi-flow cat back on and the car was a little quieter, less stinky at startup, and best of all, I could control boost perfectly.

Now that my conversion to non-sequential turbo operation is complete, I can give you my thoughts on the subject.

Overall, I love being non-sequential and I wouldn't go back even if I could. The whole system is now, literally, 100 times more simple than the stock system. So much stuff has been removed that you can now see parts of the engine that used to be buried in hoses and other strange devices. With so much new "breathing room" in the engine compartment, almost everything seems to run cooler.

All you have to do is look at my "before" and "after" dyno sheets to see that the power delivery is also much much smoother than the stock system. This is another benefit I really like.

However, you can also look at the dyno sheets and see that there is definitely some low end loss. Lag is definitely more noticeable if you are below 3200 rpms or so.

Although I do miss the low end turbo response of the stock setup, I have modified my driving style so that I cruise around at a slightly higher rpm range than I would with the stock setup. Although this isn't always possible, it's been working out well for me most of the time.

In the end, this was an incredible learning experience for me. I fully understand how the system works now--it's too simple not to understand it. Also, the more I learned about the stock setup (as we were taking more and more stuff out...never to put it back in) the more I hated the stock setup for it's complexity and unreliability. But, maybe I am just bitter because it failed me and my car sat in my garage for a month while we did the conversion. :)

The biggest thing for me is that I am enjoying my car much more now. It's more powerful, accelerates smoother, runs cooler, is more reliable, and the engine compartment looks great. Most of these things probably could have been accomplished without going non-sequential...but I probably never would have done all of the "extras" (ceramic coating, polishing, etc.) if I didn't do the conversion. The added peace-of-mind is also nice.

Extra special deluxe thanks go out to Jim, Justin, and Trev for all of their help. Thanks again guys!

05/29/00 - Update!

For an interesting dyno comparison of Non-Seq vs Seq, check out:

compare.html

turbos back on