MrWizard wrote:
I'm confused by what you said
Timing and cam, I understand
But isn't Turbo the boost?
If there was no turbo, there would be no boost
Boost is the increased intake pressure applied by the turbo
Boost is a measure of resistance to the airflow thru the head, intake and exhaust flown effect it. Plenty of things effect airflow, not just the turbo.
A cam will allow more air with less resistance, so boost drops but power potential goes up (fuel makes power not boost). A different cam can raise or lower the measured boost, but hp output remains unchanged.
Timing has an effect on boost as well. If timing is advanced boost will go down, because there is a lower volume if exhaust..but power will generally go up. The opposite is true with retarding timing, there is more exhaust flow so more boost but generally less power.
Even a small turbo change can effect boost but not power, for the same reason as the cam. Last summer we put a different, slightly larger, turbine on my dad's stock turbo. The tuning and compressor stayed the same. Boost went done across the board, and so did EGTs. Airflow!
The head is also a factor. A 12v head can have same motor build as a 24v head, assume all parts are equal but the head, and the 12v head will show more boost but the airflow is probably similar.
You can also get into tuning on have HPCR trucks to effect boost. With the same timing I can make more or less boost based on the rail pressure. It goes back to the exhaust flow.
So a little length, my apologies, but the point is that boost is not a measure of hp. My stock turbo/cam would make over 35 psi of boost at about 350 rwhp. My current turbo/cam makes 30-31 psi at 415rwhp, and the same or lower EGTs. EGTs take airflow, so I have more airflow with less boost.
