View Single Post
Dynamohum Dynamohum is offline
Registered User
 
Dynamohum's Avatar
 
Join Date: Jan 2008
Location: Midland Ontario Canada
Posts: 173
Garage
Quote:
Originally Posted by midlife View Post
I am interested in the blow through vs suck through argument, because I am planning on turboing my 3.2.

Here is my thoughts on this:

The AFM measures flow, not mass flow. It does not know the pressure of the air. On a blow through, say you were at 1 bar of boost, there would be roughly twice as much air going through for the same AFM reading. This is OK because the rising rate regulator is also increasing fuel flow proportionally to boost. I would think you would need a different chip for a suck through.

Arguments against suck through:

On stock NA engines, I believe the AFM maxes out at high RPM. With a suck through boosted application the increase air flow would cause the AFM to max out at even lower RPM's, and you will lose all part throttle air/fuel ratio controll. You would need an AFM with a greater range.

Also a turbocharger is more sensative to pressure drop on the suction side.

Just my .02
Hi, Seems like there are quite a few of us at various stages performing this 3.2 Turbo conversion, contemplating Draw VS Blow. Perhaps if we post this as a new thread we might get more feedback?

Re: the AFM here is a link from Proto on pros & cons of some different systems
http://www.geocities.com/protomotive/psvsaf.htm

Personally, I would like to do away with the Moto AFM and go to something better and perhaps this will come later, but for now lets get this working at its best.
__________________
Thank You for your time, Paul. We do because we can.
87 911 3.2 (Turbo conversion, build in progress, Thermal Barrier Coatings, High Pressure Dry film coatings) Modified heads, boat-tailed case, ARP hardware, OBX Header, 930 clutch disk, G50 Trans
89 5.0 Mustang convertible (For Sale)
Old 01-27-2009, 02:12 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #38 (permalink)