Re: Is this a good deal?

[JTesta1966@aol.com]

In a message dated 5/23/00 2:15:25 AM Eastern Daylight Time, bob@tecmark.com 
writes:

<< Reason for this is that I came across a "Air Research" aftermarket TBI
 system for about $300 - includes the controller (set with buttons on front
 and small LCD display, no laptop connection), BIG MAF sensor, *900* CFM
 throttle body (4 barrel) with 4, 85lb/hr injectors which shoot in from the
 side,  >>

Too big is bad in NA engines as they rely on the vacuum for airflow. a 
injected car might be less suseptible, but still need a certin airflow to 
keep the air/fuel flowing in the right direction. A TB too large will 
possibly create positive pressure in the manifold (depending on your RPM 
range) and hinder actual airflow into the cylinders. This is more important 
on carbed engines where you need the pressure differential to make gasoline 
flow out of the carb, but I'd haveta think it'd make a difference in an 
injected engine as well. maybe you can use a throttle stop to limit the 
available CFM until the motor is built to require the 900cfm you have 
available. An olds engine wont rev that high, their not known for their 
bottom ends....I build a few pretty healthy Rocket 350's and did a decent 
amount of research on what works with them. Assuming you have a healthy 403, 
which wont see much duty above 6500RPM you'd want more like a 700-750CFM TB 
to assure proper airflow. maybe you could fabricate a stop at a little more 
than 3/4 throttle, and scale the TPS to make THAT point WOT. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Testa                                                         TType86 on 
#BuickGN
ASE Master Technician                                     
buick.fiendish.net:6667
L1 Advanced Engine Performance                          NJ Lic MV Inspector
jtesta1966@aol.com                                  NJ Lic Emission Repair 
Tech
http://members.aol.com/jtesta1966/buick.htm
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