<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Robert Herndon:
I can't comment on Pontiacs with EFI, but I can on BMW and Porsche.
The shop I work for has taken a number of the BMW 'M' 4-Valve Six-Cylinders and converted them to Weber carburetors.
The difference in power output is unreal. The EFI doesn't even come close.
There is a reduction in smoothness at part throttle and the engine is obviously more tempermental when cold, but HP and TQ are higher than even the motors with upgraded throttle bodies, injectors and ECU upgrades.
Years ago, I also recall the Rochester Fuel Injected Corvette (375 HP) produced much less HP and TQ on the dyno than the carbureted (365 HP) version of the venerable 327.
Obviously, EFI is all-around the best choice for driveability and economy, but I see some serious limits to its airflow potential in most applications.
Additionally, when speaking of EFI on a Pontiac, most systems I have seen will not allow use of stock A/C.
Why not just adapt the Tune Port Assembly from a SBC for use on the Pontiac? The port arrangement is similar and I am sure the angularity of the cylinder deck could be compensated for with a properly fabricated intake manifold.
I personally, would like to see a 4V TBI Unit that would bolt on in place of the stock Q-Jet and allow use of stock A/C and Alternator Brackets.
Just curious...Robert
"If I had better junk in my garage, I know I could go faster."<HR></BLOCKQUOTE>
Robert, those Webbers will give excellent torque & hp, but fuel economy will be cut almost in half (big problem for a manufacturer). They're temperamental to get right as well. I have a little background on them from Nissan Z inline 6 (L6) usage. I don't know much about the BMW electronics, but often times the early efi systems were very limited and not able to reprogram until later systems. If it has the flapper door air-flow-meter(AFM), that's a restriction as well. For instance the 81-83 turbo Zs (limited to about 250hp) are modified by reprogramming a later year ECU, replacing the flapper-door (AFM) with an MAF from a Ford Cobra to get above 300-350 hp.
A/C can be adapted like anything else. If you use system with timing control via a crank trigger, A/C or electric fans can wack it out thru interference, but you just have to shield the trigger and you should be fine--unless I'm not thinking of something here.
The sbc system adapted to a 400+cid low rpm torque developing Pontiac? Don't know about that one. You'd have to upgrade several items, so you might as well have a custom built system.
Having bungs put in an aluminum intake isn't a big deal and would be worth the benefits. I would have no problem using salvaged injectors from another application as long as they were refreshed by a pro service like Marsh Injector Service (I think that's the name).
Doug
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[This message was edited by PonchoV8]
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[This message was edited by PonchoV8 on December 14, 2003 at 01:14 PM.]