@buttondoor posted:Be forewarned, I am no EFI expert. I had a similar build done a couple years ago (636 bhp). Dennis Quella had recommended we go with the Sniper 2 Terminator X. But by that point, those were backlogged, and my builder got a FAST EZ instead. Ultimately, we couldn't get it to work well for any length of time once we installed it in the car, it kept fouling O2 sensor and plugs, and the EZ is not laptop adjustable. I know at least one P-car owner using a better FAST model that has worked well, but with more adjustability. I know the Sniper 2 has a generally good reputation now. I also know a member on here who had one installed/tuned by a performance shop, who has had many of the same troubles my system had.
I decided to swap out to a Holley DP chokeless (I'm in NC so that can work) carb custom set up and tuned by Chuck Nuytten out of Rockwall, TX. He is well known for this, he will have you furnish all relevant engine specs and your performance/driving style needs and build accordingly. I have nothing but positive things to say about this carb so far. In my (generously long) phone conversation with Chuck on the front end, as I recall he said my issues were common and that the extremely limited O2 sensor placement option in Panteras can inherently create challenges. My point is, if you were going to spend the money to "upgrade" to a Sniper 2, Chuck is another option, for less cost, easier installation, easier parts availability in a pinch, etc. The only possible drawbacks I see would be some sacrifice of fuel economy, a little attention to the throttle on cold start, and a good mechanic friend of mine says Holley carbs can get sticky with periods of sitting unused.
What kind of intake manifold are you using on your engine? An EFI throttle body system should work good on a Pantera . I know of a couple of Panteras here in Arizona that run very well with them. You are quite possibly pushing the limit of a throttle body system with the horsepower that you are making. I have been using the FAST XFI 2.05 sequential port fuel injection system for 12 years and haven't had any problems with it. I have a CHI 3V single plane air gap intake manifold and the engine is making about 550 horsepower at the flywheel. I have two O2 sensors that are on each exhaust pipes right next to the header collector. One O2 sensor is for the in dash O2 gauge and the other runs the EFI. Although this FAST system is quite old and has not been updated in at least ten years, it performs like a modern fuel injected vehicle. It does have a great deal more tunability than the throttle body systems that I have seen, which could be why I have not had any trouble with it. It also may have helped to have the engine tuned on a dyno by someone that was an expert in EFI systems. I am certainly not and know just enough about EFI to be dangerous!