Hello everyone. I am about to step up and buy the injectors I should have purchased in the first place. Several weeks ago there was a post that had a discussion about injectors and the perils of using an injector that is too large (or small). Up until that time I was leaning toward 120lb injectors for my twin turbo 451. The thought being it would give me some room to grow. Now I am wondering if the 96lb would be a better choice. Does anyone have any experience or suggestions? The car is now, and will remain a street car. It is using sequential EFI (Autronic SM2). The system is running at 45psi currently, and while I am not against turning up the pressure, I really would rather not. I also have no intention of going over 15 pounds of boost. Thanks for the input everyone.

Injector sizing is strictly a function of HP level and fuel type. 96 lb/hr injectors would handle 950 HP on gasoline. A street 451 on 2 bar would be right in the ball park.

Too small an injector is a no-no.
Too large an injector can cause idle control issues, but the high flow low-Z injectors are pretty good as long as the driver is a peak-and-hold type.

The 96's would be my choice. Just watch the duty cycle under full power conditions. As long as you stay under 85% you're good to go.

I had done the calculations earlier and knew that the 96's would be sufficient. However the 120's are pretty much the same cost and would leave me with injector to spare in case I decided to turn up the boost or build a larger motor in the future. I am confident the 120's would idle acceptably well. That said, the discussion I recall was talking about the operation at light load/part throttle. Would the 120's be on the ragged edge under those conditions? The 96's would have a surplus capacity with the current setup, just not as much. For what it is worth I really don't have any plans for higher boost or a bigger motor right now. I just have a tendency to try and overbuild everything. I guess I know I am guilty of the usual hot rodder mentality, if a little is good, then more is better, and too much is never enough. The 120's meet that need. That said, I don't need any extra capacity that reduces the daily operational effectiveness.

Used 96er's should hold their value pretty well if you would need to upgrade in the future, a point to consider.

I was running 120s in the hot rod. It idles around 0.9 ms on time and can see on times as low as .85 ms under cruise. That's barely cracking the injector open.
It can be done but be prepared for very low pulse widths for cruising under vacuum.

I have never been very good as a salesman, so the thought of selling the injectors later is not pleasant (I already have to get rid of the 52lber's that are coming out). However, you have a very valid point that it could be done.
The short pw's during idle and cruise seem like an issue. While I think my ECU could pull it off (the injectors too). It sounds like a better fit to go with the 96's.
Thanks for the advice and insight everyone!

I get the first ride!

You've got it! When I finally get this thing tuned I'll be finding any reason to drive it!