I am wondering what is the biggest shot of nitrous that can be used on the 2.0 zetec stock bottom end without blowing anything and being able to use it all the time. Thanks for the help.

What do you mean "all the time"?

You do know that:
1: the bigger the shot, the faster you go through a bottle +
2: the more you use it, the faster you go through a bottle =
3: bottle refills are between 30 and 60 bucks.


You will need to get some king of ignition timing control in order to spray the big big shots. Cold plugs and 100+ octane gas will help too.

Having said that, the biggest shot I've heard of on a focus with stock internals is 150.

Yeah right now I am running a 75 shot with cam gears, underdrive pulley, header, no cat and free flowinf exhaust and a programer. I am just wondering if I can run a 100 shot safely?

there are a few people that have run 100 shots pretty regularly, a few. just get some colder plugs, run good gas, and pull a few degrees of timing on a small shot if you want reliability.

To be TOTALLY reliable, I would recommend no bigger than a 50...A 75 can be safe , just run GOOD fuel and pull some timing with the colder plugs!!