well, youll need a very free flowing set of heads, forged pistons with a realy wide ring gap, an ignition booster, something to retard timing, id do it in 2 stages, to do a 250 shot on the cobalt is going to be tricky. i spray 300 through my Z28, the motor was built specificaly for nitrous. you can try it though, make sure there is a video camera presant the 1st time you sparay, i wanna see your blower and head come through the hood

 

I ran a 2-stage 400 shot (150hp off the line 250 in 3rd) and that was on a built smallblock and it really didn't like it... I bent some pushrods (chromoly 1 pc) collasped some lifters and cracked a piston and I only sprayed it 3 times...
I wouldn't go above a 125shot...

 

good thinking. no one thought or mentioned traction. as it is, this car cant seem to hook in first gear much at all. surely not going to spray in 1st, but nonetheless it's gonna be a little much.
since he seems to be building a motor for more power, i highly doubt a 250 shot is going to be terribly successful. and when you run that, you'll have to seriously retard your timing. which means it wont be very streetable at all....if you're gonna drive on the street at all.
150shot max in my opinion.
someone told me on this forum that the ecotec is so great and can handle up to 1200hp, and that GM even has a step by step book on how to get there. So, if thats true, maybe one should consider that route instead of 250shot of nitrous.

best wishes

Rick

 

actually..you can runa dual stage n2o setup...100shot per stage...probally be the safest way due to only letting the engine fill 100 at first first..but when the second silonide fires...hmmm..bad news for the ecotec...lower your compression is step one...totally redo internals...next eaiser with a programmer if one comes out.down your timing a click or two..less detionition in the cyl when on the spray..third i guess prey and hope a rod doesnt shoot threw the firewall and stab you in the chest...200 is probally too big for us. buy different size jets..and gradually up the shot until 200..i mean this is your first time on the bottle. im still scared to hit a 75shot...the only way to explain n2o is like your pressing the throttle down again...on turbo motors you will see a 2-3 psi increase in boost...probally not the same on s/c.you are making that motor take 100 more horses...and if it doesnt like it..the bad news bears are comming to town. but good luck and take into consideration what people on this forum says...some actually know what they are talking about