hey guys im new here i have looked at this site for about a year now about every other day and finaly made a profile so i can ask ? so my question is ive got a mildly built up 305 ho in an 83 z28 i dont realy no much about what is done to the motor but the person i bought it off sed it was rebuilt 35 grand ago and i tranny was done last summer from looking under the hood it is all chromed out and i see that it has two 4 barral edolbrock carburaters and intake on it and hooker headers every thing else is internal and i cant tell what else is done. i am very happy with the power of the car but i have soem extra cash and have made my mind set on getting nos for the car because nuthing would look cooler to me then to see 2 ten gallon tanks in the rear window of nos and for the extra power when i realy want to make a fool out of someone on the road acationaly.
my question is how much of a hit of nos should i get i know ther are all kinds like 100 hp shots, 150 hp shots , 200, 500 and so on wat should i get so i dont blow my motor to smithereens because i want tit to stay reliable.

 

Dual four barrels on a 305? Are you sure it's a 305? First, if you're thinking about nitrous, you should really try to find out what internals you have and what shape their in. Second, unless your 305 is radically modded (you probably would have noticed by now), the prevous owner probably thought it would look cool and just stuck that dual carb setup on, figuring, "two is better than one, right?". This theory would be consistent with the idea that he went to Napa and got all the crome valve covers, ect. he could. Basically if you say that this 305 is mild, then it could probably benefit from a correctly matched single carb setup. Besides, with the dual four barrels, you would need to run two plate systems, or a trick direct port job. My advise, save the dual four barrels for a 600HP 415 and get a single carb setup.

Now, sorry for that departure, but let's get to your question. I'm going to venture a guess that your "mild" 305 is going to have all cast internals, in which case, I wouldn't run N2O until you get some fordged internals. That's my opinion, but plenty of people around here will tell you that you can run a 150HP shot no problem.

In my conservative opinion, I would say you'd be foolish to run N2O on an unknown motor. In my own experience, when you buy a car with a "freshly rebuilt" engine, plan on rebuilding it after about 5000 miles (that's how my experience went). And I'm sure the tranny rebuild is no cherry either, so if I were you, I'd swap the carbs and cruise it around for a while to give yourself a chance to work out the bugs. But that's just me

 

i just got done talking to the guy and to my surprise he said that he has all the reseets {sorry i cant spell} to the motor for every thing that they put into the motor and from what it sounded liek over the phone the parts seemed to be pretty high quality ounce i get the list i will put it up on the sight.
the car is actualy pretty nice it has t tops it has the 92 i-roc ground affects on it and its lowered and is painted black with white racing stipes and has all americam racing rims on it, and it also has a hooker cat back exaust with hooker headers. there is no rust at all on this car and i actualy personaly know the person that revuilt the tranny so i know it was done right. ill be shure to get back to u guys on teh engine specs when i get them

 

Well hell! that sounds pretty good, but did you ask him why he went with the dual carbs? How big are they? (cfm) Why did he rebuild the 305 instead of going with a bigger motor? At any rate, if the motor has good quality fordged internals, then you could probably go with a 200+HP shot. Good luck.

P.S.: What are the drivetrain components like; how old? what type? (transmission, rear end) If the engine is strong enough, that will be your limiting factor in how much power you can make.

 

I think it would probably be a pretty good idea to figure out what your compression ratio is. If it is the same as stock (9.5:1) you may be fine, but that still seems a bit high to me, and i would recommend against nitrous if its any higher than that, because you could seriously damage the engine.

I don't know too much about nitrous, but just check into your compression ratio before you install an N2O system.