Hi
I would not put more than 100hp, you would need forged pistons for more. Only the 85 had forged pistons standard, however the trans and diff wont last with 300hp of NOS. Don't forget the aluminum half shafts, they can twist like licorice.
A high mile engine will turn into little pieces very quickly with 300hp NOS, a small block is fairly bulletproof in standard form only.

I would run a direct port NOS setup, drill and tap the runners close to the injectors. Yes you want to loose the standard advance curve.

Good luck ...... if she blows build an engine for NOS, forged steel crank forged rods and forged pistons with a 4 bolt block.

 

I think there are a lot more things to consider especially if we are talking about an otherwise stock Corvette.

First, the cast pistons can't take it for long. Even if you got everything thing else right it wouldn't be long before you melt one or break a ring land. At the very least you need to pull the pistons and run a crap load of ring gap. So much that off-nitrous sealing would suffer and just driving it to the strip might be a challenge.

Second, the stock exhaust system won't be able to move that much air. You're talking about more than double the horsepower, all that exhaust has to go somewhere. It would back up into the combustion chamber and the motor would fall on it's face.

Third, I don't know what trans you have hypothetically but the auto would probably grenade pretty quickly and I guarantee a stock clutch in a manual would let all of it's smoke out trying to put that much power through it.

Fourth, traction is going to be a factor. Street tires would be a joke. Drag radials might have a chance but slicks would be pretty close to a must in this case. If you do have an auto that d36 rear would eat it's self IF the power actually made it that far through the drive train lol.

Then you need to consider things like delivery, you can't just put a couple of nozzles at the throttle body and expect the mixture to be consistent in each bore. You would need a direct port system of you won't have a chance. Timing of course, you covered that. Spark plugs, you need a non projetor tip and probably 4-5 ranges colder. Factory head gasket may not be able to hold the cylinder pressure, studded or not.

That's all I can think of off the top of my head, I'm sure there is more to it. Basically you need a lot of supporting mods to have a chance of making a single pass and like I said in the beginning, the odds are against you. If the motor makes one pass consider yourself very lucky.

Otherwise if you just want to make a cool video blowing up an l98 that's the way to do it. Good luck.

 

Oh, I forgot about half shafts and spindles, good call. Get steel half shafts and keep replacement spindles on hand.

 

..... Sigh ! ... naysayers ! ... Go For It ! ... these guys already told you the worst that could happen ... take plenty of pics if/when it does .....

 

You really cannot throw a 300 HP shot at a stock 225 HP engine. It will not be able to get enough oxygen (or air) in the chamber to make an additional 300 HP. The rule of thumb is you can usually hope to make a maximum of 35% more power then the base power of the engine. So a 225 HP base engine HP could support 105 HP N2O shot. That being said some people have claimed up t 50% increase in power. The maximum additional power available is 58% but in the real world that is not obtainable. N2O contains 58% more oxygen by volume then air if you could get in N2O only with the required amount of fuel you could make roughly 58% more power. If you put in too much N2O it will start to actually get blown back into the intake faster then the engine can take it in and in short order you will have an intake manifold explosion that will ruin your engines day.

So 300 HP on a engine that only has the ability to make 225 HP with its stock intake, heads, cam, and exhaust, even with good lower end parts will not work. The intake will load up and cause a backfire.