I have pretty much replaced EVERYTHING from the transmission back, and have plans to drop in another motor when this one goes, but for now I am going to have fun with my little 305. I am going to be installing a wet nitrous kit. I am curious as to what size shot I should try on the little motor. I don't wanna kill it after the first few shots, but would like to feel some "kick" behind the juice. As I said earlier, plans are to drop in a new motor fairly soon, but I just figured that I would play with what I have now.

 

if the engine is in good shape, with a progressive shot with good tuning and FI you should be able to hit it with 250-275hp without hurting it. With a straight shot I wouldn't try more than 150-175hp...

 

I had a power shot 125 on my 305 and had headers msd duel plane intake and a superchip and it was strong for what it was but I also wouldn't go over 175

 

I put a 100 kit on my 305 but I tuned the fuel jet down a bit. I couldn't get it to hook at the strip but ran 13.3 @ 107. I was going to try 150 with a progressive but like you decided on a new engine instead. It was fun though!

 

I don't understand why progressive is different. Here is why.

N2O solenoid can be pulsed at 5Hz max rate. That is .1sec on .1 sec off.

If the solenoid is on .1 sec which is the smallest on time possible, then at 3000 RPM (3000/60 = 50 rev/sec) then the engine did 5 crank revolutions during .1sec. All 8 cyls will see the complete 250HP shot. Suppose you are doing a PWM so that it is a 125HP shot at this RPM so it is 125/250 = .5 or 50%. That means you spray the engine with 250HP for 5 crank revs then 0HP for 5 crank revs.

Either way, the engine is still seeing 250HP all at once. Convince me that somehow the intake spreads out that 250HP shot to all 10 crank revs.

 

I looked into what NOS claims their solenoids can handle. They say up to 30Hz. That .016 sec on and .016 sec off.

At the 3000 RPM example, then the engine does one rev in .020 seconds. That means the solenoid will be on for almost 1 crank rev so that 4 cyls will get the 250HP shot. Then the next 4 cyls on the next crank rev will get 0HP shot.

Looking at the time for this, I am guessing that because of the fairly matched rate the intake will filter out the shot and spread it out to some amount to all 8 cyls every 2 crank revs. Each complete engine cycle (8 cyls) should be fairly even for the 125HP shot.