I am in the process of recieving a Weiand 142 roots blower for my 305 tbi. I plan on running about 5-6 psi on the stock internal L03, and on top of that, running a small shot of nitrous for an intercooling effect, but how much nitrous can it handle?

 

ttt

 

are you planning a dry shot for the cooling effect?

 

Wet, will be using the nos 05153 kit

 

wet, i would worry about the tranny, etc. the cyl pressure from the blower and nitrous is what you need to be carefull of for the engine.

 

I'm not too concerned about the tranny, as I have run over 500 hp through similar setups before and all was fine. I am aware of the cylinder pressures, but I just don't know how much it can take. Weiand says to keep the effective compression ratio below 12.1:1 for the blower which would be around 5 or 6 psi for the L03, but I'm not sure how much nitrous will effect things on top of that. Basically I know a lot about how both work and what I should be aware of, but I'm in the dark when you combine the 2 power adders together. Could I run 5 psi boost and a 120 shot on top of that or would I have to run a much smaller shot?

 

Probably have to run a smaller one like a 75 shot.

 

Can anyone explain why please?

 

because you said you were only going for a "cooling" effect, keeping it fueled sufficiently will be the harder part.

a 305 has a smaller bore therefore the psi per square inch of surface area on the top of the piston with the boost plus the 75 shot might be similar to that say for an example of a 200 shot. not that you will get 200 more hp, but the cylinder pressure will be quite intense for your cast pistons

 

Just because I said I was going for a cooling effect doesn't mean I don't want to squeeze as much nitrous into the motor as possible without blowing it up. If I can run a 100 shot or a 120 shot as opposed to a 50 or 75, I want to. I don't want to hold back just because someone says so, but because there is a way to prove I will otherwise. Is there some type of formula to determine cylinder pressure, or how much cylinder pressure is too much? Maybe a chart of some sort? I'm going to push the line with this thing and hopefully run some #'s unheard of for this engine before.

 

I suggest if you are shooting for an un-achieved number that you start on the dyno or at the track blower only and then creep up on it til it dies. There is no real math and charts for boost and nitrous because even using just one or the other creates alot of variables, stack the two together and it would take a supercomputer to model the kind of mushroom cloud you are heading for.

 

I would run the minimum tune, then read look pieces of your motor in the plugs. Go real rich on the nitrous as boost also increases the need for fuel.