If we go back about 15-20 years... My 355 SVO powered Cougar. Bona-fide 550 HP.

Never did make any power at the low end (of course not, it was not cammed/flowed for it) so on a whim I decided to add a plate Nitrous system.

Oh my God, what glee. My question is this: Nitrous made a huge difference at the low end but was barely detectable when activated at 5500 and above.

I have argued with a couple of friends of mine; they claim Nitrous is only good at the top end, my experience differs. I believe that the reason it was so ineffectual at higher RPM's in my application was because my VE at that engine speed was about maxed out. On the other hand at low RPMs the Nirtous enabled a much greater cyclinder density, making the huge diference.

What do you think?

 

I will offer a guess.

At the RPM limits of your engine, you've approached the maximum of your cam/flow and therefore adding nitrious didn't offer an obvious increase in power. Since your engine was lacking in the low-end (relatively speaking of course), you would notice the increase in power because of the nitrous.

I think most people would disagree because they are installing NOS on stock engines, or maybe slightly improved near-stock engines - which generally don't have a useful upper RPM range anyway because of the lack of flow, lack of strong factory parts, suitable ignition, etc.

But, that's just a guess.

 

I agree. Nitrous adds (say a 150 shot) instantly, unlike a procharger where boost increases as rpm increases so you really feel it at lower rpm. All engines are basicaly just an air pump and HP curves nose over at some rpm based on VE as you stated. I read an article in Hot Rod where they sprayed more and more Nitrous on an engine. They managed to blow it up but didn't make any more HP after a point.