The following questions have always boggled my mind and I was thinking maybe some of the guru's on here could possibly shed some light or valuable insight on this topic. Why is it possible for an engine to handle a +400hp gain via forced induction whether it be from a turbo or a supercharger, but be limited on how much nitrous it can take? it's not unheard of for a 400hp motor to make over a 1000hp with boost, but you rarely see a 400hp motor that can handle a 600hp shot of nitrous. both methods are essentially adding more oxygen and drastically increasing cylinder pressure so why does FI yield bigger gains? Also another thing...why can you get away with running high compression on a Nitrous setup, but not boost? what makes boost require a low compression ratio?

So lets here it folks

 

curious too

 

Whether its FI or Nitrous, in the end it doesn't matter how it gets there honestly. I am sorry but if you have heard that a 400hp engine can handle 1000hp FI than you are wrong and your engine will blow. Either way you must add more fuel with either setup so that plays a big roll in how much of a shot or how much boost you can run. In the end its how much your bottom end can handle. If your bottom end can handle 1000hp weather it be from Turbo or Nitrous, than you pick the poison. However I will say though that a shot of nitrous without a progressive system can be more lethal than a turbo because it takes time for a turbo to build boost, but nitrous hits right away. Take a look at my two graphs here, first one is of my 700+rwhp camaro running 15 psi of boost. The boost takes a bit to come on therefore is not as stress full on an engine. However the second graph with a 200 shot on the Viper, look at how fast and hard the nitrous hits, especially the torque. that cannot be good longevity wise for any engine.

Turbo Camaro


200 shot Nitrous Viper

 

mu car should be making vaery close to 900rwhp on nitrous!

 

300 whp from 200 shot?

 

Not getting 300whp with a 200 shot, I am getting about 165whp but am getting about 275rwtq. These massive V10's love the juice as far as the torque goes. Some have reported a bit more than 300rwtq with a 200 shot on the Vipers.

 

I just used the 400hp setup as an example. I'm not talking about an LS1 here or any particular engine. Theoretically 14.7psi will double an engine's hp level so a 300hp motor with 14+ psi should make ~600hp, but none of this really has anything to do with the question at hand.

Just so I don't confuse anyone lets say you have fully built bottom end..an FI car will still net bigger gains than a nitrous car and the question is still why? if its the huge tq increase then that's an easy solution...run a progressive or setup multiple stages via RPM, but the outcome will still be the same...FI will still make more power

 

n20 = FI w/o the lag

 

As far as the compression question goes...

Nitrous has 36% oxygen by weight and the atmosphere has 23%. Additionally, nitrous oxide is 50% more dense than air at the same pressure. Thus, a cubic foot of nitrous oxide contains 2.3 times as much oxygen as a cubic foot of air.

Forced induction gets more oxygen into the combustion cycle by cramming a TON more air into the cylinder, nitrous oxide adds more oxygen by adding a small amount of n2o (in relation to FI) into the cylinder. The end result is the same...oxygen + fuel = power. However the nitrous setup doesn't have as much volume of gas (air/oxygen/etc) in the cylinder as FI so the compression can be a little higher.

 

Nitrous is power/torque now. Take a FI car, power increase in direct relation to RPM. Nitrous is power now. The cylinder pressures goes through the roof when hit a large shot of nitrous at one time, hense multi stages and progressive controlls.
The nitrous is also OFFSETTING the air flow going into an engine. you can not pressurize an NA intake no matter how hum nitrous you shoot. So your final out come will be how well does the engine breathe, this will tell you how much nitrous it can inhale and use. This is also why nitrous cars back fire, you can actually stall the in coming air in the intake, allowing the flame from the cylinder to travel into the intake and BOOM.

Boost cars are completely different. The air is getting shoved into the cylinder. BUT it linked to rpm of the engine. You can not take a turbo car and just dump 20psi in it. And if your belt driven and try it you will over spinning the blower supper heating the air, not to mention the load could pull the engine down. To make the boost you have to the air flow to start with (RPM), this is why turbo cars have to increase RPM to get things moving.

Now the compression one is on a nitrous engine back to the air flow of the engine. The a little higher compression allows the engine to work more efficently, as long as you have the octane there. And this is only up to a point, the larger the engine, the larger the shot, the less final compression. Most hi compression nitrous engine are 15 or less to one, where as your NA can over 15-1.
Forced cars are adding more cubic inches so they are increasing the size of the engine. a 408 @15psi is really a 816 inch engine. And the final compression ratio is higher due to the amount of boost pressure getting dumped into the cylinder. Start with too hi of ratio and you will lift the heads right off the engine, or stick a rod throu the piston.

just my thoughts.

 

so for example (and im completey making these numbers up) say you build something say with 8:1 CR fully forged yada yada yada and feed it 25psi of boost and make 1200hp. Could you take the same exact setup and use a progessive controller or multi-stage it, spray a huge shot & make the same amount of power?