Compression and Nitrous

[1viadrft]

I've been looking into nitrous lately... just reading up really. I had this question: Say you had an NA car and wanted to run a crazy 200+ shot of nitrous... theoritically the engine would combust/detonate much like a Turbo/Supercharged engine, right?

So I'm thinking you would have to lower the compression of the engine?

[Polygon]

It would be a good idea.

N2O works by chemically separating the oxygen from the nitrogen. Since there is more oxygen you can add more fuel and thus a bigger boom. Just like with a turbo or super you will be risking detonation the more N2O you run on high compression. If you want to run a 200 shot I would lower the compression to between 8:1 and 9:1 for a street car.

[1viadrft]

How do you think the lower compression would affect an NA though... on a street car application?

[Polygon]

Without the N2O the engine wouldn't be as responsive and you would lose some power.

Just as long as you don't go crazy with the amount you run you shouldn't really need to lower the CR.

[1viadrft]

What's considered crazy?

[slideways...]

depends on the car. i wouldnt spray your vg30de with more than a 100 shot, and thats pushing it on 92 octane IMHO

[1viadrft]

Originally Posted by slideways...

depends on the car. i wouldnt spray your vg30de with more than a 100 shot, and thats pushing it on 92 octane IMHO

We are not talking about a stock VG30DE here... I'm trying to figure out compression #'s for a VG30DE running a huge shot. I'm well aware of what a stock VG can handle... but we are not talking stock. Thanks.



As me and Polygon were discussing... I'm wondering what he would consider a "crazy" shot of nitrous without lowering compression.

[Chiquae07]

317419023874908274980237409172340 shot. that would really blow the welds on the intake.... id say maybe 150 about.

[SaabJohan]

Originally Posted by Chiquae07

317419023874908274980237409172340 shot. that would really blow the welds on the intake.... id say maybe 150 about.

The intake isn't the problem. The problem is peak combustion pressure. If you use a lot of nitrous oxide cylinder pressures would go sky high. Usually it's the piston or con rods that will go first, but even the cylinder head might collapse, so can exhaust valves and lifters. The head gasket might also blow.

More power also means more heat, this can overheat pistons, valves, spark plugs and similar if they aren't modified.

The cooling provided by the nitrous can prevent overheating somewhat, it can also decrease the risk for detonations. But in order to keep temperatures, cylinder pressures and detonations under control a rich fuel mixture combined with ignition retard is usually required. In extreme cases the compression ratio may need to be reduced, an option to that is to use water injection.

[Chiquae07]

this was like from 3 months ago or so. it was kind of a F & F joke. you'll aslo fry the piston rings.

[chevy2808]

also wouldnt hurt to add a n2o cam to help with the engine performance when not using n2o, and to optimize the nitrous when in use. buying a cam would be overkill on a 150 shot though...