What compression ratio for NOS?f

[Drag_on]

Well, I sucked a valve on Monday so now I get to play. I am going to put an all forged rotating assembly and a nice set of heads (between VT and Patriot right now). I have the common dilema of choosing stage one or two heads and 9.0:1 or 10.5:1. I don't think I'll have the money to do a turbo or supercharger system anytime soon. So NOS is a logic option.

My questions are:

1. What compression works best with NOS? I assume lower just like a blown motor. If lower, will the above built engine be able to handle a 100 shot for quite a while on 10.5:1 compression (I understand this is speculative, but input is always good)?

2. If lower is best, what about lower compression and stage 1 cams?

3. Can this setup hold a 150-175 shot safely (speculative again)? What is the highest shot I should run?

Thanks for the help

p.s. I'm not affraid of reading, so if you know of anygood write-ups then please post them (couldn't find any on this topic).

 

[Justin03GT]

n20 likes high compression, boost likes lower compression...go 10.5 and spray a 225 shot and enjoy

 

[wei462]

I am interested in this as well. I will be going with a 5cc dish with the stock bore on a 00 GT.

 

[FORCED2DV8]

Just like any other power adder, blower ,turbo, lower compression allows you to run more boost or nitrous, a engine can only handle so much compression before she blows, wether thats a static compression ratio or one that changes with a power adder. If your building a motor to run NOS as your power adder the go with slightly lower compression, build the bottom end to with stand the extra HP, and youll have 2 advantages, 1 the lower static compression ratio will not be so hard on the engine, as would a turbo or blower which runs all the time, and 2 the engine will be able to handle the 200 shot of NOS in it, or what ever you decide to spray, You cna also talk to cam manufactures as they design and make cams specifically for a NOS setup.

 

[98blkGTvert]

The static compression level of the motor does not matter with nitrous, to a point. The important thing with nitrous is the amount of timing advance the motor is setup for. Nitrous expands very rapidly in its combustion process. Because of that, less timing advance is needed. This is true for 'small' scale shots of nitrous, ie less than 300hp.

If one is using a large amount of nitrous( over 300hp ) them the overall dynamic compression level can become a problem. Lowering the static compression will help.

On my old C5 setup, I was running a 200hp shot of nitrous on 11.8:1 compression without a problem.

Keith

 

[Torinalth]

VT engines told me that going HC i should look into Nitrous as the best way to add on to NA power.. just as stated above, nitrous reacts very well to compression. going with a wet kit, a forged block with ARP head studs, and a good gasket i was told that a 300 shot would not have any issues. though i was not told it directly, the way he was talking it sounded like a forged block can handle a good deal more then 300. bes to talk to the builders and see what they say.

Torinalth